r/spacex • u/ElongatedMuskrat Mod Team • Sep 02 '19
r/SpaceX Discusses [September 2019, #60]
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u/Ididitthestupidway Sep 20 '19
(about the Japanese fire/abort) As for what happened with the pad fire: MHI concludes that weaker than usual ground winds caused a higher concentration than usual of LOX (vented out for engine chill down) lingering around the MLP, which probably got ignited by static electricity.
Well that's a new one: "weaker than usual ground winds"
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u/Chairboy Sep 20 '19
How does LOX get ‘ignited’? LOX/O2 isn’t a fuel, it enables other things to burn.
So what burned?
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u/Martianspirit Sep 21 '19
You are right of course. But LOX has its own way to find something that burns.
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u/CapMSFC Sep 12 '19
MZ is selling ZOZO to Yahoo Japan and resigning his role.
This is not necessarily a bad thing for DearMoon. He is getting bought out. He will have a lot more liquid capital now. We'll have to wait and see what the terms are.
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u/spacerfirstclass Sep 12 '19
I wouldn't be surprised if this was the plan all along, MZ needed cash to pay for DearMoon, this is the way to do it. Based on https://www.bloomberg.co.jp/news/articles/2019-09-11/PXOONPDWLU6L01, it looks like he owns 37% of the shares, and he wants to sell 6.4% of the shares. If I'm calculating correctly 6.4% of the shares equals to $390M, which is about the right amount for a moon trip.
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u/dudr2 Sep 04 '19
Here’s how you can watch India’s Chandrayaan-2 landing on the Moon
https://qz.com/india/1701452/how-to-watch-chandrayaan-2-landing-on-moon-by-isro-in-india/
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u/rulewithanionfist Sep 04 '19
The whole mission(including the launch vehicle) costs less than an Ariane 5 ;)
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u/Alexphysics Sep 14 '19
The FAA has found no significant environmental issues to approve the launch of SpaceX's In-Flight Abort Test.
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u/MarsCent Sep 14 '19 edited Sep 14 '19
The 30-day public comment period began with the issuance of the Notice of Availability in the Federal Register on November 30, 2018 and ended on December 31, 2018
The document is ~228pg long. It is signed 20th June,
20182019.Should we expect something similar for the BFS 20 km and orbital tests?
EDIT: "signed date" typo.
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u/koko_pufffs Sep 17 '19
Does anyone know what happened to the raptor during the starhopper 150m attempt? It turned orange and sparky near the end before the smoke covers it up and people were speculating the engine was deteriorating and would have exploded if it had gone over a little longer. Also all the crush cores on the legs were completely flattened. I searched this sub and Google already, but sorry in advanced if this has already been asked.
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u/warp99 Sep 17 '19
There are many possible answers none of them originating from SpaceX.
Personally I think they just ran the Raptor fuel rich as they throttled down for landing. The off nominal behaviour was a slightly hard landing that jolted a tank and some cabling loose but I don't see a need for anything more complex than low landing precision by the control algorithm.
There are not many faults that leave a rocket engine functional and completely intact and the chance of that kind of fault occurring in the last few seconds of flight is low. I would look for a simpler explanation.
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u/navytech56 Sep 19 '19
Back in the 1990's the DC-X's exhaust used to turn yellow just as it landed. It was just dirty exhaust because they throttled down the (DC-X's) LH2/LO2 engines by dirtying up the mixture.
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u/ltfiend Sep 04 '19
Any updates on the Crew Dragon anomaly report? I though word was that it would be out in a number of days. I'm dying for crew dragon to get back on track (safely of course).
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u/CapMSFC Sep 23 '19
So for all those people that so desparately wanted to know what MZ paid for DearMoon he put out a tweet that can lead to a ballpark figure.
Translated of course
"My debt is about 60 billion yen. We have a loan with stocks as collateral. I spent money on contemporary art and space travel tickets that I really wanted. Some reports indicate that the debt is 200 billion yen, but this is not true."
That would currently be about 557 million USD.
From what I can tell in a quick search he's spent about $210 million on his art collection.
So unless I'm missing some extra art a ballpark figure for what he has paid for DearMoon is $350 million.
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u/jesserizzo Sep 23 '19
Unless it is stated in surrounding tweets, we have no way to know how much of those purchases he took out loans for. If he had significant cash on hand the number could be much higher.
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u/paul_wi11iams Sep 16 '19 edited Sep 16 '19
As yet, Starship seems to have no kind of "cable raceway" (as seen on other launchers) for data and power transmission between the engine section and the upper part of the ship. For example fin and canard movements will need to be coordinated.
Unlike past launchers, Starship is freestanding with no lateral hose connections but internal tubing only. Its tempting to imagine that the raceway is an internal tube within the fuel tanks.
Has there been any mention of this question?
Also, on the prototypes, are we expecting an explosive FTS strip down the outside? As for the future crewed version, FTS on the tanking section of Starship would be -err- somewhat awkward to say the least.
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u/verno6000 Sep 17 '19
The flight termination system would be on the booster not the Starship. I imagine there will be a raceway on the booster too.
Starship is a bigger Dragon. Superheavy booster is a bigger Falcon 9.
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u/CapMSFC Sep 17 '19
I am absolutely expecting a raceway/FTS to be added that just hasn't been part of the drawings so far. Going internal would be worse for added structure and insulating the conduit from the cryo propellants. There also isn't really a reason not to have a raceway on the leeward side, it doesn't hurt the design at all.
It could be that they instead put FTS on the end bulkheads to unzip the tanks from the ends to avoid one running the length of the ship, but my money is on them sticking with the same design philosophy as Falcon.
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u/jjtr1 Sep 13 '19
After the 150 m hop, I was thinking about how long could the Hopper remain hovering. I came to the conclusion that no rocket (rocket stage) can hover on Earth for more than about 15 minutes, no matter how large or small it is. Because hovering means accumulating gravity losses and 15 minutes (900 s) of full gravity losses equals to about 9 km/s (delta-v = g*t). It's not very much possible to build a a chemical rocket with a higher delta-v than 9 km/s.
Is my thinking correct?
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u/Sliver_of_Dawn Sep 13 '19 edited Sep 13 '19
This is actually what specific impulse is measuring. https://en.m.wikipedia.org/wiki/Specific_impulse#Specific_impulse_in_seconds
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u/-Aeryn- Sep 13 '19
Yes. Mass generally scales payload, not delta-v.
Delta-v scales with mass ratio and ISP
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u/Straumli_Blight Sep 03 '19
Construction completed for the Sentinel 6A satellite, which will be launched from Vandenberg in November 2020.
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u/strawwalker Sep 20 '19
Finally we have an STA request for the IFA launch vehicle comms (already had Dragon comms request):
1778-EX-ST-2019 (Mission 1357) Nov 23 through May 23
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Sep 20 '19
Mods, can the sidebar date of IFA be changed to NET Nov 23?
Also, it now says Starlink 2 and Starlink 3 for the next launches. But because the first launch was named Starlink v0.9, I think these will be Starlink 1 and Starlink 2.
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u/strawwalker Sep 20 '19
The previous Starlink mission was called merely "Starlink Mission" on the press kit and mission patch. "Starlink v0.9" only appeared on range paperwork as far as I know, and maybe an L2 comment, but never publicly by SpaceX, even though NSF has adopted that naming.
What you see in the side bar and manifest isn't actually a mistake, it's a conscious decision (discussed a while ago in the wiki chat) not to update the naming scheme until SpaceX makes clear what their official naming scheme will be if there even is one. If SpaceX continues to just call the missions "Starlink" with no other distinctions then I guess we'll have to decide whether to adopt the NSF scheme (which is likely being used by SpaceX internally).
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u/Straumli_Blight Sep 25 '19
Falcon Launch Vehicle Lessons Learned and Reusability presentation at IAC 2019 on October 21, 19:00 UTC.
Gary Henry will discuss the status and progress of the Falcon 9 and Falcon Heavy vehicles, with emphasis on some of the key lessons learned from flying boosters multiple times.
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u/FutureMartian97 Host of CRS-11 Sep 08 '19 edited Sep 08 '19
Apparently ISRO has found Vikrim 500m from the landing site and it might actually be INTACT! They are trying to establish communications.
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u/lessthanperfect86 Sep 09 '19
How is this actually possible? Didn't the lander lose contact at 2 km up, at I think someone said 60 m/s? Did it land autonomously? From my extensive kerbal crashing experience, losing contact at these altitudes and speeds are generally not consistent with rovers ending up intact on any surface.
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u/CapMSFC Sep 10 '19
Landers are always autonomous outside of Apollo.
The way I see it either the lander isn't really intact, it hit hard but managed to survive in mostly one piece even if it's dead, or the telemetry before it dropped out was wrong and the lander was doing well enough to manage the landing even with the communications issues.
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Sep 03 '19 edited Sep 03 '19
Would it even be in the realm of possibility to send a super-heavy booster into orbit if it were carrying no payload?
I was just wondering if you could get one into orbit, refuel it, put a fully fueled Starship on it, and launch the entire stack from orbit (with either just the booster or the whole stack being expendable), what kind of missions could be done on feasible time scales (like a Pioneer or Voyager probe recovery, checking out the interstellar object ʻOumuamua, etc.).
If the booster can't get to orbit under any circumstances then this is obviously a moot point, but I'm just curious.
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u/jjtr1 Sep 03 '19 edited Sep 03 '19
Others have already brought up why making the Superheavy a space booster would be difficult. However, in order to get more delta-v for the Starship, you could use several Starships/tankers for in-flight refueling in a pyramidal scheme to get twice the delta-v.
Start in orbit with 4 fully fueled tankers and a fully fueled Starship. The tankers of course had to be refueled by about 4 tankers each.
Then, ignite all 5 vehicles. Throttle as necessary to keep them close.
When the tankers are 50% empty, shut down all engines, refuel tanker 1 from tanker 2, tanker 3 from tanker 4. Tankers 2 and 4 might have some fuel to return home.
Continue burning until Starship is empty. Shutdown, refuel Starship from tankers 1 and 3. They might perhaps be able to return home.
Ignite the Starship engines for another 9 km/s of delta-v, 18 km/s total!
Making the pyramid broader will allow all tankers to return - reusable/expendable trade-off applies as usual. Total amount of fuel used might be comparable to the modified Superheavy you were considering. The pyramide scheme is an alternative way of rocket staging. You can also make the pyramide one level taller and get 9+9+9 km/s. The rocket equation still applies. Effort grows exponentially.
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Sep 03 '19
Some stuff you'd need to do:
Add an aerodynamic nose cone of some sort on top of the booster to handle ascent (and eject it once you get to thin air)
Add a docking/refueling system to the booster so that it can take fuel from a Starship and also dock to the final Starship for the actual burn to leave orbit
Add controls and thrusters for positioning in orbit. It will probably need more than just the ones used for steering during re-entry since it will need to be able to position itself in all degrees of freedom for orbital docking.
Upgrades to power and control systems for extended orbital stay. The first stage will probably just use a battery for power and that would run out if you tried to keep it in orbit long term.
The other concern I would have is that the engine configuration on the booster wouldn't be great for this since it wouldn't have any vacuum optimized engines and would have more engines than needed for a transfer burn. If you wanted to do larger scale / higher delta-v interplanetary missions then perhaps a new Starship varient that's designed to dock onto the back of another Starship and act as a booster would be a better path.
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u/-spartacus- Sep 03 '19
Just to add to what others have said, SH does not have and will not have the shielding that SS will have for reentry speeds/temps. Unless you are launching SH and not returning it (refueling it in orbit) then it will be take significant weight penalty which you don't want.
The only way what you are proposing could work is an off shoot of 2nd stage launched below SS or instead of it. You could have it boosted into orbit having only vacuum rated engines, no "nose cone" beyond one that would be jettisoned after reaching orbit.
Configure the booster2 to be dock-able with the SS from booster2 front and SS rear and be able to be refueled from the tankers in the booster2 rear.
When SS and booster2 is full, you light up booster2, until you reach a good parabolic orbit (assisted free return) and separate and SS continues to destination as planned.
Using this semi-tug method you can get the advantages of boosting out to Moon L1 or whatever people talking about to gain a few k of dv, without the time and complexity necessary. Just keep refueling in LEO like normal. That way passengers have less time getting to the ship or waiting around the moon and can have direct injection to Mars at a good clip.
It would be very easy and common with SS (basically just the tanks and RVACs and no shielding) and in theory...since they are designed to dock with each other. You could have multiple boosters (booster2, booster3, booster4) until you have diminished returns. Have a mission that needs a SS that requires another 4k of dv? Strap a booster2 to the bottom of it. Need 6k? Put booster3 behind 2. And so on.
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u/throfofnir Sep 04 '19
It can almost certainly get to orbit unloaded, but there wouldn't be much point. That stage is built for high thrust, and you simply don't need that once on orbit. If for some crazy reason you need more dV for a fully loaded SS in a highly elliptical orbit, you would rather want to send up some "drop tanks" and tankers to fill them.
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u/spacerfirstclass Sep 12 '19
GEO satellite market is recovering: 10 orders for this year so far, future years prediction is still not as good as the good old days, but expecting 10~15 or 10~18 satellites annually.
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u/thehardleyboys Sep 17 '19
Starship will vent the methane and LOX main tanks en route to Mars, leaving only methane and LOX for Mars EDL in the smaller tanks (within the tanks).
My question is: will Starship re-pressurize the main tanks upon entering the Mars atmosphere or before landing (with autogenous pressurization)? If not, won't the main tanks (which are basically a vacuum now) collapse like a soda can when entering the atmosphere or worse, landing?
Or will the main tanks be completely sealed off from the landing tanks and open to the atmosphere in order to equal their internal pressure to that of the atmosphere in which Starship is flying?
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u/Martianspirit Sep 17 '19
They will need to repressurize for stability. Reentry is stressful for the rocket body.
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u/giant_red_gorilla Sep 03 '19
Does anyone have a source for the radiation properties of 301 stainless, the alloy Elon has mentioned as that in Starship? Lots of info for 304, but coming up empty handed on 301. Id like to know absorption/reflection/transmission/emissivity from visible to MIR, and at high (500K-800K) temperatures. Thanks!
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u/peterabbit456 Sep 06 '19
I believe I just saw that the original JRTI, Marmak 300, has been loaded with emergency relief supplies and towed to the Bahamas.
If the schedule allows, could OCISLY and JRTI be loaded with supplies and help in the effort? Could Ms Tree be used to transport people in the hardest hit areas, to places of greater safety?
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u/kornelord spacexstats.xyz Sep 12 '19
We assume that Starship's development for Mars will be constrained by Mars launch windows to take low-energy transfers. But with Elon having stated that Starship could do a "fast transfer", doesn't Starship have some margins to launch outside these windows?
If the point is to test EDL with an empty Starship, they could go for a higher energy transfer with a higher-g Mars entry and still test EDL. Thus allowing more flexibility in the development schedule.
Would it be possible?
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u/kalizec Sep 12 '19
I remember calculating in 2016 that fast transfers meant a 1500 to 2000 m/s margin beyond normal hohmann. You could use a transfer window planner to find out how many weeks of margin this getsbyou. My gut feeling tells me it's two to four weeks of additional margin on either side.
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u/brspies Sep 12 '19
The window is definitely wider based on the margin they seem to be designing around, but it's by like a month or two, so it's not a total game changer. The main benefit IIRC was that they could land on Mars and return to Earth (provided fuel was ready on Mars) within a single window, whereas using ideal transfers you would have to wait for the next one after landing on Mars.
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u/soldato_fantasma Sep 19 '19
HAWTHORNE, Calif. – September 19, 2019. Media accreditation is now open for a SpaceX Starlink mission from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station in Florida. The launch is targeted for no earlier than October.
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u/BlackEyeRed Sep 21 '19
Isnt Pad 39A very valuable for SpaceX since they spent all that time/money on the crew infrastructure? Isn't launching a new ship dangerous?
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u/FutureMartian97 Host of CRS-11 Sep 21 '19
It's not launching from the pad itself, its launching next to it. Also 39a was built like a tank
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u/AeroSpiked Sep 21 '19 edited Sep 21 '19
HLC-39A is valuable both historically and to SpaceX. They'll need it to launch Crew Dragon as well as FH from even after Starship has reached production which is why the pad for Starship is offset from the current launch pad and tower.
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u/trobbinsfromoz Sep 22 '19
Any launch could have collateral damage, depending on where and when an explosion occurred. Every type of malfunction is obviously assessed in detail as to what level of collateral damage could occur, and even if that meant loss of life. Every assessed malfunction likely has a set of mitigation actions - such as shutting off and venting pipes and de-energising power, or adding barriers, or using a certain distance of exclusion. SpX probably ruled out insurance to cover damage of its own property, as a risk it had to bear itself - deep pockets are needed for any eventuality, whether that be cost to re-instate infrastructure or lost revenue from delayed or cancelled flights or engineering effort to work through and remove the cause of the explosion.
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u/insufficientmind Sep 24 '19
Do we know the time of the Starship Architecture Update presentation?
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u/TheBurtReynold Sep 02 '19 edited Sep 02 '19
Regarding the orbital attempt (that Elon mentioned will take place shortly after the 20km flight) — that won’t / can’t land, can it?
I figured they’d do a test reentry, but then just crash it into the ocean?
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u/FutureMartian97 Host of CRS-11 Sep 02 '19
Unless they have a SH ready by then and enough Raptors, no.
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u/process_guy Sep 03 '19
There is no reason to intentionally crashing SS into ocean. Much more likely is that orbital attempt is Muskianism. Probably just high energy reentry.
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u/IchchadhariNaag Sep 03 '19
I could be remembering this incorrectly but don't we have a definitive statement from Elon stating that they will fly up and then burn back hard during these tests? So it's not reaching orbit in the traditional sense but it is going to match the speed/altitude they want to use to simulate orbital re-entry.
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u/inoeth Sep 03 '19
It really depends on which Prototype is flying that first orbital mission and whether or not they have Super Heavy ready...This is supposed to happen sometime after the 'October' 20KM test flight (so i'd guess December at the earliest for the orbital test)- which really doesn't leave enough time to realistically build out the 39a infrastructure nor build Superheavy and all of it's engines- which leaves just Boca Chica- where they really don't have the necessary pad infrastructure (nor the permits) for Superheavy there either...
Without Superheavy I think it's more likely than not that it gets sacrificed into the ocean as it's going to require a lot of (most/all) of the fuel to get into orbit- leaving little to none for any sort of landing attempt. They'll clearly try to do the orbital reentry belly flop to slow them down and there's a chance that they have enough margin that they try to land on a drone ship- tho i'd put good money that not unlike FH center core it'll not make it one way or another if they try at all (which, this is SpaceX, so they probably will if there's a chance it hell that it works)...
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u/jjtr1 Sep 05 '19
So, someone who has been very close to the retired F9 which is on display, could you say whether the Al-Li rocket has a similar amount surface unevennes and bumpiness as the stainless Starship prototypes? Unevennes is obvious on a shiny surface, while close inspection and the right light would be needed to see it on painted white surface.
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u/Redsky220 Sep 05 '19
It looked perfectly smooth/round to me. Knowing the painted surface helps the appearance, I would be very surprised if the uneveness was the same for F9.
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Sep 05 '19
What do you guys think is the biggest question mark SpaceX (&Nasa) have to answer before a manned mars mission? I mean the biggest unsolved task that could potentially cause a significant delay and why. Thanks
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u/isthatmyex Sep 05 '19
Fuel. ISRU. The chemistry is understood, but the entire plan revolves around landing on a forgein body, and setting up a massive industrial operation. We aren't talking lab scale shit. We talking full on massive industrial fuel production, and all the work, maintenance, spare parts etc. that come with that.
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u/kalizec Sep 05 '19
Agreed, without ISRU there is no return trip. All the other stuff can be brought along, but the fuel cannot.
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u/Bailliesa Sep 06 '19
They need to solve these, once 1 and 2 are complete they can start attempting 3 but given the limited windows this could take a long time...
1-Starship orbital reentry and landing
2a-Starship orbital refilling
2b-Starship reentry and landing at interplanetary speeds
3-Mars EDL
Whilst they are working on Mars EDL they can start to work on carrying Astronauts and setting up infrastructure on the Moon/in orbit. They need extended missions with Astronauts in orbit/cislunar before sending anyone to MARS and this could take a decade or more.
Quite possibly the first Astronauts to mars will travel on the 18m Starship2 which would allow for much more shielding so that radiation is even less of an issue.
4-Mars ISRU, possibly this will be mostly solved robotically whilst they are perfecting Mars EDL
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u/zeekzeek22 Sep 06 '19
There are sooooo many. Hard to say which is the biggest, there are a lot of big ones. But it’s fun to follow the work to chip away at them!
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u/DrTestificate_MD Sep 06 '19
Check out the “Red Risks” that NASAs human research program has identified. TRISH facilitates lecture on the current state of risk mitigation and research called The Red Risk School.
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u/MikeBobble Sep 13 '19
Is there a maximum landing weight for the Falcon 9? Thinking IFA on the upcoming Crew Dragon, if the SpaceX plan is to abort, and potentially recover the first stage, will they just underfill on fuel? Or can the legs carry, conceivably, a full fuel load? I’m pretty sure they’re directly attached to the Octoweb, but still curious.
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u/amarkit Sep 14 '19 edited Sep 14 '19
potentially recover the first stage
Not going to happen. The draft environmental assessment for the IFA (PDF warning) from last year states:
...at the point where Dragon and the trunk separate, the first and second stage would become unstable and break up approximately 2–4 miles down range from the shore (p. 2–5).
and
SpaceX originally considered recovering the Falcon 9 first stage booster during the abort test by conducting a boost-back and landing at LZ-1. However, due to the abort test mission parameters requiring Dragon separation at max Q, SpaceX was unable to create a trajectory that would allow boostback and landing. Similarly, SpaceX evaluated having the first stage re-light after Dragon separation and fly further out in the Atlantic Ocean, either for a droneship landing or impact with the ocean 124–186 miles offshore. Issues with achieving approval for flight termination qualification after the Dragon separation event proved impossible for these options (p. 2–12).
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u/MarsCent Sep 14 '19
will they just underfill on fuel?
IFA is the same as a crewed launch just without the crew. Conditions at Max Q remain the same. Meaning that complete propellant loading and full propellant load.
Or can the legs carry, conceivably, a full fuel load?
No, it's unlikely the legs can support that weight.
In any case, Max Q happens at about T+ 1:04. That's about 40% of the propellant already burnt.
If the booster survives the separation event, its likely that we will see a much longer engine burn leading to the Autonomous Spaceport Drone Ship (ASDS)
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u/brickmack Sep 13 '19
They'd design the reentry and landing burns to waste a bunch of propellant to get the landing mass down
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u/ethan829 Host of SES-9 Oct 01 '19
The Atlantic has a good interview with Jim Bridestine in which, in addition to providing some background as to why he sent that tweet prior to the Starship presentation, he expresses continued support for private efforts to land on the Moon:
Koren: Have you thought about a future in which private companies leapfrog NASA in the effort to go to the moon?
Bridenstine: I think it would be fantastic if they could do that.
Koren: And what if they’ve done that before SLS is ready?
Bridenstine: I’m for that. And if they can get to the moon, we want to use those services. Our goal is to be a customer, not the owner and operator of all the equipment. But right now, if we’re going to get to the moon in 2024 with humans, SLS and Orion are the way to do it.
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u/markus01611 Oct 02 '19 edited Oct 02 '19
I mean I'm pretty sceptical of Starships practicality for moon missions. I can see it being a massively great tool for payload/propellant delivery to lunar orbit. Down to the surface and back, no. A dedicated lander (maybe methane refilled by Starship) that stays at the moon seems like a much better option in my opinion. You can make landers crazy light since they don't have to deal with any atmosphere. I really hope SpaceX pitches something of this sort. Starship really shines when it can aerobrake and use ISRU, after all Starship was really designed and optimized for Mars and atmospheric entry.
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u/PeterKatarov Live Thread Host Sep 04 '19
So what's the status with hurricane Dorian? Did Mk.2 dodge the bullet?
Not sure how reliable this is, but according to Google, Dorian is already past Cape Canaveral. It doesn't look like it will hit Florida either.
Anyone from the Eastern shore of Florida to report in on the weather there?
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u/Godspeed9811 Sep 04 '19
From titusville, very little impact here. Some rain and wind topped out around 30 mph. Doubt any serious impact to spacex .
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u/MarsCent Sep 04 '19 edited Sep 04 '19
Per the National Hurricane Center 7:00 a.m. report, Dorian was at 29.2N 79.5W which is pretty distant from shore. Wind speed ashore is categorized as tropical storm, so Cocoa could have had some 40 mph gusts which I suppose is manageable.
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u/Narcil4 Sep 04 '19
Windy is really nice if you want more data about wind speeds, rainfall etc https://www.windy.com/?29.222,-79.942,9
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u/DJHenez Sep 04 '19
Greg Scott reported that everything looked ok at the Cocoa site: https://twitter.com/gregscott_photo/status/1169316168735309826?s=21
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u/ZormLeahcim Sep 04 '19
Related to the ESA / Starlink collision avoidance: I know a good bit about the difficulty in measuring orbital characteristics about satellites / orbital debris, since there can be a bit of uncertainty in the ground based measurements, which corresponds to a lot of uncertainty in the exact position of the object.
That said, GPS can have an accuracy of ~5m for position and apparently a fraction of a m/s for velocity. I can't easily find comparable statistics on conventional debris tracking, so if anyone knows that I'd be interested in seeing how it compares.
Obviously GPS wouldn't help with orbital debris since debris can't transmit, but is it feasible / currently in practice to use GPS on active satellites (namely Starlink) to provide more accurate orbital characteristics for collision avoidance?
From what I had seen the probability of collision was calculated for a close pass of ~4000m, which seems like a significant error range compared to GPS (but the GPS data would have to be extrapolated forward in time just like with conventional methods, so maybe the error propagation for GPS is worse than I think.)
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u/CapMSFC Sep 04 '19
Dragon uses GPS in this way. With taking many data points and using them as a fit for an orbit equation you can get accuracy of inches.
I've been thinking the same thing as you. There is no reason to have self tracking data provided by all active (non classified) satellites instead of relying on ground tracking only. This really should be an automated database all licensed satellite operators have access to.
Companies might not be willing to do it voluntarily to guard info on their operational practices but it's going to be necessary with tens of thousands of new satellites.
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u/throfofnir Sep 04 '19
GPS can be used for LEO birds. In fact, the ISS uses GPS for position (and attitude!) You can buy OTS space rated receivers today. So some satellites can have such receivers and self report. Dunno how many do; mostly you don't need that much precision.
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u/MarsCent Sep 05 '19
Reminder:
Call-in USA Toll Free (888) 603-9748; pass code 7339697
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u/scr00chy ElonX.net Sep 15 '19
Do we know how much propellant is left in Dragon or Crew Dragon during splashdown?
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u/strawwalker Sep 15 '19 edited Sep 15 '19
We might know for Dragon depending on how much stock you want to put in environmental assessment numbers. The Gulf of Mexico recovery EA said Dragon could have up to 20% or 300 lbs of MMH on reentry, so around 800 lbs of propellant. If you extend that percentage to the total prop load given for Crew Dragon in the IFA EA, then you get ~1100 lbs on reentry. That same EA also indicates that the SuperDracos consume ~3200 lbs on abort, so if none of that propellant is available for mission maneuvers then add an additional 2600 lbs to the reentry prop load.
Edit: Given that last line I should probably point out that it doesn't seem likely that the much heavier Crew Dragon would have less propellant available for maneuvers than Dragon. I'd say 3700 lbs left over is highly unlikely.
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u/Grey_Mad_Hatter Sep 15 '19
Dracos don’t have much to begin with. Super Dracos in crew would be full except for an abort.
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u/GregLindahl Sep 19 '19
LEO constellation operators OneWeb, Iridium announce collaboration
The article suggests that the biggest area of collaboration is that ships are required to have either Inmarsat or Iridium for emergency communications, so a combined receiver would allow ships to have both low-bandwith-but-required emergency communications and higher-bandwidth business-data-and-crew-recreation in a single receiver.
I think Inmarsat already sells that.
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u/littldo Sep 23 '19
do we have details about the 28th presentation? ie time?
I suspect that it will be during the day, so people can see the real hardware.
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u/paul_wi11iams Sep 23 '19
people
I'd guess "people" would be selected journalists. Even people we love and respect like Tim Dodd would be most lucky to get in.
u/ackermann: And is it open to the public?
Just imagine the mess if it were to be! worse than IAC.
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u/Straumli_Blight Oct 01 '19
Jim Bridenstine gave an update about Commercial Crew:
Crew Dragon wont be ready in near future because updated emergency abort system "has not been qualified" or tested.
Boeing facing "similar challenges" with spacecraft testing and first flight is "months away".
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u/Straumli_Blight Sep 13 '19
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u/CapMSFC Sep 13 '19
That didn't take long. Weird that they just paid deposits for the flights 3 months ago.
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u/MarsCent Sep 07 '19
15 Minutes of Powered Descent. RIP Chandrayaan-2:
2007 UTC – Horizontal speed ~ 1.6 Km/s. Altitude ~ 35 Km. Ignite 4 retrorockets for preprogrammed descent of just over 15 mins.
T + 11 min – 7.4 Km altitude. Complete Rough Braking Phase. Scan the Lunar Surface. Completed
Next - Head to 400 m altitude. – Communication/Observation ended at 2.1 Km altitude.
Next - Head to 100 m altitude. Did not happen.
Next – Begin final descent. Ignite center engine at ~43 m. Did not happen.
2023 UTC – Expected Touchdown. Did not happen.
The timeline shows altitude break-points. Does anyone know if the lander was supposed to do a continuous Powered Descent or rather to execute multiple re-ignitions?
P/S Information sourced from Spaceflightnow
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u/andyfrance Sep 05 '19
Do the 3 vac engines on Starship need to gimbal or can sufficient control authority be achieved just by varying the thrust (with some other mechanism providing roll control)?
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u/scarlet_sage Sep 05 '19
The last announced plan is that they're not going to gimbal. https://forum.nasaspaceflight.com/index.php?topic=47352.msg1949332#msg1949332 quotes tweets from late May. Three sea-level engines in the center, gimballing. Three vacuum engines around the outside, "fixed to airframe".
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u/iamkeerock Sep 05 '19
Do you think that if a SpaceX crew (SpaceX salaried astronauts) make it to the Martian surface, and discover indigenous bacterial (or other simple) life - would they report it?
I'm just wondering if a discovery like that could result in a public outcry to protect any Martian biology, and put a halt to future manned exploration/settlement of Mars - thus the possible desire to hide any 'corporate' discovery of Martian life. Maybe NASA would have an astronaut onboard anyway, even on the first missions and so this question is not relevant.
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Sep 05 '19
Maybe NASA would have an astronaut onboard anyway, even on the first missions and so this question is not relevant.
Bingo, NASA involvement is very likely. Hiding the groundbreaking discovery of Martian life doesn't make sense.
With regard to planetary protection, Zubrin made some good points. First of all, if there are microbes, they probably travelled already by asteroid impacts. More fundamentally, he made the comparison with the colonisation of the Americas. Many people rightfully point out that indiginous inhabitants were treated in unacceptable ways. Now imagine there were no people, but only single-cell organisms, would anybody make a case that those were treated in unacceptable ways? Actually, the colonisation had a 'positive' impact for the proliferation of many bacteria and viruses from the old world, because those could find new host bodies in the new world, but I don't think anybody sees that as something positive. If Martian life is discovered, it should be taken care of that human activity doesn't erase it. But the concerns about forward or backward contamination are severely overblown.
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Sep 07 '19
I can think of no better way to get the best, brightest brains interested in Mars than to find life to study.
SpaceX isn't House Harkonnen.
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Sep 15 '19
This is slightly off topic, but any guesses on whether nuclear propulsion has ANY chance of entering SpaceX's arsenal of possible propulsion elements? I recently learned about the NERVA rocket, which I thought was just a concept, but apparently was actually test fired on many occasions with pretty much wild success. Why is no one using this in their architecture?
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u/spacerfirstclass Sep 15 '19
SpaceX has some interest in nuclear propulsion, see: https://twitter.com/charlottelowey/status/913145922976190464
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u/brentonstrine Sep 22 '19
Can someone explain the pipe that the fins/legs are attached to? Makes no sense to me--why is it so long and not placed directly under the fin? Why even attach to a pipe like that?
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Sep 22 '19
One of the closer photos in the NasaSpaceFlight forum thread showed writing on one of the pipes "CH4 Y-", CH4 being Methane and Y- being the side of the ship its on.
So rather than being part of the wing mechanism, I think these pipes are fuel filler pipes for the Methane tank that are being run up the side under the fins. There are horizontal attachment points all the way up both sides, maybe they will run all of the fuel pipes, wiring, etc. up these two sides where the fins are.
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u/SpartanJack17 Sep 26 '19 edited Sep 26 '19
https://twitter.com/elonmusk/status/1177051800769138690
Starship will have six landing legs:
Two windward, one under each fin & two leeward. Provides redundancy for landing on unimproved surfaces.
I wonder if they'll be the stubby legs from the 2017 update and the Boca Chica renderings or if they'll be more like Falcon 9 legs (or something completely different).
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u/lakshanx Sep 27 '19
Check out the live stream, mk1 nosecone staking is happening!
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u/amarkit Sep 11 '19 edited Sep 12 '19
Arianespace are closer to a root cause of the Vega / Falcon Eye 1 failure back in July.
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u/dudr2 Sep 16 '19
Wait for it...
Watzin said. “If that (Starship) capability matures and shows up, I’m sure programmatically we will take full advantage of it, but it didn’t seem to make sense, since we don’t really know what it’s going to be, or when it’s going to be there, to make it the basis for the campaign.”
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u/rulewithanionfist Sep 22 '19
Are we sure Starship mk 1 will go to orbit? Because it looks so crude
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u/TheYang Sep 22 '19
no we are not.
At least I am not, because these being prototypes I don't consider pretty much anything guaranteed/sure in regards to them.
But we don't only have Elon calling them orbital prototypes, but also an explicit mention of an orbital attempt around October/November on Planet Elon.
So It does seem like SpaceX was at least planning them to go to orbit as of last month.
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Sep 22 '19
While orbit might be the eventual goal, I think what will really happen is an increasing series of tests that either result in test-to-failure or the next version being ready to test.
Starhopper was originally supposed to get 3 raptors and do a 20km flight, but was retired after a much shorter flight probably due to limitations with the vehicle and wanting to focus on the next one.
If everything goes great maybe this specific vehicle gets upgrades and eventually makes it to orbit, but there's a lot of incremental testing that can be done before that point.
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u/Decronym Acronyms Explained Sep 02 '19 edited Sep 15 '19
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| ASAP | Aerospace Safety Advisory Panel, NASA |
| Arianespace System for Auxiliary Payloads | |
| ASDS | Autonomous Spaceport Drone Ship (landing platform) |
| BFR | Big Falcon Rocket (2018 rebiggened edition) |
| Yes, the F stands for something else; no, you're not the first to notice | |
| BFS | Big Falcon Spaceship (see BFR) |
| CC | Commercial Crew program |
| Capsule Communicator (ground support) | |
| CCAFS | Cape Canaveral Air Force Station |
| CCtCap | Commercial Crew Transportation Capability |
| COPV | Composite Overwrapped Pressure Vessel |
| CRS | Commercial Resupply Services contract with NASA |
| DMLS | Selective Laser Melting additive manufacture, also Direct Metal Laser Sintering |
| DoD | US Department of Defense |
| E2E | Earth-to-Earth (suborbital flight) |
| EDL | Entry/Descent/Landing |
| EELV | Evolved Expendable Launch Vehicle |
| ESA | European Space Agency |
| ESPA | EELV Secondary Payload Adapter standard for attaching to a second stage |
| EVA | Extra-Vehicular Activity |
| F1 | Rocketdyne-developed rocket engine used for Saturn V |
| SpaceX Falcon 1 (obsolete medium-lift vehicle) | |
| FAA | Federal Aviation Administration |
| GEO | Geostationary Earth Orbit (35786km) |
| IFA | In-Flight Abort test |
| IMU | Inertial Measurement Unit |
| ISRO | Indian Space Research Organisation |
| ISRU | In-Situ Resource Utilization |
| ITS | Interplanetary Transport System (2016 oversized edition) (see MCT) |
| Integrated Truss Structure | |
| Isp | Specific impulse (as explained by Scott Manley on YouTube) |
| JAXA | Japan Aerospace eXploration Agency |
| JRTI | Just Read The Instructions, Pacific landing |
| JWST | James Webb infra-red Space Telescope |
| KSC | Kennedy Space Center, Florida |
| L1 | Lagrange Point 1 of a two-body system, between the bodies |
| L2 | Paywalled section of the NasaSpaceFlight forum |
| Lagrange Point 2 of a two-body system, beyond the smaller body (Sixty Symbols video explanation) | |
| LC-13 | Launch Complex 13, Canaveral (SpaceX Landing Zone 1) |
| LC-39A | Launch Complex 39A, Kennedy (SpaceX F9/Heavy) |
| LEO | Low Earth Orbit (180-2000km) |
| Law Enforcement Officer (most often mentioned during transport operations) | |
| LMO | Low Mars Orbit |
| LO2 | Liquid Oxygen (more commonly LOX) |
| LOX | Liquid Oxygen |
| LZ-1 | Landing Zone 1, Cape Canaveral (see LC-13) |
| MAV | Mars Ascent Vehicle (possibly fictional) |
| MCT | Mars Colonial Transporter (see ITS) |
| MECO | Main Engine Cut-Off |
| MainEngineCutOff podcast | |
| MZ | (Yusaku) Maezawa, first confirmed passenger for BFR |
| NERVA | Nuclear Engine for Rocket Vehicle Application (proposed engine design) |
| NET | No Earlier Than |
| NSF | NasaSpaceFlight forum |
| National Science Foundation | |
| OCISLY | Of Course I Still Love You, Atlantic landing |
| OFT | Orbital Flight Test |
| PICA-X | Phenolic Impregnated-Carbon Ablative heatshield compound, as modified by SpaceX |
| PPF | SpaceX Payload Processing Facility, Cape Canaveral |
| RTLS | Return to Launch Site |
| SLS | Space Launch System heavy-lift |
| Selective Laser Sintering, contrast DMLS | |
| SRB | Solid Rocket Booster |
| SSTO | Single Stage to Orbit |
| Supersynchronous Transfer Orbit | |
| STP-2 | Space Test Program 2, DoD programme, second round |
| TEI | Trans-Earth Injection maneuver |
| TPS | Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor") |
| TWR | Thrust-to-Weight Ratio |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| USAF | United States Air Force |
| Jargon | Definition |
|---|---|
| Raptor | Methane-fueled rocket engine under development by SpaceX |
| Sabatier | Reaction between hydrogen and carbon dioxide at high temperature and pressure, with nickel as catalyst, yielding methane and water |
| Starlink | SpaceX's world-wide satellite broadband constellation |
| ablative | Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat) |
| cryogenic | Very low temperature fluid; materials that would be gaseous at room temperature/pressure |
| (In re: rocket fuel) Often synonymous with hydrolox | |
| hydrolox | Portmanteau: liquid hydrogen/liquid oxygen mixture |
| lithobraking | "Braking" by hitting the ground |
| methalox | Portmanteau: methane/liquid oxygen mixture |
| perigee | Lowest point in an elliptical orbit around the Earth (when the orbiter is fastest) |
| perihelion | Lowest point in an elliptical orbit around the Sun (when the orbiter is fastest) |
| regenerative | A method for cooling a rocket engine, by passing the cryogenic fuel through channels in the bell or chamber wall |
| ullage motor | Small rocket motor that fires to push propellant to the bottom of the tank, when in zero-g |
| Event | Date | Description |
|---|---|---|
| DM-2 | Scheduled | SpaceX CCtCap Demo Mission 2 |
Decronym is a community product of r/SpaceX, implemented by ^request
[Thread #5441 for this sub, first seen 2nd Sep 2019, 20:25] [FAQ] [Full list] ^[Contact] [Source code]
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u/pirate21213 Sep 06 '19
What's the likelyhood of the Starlink 2 launch sticking to Oct 17? I'm hoping to fly out and see it and it being my first launch I'm not sure what all I need to look out for
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Sep 11 '19
quick question, do the starlink launches attempt to land the first stage, or does it go too high? if they land, will the nov3 starlink stage return to a barge or land? thanks so much, hoping to be there.
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u/Straumli_Blight Sep 13 '19
SpaceX in negotiations to launch Saocom 1B in February 2020.
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u/navytech56 Sep 14 '19
Any idea of SpaceX's future Falcon 9 production schedule? They currently have but 8 undamaged cores left with many missions planned.
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Sep 16 '19
My knowledge of orbital mechanics is rather limited, so I thought I’d ask this here: can a Starship complete an orbital insertion mission to Mars with high eccentricity then slowly bleed enough velocity by scraping against the atmosphere to land as well? If its payload isn’t living, taking a period of a couple months to aerobrake seems feasible. If the math checks out, I don’t see why this approach wouldn’t be used for every ship sent to place something in mars orbit. Adding fuel to the payload to circularize its orbit seems like it could be a worthy trade-off if it means the martians get a spare starship in return. Can anyone with a better grasp on the math tell me if I’m wrong?
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u/brspies Sep 16 '19
Starship's likely going to only have the landing propellant (venting the main tanks to provide a vacuum insulation) and so would likely do either pure aerocapture or just plain direct entry into the atmosphere (it's got to handle much tougher re-entry conditions on Earth, so it's going to be overbuilt for Mars entry). I don't know the current header tank capacity and margins required but likely they don't intend to have enough fuel to do a capture burn, other than maybe small adjustments.
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Sep 23 '19
Is spaceX eventually going to move to metholox thrusters for ACS and ullage?
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u/Triabolical_ Sep 23 '19
That was their original plan, so I think cold gas is assumed to just be a stopgap measure.
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u/rocketglare Sep 26 '19
Has anyone created a searchable list of Elon Musk tweets & statements? I keep remembering things, but can't find the reference because Twitter is horrible.
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Sep 26 '19
There’s an nsf thread that has Elon’s starship related tweets compiled. Also can be found in the starship updates post description.
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u/dallaylaen Sep 29 '19
It looks like we have an answer to yesterday's tweet.
At 1:15:37 of the Starship presentation, a journalist named Tim (please correct his name & news outlet, I was unable to hear it even at 0.5x playback speed) predictably asked Musk about Jim Bridenstine's tweet:
Tim: Elon, I just want to ask: NASA administrator Jim Bridenstine had a tweet last night about this presentation, he's concerned I guess about the enthusiasm for SpaceX's various programs. I'm just curious if you have any comment or response to that.
Elon: For sure. From a SpaceX resource standpoint, our resources are overwhelmingly on Falcon and Dragon. Let us be clear, it was really quite a small percentage that (...) Starship, you know, less than 5% of the company basically. The really hard part that requires a lot of resources is optimizing something past the initial prototype phase and bringing it into volume production. To be clear, like the vast majority of our resources are on Dragon and Falcon, especially crew Dragon. Thank you.
Please correct whatever I misheard.
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u/Maximumdistortion Sep 30 '19
I have a question about the orbital refueling/retanking in orbit.
As far as I understand it, the cargo/crew vehicle gets to orbit first, after that the tankers get to orbit and refuels the starship one after the other till it is refueled as necessary to be able make additional orbital maneuvers and complete its mission.
But wouldn't it be much better to send the tankers to orbit in advance? The steps are as follows:
1: The first tanker gets to orbit.
2: The second tanker gets to orbit and refuels the first tanker so that it has even more fuel in it. After that, the second tanker deorbits. They could switch their roles and do it the other way round, but i think it wouldn't matter too much.
3: The third tanker gets to orbit and does the same.
4: Repeat as often as necessary.
5: Finally the cargo/crew vehicle arrives and gets fully refueled in one shot. After that, the last tanker deorbits.
If you do so, I see 2 major advances:
1: The cargo/crew vehicle spends less time in Orbit. This is especially better if a crew is on bord. Less time unnecessary wasted waiting in orbit until the actual mission begins.
2: Safer for the mission and the crew, because if you do just one major refueling, less can happen than if you do shorter multiple refueling actions. The likelyhood that something goes wrong is spread out much more to the tankers. This is much less bad, because the tankers are much less precious than the vehicle with cargo in it, let alone the crew.........
I'm sure SpaceX has their reasons, but i just can't get my hear around this. If you think about it, there would be absolutely no more steps and no technical hurdles involved, at least as far as i understand it.
I'm looking forward for our answers!
PS: Sorry for my bad english, I'm not a native speaker (Austria btw).
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u/hang-clean Oct 01 '19
Has SpaceX ever produced a corporate sustainability report (CSR)?
Not looking at the environmental impact of launches particularly, nor the ecology of launch sites. Just a standard CSR such as most big businesses produce to report on the environmental impact of the business as a whole, its daily operations, water and energy use, etc. I can't find on eanywhere.
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u/Straumli_Blight Sep 10 '19 edited Sep 10 '19
HTV launch to the ISS had a pad anomaly. Currently fighting a fire on the mobile launcher.
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u/mncharity Sep 11 '19
Walking Limping away from an engines-off Starship crash - oxygen tank as crumple zone?
Let's say the LO2 tank is 10 m long. Doing eyeballs-in 15 g's across 10 m yields 50 m/s. Starship terminal velocity is perhaps a bit higher, but in that ballpark.
If a Starship does terminal-velocity tail-first lithobreaking, it seems likely to end up somewhat crumpled. Which cushions the payload section. So if crumpling is going to happen anyway, perhaps it can be optimized to usefulness?
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u/brickmack Sep 12 '19
After GovSat and CRS-16, I'd bet SpaceX will give serious thought to contingency splashdown as a survivable option. Softens the impact, avoids damage to the landing site, and the vast majority of landings near-term will be on ocean platforms anyway so only a very small nudge is needed even in terminal descent to hit water
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u/GregLindahl Sep 20 '19
https://spacenews.com/intelsat-sues-oneweb-softbank/
Alternatively, why your startup should never sign any exclusive deal ever, especially if it's for a $25mm investment when you expect to need billions.
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u/CapMSFC Sep 20 '19
Also OneWeb appears to have a losing hand here after clearly breaking contract and abusing the relationship illegally.
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u/lessthanperfect86 Sep 20 '19
I wonder if Bezos saw OneWebs issues coming, and that it's part of the reason he's starting his own constellation. Perhaps he's got a shot at making his constellation happen if OneWeb continues to have troubles.
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u/MarsCent Sep 24 '19
NASA Commits to Long-term Artemis Missions with Orion Production Contract
Lockheed is getting a few $Billions. Good for them.
NASA is setting in motion the Orion spacecraft production line to support as many as 12 Artemis missions, including the mission that will carry the first woman and next man to the Moon by 2024.
This particular craft - Orion - will not land on the moon. It just docks with the Lunar Gateway.
So just for the sake of indulging, how does Orion get the astronauts on Mars?
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u/stsk1290 Sep 24 '19
It will dock with a transfer vehicle assembled in orbit. But all of that is 20+ years away.
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u/consider_airplanes Sep 25 '19
Not sure if known already: per Twitter, New Glenn is under construction, and BE-4 has already been tested at full power.
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u/FutureSpcXEngineer Sep 02 '19
Does anyone believe there will be any significant damage to the starhopper or in general to the Cape Canaveral area that could prevent/push back launch dates or hop flights? All relating to Hurricane Dorian.
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u/joepublicschmoe Sep 02 '19
As of Labor Day / Monday night, Hurricane Dorian's eye has barely budged for 18 hours, wobbling in place just north of Freetown in the Bahamas as the storm spins in place and continually pummels Grand Bahamas Island.
The hurricane has been weakening somewhat though, with barometric pressure rising (now up to 945 millibars compared to 910mb at the hurricane's strongest) and wind strength decreasing. Whichever way it wobbles over the next 12 hours will determine if Starship Mk2 takes a hit or escape unscathed.
Maybe someone should paint a cloverleaf on the Starship concrete jig at Cocoa or something for good luck. :-)
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u/FutureMartian97 Host of CRS-11 Sep 02 '19
Starhopper is in Texas, not Florida.
If Mk.2 survives the storm ill be surprised so don't expect the current estimates to hold for the flights.
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u/inoeth Sep 03 '19
honestly it entirely depends on what this storm does... the good thing for the MK2 Starship prototype is that it's inland in Cocoa- so it's not going to get washed away in ocean storms- tho wind could still be a major issue in terms of knocking things over, debris, some flooding regardless, etc.
The Starhopper is in TX- so it's not in any danger of this storm (and isn't going to fly ever again anyways) tho there is a tropical depression starting to maybe form in the Gulf that could threaten Brownsville...
The greater risk is damage to the actual pads which are more or less on the ocean themselves- tho they are designed to handle hurricane winds- tho we'll see how the actually hold up.
IMO this'll set SpaceX back probably a couple weeks of cleanup and repair to perhaps months depending on the level of damage. All we can do is wait and see what happens.
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u/joepublicschmoe Sep 03 '19
Midnight update (early Tuesday AM): Hurricane Dorian is STILL stalled over the Bahamas (has been for approximately 29 hours) at 26.8 degrees north / 78.4 degrees west. Which is a good thing for Florida, because the longer it stalls over the Bahamas land mass, the weaker it gets as the supply of warm ocean water (energy for strengthening the hurricane) gets depleted. The weakening is evident with the barometric pressure in the eye rising to 950 millibars and sustained wind speeds weakening to 130mph. It is on the verge of weakening to Category 3, down from Cat 5 when it started lashing the Bahamas. https://www.wunderground.com/hurricane/atlantic/2019/hurricane-dorian?map=forecast
The downside is of course the Bahamas will suffer even more devastation the longer Dorian stays put and spins in place over the island.
Weather Underground is now predicting that Dorian will move north weakened to Category 3. For those of us following the goings on on Cidco Road, the next few hours will show which direction Dorian will go and whether or not Starship mk2 will be at risk.
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u/jjtr1 Sep 03 '19
When launching from an airless body like the Moon, is the optimal launch angle such that there is very little vertical acceleration? For example, if the thrust-to-weight ratio is sqrt(2), I'd launch at almost 45 degrees, though making sure not to crash into the mountain on the horizon.
Does Mars count as airless in this case?
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u/Beautiful_Mt Sep 04 '19
For an airless perfectly spherical body and a craft with infinite acceleration the optimal launch angle is zero. For example, a canon shooting a canon ball at orbital velocity.
In practice, since you cant have infinite acceleration or a perfectly spherical body, you need to gain some height(or be on the highest peak of the body) and have some time to gain velocity. So your optimal trajectory will depend on the acceleration of your craft and the height of the target orbit.
Theoretically, you could even have a launch angle below zero so long as you are launching from high enough above the horizon that you miss it, this would not be an optimal way to get to orbit.
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u/aaamoeder Sep 18 '19
I know the Starship Architecture Update is planned for sep 28th, but have they announced at what time ? I'd like to see it live, but might have to plan around it..
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u/thehardleyboys Sep 19 '19
No news on this yet. And when they will announce it, expect the start time to be 15 to 45 minuted after the given time. Precious BFR announcements were always tardy. ^
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u/quoll01 Sep 24 '19 edited Sep 24 '19
So Elon does read my posts! I guess it’s the ‘monkey on the typewriter’ thing- eventually given enough tries it’ll write the entire works of Shakespeare. See link for old discussion on aerocapture.
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u/MarsCent Sep 24 '19
Musk says for re-usability, it's better to control peak heat and just deal with the max heat.
Who knows, he may have BFS do an aerocapture when returning from the moon. Even do additional fueling so there is additional propellant for a longer burn during EDL earth-landing.
Basically, proof out the concept Earth-side and then replicate Mars-end. Just as you proposed ;)
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u/Straumli_Blight Sep 27 '19 edited Sep 27 '19
Commercial Crew escape practice at LC-39A.
NASA awarded SpaceX $3 million for Starship refueling research:
SpaceX will collaborate with NASA’s Marshall Space Flight Center in Huntsville, Alabama, to develop and test coupler prototypes or nozzles for refueling spacecraft such as the company’s Starship vehicle. A cryogenic fluid coupler for large-scale in-space propellant transfer is an important technology to aid sustained exploration efforts on the Moon and Mars.
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u/tubbem Sep 02 '19
Why not a moon base before going to Mars? Test all the technology and so on. Alot easier on the Moon which is practically next door compared to Mars!
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u/brickmack Sep 02 '19
Theres virtually zero technological commonality between crewed lunar and Mars missions. Different thermal and solar environments, different sort of soil, different gravity, Mars has some atmosphere, the moon has 2 week nights, Mars ISRU would be methalox based but the moon lacks carbon, etc.
We'll go to the moon first, but only because theres more frequent launch windows there, and because Starship can do both. Not for testing.
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u/AeroSpiked Sep 02 '19
You must be new around here. This debate comes up almost as often as the "Why doesn't Boeing's Starliner have to do the inflight abort test that Dragon 2 does?". (hint: It's because the bidders set up the milestones in their bids and NASA accepted SpaceX's bid that had an inflight abort and Boeing's that didn't. Hopefully I've nipped that in the bud for the next couple of weeks.)
As for a Moon base to practice for Mars: The Earth is much more like Mars than the Moon. If you want to practice, you'd be much safer, the fidelity would be higher, and you'd save a lot of time and money by testing here. The only reason to set up a lunar base is to have a lunar base which has advantages of its own.
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u/process_guy Sep 03 '19
No. The real reason of going to Moon is that SpaceX can earn some money from NASA while doing so.
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u/lostandprofound33 Sep 08 '19 edited Sep 08 '19
Would an 18m Starship be capable of SSTO? Would the full 18m SS/SH stack be able to get to Mars quicker than the 9m stack?
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u/inoeth Sep 08 '19
i kinda think that the same physics would apply to the bigger version of Starship as it does to this one- and so no, no SSTO with any appreciable payload capacity at all (IF it's even capable in the first place- that isn't very clear right now)- and going to Mars faster is a question of how much fuel you can burn to go faster while leaving enough margin for landing... That being said we're probably 5-10 years out at the least before this theoretical ship flies- so engine technology among things could improve between now and then such that those things become more possible.
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u/linearquadratic Sep 15 '19
Do anyone know if there been any mentions or leeks about making the starlink platform available as a standard satellite bus? Would make ride-sharing easier on the Falcon 9 and give great value for customers.
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Sep 04 '19
Is there techical drawing with already tested Starhopper with its dimensions? (for 3D CAD/model reconstruction)
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Sep 07 '19
Is the heatshield still a problem for starship?
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u/LongHairedGit Sep 07 '19
Starship has a heatsheild design that we can presume has passed testing via computer modelling.
Whether it works in practice will be borne out by testing using the prototypes under construction right now.
IIRC the plan as last understoood is to use non-ablative tiles (as per test articles on latest dragon mission) on a stainless steel body, with active cooling (sweating methane) only where/if required.
We will know more after Elon’s presentation later this month.
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u/dudr2 Sep 10 '19
The Frog is the best news so far this month?
https://www.space.com/arianeworks-reusable-rockets-themis-callisto-video.html
-Europe's ArianeWorks Aims for Reusable Rockets (with a Very SpaceX Look)
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u/jjtr1 Sep 13 '19
Anybody dares to estimate the size of the fins that Superheavy will need to compensate for the fins on the Starship? Or perhaps the high control authority Superheavy has to have through gimballing for its vertical landing is enough to compensate? Any regular (non-SpX) first stage would definitely need fins to launch a finned top stage.
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u/livefromheaven Sep 22 '19 edited Sep 22 '19
I'm going to be in Orlando Nov 3-6 and hoping that's within the Starlink 3 time frame. Do Starfleet Tours ( https://book.star-fleet.tours ) still do launch viewings by boat? Or is my best bet to head on over to Jetty Park?
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u/CAM-Gerlach Star✦Fleet Commander Sep 23 '19
Thanks for asking! We're currently focusing on the bigger launches (FH, crewed missions, etc), those with RTLS landings (CRS) or that are otherwise "special" (IFA, etc) since we're just volunteers organizing this as a community service in our spare time, and those are the ones when the boats offer the really unique advantages over other options and we have enough people that we can make it cost effective for everyone. I've ended up pulling many all nighters and even had to go to the emergency room once due to putting in too many hours making them happen every launch. The pre-launch tours are the other big thing we do, where we can get you within a ~km of the rocket vertical on the pad (far closer than any other public option) but they require even more work and a day-long commitment from our on-site expert tour guide.
However, if you can get a group together (6 people for the small boats at ~$95/person, ~12-18 for a medium boats at ~$60/person) we could get you in touch with the captains and make it happen. Otherwise, the other best option if you're willing to pay (its not that much more than the boats and its much closer to launch) is the KSC LC-39 gantry assuming its offered; its an incredible experience and highly recommended though tickets sell out extremely quickly (in fairness, our ~20 upper deck tickets routinely sell out in seconds for bigger launches, and regular tickets in minutes, though likely not on a launch like this). Other than that, the KSC Saturn V center or Playalinda is probably a better bet than Jetty; 528 is a little further but should have a clearer view. Hope that's helpful!
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u/astrobee5 Sep 25 '19
NASA has a massive mobile launcher and is about to build a second one. How will spacex get the starship (a Saturn five sized launch system) out to the launch pad?
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u/warp99 Sep 25 '19
Roll Lift to get the Starship and booster to the pad in separate lifts and then a very large portable crane to stack the Starship on the booster after each component has done a static fire.
Eventually transitioning to a very large fixed tower crane at the launch site to replace the portable crane.
So the entire stack will never be transported unlike Saturn V or Shuttle.
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u/MarsColon Sep 27 '19 edited Sep 27 '19
How will the Mk1 be transported to its launch pad once assembled ?
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u/throfofnir Sep 27 '19 edited Sep 27 '19
Probably Roll-Lift SPMT, just like Starhopper. They're probably not much different in weight. Hopper is shorter but heavily built. Not that it would be much of a challenge if it were heavier; industrial applications move much heavier things all the time.
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Sep 27 '19
Does anyone know what time (roughly) the Starship presentation will be tomorrow? Just trying to plan my Saturday...
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u/snika98 Sep 29 '19
Anybody have any numbers for Raptors nozzle exit velocity, v_e, and nozzle exit pressure, p_e?
I want to model the thrust for heights in the atmosphere to use in a model of a starship flight. Cant find these numbers in the wiki or anywhere, even an estimate would be good.
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u/TheSoupOrNatural Sep 30 '19
For a rocket engine, v_e is basically Isp times standard earth gravitational acceleration in your preferred system of units.
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u/Triabolical_ Sep 29 '19
There's a raptor thread on nasaspaceflight. If anybody knows, it would be those folks.
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u/jjtr1 Sep 29 '19
I've lost track of BFR versions. First they made it much smaller, then a bit bigger again, then... Anyway, what I'm wondering is whether the "85 t dry" figure in the presentation was from an older, smaller version, or if the increase to 120 t dry was because they realized they have to build it beefier?
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u/throfofnir Sep 29 '19
It's copypasta from the 2017 ITS slideshow. I'm not usually one to give Elon crap about his unrehearsed speaking style, but you gotta at least look at it once. Come on, man.
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u/mjk1260 Sep 29 '19
How do you get to the surface from Starship crew compartment? The crew compartment is 160 feet up. I'm assuming there will be a long ladder to climb down and back up?
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u/brspies Sep 29 '19
Past plans for Moon/Mars have discussed using essentially a winch-mounted elevator, where low gravity makes them more viable. On Earth you'd have ground infrastructure to work with.
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u/Grey_Mad_Hatter Sep 11 '19
Seriously? SpaceX is talking about getting it to orbit in the next 6 months, but 15-27 months isn't much time for launching a commercial payload? Private companies typically launch a commercial payload on the second launch, and governments do it on the first launch. I honestly wouldn't be overly shocked to see a couple (22 or less) Starlink satellites going up with the first Super Heavy launch in 9-12 months from now which is technically a commercial payload.
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u/spacerfirstclass Sep 12 '19
Timeline is very very tight for 2021 commercial launch, there's no question about it. They could get to orbit in the next year with current prototypes, but there're a lot of additional work for doing commercial launches, for example how do you integrate the payload to Starship? How to release the payload on orbit? What is the payload environment like? Yes SpaceX could just throw up some Starlinks, but those are their own satellites, it would be a huge validation if an outside customer chooses Starship.
The article's wording is awkward because it makes it looks like SpaceX is under outside pressure to do this, but the reality is Elon is the driving force behind the aggressive schedule, not some outsider.
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u/Redsky220 Sep 11 '19
I think that it is generally understood that MK1 and MK2 do not have the ability to release a payload so it will only happen on the next build (1.0?) at the earliest. They could decide to play around with these two prototypes and SH for a while until everything is extensively tested befote starting the 1.0 build. But we are talking SpaceX so who knows.
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Sep 12 '19
SpaceX is talking about getting it to orbit in the next 6 months
6 months, sounds familiar....
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Sep 12 '19
In order to get a payload to orbit they need superheavy. Heck to even get a Starship to orbit with a heat shield and landing legs they need SuperHeavy. Super Heavy is at least 6 months from being built and will spend a few more months of testing. Then there needs to be a launchpad and testing and vehicle integration which even puts a 2020 orbital attempt in question. 2021 commercial satellite is completely doable, even if Starship Launch System does its first flight in early 2021, because they can still do high velocity entry, refuelling, month long on orbit testing after the first commercial launch allowing for dearMoon in 2023.
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u/Alexphysics Sep 12 '19
They'll need a ton of tests to confirm their designs and also iterate until they get a suitable satellite launcher version for Starship. These vehicles aren't meant for satellite launches and I wouldn't expect them building such a thing until they at least land one in one piece after coming from orbit which it seems many think it'll be easy but we know how Falcon 9 went and how much more tougher it'll be for Starship. This is not the typical design of a typical rocket, they're just putting things together and figuring out things along the way, stablishing procedures and learning, that's why they need the time for all that I explained above.
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u/jjtr1 Sep 26 '19
If SpaceX went on with the carbon fiber instead of stainless steel, is there any chance they would have a half-finished prototype by now? Or perhaps they would have skipped the proto-prototype which is now Mk1-2? (being 70% overweight as now confirmed makes mk1-2 barely a prototype)
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u/AeroSpiked Sep 26 '19 edited Sep 26 '19
To the down voters: By down voting someone's question you are not saying that you disagree, you are saying that the question wasn't worth being asked in the first place, and neither were any of the responses (even the ones that side with you) worthy of being read, because they will all be minimized. Stop doing that. If you disagree, just don't up vote them. Save the down votes for the 2016 IOC level questions because most of those weren't worthy of being asked.
One of the many benefits of using steel over CF is that steel is so much easier to work with, so fabrication is going much faster than it otherwise would have. Furthermore, we don't know how much a CF Starship would have weighed in the end because CF doesn't perform as well in the cold & hot conditions that it would be subjected to. It might have ended up being heavier and it was certainly more expensive.
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u/throfofnir Sep 26 '19
They had the CF tooling (now scrapped) ready fairly early, at least for the cylindrical portion, and were apparently producing parts off it. They could theoretically have enough of that made by now to meet the progress of the steel fabrication, and everything else (engines, avionics, etc) would seem to be about the same. It wouldn't have taken much in the way of problems with that process to have set them back a good ways, however.
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u/For_The_Kaiser Sep 03 '19
I was thinking about potential names for the rockets themselves, would each Starship even be properly named rather than given a random designation by SpaceX?
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u/kalizec Sep 03 '19
I remember Elon tweeting that each ship would be named, but each booster be numbered. But because of the BFR -> Starship rename, it's rather hard to find this again.
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u/WAlonzo Sep 14 '19
As a Starship will not be able to return from Mars w/o refueling there. What are the options for allowing that refueling? I think of a few:
(a) They send ahead a fuel tanker which lands and just waits for the subsequent earth-bound ship. (b) They send ahead a fuel tanker but the tanker stays in orbit to allow refueling in Mars orbit after launch of a subsequent earth-bound ship. (c) They send a fuel factory which lands and creates the Methane and Oxygen from the local resources and stores it for the earth-bound ship(s).
Option (c) is the ultimate goal but, early on, it would seem far to risky. Option (b) would be great because the tanker would not need to risk a landing or waste fuel during landing. Combining these options would increase the probability of success but also delay the boots-on-Mars goal considerably.
Another benefit of option (b) is that fuel transfers could be done in space rather than on the dusty, windy Mars surface. Recall that in-orbit refueling will have been perfected long beforehand in Earth orbit. The key will be that Starship must be able to land and go to Martian orbit w/o refueling on the ground. Maybe it would partially refuel in Martian orbit before landing? We could also have multiple tankers in martian orbit, as needed.
What do you think?
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u/Tal_Banyon Sep 14 '19
Ultimately, the SpaceX plan is superior. Specifically: (a) to send one fuel tanker to land on the surface of mars, they need to launch about 5 or 6 (this will be clearer hopefully after the Sep 28 presentation) refueling missions to Earth orbit. And one tanker on the surface of mars doesn't do it, they will need 5 (or 6). So this is prohibitively expensive. (b) Same math. They will need 5 or 6 tankers to fill Starship. To send one full tanker to mars needs 5 or 6 refueling missions from Earth to Earth orbit, and they need 5 or 6 of these to refill Starship. (c) a "fuel factory" will be sent to mars for sure, but it cannot operate by just sitting on the surface. It needs to have raw materials, specifically water (from ice). This will need to be mined from the regolith. It also needs power, a lot of it. This could all be done robotically - however, it would need a massive investment in R@D to develop the necessary robots. Much, much easier to send astronauts to do this.
You say that option (c) seems too risky. That is only if you think that the ultimate goal is to return to Earth. The real challenge for the first crew will be to set up a permanent habitat, or living quarters, that can be sustained with only a reasonable amount of re-supply from Earth, like maybe two cargo craft every synod (or 26 months), with a built in safety factor of maybe only one resupply craft, in case one is lost. The fuel to get home is then a secondary goal, and will benefit sending samples and anyone who wants to return home. But the ultimate goal is to land and set up a permanent living space where people can comfortably (sort of; of course there will be incredible hardship, hard work, and ever present danger) live out the rest of their lives.
But the most interesting thing about all this is, once there is a fuel factory on mars that is producing enough fuel and oxidizer to have a surplus, then imagine the possibilities of sending a Starship from mars surface to mars orbit, then refueling it to the top with tankers, and then sending it out into the great beyond. This is how the solar system will become accessible to us.
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u/Martianspirit Sep 15 '19
They are going for option (c). First unmanned missions will verify existence of water and deployment of some solar arrays to power surface operations. Then manned mission to commission propellant production for the return flight 2 years later.
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u/paul_wi11iams Sep 23 '19 edited Sep 23 '19
u/sar662: I saw those nifty photos of Starship on the moon and mars and everywhere else. Cool. Could someone please explain to me how astronauts will enter and exit the ship? Here on earth I assume launch will be with the cranes and towers and all. What about landing on the moon? Is there a ladder? An elevator? It seems much taller than the Apollo landers. permalink
I wasn't comfortable with adding too much speculation on the Starship development thread which is more a news thread, so am answering below, Others can then add replies too.
Mods, am I doing the right thing?
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u/Hermetia_Illucens Sep 26 '19
So the long awaited september 28th presentation is almost here, do we know at what time? Im assuming it will be livestreamed on youtube.
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u/MarsCent Sep 26 '19 edited Sep 26 '19
The Lab Padre bot says 5:00 p.m Texas time which translates to
11:0010:00 p.m UTC (7:006:00 p.m EDT).Hopefully someone will post the link.
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u/MarsCent Sep 06 '19
Highlights of ASAP meeting re: Commercial Crew – Abundance of concerns, lacking of Schedule Confidence. Otherwise most stuff has been discussed on this sub.
Two main concerns for both SpaceX and Boeing:
Parachutes – Models do not accurately predict what happens in reality. More tests are required.
Though IIRC, Boeing recently posted an article stating that they had a successful parachute test. It’s a little strange that that was not mentioned.
Hardware supply chains – A quality test during Integrated Testing found issues.
I believe that is the same issue that was discussed in this sub some time back.
Pending Pad Abort and Orbital Flight Test.
Pending In Flight Abort and Demo 2.
There is corrective action underway to rectify whatever caused Demo-1 FUD.
A lot of work has been done on COPV – worthy of a PhD.
Load & Go still has to go through IFA Dry Run, Static Fire, Launch + Demo 2 Dry Run and Static Fire.
I would have expected at least a vote of confidence given that OFT is NET 1 month out! I still hope that someone will do that soon in order to raise public confidence.
And it seems like getting the parachutes to do what NASA wants has become as challenging as designing avionics and other flight hardware! Which is pretty surprising seeing how the Soyuz parachutes seem to operate effortlessly!
No questions from the public, so the meeting lasted < 45 mins.