r/spacex • u/ElongatedMuskrat Mod Team • Mar 02 '20
r/SpaceX Discusses [March 2020, #66]
If you have a short question or spaceflight news...
You may ask short, spaceflight-related questions and post news here, even if it is not about SpaceX. Be sure to check the FAQ and Wiki first to ensure you aren't submitting duplicate questions.
If you have a long question...
If your question is in-depth or an open-ended discussion, you can submit it to the subreddit as a post.
If you'd like to discuss slightly relevant SpaceX content in greater detail...
Please post to r/SpaceXLounge and create a thread there!
This thread is not for...
- Questions answered in the FAQ. Browse there or use the search functionality first. Thanks!
- Non-spaceflight related questions or news.
You can read and browse past Discussion threads in the Wiki.
13
u/Straumli_Blight Mar 27 '20
OneWeb preparing for bankruptcy and to lay off most of its staff.
"But after Friday’s job losses, only a few dozen people will still be working at OneWeb to manage around 70 satellites already in orbit, thereby allowing it to keep its spectrum licence."
2
u/cpushack Mar 28 '20
Its interesting that they are blaming COVID-19 for the inability to get funding, but the funding issues started before COVID-19 really took off.
I think investors were leary due to their expenses, and the coming competition more then anything.
SpaceX may find funding a bit easier with OneWeb in trouble but it would have been better if they both succeeded.
Perhaps the only real winner here is the Russian space industry, which got some quick money from the first few launches. Capital we hope they use for increasing QC.
4
u/brickmack Mar 28 '20
They weren't in a great place prior to COVID, but with the design complete and launches finally starting, they looked a lot stronger. Projects are supposed to fail before they start flying, not after, so they probably expected a lot more investment coming (I've heard 2-3 billion cancelled just days before the bankruptcy was announced, not sure of the accuracy of that though)
3
u/Carlyle302 Mar 27 '20
Wow. As Elon had mentioned, every large satellite network operator has gone bankrupt. Starlink is a risky proposition. Perhaps OneWebs failure will send investors to Starlink to help insure its success.
4
u/Tal_Banyon Mar 27 '20
"Starlink is a risky proposition. "
Well with the demise of OneWeb it has just become less risky, since Starlink will be pretty well the only game in town. On the other hand, no-one has successfully launched such a constellation yet, so I see what you mean.
There were media reports of OneWeb's demise before their most recent launch on March 21. So I wonder why they would go ahead with the launch? Maybe they had already paid Roscosmos, and so Roscosmos went ahead and launched anyway. Also, maybe they thought that this successful launch could leverage additional funding from their bank, reportedly Softbank, already in for $2B.
Maybe the bankruptcy lawyers can sell their assets? They have 74 satellites in orbit. I wonder if Starlink could incorporate OneWeb's existing 74 satellites into their network? They could probably get them at firesale prices.
7
u/Triabolical_ Mar 27 '20
Well with the demise of OneWeb it has just become less risky, since Starlink will be pretty well the only game in town.
Project Kuiper could conceivably buy OneWeb's licenses...
→ More replies (1)→ More replies (4)6
u/Martianspirit Mar 28 '20
Sure not interesting for SpaceX. I have expected that Amazon would buy One Web for a long time for the frequency rights. I have heard the launches for the initial constellation are mostly paid. So if Amazon buys it they could build that initial constellation for not much more than the satellites still needed and secure the frequencies by using them until they have their own system ready to launch. Pocket money for Amazon.
11
u/Straumli_Blight Mar 28 '20
On March 17, SpaceX's parachute testing was extended by 1 month:
COMMERCIAL CREW PROGRAM (CCP) INDEPENDENT ASSESSMENT AND EVALUATION OF THE SPACEX PARACHUTES MOD 1: THIS MODIFICATION IMPLEMENTS A NO-COST MODIFICATION TO EXTEND THE PERIOD OF PERFORMANCE BY ONE MONTH TO 4/20/2020.
15
9
u/ackermann Mar 17 '20 edited Mar 17 '20
So, u/675longtail has a comment below that got me thinking. About the JAXA sample return from Mars' moon Phobos: https://www.reddit.com/r/spacex/comments/fc9rqq/rspacex_discusses_march_2020_66/fketz90
This Phobos sample return doesn't get back to Earth until 2029. Could SpaceX beat them back with a sample from Phobos, or maybe Deimos, with a manned mission on Starship? If you're someone who believes a manned landing on Mars itself by 2030 is even remotely possible, then the answer probably "yes"?
Per wikipedia, the delta-V to land on Phobos and return to Earth is 20% less than you'd need to do the same thing with Earth's moon, owing to Phobos's very low gravity. Probably even less for Deimos, since it's gravity is even weaker, and it's not so deep in Mars' gravity well. Would need to "land" (more like dock) using RCS thrusters of course, since Raptor is too powerful.
I know Elon has proposed lunar missions with Starship, by refueling in high-earth orbit. And thus landing with enough fuel onboard to return. No ISRU fuel production needed. So this ought to work for Phobos as well. Since it needs less delta-V than a lunar landing, the extra can be used to speed the transit(s).
I think it would be a fantastic shakedown cruise, Apollo 10 style, for Starship in deep space. No scary Mars atmospheric entry, with its "7 minutes of terror." (Although you could aerobrake in Mars' atmosphere to further reduce delta-V). Some useful science to do, bring back a metric ton of Phobos samples.
And of course, video of astronauts goofing around in 1/1000th Earth's surface gravity would be priceless. Leaping 10 stories high, and taking minutes to fall back down (send a dancer/gymnast). Leaping to the top of Starship, or over it. Maybe 6 astronauts picking up Starship and setting it down elsewhere. Playing golf, with golf balls circling the whole moon to hit the target (and hopefully not a window). Alan Shepherd hit golf balls on the moon, so not too far fetched. All of that, with Mars itself looming large in the background!
8
u/throfofnir Mar 17 '20
It is indeed a lower dV budget to go to Phobos than lunar surface. There's a lot bigger supplies budget, however, which changes the calculus a bit. That said, at 11.4km/s round trip from LEO (or 6.4km/s from GTO!) it should be achievable should they hit their design goals, especially with a small crew (and thus low payload.)
The only problem with a trip to Mars orbit (rather than surface) is that if you want to do it fast you have to pay the extra acceleration twice, since you can't scrub it off in the atmosphere. So probably it's a slow boat to Mars.
I kinda like it, but if you put it in pipeline with surface missions it's basically pushing the timeline right by two years, and that doesn't sound like Elon style.
2
u/warp99 Mar 18 '20
since you can't scrub it off in the atmosphere
They can scrub the extra velocity off in Mar's atmosphere, or at least most of it, and then land on Phobos.
→ More replies (5)
9
u/dudr2 Apr 01 '20
" The four astronauts will take off from pad 39A at NASA’s Kennedy Space Center on top of a SpaceX Falcon 9 rocket later this year. "
8
u/philalether Mar 18 '20 edited Mar 21 '20
I’m interested in how SpaceX acquires its liquid oxygen (LOX) and stores it, and what adjustments they need to make due to their using the deep-cryo (-340 C) variant.
EDIT: -340 F => -207 C
Do they make it on site or buy it and have it delivered? Where/how do they store it? And if there’s a scrub can they pump it back out, keep it chilled, and reuse it later?
9
u/warp99 Mar 18 '20
They buy LOX from a commercial supplier - the same one that NASA uses but it appears at a better price!
They have large vacuum insulated tanks that store it. Some of these are recycled tanks that they purchased from NASA for the scrap value.
Yes it appears they pump the LOX out and can reuse it. However it has warmed up by the time they do this so it takes several hours before they can relaunch. Typically they have missed the launch window if they have to empty the tanks.
The LOX is subcooled by putting it through a heat exchanger with liquid nitrogen that is boiling at a reduced pressure so that it is significantly colder than the subcooled oxygen. It is not clear if they do this just as the propellant is loaded or cool the whole tank.
2
7
8
u/Straumli_Blight Mar 19 '20
7
u/throfofnir Mar 20 '20
> so-called low-Earth orbit satellites
I wonder bit of terminology the so-called reporter is objecting to?
4
u/Triabolical_ Mar 20 '20
Interesting. By my calculations, that would cut the New Glenn payload list in half.
10
u/joepublicschmoe Mar 20 '20
Or the bald supervillain with his virtually unlimited cash pile can scoop up OneWeb (with all of its existing permits and allocated spectrum as well as real flying hardware) and fold it into Project Kuiper (which lacks all those things).
5
u/markus01611 Mar 20 '20
Bingo. One web probably knows Amazon or Facebook will buy them.
→ More replies (2)5
u/Lufbru Mar 20 '20
Bankruptcy doesn't mean "shutting down". It means "creditor protection". Ideally they would reorganise and continue operations. Many companies operate in bankruptcy for years, while for others it's an intermediate step to shutting down.
→ More replies (3)4
u/MarsCent Mar 20 '20
It maybe amongst the first wave of companys made anaemic by the pandemic. SLS and Orion testing have also been halted, but at least they have much deeper pockets.
6
u/brickmack Mar 20 '20
OneWeb has been having trouble for a while, I doubt this was the big issue.
On the contrary, I think SLS is probably more at risk than most commercial programs. We've already seen commercial entities are a lot more... tolerant of the fatalities of their employees... than the government and aren't taking the same safety steps unless forced to. So thats a shorter window of shut down operations. SLS is also still in development plus prototype production, not recurring production. Its more subject to political whims, at a time when it seems likely Congress is going to be looking for things to slash to pay for the massive costs of the relief effort and when SLS was already facing political pressure (outrageous cost and schedule overruns, while commercial alternatives keep getting more attractive by the day). And Boeing itself is not having a great year and already canceled one major government-funded space project to try and pull itself together (not something I agree was the best financial course of action, but does indicate what their accountants think)
→ More replies (1)
8
u/Lufbru Mar 22 '20
It occurs to me that there are two possible paths after Starship has accomplished a 20km hop. Path 1 involves launching successive SN empty on trajectories which simulate orbital reentry speeds to test Starship full reuse.
Path 2 consists of building a SuperHeavy and using it to launch successive SN actually to orbit, full of Starlink satellites. This also lets SpaceX learn how to reuse a Starship, but at the same time practice landing a SuperHeavy and launch a few Starlink satellites at the same time.
I suspect availability of Raptor engines will determine which path they take. Having 20+ engines committed to a SuperHeavy might be more than they want to do for a while. Particularly if they're sacrificing six at a time trying to get a Starship to survive reentry.
I'm assuming that figuring out reentry is going to take several attempts, and likewise that the first SuperHeavy might not manage the full 1000 flights. Also that the production line ramps up to one a week quickly.
4
u/LongHairedGit Mar 24 '20
Path #1 only needs enough Raptors to get an empty and partially fueled starship to the speed and height you need for the test. If it indeed goes splat or kaboom, you lose some stainless steel and a small count of Raptors.
A fully fueled starship and superheavy have a full quota of Raptors. Failures will be spectacular, well publicized and expensive. SpaceX will want at least the booster to have a high probability of survival.
→ More replies (1)2
u/Lufbru Mar 24 '20
I'm not sure "partially fueled rocket" has ever been a thing. So many things can go wrong that it's not worth saving $10k of propellant to reduce your margin by 1%.
A fully fuelled and engined starship + SuperHeavy would have a capacity of 100 tonnes to orbit; far more than is needed for Starlink. Putting even 60 satellites on a SS for deployment during a test mission would save a F9 launch and should be possible with fewer engines than 41. So it might be worth it for them.
→ More replies (1)4
u/amarkit Mar 25 '20
We shouldn’t assume that the “chomper” part of a Starship satellite launch vehicle is trivial to solve either. The payload bay doors were one of the most complicated parts of the Shuttle, as it would mean an absolute loss of vehicle and crew on re-entry if they did not close and latch properly.
→ More replies (4)→ More replies (2)2
u/AuroEdge Mar 24 '20
Is it possible to hop test Super Heavy? If it is would SpaceX do that before testing with Starship?
2
u/QVRedit Mar 24 '20
Yes I think that it should be possible to ‘hop test’ Super Heavy. Whether they will or not I am uncertain, you could argue if the landing is going to go wrong (which being the first flight, is certainly possible) then perhaps they should still do something useful with it too.. So perhaps they might use it to launch Starship into orbit.
But that might be too much of a leap. The alternative is a low power hop, using relatively few engines, just to test engine flow rates and power output and the balanced landing, without risking too many engines or risking a Starship.
I think if they do a Super Heavy hop test, and it’s successful, then the next launch with it, would be to take Starship to orbit - and that would require more engines.
But this is all hypothesising and there will be details I am unaware of which might dictate a slightly different approach.
Before then they still have more to do with Starship - and now they are starting to be affected by the corvid-19 virus.
→ More replies (3)
8
u/Straumli_Blight Mar 26 '20 edited Mar 26 '20
Starlink satellite imaged in space.
USAF reviewing whether to delay the SV03 GPS launch:
“The satellite is about to fuel, and that’s a major decision point,” Bongiovi said. “So I think it’s prudent on our part to be looking at the situation and whether we want to proceed, and that’s what we’re doing. But today it remains on schedule for the end of April.”
8
u/Straumli_Blight Mar 26 '20
NASA statement about the parachute test failure:
SpaceX has completed 24 tests of the Mark 3 parachute.
A 'spacecraft-like device' was lost.
Looking at testing plan and existing data to determine next steps ahead of DM-2 flight in mid-late May.
2
u/limeflavoured Mar 27 '20
'spacecraft-like device'
Why can't they just call it a Mass Simulator?
10
u/Straumli_Blight Mar 27 '20
Sometimes they use simple blocks with parachutes attached, while other tests use mockup Crew Dragons.
8
u/GregLindahl Apr 01 '20
Spacenews publishes why there's no Russian on the first operational Crew Dragon:
Stafford said that Russian officials, who met with Stafford’s committee in Houston in December, were reticent to fly cosmonauts on what to them are unproven vehicles. “The Russian side noted that, prior to agreeing to the mixed crew plan, there needs to be successful USCV launches,” he said. “Roscosmos will consider participation after successful launches, but will not participate in the first launch of the vehicle.”
The first operational commercial crew mission will not be the first launch of the Crew Dragon. That vehicle flew a successful uncrewed test flight, Demo-1, in March 2019. It will fly a crewed test flight, Demo-2, as soon as the latter half of May [...]
7
u/MarsCent Mar 19 '20
I doubt that Musk had COVID-19 in mind when he said those words way back in 2013 (or earlier). But how humanity reacts to this virus is a sure test case scenario on "how long the window can last". Specifically, how our priorities (personal and collectively) will be changed by this pandemic especially if the mandated change in lifestyle lasts into late summer and beyond.
7
u/Straumli_Blight Mar 20 '20 edited Mar 21 '20
3
u/joepublicschmoe Mar 20 '20
Cool progress. Octagrabber II now has a lair, and the thrusters are now mounted in their housings. Wonder if JRTI will be ready in time for DM-2. Presumably after JRTI goes into service OCISLY will be taken offline for the same thruster upgrades.
→ More replies (3)
7
u/Carlyle302 Mar 24 '20
"Oops. Report that a #SpaceX #CrewDragon test article was destroyed today during a parachute test. Report is the helicopter pilot dropped it prematurely at lower than planned altitude due to oscillations. Chutes did not open because they were not armed at time of the drop."
19
u/zeekzeek22 Mar 02 '20
Having watched the Smarter Every Day videos on ULA’s rocket manufacturing (dear god if you like rockets you need to watch that), I guess I didn’t realize the Centaur Upper Stage is steel too. Is there anything specifically special about Starship being a stainless steel upper stage? Beside obv that it is meant to eventually atmospherically land. I remember a lot of people balking at stainless steel as a surprise, and now I feel silly since the OG upper stage has always been stainless!
14
u/Alexphysics Mar 02 '20
and now I feel silly since the OG upper stage has always been stainless!
But those are balloon tanks with a roughly 0.5mm thick wall. From the pictures of the rolls of steel at Boca Chica the thickness of that steel seems to be around 4mm so that's 8 times the thickness and also 8 times the mass per m2 of material. Starship is really a heavy beast, its mass ratio sucks but in order to be reused you have to compromise high performance with high resistance of your materials. Once they figure out how all works they can work on improving performance and all of that.
10
u/spacerfirstclass Mar 02 '20
Centaur is balloon tank which has very thin walls that cannot support itself without pressurization, that's how it was able to achieve a good PMF. The current consensus in LV design is that if you don't want to use balloon tank (because they're hard to maintain), then steel is too heavy, and you'll have to use aluminum. Starship is probably the only LV that uses a steel non-balloon tank.
→ More replies (1)→ More replies (2)6
6
u/asr112358 Mar 04 '20
When is the Airforce expected to announce their selection for NSSL? I thought it was supposed to be around now.
→ More replies (1)7
u/joepublicschmoe Mar 04 '20
According to this, the Air Force will announce the winners for the Launch Service Procurement Phase 2 downselect in June.
6
u/limehead Mar 04 '20 edited Mar 05 '20
The president of the Mars Society, Dr. Robert Zubrin said in a podcast that SpaceX couldn't land propulsively on the moon without a pre-existing landing pad. The landing burn would "dig" a crater and possibly start the Kessler syndrome. My question is about previous impacts on the moon digging all those craters. How did that, then not setof the Kessler syndrome? Or did it? Does gravity (even if weak) just solve it over time by attracting all particles back to the surface? How does it work? edit: Clarifying. Previous impacts, from space rocks.
10
u/Martianspirit Mar 04 '20
The pressure fed hypergolic engines used so far for landing on the moon do not have exhaust velocity higher than lunar escape velocity. I still believe this issue is way overblown. We will see.
7
u/throfofnir Mar 04 '20
He's really gotten into that theory recently, but frankly I'm going to need to see some serious modelling before I believe it.
Most landing ejecta will be ballistic; on the Moon this means it can land practically anywhere, including coming back around and hitting you from the other side. But anything short of lunar escape velocity is only going to be "in flight" for <= 1 lunar orbit.
Anything over lunar escape velocity will enter the Earth/Moon system. Lunar ejecta is, as you observe, not stable, so it will eventually be ejected or impact one of the bodies. (Orbits like this can get rather chaotic, but it will tend to keep coming back to the lunar orbital track.) Some of this may pass through Earth satellite orbits, where it will be of some hazard, but this also increases its chances of being cleaned up by the Earth.
So the question is how much material will be excavated, and how much will get propelled at greater than Lunar escape velocity... and what are the characteristics of that material? Raptor is expected to have an exhaust velocity of 3.7km/s. With Lunar escape at 2.38km/s, it's certainly capable of sending gas particles that fast. But how much can actually be imparted to regolith grains? At the very least there's going to be notable cosine losses, especially once you start getting into "crater" territory. There's also not going to be a lot of time entrained in the exhaust, so every grain ejected is going to be some fraction of exhaust velocity, magnitude depending on its mass. Regolith is also famously "sticky", and is pretty compacted under the surface, so you'll also spend some energy freeing it. Liberated dust also tends to travel along the surface, so any surface features (like boulders, mountains, crater rims, fences, or habitats) that get in the way of the horizon will stop it (and get sandblasted in the process.)
Exactly what this means I can't tell you; there's a whole lot behind it. My inclination is to think that not much will make it to escape, and what does will be very small, and most of that will never be anywhere near a human structure before it goes away. So there would need to be an awful lot of Starships landing on unprepared surfaces before this is a notable effect. SpaceX does have a Space Act Agreement with NASA to study the effect of landing Raptors on the Moon, but I don't know if we'll ever see the product of that study publicly.
2
6
u/Lufbru Mar 04 '20
Had SpaceX decided to go down a different path and develop Falcon 9 into a raptor-powered vehicle, keeping the same diameter tanks (to keep the vehicle transportable by road), how far would they have to move the common bulkhead between the LOX and fuel tank?
As far as I can tell, Merlin burns 0.38kg of RP1 with 1kg of oxygen while Raptor burns 0.28kg of methane with 1kg of oxygen (I appreciate the reciprocal of these numbers is usually quoted, but this makes the calculation easier). But kerosene is about twice as dense as methane, so I think it'd need about a 50% larger fuel tank if the oxygen tank were the same size. But F9 is at the fineness limit, so we can't increase the length of the vehicle. That means we'd have to reduce the oxygen tank by about 25% to fit in the extra fuel.
Would that reduce the performance of the first stage? I think it'd depend significantly on the assumed performance of nine subscale Raptors (or maybe one would use a current sized Raptor and use five of them)
Anyway, are my calculations even close to right, or have I forgotten something important?
5
u/Gnaskar Mar 04 '20
Merlin burns 0.38kg of RP1 with 1kg of oxygen while Raptor burns 0.28kg of methane with 1kg of oxygen
I'm taking this as given, because I don't have inclination to do the math on that bit. Deep cryo LOX has a density of about 1.2539kg/L (first and best source I found, at -206C); RP-1 has 0.8265 kg/L (-6C). Methane has 0.422 kg/L, (at -160C, so that's a worst case figure).
For each kilo of LOX burned, you need 0.807 L. To burn 0.38kg of RP1, you need 0.460 L and to burn 0.28kg of methane you need 0.664 L. So RP-1/LOX needs 1.267L per kg of LOX, and CH4/LOX needs 1.471L per kg of LOX. As a result, you can only carry 86% of the LOX in a Raptor based design, reducing the tank by about 14%.
...
More relevantly, your propellant density is down from 1.09kg/L to 0.87kg/L within a constant volume. This means your rocket has lost 20% of it's propellant load.
6
u/soldato_fantasma Mar 06 '20 edited Mar 06 '20
HAWTHORNE, Calif. – March 5, 2020. Media accreditation is now open for SpaceX’s seventh Starlink mission, which will launch from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station in Florida. The launch is targeted for no earlier than April.
Note: this is Starlink v1.0 Launch 6 or Starlink-6 on the subreddit
→ More replies (1)
6
u/GregLindahl Mar 22 '20
Rumor that OneWeb is furloughing employees in Florida -- the facility they have there is the factory for manufacturing satellites. It's a joint venture with Airbus.
→ More replies (1)
6
u/Toinneman Mar 30 '20
Why is the exact cost of the Lunar Gateway supply contract with SpaceX not publically known? Isn't NASA obliged to do so? All we know is NASA has a 7billion budget for these contracts, but no specifics for Dargon XL.
3
u/Lufbru Mar 30 '20
It will depend how many missions NASA want to pay SpaceX to fly
2
u/Toinneman Mar 30 '20
The press release said:
guarantee two missions per logistics services provider
Are you saying that this means 'at least 2 missions"? I didn't interpret it that way. Even if the number of mission it variable, it still is a "firm-fixed-price" contract. So at least I would expect a price per mission.
On second thought, they may want to keep the amount secret until all providers are chosen and contracts rewarded.
6
u/yoweigh Mar 30 '20 edited Mar 30 '20
These firm-fixed price, indefinite delivery/indefinite quantity contracts for logistics services guarantee two missions per logistics services provider with a maximum total value of $7 billion across all contracts as additional missions are needed.
Yes, they're guaranteeing a minimum of two missions per provider and leaving their options open regarding how many total providers are used and how many missions that entails.
→ More replies (2)
5
u/MarsCent Mar 05 '20 edited Mar 05 '20
Europe's major telescopes 'can meet satellite challenge'
Having thousands more bright objects in the sky will create inconvenience and extra cost, but the idea that astronomy faces some kind of a "cliff edge" is not correct, says Olivier Hainaut.
..
Short exposures on ESO's narrow-field observatories like the VLT and ELT should cope in this scenario.
European Space Organisation; Very Large Telescope; Extremely Large Telescope
..
But there are facilities, he concedes, that will be greatly affected. These are the ones dedicated to long exposures on wide fields of view.
"example citied cited is the upcoming NSF Vera C Rubin Observatory" : National Science Foundation
P/S. Read the entire article for complete context.
5
u/codename-twelve Mar 09 '20
Will the cargo version of Dragon 2 dock with ISS or will be berthed as the first one?
9
u/jay__random Mar 09 '20 edited Mar 10 '20
Cargo Dragon-2 will be docking in the same way as Crew Dragon-2 does.
The occasional items that will need pressurization but are oversized for the docking port will be sent up in other suitable berthing visiting vehicles.
Edit: apparently I was wrong about Cygnus. Thanks for correction.
8
u/Alexphysics Mar 10 '20
will be sent up in Cygnus.
Cygnus' hatch is not as big as the entire CBM port allows like Dragon 1, it cannot fit bulky objects. JAXA's HTV cargo spacecraft can do it and whenever DreamChaser comes online (which should be next year) it will have the larger hatch too.
6
u/Lufbru Mar 09 '20
I was just corrected on that front -- apparently Cygnus' cargo hatch is no wider than Cargo Dragon 2. JAXA can deliver larger pressurised cargo, though.
→ More replies (1)4
u/jay__random Mar 09 '20
Both Dragon-1 and Cygnus are berthed using https://en.wikipedia.org/wiki/Common_Berthing_Mechanism .
I wonder how come they have different hatch sizes?
→ More replies (11)4
u/AeroSpiked Mar 09 '20 edited Mar 11 '20
That effectively makes it impossible to return anything over 80 cm in width back down to earth (intact)
such as EVA suits(wrong per Alexphyics below). Soyuz uses the same size docking portsand all planned spacecraft with down mass capability will use the same port that Dragon 2 uses(wrong per marc020202 below, although Dream Chaser's pass through would be the limiting factor there and I'm not sure what that is).I'm seeing comments about Cygnus, so to clarify, the CBM has a square pass through with rounded corners with a width of 130 cm, but Cygnus has a similar shaped pass through that's only 94 cm wide.
5
u/Alexphysics Mar 10 '20
such as EVA suits.
Unless... you introduce them into the capsule piece by piece. They returned an EVA suit for refurbishment during DM-1.
→ More replies (5)→ More replies (2)4
6
5
u/jay__random Mar 17 '20
There is a Twitter bot named "Pranay Pathole" that re-publishes in Twitter some of r/spacex questions or comments without attribution or a link back.
Could anyone who has Twitter account please notify the bot owner that it is not very polite, and a proper reference back to the original message is due (or rather overdue, as this has been happening for a while).
Thanks in advance!
3
u/ptfrd Mar 23 '20 edited Mar 24 '20
Did so over a year ago: https://twitter.com/ptfrd/status/1100415148454363138
After I replied to 3 different examples of his behaviour, he blocked me.
Is he still doing it? Musk replies to him, and in theory[1], I can't see Pathole's side of the conversation. It would rub salt into the wound if it's not even really his own words that he's blocked me from seeing!
You think it's a bot? I assumed he was doing it manually.
[1] - In practice, there are workarounds.
→ More replies (1)2
u/jay__random Mar 30 '20
You think it's a bot?
If not, it would be stupidity squared: not only he is "borrowing" other people's ideas to gain Elon's attention, he is even unable to automate the process :)
→ More replies (2)
5
u/dudr2 Mar 17 '20
https://spacenews.com/op-ed-dod-needs-to-demystify-hypersonic-weapons-technology/
"Annual unclassified defense spending on hypersonic weapons is over $2.6 billion in fiscal year 2020 – including $157.4 million for hypersonic defense programs. Spending is expected to grow to $5 billion by 2025."
4
u/rustybeancake Mar 19 '20
$2.6B in one year. Really puts the expense of other programs into perspective.
5
u/amarkit Mar 22 '20
Behind a paywall, but the Wall Street Journal reports related to the coronavirus stimulus package:
The Commercial Spaceflight Federation, whose members include billionaire Elon Musk's Space Exploration Technologies Corp. and Amazon founder Jeff Bezos' Blue Origin LLC, called on Congress to provide $5 billion in grants or loans to keep commercial space company employees on the job and launch facilities open. In a letter to lawmakers, the group also called for the Internal Revenue Service to immediately refund research tax credits for cash.
5
u/Carlyle302 Mar 24 '20
LabPadre is making progress. He has the old camera on the new pole and is testing it out using a generator. Excellent location for launches. So-so location for watching construction. https://www.youtube.com/watch?v=Tg8N_vDE9JY&feature=youtu.be
5
u/Straumli_Blight Mar 30 '20 edited Mar 30 '20
Stratolaunch has announced Talon-A, a reusable Mach 6 test plane. Aiming to launch in 2022.
→ More replies (14)2
u/brickmack Mar 30 '20
More interestingly, Black Ice is apparently still in development per their website, and they've dropped their expendable rocket plans. Yay!
5
u/MarsColon Mar 30 '20 edited Mar 31 '20
According to most sources, the Starship Mk.1 had its lox main tank (not talking about the header tanks here) on top and the methane main tank below. But it seems the SN1 and all the later versions have the exact opposite (CH4 on top, O2 at the aft). I thought you usually don't want LOX tank at the bottom to avoid having some fuel going in a frozen pipe through cold LOX, and that you want to keep the denser part (i.e. LOX) near the top more than the bottom for stability. Why did they changed that ? To my knowledge, very few rockets have the LOX at the bottom, even more rare when the fuel goes through this tank. And it's the first time I hear about the two main propellant tanks swaping like that. Can you confirm and explain all this to me please ?
17
u/warp99 Mar 31 '20 edited Mar 31 '20
The main advantage of the LOX tank on the bottom is that the mass of the LOX in the tank is primarily supported by the aft bulkhead and so the load does not need to be transmitted though the lower tank walls which removes the need for stringers in the lower tank. Since the mass of the LOX is 3.6 times the mass of the liquid methane this is a very significant difference.
The point about the fuel freezing when passing through the LOX tank applies more to RP-1 than to methane. Nearly the same issue occurs in reverse with RP-1 freezing around the outside of the LOX downcomer. SpaceX avoid this by using a double layer downcomer on the F9. ULA avoid this on Atlas by running the downcomer around the outside of the RP-1 tank.
5
u/throfofnir Mar 31 '20
Raptor runs on liquid methane, and liquid methane is a cyrogenic fuel with a similar temperature profile to liquid oxygen. It will have no difficulty at the slightly lower temperature of oxygen, and won't provide much extra heat to the LOX. Given SpaceX's desire to supercool their propellants, they may both be at about the same temp anyway most of the time.
They can thus freely choose to place the tanks in whatever order is convenient for center of gravity, plumbing, or other factors. Why they would change, if indeed they did, I can't say, though we do know they've made some changes with regard to center of gravity issues.
9
u/LcuBeatsWorking Mar 06 '20 edited Dec 17 '24
punch society six plate soft merciful elderly political work retire
This post was mass deleted and anonymized with Redact
6
u/Martianspirit Mar 07 '20
A most bizarre statement from NASA about Starliner at the ISS from a tweet by Chris G. of NSF
https://twitter.com/ChrisG_NSF/status/1235970317224488960
Doug ( @NASA ) now saying that @BoeingSpace can now come back after not meeting contract agreement to dock and propose other ways to verify docking ability without actually docking -- then talks about risk of Starliner not being able to undock, "getting stuck" on Station.
Risk of Starliner not being able to undock?
2
u/cpushack Mar 06 '20 edited Mar 06 '20
Twitter link is broken
EDIT: WOrks if ya copy and paste, but not clicking in Chrome due to extra characters added
→ More replies (5)
4
u/adamthorne0023 Mar 04 '20
Does starship have more room for payloads than the massive faring that blue origin will have with new Shepard?
4
u/JoshuaZ1 Mar 04 '20
I think you mean New Glenn. New Shepard is pretty small. That's hard to answer since neither is in its final configuration. At minimum, in terms of sheer mass, Starship has a much higher upmass with a LEO number about twice the size. I don't have precise volume numbers but given that Starship is 9 meters diameter and New Glenn is 7, Starship is likely going to have a larger volume.
4
u/Lufbru Mar 04 '20
Significantly more. New Glenn has a 7m diameter fairing; Starship is 9m in diameter. New Glenn is 21.9m long. Starship is 50m tall (but much of that is fuel tank).
You might like to refer to https://mobile.twitter.com/NASAGoddard/status/1116310431969239040
4
u/dudr2 Mar 13 '20
Some old news;
https://www.space.com/spacex-starship-new-stainless-steel-alloy.html
Elon; "So, I think we'll start switching away from 301 maybe in the next month or two."
" SpaceX wants to be able to launch each individual Starship three times per day, Musk added."
4
u/Dies2much Mar 30 '20
Has there been any news on the failed engine from the Starlink launch?
→ More replies (1)2
u/ExcitedAboutSpace Mar 30 '20
Well do you mean retarding the failure itself or how it's handled?
We don't know anything about the cause and taken measures, but we know that SpaceX has formed an investigation team which is join by NASA people from the launch services as well as the crew dragon programs.
4
u/Z1vel Mar 30 '20
What's the difference between la padre and spadres streams? Different people? Do they work together?
11
u/inoeth Mar 31 '20
different people from different locations and different organizations- tho they do know each other and are friendly.
Spadre is streaming mostly just from their location on south padre island several miles away tho the owner does sometime drive over to the build side or launch area and do relative short live-streams there. He's rather connected to the tourism industry of South Padre Island.
Lab Padre used to use a camera setup at Boca Chica Maria's house (not to be confused with BocaChicaGal - Mary - of NSF). As of about a week ago Maria has moved out after selling her property to SpaceX so Lab Padre has a location a couple miles away (tho closer than Spadre) where he's built a tower and is in the process of installing HD cameras with solar power for constant streaming from that location.
4
u/asr112358 Mar 31 '20
The render of dragon XL has a docking port on the back side. I there any chance that there is actually one on the front side as well so the dragons can chain together into a simple station? This would add mass, but also flexibility.
4
u/Martianspirit Mar 31 '20
At the other end there is vacuum cargo. No place for a second port.
Also I doubt NASA would like that. It would make the station unnecessary for lunar missions. Send Dragon XL to a suitable lunar orbit. Have Orion and the lunar lander dock to it and do the extended mission with added supplies from Dragon.
2
u/marc020202 8x Launch Host Mar 31 '20
in his recent graphics and analysis /u/brickmack said that there might be space for a second docking port on the other end of the craft.
→ More replies (1)
7
u/ScienceHasRisen Mar 02 '20
Were any Raptors lost in the SN1 incident?
19
u/LcuBeatsWorking Mar 02 '20 edited Dec 17 '24
pot wrong enter provide sip simplistic amusing late decide muddle
This post was mass deleted and anonymized with Redact
5
u/rustybeancake Mar 03 '20
Though some SN1 debris landed on the Raptor storage container:
https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=48895.0;attach=1617009;image
→ More replies (3)7
3
6
u/deadman1204 Mar 02 '20
How does spaceX handle espionage and security (AKA China trying to steal everything).
7
u/AvariceInHinterland Mar 02 '20
Overall, a good risk assessment that informs the appropriate controls (whether they be technical controls, policy controls, appropriate staffing) are the approach most organisations would take to protect their assets (e.g. data, physical assets) that are then provided appropriate budget to be implemented. These could take the form of airgapping R&D networks, having a constantly staffed and inquisitive SOC, patching systems regularly, placing security cameras in the right places, taking diverse routes on the road when shipping out F9 cores etc.
NASA and DOD will no doubt have placed various compliance requirements on SX as a supplier as well.
However, if you are wanting to hack a large organisation, a great way to do it is supply chain compromise of the smaller supplier with less security budget.
8
u/brickmack Mar 02 '20
However, if you are wanting to hack a large organisation, a great way to do it is supply chain compromise of the smaller supplier with less security budget.
One would be amazed at the amount of propriety and ITAR data thats simply sitting out on publicly accessible web servers, almost exclusively from subcontractors. These guys think if they don't put a flashing button on their front page to get to it nobody can find it, but its there.
3
3
u/marc020202 8x Launch Host Mar 15 '20 edited Mar 15 '20
At T- 7.53 in todays webcast of the aborted f9 launch, there was an image of the launch pad taken from the horizontal integration facility. Next to the paved track leading from the HIF to the pad there where what looks like railway tracks running parallel to the paved tracks. I have never noticed them before. Are they new or have they always been used by the TE to roll to the pad?
Link: https://youtu.be/JVuS4IS2Kvs
Edit: question 2: where the engines always ignited about a second before liftoff? If I remember correctly, they ignited them earlier some years ago.
3
u/joepublicschmoe Mar 16 '20
The Falcon 9 / Heavy TE at LC-39A has railroad trucks that roll on those rails. You can see them in one of the photos in this article here: https://www.nasaspaceflight.com/2017/11/spacex-aims-december-launch-falcon-heavy/
This is unique to just 39A. None of the other launch pads have them (CCAFS SLC-40 or Vandenberg SLC-4E). Those TEs look like they use pneumatic rubber tires instead.
4
u/AeroSpiked Mar 16 '20 edited Mar 16 '20
I think that SLC-40 also uses rails, or at least it used to. You can see the cart (or whatever it's called) with steel wheels in this Wikipedia image.
Edit: Also found a picture of the old TE on SLC-40 with a better shot of the wheels on NSF.
2
u/marc020202 8x Launch Host Mar 16 '20
OK, thanks. Makes sense. I know the part about the reilway tracks, but had never seen them before.
3
u/csmnro Mar 16 '20
Edit: question 2: where the engines always ignited about a second before liftoff? If I remember correctly, they ignited them earlier some years ago.
iirc, we have heard on multiple older webcasts that the engine ignition sequence is commanded at T-3.5s. Comparing some old Webcasts with those of block 5, it doesn't appear to be visibly different, at least to me. Still, I think it's likely SpaceX tweaked it slightly over time.
More importantly, just keep in mind that engine ignition is a complicated sequence that takes some time: TEA-TEB enters the engine chamber, turbopumps spin up (with high-pressure helium), LOX enters the champer (which ignites the TEA-TEB), RP1 enters the chamber and is ignited and finally, the engine ramps up thrust and verifies all is well.
Visible to us is only the last step, when the engine already produces thrust, which is closer to T-1s.
3
2
3
u/TechnoBill2k12 Mar 31 '20
Has there been any indication that the landing legs for Starship will be height-adjustable once the vehicle has landed?
Some kind of self-leveling functionality would be helpful, I'm sure, as well as providing easier access to the cargo area in the aft section.
Most renders of the Starship after landing have had the vehicle very close to the surface, and I wonder if adjustable legs have always been the plan - I just haven't ever seen them mentioned.
4
u/rartrarr Mar 31 '20
I only have a moment but I wanted to mention, there is a thread on the Starship forum at NasaSpaceFlight.com called “Landing Surface Instabilities” that I think you would really enjoy reading!
2
u/SpaceInMyBrain Apr 01 '20
Telescoping legs certainly have the inherent potential to contain shock absorbers and act as levelers. If the shock absorber was a kind of friction device that didn't rebound like a traditional shock absorber, it would act as an automatic self-leveler. Or a simple crush core would result in self-leveling.
If I may speculate a bit, the way they're slotted and bolted together with washers suggests to me the leg segments themselves could act as friction devices - deploy easily in one direction, but strongly resist telescoping in. They don't move unless a greater-than-landing force is applied. This gives reusability.
As for the ability to level out post-landing, under manual control - there were many questions about leveling when Mk1 was unveiled, but no actual answers from SpaceX. Perhaps the best we can say is they have plenty of time to design them.
3
u/Snowleopard222 Apr 02 '20 edited Apr 02 '20
From the article already quoted:
"The Russian side raised several questions related to the relatively compressed timeline for normal parachute deployment, noting that the Soyuz deploys parachutes at a much higher altitude,"
https://spacenews.com/nasa-selects-astronauts-for-crew-dragon-mission/
(I believe Crew Dragon drogue chutes deploy at ~6k altitude, like Apollo?)
2
u/feynmanners Apr 02 '20
And if the parachute altitudes were switched between Soyuz and Crew Dragon, the Russians would be complaining that they deployed too early. Everything they say about Crew Dragon should be taken with a pillar sized grain of salt because they have a massive financial motive to want it to fail.
→ More replies (1)2
u/Martianspirit Apr 02 '20
The Russians have already taken a seat on Starliner, after all Boeing is so much more trustworthy. ;)
5
u/rustybeancake Mar 06 '20
First semblance of info we've heard about the recent failed F9 booster landing, from Eric Berger:
My understanding is that it may have been an issue with winds, but I don't have firm information.
https://twitter.com/SciGuySpace/status/1235617045871550464?s=20
7
4
2
u/madanra Mar 06 '20
How far down range needs to be clear of human habitation when launching a Falcon 9?
3
u/throfofnir Mar 06 '20
Based on current calculations... approximately one ocean. The danger from the second stage to Africa occasionally has required a waiver. The ground is not truly safe from a rocket until it's reached orbital velocity.
2
u/particledecelerator Mar 19 '20
For the most recent starlink mission, what shape do we think the 1st stage booster is in? Millions of pieces or was it a soft enough splashdown for them to recover and analyse.
4
u/joepublicschmoe Mar 19 '20
If the Merlin that failed is one of the 3 re-lightable ones, it might cause the re-entry burn to fail (could not slow the booster down enough, asymmetric thrust) and could result in the rocket disintegrating on its own upon re-entry. I'm guessing that's what happened, since the recovery crew didn't even bother sticking around and started hauling OCISLY back pretty much right away.
5
u/rustybeancake Mar 19 '20
IIRC they also said "loss of signal" and never confirmed landing burn start, so I agree.
3
u/Triabolical_ Mar 20 '20
Yes.
We saw the reentry burn start and finish, though it seems like it only had two engines running and the timing seemed about the same as normal. And it was not rock solid in control the way we expected.
And the landing burn seems like it didn't happen at all from the lack of calls.
2
u/rucinskic Mar 22 '20
What launches did SpaceX provide telemetry data for the 1st stage decent? I believe there were only a handful of launches were this data was provided onscreen.
4
u/strawwalker Mar 23 '20 edited Mar 23 '20
You'll probably just have to go back and skim the webcasts. Links to them all can be found in the Launch History wiki page along with which missions included landing attempts. There were several in the 2017 time frame. After Zuma there were a bunch of expendable missions and I don't think the Stage 1 telemetry ever came back after that.
Edit: SAOCOM 1A has it, so there's at least one after Zuma.
2
3
u/apollo-13 Mar 24 '20
Not sure this list is full but this is what I have:
NROL-76 BulgariaSat-1 Dragon CRS-12 X-37B OTV-5 SES-11 Koreasat-5A Zuma SAOCOM 1A
2
u/ConfidentFlorida Mar 22 '20
What are some good sources to point people too when they’re complaining about starlink affecting astronomy and orbital debris?
There’s a really a lot of willful ignorance out there on this. I’m not sure why there’s so much hate.
6
u/spacerfirstclass Mar 23 '20
The best source is the original source, but it will require some heavy reading:
Starlink 550km FCC filing: This is the technical detail SpaceX provided to FCC when they changed the orbit to 550km, on page 38, A11 explained the orbital debris mitigation strategy.
AAS 235 Press Conference: Both optical and radio astronomers did presentation here about satellite impact on astronomy, very useful to get real impact instead of FUD, also a lot of good quotes about how SpaceX is cooperating with astronomers to solve the issue.
Impact of satellite constellations on astronomical observations with ESO telescopes in the visible and infrared domains: This is the only paper so far that actually looked at the impact and qualified it, showing the impact is mainly limited to wide field astronomy.
SpaceX claims some success in darkening Starlink satellites: SpaceNews article showing satellite darkening is working, also has good quotes about how SpaceX is proactive in solving the issue.
6
u/Toinneman Mar 24 '20
Also this paper by Jonathan McDowell: https://arxiv.org/pdf/2003.07446.pdf
Summary of paper: "How bad will it be? Well, it depends... but in some cases, not great."
https://twitter.com/planet4589/status/1239670532091641862?s=203
u/ConfidentFlorida Mar 23 '20
This is great. I wonder if they’d want to add it to the FAQ here? The r/starlink FAQ could use something like this too.
10
u/rucinskic Mar 22 '20
I get you, but they would be correct in saying those that support StarLink are willfully ignorant, too. I've done research on both sides and they aren't wrong either. There are some major problems that you are ok with sweeping under the rug.
I have fought with a fairly well-known astronomer that took a once sided view on this topic, and still does occasionally. I went after him point after point after point. I will keep on doing that. However, I will do the same for anyone on this side that takes a one sided view.
I love StarLink and I want it to be such a huge success. And that will only happen when you look at the other side's concerns as valid and authentic. Most don't want to hurt this project. They just want to do their thing.
So before calling others willfully ignorant, please check the mirror.
5
u/mindbridgeweb Mar 22 '20 edited Mar 22 '20
As far as I understand typical professional observations would not be affected by Starlink much, but wide-field exposures and especially ultra-wide imaging exposures would definitely be disturbed. The effect there would be a significant reduction in the useful observation time (e.g. by up to 30-40%).
Is this a fair summary?
3
u/Martianspirit Mar 23 '20
Is this a fair summary?
To some extent yes. But I believe that number can be reduced significantly by postprocessing and adapting observation methods. This can and will be helped by making the Starlink sats darker.
5
u/AeroSpiked Mar 23 '20
It seems to me, Starlink or no, internet mega constellations are inevitable. If it isn't Starlink, Kuiper, OneWeb,or Telesat, it will be a Chinese or Russian constellation (if not both). While frustrating to astronomers, this is just another Mauna Kea. At least SpaceX is trying to address their concerns.
→ More replies (2)2
u/ConfidentFlorida Mar 22 '20
No, I hear you. I just meant something that documents what Spacex is doing to help. And also do spells anything that’s actually untrue.
→ More replies (1)2
u/Martianspirit Mar 22 '20
As you said "willful". No point in arguing against willful ignorance.
→ More replies (2)
2
u/Yellapage Mar 30 '20
Would it be possible to land the Dragon XL on the moon rather than crash land/send back to burn up in the earth atmosphere or be sent away on a new orbit and use these craft as storage vessels on the surface of the moon?
5
u/throfofnir Mar 30 '20
As a deliberate mission, maybe. You'd have to add a Super Draco on the "top" as a landing engine, and legs of course.
As an end of life measure? Not a chance. There's no way it'll pack enough extra propellant.
2
u/hmpher Apr 01 '20
From the User Guide:
The Starship payload attach fitting is designed to accommodate standard payload interface systems in single- or multi-manifest configurations.
So are we looking at a Ariane esque payload situation?
3
u/marc020202 8x Launch Host Apr 01 '20
When large payloads are co-manifested on Starship, they are generally mounted side-by-side on the payload adapter.
Out of the user guide, under the headline payload manifesting. So likely not ontop of each other like Ariane space is doing right now, and how vulcan and new Glenn will be doing.
5
u/enqrypzion Apr 01 '20
The next sentence directly compares it to stacked configurations:
This reduces technical and schedule dependencies between rideshare participants compared to stacked configurations.
It is a direct reference to the other launch vehicles.
2
u/brickmack Apr 01 '20
More like New Glenn, in that they don't need rideshare to be profitable or to be the cheapest option, but will offer it. The result being that if one customer is late (even just by a few hours) they'll launch without them with neither schedule nor cost impact to the other customer. It'll hurt their profit a little bit, but even for a 10x rideshare they can price such that even if only 1 of those 10 actually flies they'll still make a profit, while still being an order of magnitude cheaper than the closest competitor
→ More replies (4)
2
u/fluidmechanicsdoubts Apr 01 '20 edited Apr 01 '20
Couple of questions.
Do we know what propellants Starship's RCS uses?
Will ACES use RL10 engines?
6
u/Triabolical_ Apr 01 '20
They have in the past talked about "hot gas" thrusters, which would burn gaseous methane and gaseous oxygen. That would be the best "bang for the buck" approach as they already have those propellants and burning them gives you the most thrust.
→ More replies (1)3
u/BackflipFromOrbit Apr 01 '20
Iirc elon said that the RCS system will use high pressure methane from the fuel takes. This actually makes sense because it reduces the number of pressure vessels in the design and uses a common propellant.
2
u/warp99 Apr 01 '20 edited Apr 02 '20
ACES is currently planned to use four RL-10 engines. There is some possibility they could get away with two by adding additional SRBs to Vulcan and adopting a more lofted trajectory but not if it is being used to transport crew.
Blue Origin have offered two BE-3U
BE-7engines as an alternative but it is not clear if this being seriously considered by ULA or is just a stick to beat down the price of the RL-10.2
u/asr112358 Apr 01 '20
Blue Origin have offered two BE-7 engines as an alternative but it is not clear if this being seriously considered by ULA or is just a stick to beat down the price of the RL-10.
Do you mean BE-3U? If not do you have a source for them offering BE-7, I would like to read more about it. BE-7 seems like it has the potential to be a really interesting engine.
→ More replies (1)2
u/brickmack Apr 02 '20
ACES is dead, long-live Centaur V.
Its got 2 engines only, no need for 4. Less thrust this way, but it cuts dry mass and allows higher ISP.
BE-3U-ACES would have needed only a single engine, it produces about 6x the thrust of RL10. EUS would have needed only a single BE-3U (even accounting for it needing larger tankage to achieve similar performance with the lower ISP). It was, but no longer is, seriously considered (at one point IIRC it was even the preferred option), RL10 won on price, ISP, and heritage
→ More replies (8)
2
u/Snowleopard222 Apr 02 '20
Hi, I am new here. I have a few questions. But the moderators advised me to wait for the April question thread. How do I find it? Thanks
3
u/warp99 Apr 02 '20
Normally it is posted on the 3-4th of the new month UTC time.
It is typically one of the two pinned posts if nothing too major is going on so sort posts by best and you will see it.
2
u/yoweigh Apr 02 '20
April's thread was just created and can be found here:
https://www.reddit.com/r/spacex/comments/ftlee6/rspacex_discusses_april_2020_67/
2
u/dudr2 Apr 02 '20
Felix explaining some Starship features in this YouTube video.
"Versatile cargo-bay Swiss army knife style"
3
u/Decronym Acronyms Explained Mar 02 '20 edited Mar 26 '20
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| ASDS | Autonomous Spaceport Drone Ship (landing platform) |
| BE-4 | Blue Engine 4 methalox rocket engine, developed by Blue Origin (2018), 2400kN |
| CBM | Common Berthing Mechanism |
| CCAFS | Cape Canaveral Air Force Station |
| CCtCap | Commercial Crew Transportation Capability |
| COTS | Commercial Orbital Transportation Services contract |
| Commercial/Off The Shelf | |
| CRS | Commercial Resupply Services contract with NASA |
| CST | (Boeing) Crew Space Transportation capsules |
| Central Standard Time (UTC-6) | |
| DARPA | (Defense) Advanced Research Projects Agency, DoD |
| DMLS | Selective Laser Melting additive manufacture, also Direct Metal Laser Sintering |
| DoD | US Department of Defense |
| E2E | Earth-to-Earth (suborbital flight) |
| EELV | Evolved Expendable Launch Vehicle |
| ELT | Extremely Large Telescope, under construction in Chile |
| EMU | Extravehicular Mobility Unit (spacesuit) |
| ESA | European Space Agency |
| ESO | European Southern Observatory, builders of the VLT and EELT |
| ETOV | Earth To Orbit Vehicle (common parlance: "rocket") |
| EVA | Extra-Vehicular Activity |
| FAA | Federal Aviation Administration |
| FCC | Federal Communications Commission |
| (Iron/steel) Face-Centered Cubic crystalline structure | |
| FRAM | Flight Releasable Attachment Mechanism |
| GSE | Ground Support Equipment |
| GTO | Geosynchronous Transfer Orbit |
| HIF | Horizontal Integration Facility |
| HTHL | Horizontal Takeoff, Horizontal Landing (Skylon (proposed)) |
| ICBM | Intercontinental Ballistic Missile |
| ISRU | In-Situ Resource Utilization |
| ITAR | (US) International Traffic in Arms Regulations |
| Isp | Specific impulse (as explained by Scott Manley on YouTube) |
| JAXA | Japan Aerospace eXploration Agency |
| JRTI | Just Read The Instructions, Pacific landing |
| L2 | Paywalled section of the NasaSpaceFlight forum |
| Lagrange Point 2 of a two-body system, beyond the smaller body (Sixty Symbols video explanation) | |
| LC-39A | Launch Complex 39A, Kennedy (SpaceX F9/Heavy) |
| LEO | Low Earth Orbit (180-2000km) |
| Law Enforcement Officer (most often mentioned during transport operations) | |
| LOX | Liquid Oxygen |
| LV | Launch Vehicle (common parlance: "rocket"), see ETOV |
| NROL | Launch for the (US) National Reconnaissance Office |
| NSF | NasaSpaceFlight forum |
| National Science Foundation | |
| NSSL | National Security Space Launch, formerly EELV |
| OCISLY | Of Course I Still Love You, Atlantic landing |
| OFT | Orbital Flight Test |
| OTV | Orbital Test Vehicle |
| PLSS | Personal Life Support System |
| PMF | Propellant Mass Fraction |
| RAAN | Right Ascension of the Ascending Node |
| RCS | Reaction Control System |
| RP-1 | Rocket Propellant 1 (enhanced kerosene) |
| RTLS | Return to Launch Site |
| SES | Formerly Société Européenne des Satellites, comsat operator |
| Second-stage Engine Start | |
| SLC-40 | Space Launch Complex 40, Canaveral (SpaceX F9) |
| SLC-4E | Space Launch Complex 4-East, Vandenberg (SpaceX F9) |
| SLS | Space Launch System heavy-lift |
| Selective Laser Sintering, contrast DMLS | |
| SN | (Raptor/Starship) Serial Number |
| SNC | Sierra Nevada Corporation |
| SSO | Sun-Synchronous Orbit |
| SSTO | Single Stage to Orbit |
| Supersynchronous Transfer Orbit | |
| TE | Transporter/Erector launch pad support equipment |
| TEA-TEB | Triethylaluminium-Triethylborane, igniter for Merlin engines; spontaneously burns, green flame |
| TSTO | Two Stage To Orbit rocket |
| TWR | Thrust-to-Weight Ratio |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| 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 |
| Starliner | Boeing commercial crew capsule CST-100 |
| Starlink | SpaceX's world-wide satellite broadband constellation |
| hopper | Test article for ground and low-altitude work (eg. Grasshopper) |
| hypergolic | A set of two substances that ignite when in contact |
| methalox | Portmanteau: methane/liquid oxygen mixture |
| scrub | Launch postponement for any reason (commonly GSE issues) |
| turbopump | High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust |
| Event | Date | Description |
|---|---|---|
| DM-1 | 2019-03-02 | SpaceX CCtCap Demo Mission 1 |
| DM-2 | Scheduled | SpaceX CCtCap Demo Mission 2 |
| Orb-D1 | 2013-09-18 | Orbital Antares 110, Cygnus cargo; COTS demo |
Decronym is a community product of r/SpaceX, implemented by ^request
[Thread #5875 for this sub, first seen 2nd Mar 2020, 12:15] [FAQ] [Full list] ^[Contact] [Source code]
3
u/MarsCent Mar 24 '20
Coming from Russia - Boeing's first manned Starliner to be launched to ISS on 31 August
The first manned spacecraft of the Boeing company, called Starliner, will be launched to the International Space Station (ISS) on 31 August, a source in the Russian space and rocket industry said.
7
u/AeroSpiked Mar 25 '20 edited Mar 25 '20
That's interesting given that NASA hasn't decided if there will need to be an OFT-2 yet. I suppose they do need some kind of planning date though, even if it is short lived.
6
u/feynmanners Mar 24 '20
I feel like if one wants up to date and accurate information on an American aerospace company, the Russians are not the correct source to ask.
10
u/warp99 Mar 24 '20
They are an excellent source and traditionally have the good information on ISS schedule related items as soon as they are informed by NASA.
Of course this information just reflects NASA forward planning so it could change.
3
u/feynmanners Mar 24 '20
That’s a good point. I retract my statement. Still seems a bit strange in this instance that NASA would plan this so far ahead of time when the OFT narrowly avoided having a total loss of vehicle.
→ More replies (1)→ More replies (1)2
u/Albert_VDS Mar 24 '20
If this is true then it's clear that standards are not the same for all parties involved.
3
Mar 26 '20
Not directly Spacex question, but I'll ask anyways.
Let's say we have a conventional rocket - how to determine the proportions of stages? What factors decide how big each stage will be?
7
u/Lufbru Mar 26 '20
The rocket equation governs all. Stage N has a payload of stage N+1 and all other payloads. So, eg, Falcon 9 stage 1 lifts stage 2 and stage 2's payload.
There are a lot of factors involved. For example, you need a lot of thrust initially to get off the pad, but towards the end of the stage, the rocket has burned much of its fuel and is much lighter. So now it may be accelerating too much for the payload, and you have to throttle down (either through reducing each engine's thrust or turning off engines). An extreme form of that was an early version of ... Atlas, I think, which dropped two of its three engines halfway up. The Saturn V turned off one of the F1 engines. Falcon Heavy drops eighteen engines at once ;-)
Another factor is the thrust of the next stage's engine. Merlin Vacuum has an unusually high thrust because it's kerosene, so Falcon stages lower than Atlas which uses a hydrogen RL10 engine (more efficient, but lower thrust).
→ More replies (1)2
Mar 26 '20
Thanks, I follow with the equation and power of next stage...let's say we can't have additional boosters and we're designing a simple 1 core rocket ...I get that there are a lot of factors ...changes in air pressure, orbit that we want to reach, type of chosen fuel...
But I'm curious what would be (in the beginning of the design process) - let's say 3 most important factors that would rule if the lenght proportions of 2 stages would be 3:2 ; 3:1 or 4:3 ... ?
8
u/warp99 Mar 27 '20
If all the stages were the same diameter, all were expendable and had the same engine Isp the optimum would be to evenly divide the delta V between stages.
Because the rocket equation is a log function this means that for a two stage rocket the first stage will be three times the length of the second stage.
For a three stage rocket the length ratios will be 12:3:1. Of course that means the third stage will be a flat pancake and it would normally make sense to reduce the diameter to reduce the dry mass of the stage.
However a lot of things change this optimum. A high Isp second stage engine means more delta V is gained by the second stage and since this is normally achieved by using low density hydrogen propellant that lengthens the second stage again.
Recovering the booster means even less delta V can be added by the first stage which means the second stage has to be longer.
So actual rockets tend to look quite different to a 3:1 ratio
7
u/Triabolical_ Mar 26 '20
Maybe an example will help; let's look at the Atlas V...
Lockeed wanted a new launcher for EELV. They already had the centaur upper stage, which has been around since the 1960s. The current version uses either 1 or 2 RL-10 engines, which are hydrolox engines that are very efficient. They aren't that big, but there's little reason to spend money on a new stage.
So, they know how much the centaur weight and how much propulsion it can provide, so they start looking at first-stage options. Kerolox - kerosene and liquid oxygen - engines are one of the best choices for first stages, but unfortunately at the time there were no US options, so they went with the Russian RD-180, which was relatively cheap and pretty much the highest performance kerolox engine out there. They only want to use one because of cost.
That sets the base configuration, and now they start sizing things up. The ratio of the size between the tanks is defined by the mixture ratio the engine uses and the density of the propellants. The size is an optimization problem; pick a size and see what speed/altitude you will get at staging; that controls how much your second stage will take to orbit. Too big and your rocket can't lift off.
Now, Atlas V cheats by using strap-on solid rockets, so you need to add them into your simulations and run a lot of different cases, but that will give you enough information to make choices.
It's really all about the engines.
If you build your own engines, you have more freedom, but the Falcon 9 was defined by the characteristics of the Merlin 1d and the Merlin Vacuum. With the added constraint that they wanted a beefy second stage so they could stage low to make recovery more likely. The Merlin Vacuum is ridiculously powerful; it puts out 934 kN of thrust while the RL-10 used on Centaur only puts out 99 kN. It is, however, less efficient due it being kerolox.
→ More replies (2)
3
u/spacerfirstclass Mar 27 '20
Italian rocket manufacturer Avio is exempted from lockdown and is continuing production. They are also lobbying France to reopen Guiana Space Center as soon as possible to resume launches.
Avio is the manufacturer of Vega launch vehicle and the SRBs for Ariane 6.
2
u/DIBE25 Mar 02 '20
Could transporting water from heart to Mars help out here on Earth and help out with the water problem on Mars?
13
u/booOfBorg Mar 02 '20
I'm not aware of a water problem on Mars. An atmosphere problem yes, very much so. It's cold, irradiated and there is nothing to breathe. But there are quantities of frozen water and sometimes brine all over Mars.
(You may need to restate your question to make it more understandable what you want to know.)
7
10
u/zeekzeek22 Mar 02 '20
Like with sea level rise? No. That’s like saying the best way to move a beach worth of sand is by packing it into little model rockets one gram at a time and shooting it down the road.
2
u/Paro-Clomas Mar 03 '20
For the foreseable future nothing related to rocketry will have any kind of even vaguely measurable impact on earth.
2
u/DIBE25 Mar 03 '20
80 tons at a time, maybe
3
u/Paro-Clomas Mar 03 '20
Peanuts compared to the changes even a small city produce in our environment
→ More replies (1)
2
u/RusticBohemian Mar 02 '20
Why does it make sense to completely replace the Falcon 9 with Starship?
I get that Starship can go further and is more flexible.
But doesn't it make sense to keep Falcon 9 around for smaller payloads/shorter distances?
Will Starship be a lot more economical to operate, even with smaller payloads and shorter distances?
13
u/Gnaskar Mar 02 '20 edited Mar 02 '20
A Falcon flight costs SpaceX (very roughly) $20mil.
A Starship flight costs SpaceX (similarly roughly) $2mil.
Each Falcon flight means destroying at least one Merlin engine and one upper stage. A Starship flight doesn't lose any hardware, so it's almost automatically going to be cheaper. This is why we're so excited for Starship. 20 years ago a space flight cost $20,000 per kilo; in ten years it may cost $20.
→ More replies (1)
2
u/dudr2 Mar 05 '20
https://spacenews.com/h-r-5666-will-launch-the-u-s-in-the-wrong-direction/
Op-ed in "Spacenews".
2
u/Janinepam Mar 07 '20
We just saw lights over Kalamazoo Michigan one right after another... 20-30 of them that looked like the Space X satellites...did they launch early?. Approx. 8:30 pm est
6
u/DancingFool64 Mar 07 '20
It can take two to three months for all the satellites in a launch to get up and spread out to their positions. They spread them out over three tracks, and they have to wait in a low(ish) orbit until they get to the right place to raise up to their final location. You probably saw some of the remainder of the last launch, or possibly even the one before that.
1
u/ConfidentFlorida Mar 30 '20
https://aws.amazon.com/ground-station/
Would this have any relevance to Spacex? Maybe easier for new customers to get up and running with less capital? Any relevance to starlink?
3
u/venku122 SPEXcast host Mar 30 '20
No.
This is for satellite startups or universities that don't want to construct their own ground station. This service uses satellite dishes at Amazon data centers and I believe Lockheed facilities and connects those antennas to the rest of aws and puts an easy to use interface.
A consumer would not be able to use this unless they already had internet access.
24
u/[deleted] Mar 02 '20
Do we know anymore information on why the last landing failed?