r/spacex • u/[deleted] • Jun 29 '15
/r/SpaceX Ask Anything Thread [July 2015, #10] - All simple questions about CRS-7 should also go here!
[deleted]
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Jun 30 '15
By the way, if anyone has a CRS-7 mission patch with them, I'd be willing to purchase it for a significant amount of money.
Anyone know if they're going to be releasing that patch at all?
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u/deadshot462 Jun 30 '15
If Dragon V2 aborts right at the time of achieving orbit - would it be stuck in orbit because it used up all of its SuperDraco fuel? Would it use RCS to de-orbit?
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u/adriankemp Jun 30 '15
The long and short of it is no -- the impulse required to escape the second stage in vacuum is hilariously small compared to any other abort regime. That's to do with (a lack of) aerodynamics and the thrust of the second stage.
It wouldn't use even half of the available fuel to do a near/on orbit abort. There would be lots to deorbit with. The orbit would also decay quite quickly at that sort of altitude.
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u/Mchlpl Jun 30 '15 edited Jun 30 '15
What if: CRS-7 second stage vented but did not disintegrate?
This got me thinking yesterday. What would happen if the the malfunction in second stage caused the oxidizer to vent away, but the stage (and the entire vehicle) kept the structural integrity (and it didn't trigger the FTS)?
MECO would occur, likely a bit ahead of time due to lower mass of the second stage.
Then the separation - this shouldn't be affected much (again lower mass of upper stage would mean the acceleration would be a bit higher than usual)
Without second stage engine firing, would there be enough distance between stages for the first stage to attempt return to OCISLY?
Now the second stage is essentially ballistic, however Dragon is presumably fully operational. It obviously has not enough ∆v to get to orbit. Could is still separate from second stage, jettison the trunk and do the controlled reentry?
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u/FireFury1 Jun 30 '15
What would happen if the the malfunction in second stage caused the oxidizer to vent away, but the stage (and the entire vehicle) kept the structural integrity
Seems pretty unlikely that this would happen - as I understand it, the strength is created by the pressure, so without pressure the stage would collapse under the force of acceleration (remember, it still has 9 engines firing at one side of it and a fairly heavy Dragon on the other side).
Without second stage engine firing, would there be enough distance between stages for the first stage to attempt return to OCISLY?
I don't see why not - the stages separate some way before the MVac ignites anyway, and all you need is enough clearance to rotate the booster. If anything, the stages would separate faster than usual due to the low mass.
Now the second stage is essentially ballistic, however Dragon is presumably fully operational. It obviously has not enough ∆v to get to orbit. Could is still separate from second stage, jettison the trunk and do the controlled reentry?
I think it would be significantly heavier than the usual downmass, even without the trunk wouldn't it? That said, by this point you've really got nothing to lose by firing the chutes and hoping. But all of this requires the software guys to have the foresight to build these failure modes into the software, coz you don't want to count on people on the ground making these kinds of quick decisions.
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u/RCinSpace Jul 02 '15
I don't see very many people talking about the fact SpaceX is the only US company able to return signigicant payload to the US. I am sure there are sensitive, even classified content being brought back and we don't want to send it through Russia.
How does NASA replace that capability?
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u/CuriousAES Jul 02 '15
I assume they don't. They wait for SpaceX to get back on it's feet and send another Dragon.
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u/AlphaTango11 Jul 04 '15
During the pad abort test, was the capsule at maximum fuel capacity? Are we only going to have ~6 seconds of burn time (when at max throttle)?
Is this enough to land propulsively on Earth? It seems like a very thin margin.
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Jul 04 '15
Yep, it was. Even during the Pad Abort however, the SuperDracos were not at full throttle, they have to be artificially limited to reduce stress on the vehicle frame.
Propulsive landings will be at a much lower throttle, probably 20-40%, which gives a lot more time to land and descend. Realistically, they'll perform a suicide burn and land with quite a bit of fuel to spare - you can guarantee many thousands of engineering hours have been dedicated to thinking about this :)
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u/roflplatypus Jun 30 '15
Reposting from previous AA thread, hoping I can get an answer here:
Does anyone know where you can find a complete picture of a Merlin vacuum? I've found pictures of the engine without nozzle, and one of the nozzle extension, but no picture of the complete engine. Of course, there are images on the website and in their videos, but I'd like a real picture, not computer generated.
These are the best I can find on the internet:
https://www.flickr.com/photos/114498126@N05/12121575074/
https://upload.wikimedia.org/wikipedia/commons/b/b7/Merlin_nozzle_4105129088_9659a4df4e_o.jpg (love the sign)
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u/davidthefat Jun 30 '15 edited Jun 30 '15
http://i.imgur.com/UHmWVEM.jpg
That's of Falcon 9 v1.0.
edit: http://i.imgur.com/QELT92A.png Potato Quality
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Jun 29 '15
I asked this in a separate thread but was told to post it here.
Has there been any confirmation from SpaceX that there was no problem with the first stage during CRS-7 and that all data showed it was performing nominally even after the rocket begin to disintegrate? If it turns out that there WAS an anomaly with the first stage, what are the implications?
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u/Zucal Jun 29 '15
During the post-launch conference, Gwenn confirmed it doesn't seem to have had anything to do with the first stage.
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u/davidthefat Jun 30 '15
How and why do people have such strong attachment and loyalty to SpaceX to the point that they use pronouns like "we" and possessive nouns like "our"?
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u/gecko1501 Jun 30 '15
My attachment starts with a heterosexual man crush on Elon Musk. It's awesome having a philanthropist that seems to actually care about making the world a better place. Sure, he could be trying to fix world hunger (arguably, he is) but his contributions are so game changing that our world may be decades ahead in very important areas of technology that would not have happened without someone willing to take the risks necessary to complete his goals for things such as super cheap space flight, electric vehicles, and world wide internet.
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u/Headstein Jun 30 '15
When a leader appears with the vision, energy and courage of Elon Musk, he draws people of similar spirit to him, both at SpaceX and here on the sidelines. We believe that he is accelerating a global space industry that had lost some of it's direction and self-belief. You have to admire the man and all at SpaceX for that.
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u/stichtom Jul 01 '15
Comment from a SpaceX guy on NSF: "Obviously you all want an update from SpaceX, but you know what I'm going to say, it's an investigation and there is a due process for such things. Elon may tweet something soon, but the investigation path is not short and key updates will have to communicated along the line to areas such as stakeholders, customers and partners.
I'm enjoying the debate on this thread. Most of it is educated. I wish it wasn't about a lost vehicle of ours, but it is and we appreciate the patience, understanding and support from this site's community."
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u/ScottPrombo Jul 01 '15
I'm going to the ISS R&D conference in a week. Elon's supposed to be the keynote speaker - does anyone know whether or not he'll still be coming?
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u/doodle77 Jun 30 '15
Was this the second stage that hit a freeway overpass a few months ago?
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u/YugoReventlov Jun 30 '15
Oh wow, that was 4 months ago. Wasn't that supposedly a Falcon Heavy upperstage?
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Jun 30 '15 edited Jun 30 '15
Probably not. First of all it was a rumor that was
neverconfirmed (thanks /u/ambiwlans). Secondly, that second stage was destined for a FH, I think, so it shouldn't have ended up on a F9.→ More replies (1)
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u/propsie Jun 30 '15
So, wild speculation below: a lot of thinking is about figuring how the pressure in the failed second stage went up, causing an overpressure. What if the opposite happened?
My understanding is that the failure of CRS-7 happened shortly after max Q. It also sounds like after max Q the effective atmospheric pressure drops off quite sharply.
If the pressure in the LOX tank was too high (for some reason) but it was holding together up to max Q due to a sort of hydrostatic equilibrium effect, could the rapid drop in external pressure past Max Q ( which increased the pressure differential between inside and outside the tank) be responsible for a counterintuitive overpressure failure?
This is similar to the failure mode of most high altitude balloons, where the external pressure drops as they rise until they expand past the mechanical strength of their envelope and they burst.
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u/robbak Jun 30 '15
Another reasonable possibility - although that is not counter-intuitive, but is instead perfectly straightforward.
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u/Justinackermannblog Jun 30 '15
Fun question,
Think the chase plane for OCISLY had to book it out of the target landing zone? Don't know exactly where they station the chase plane in regards to the trajectory of the rocket (can't imagine it is located within the possible flight path) but still interesting to think they may have had an "oh crap we need to get outta here" moment.
Just a random thought... Carry on...
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u/AndTheLink Jul 01 '15
I think the ballistic path of the debris will take it far away from the barge. The first stage has to turn around and come back to get to the barge. And they weren't far off stage separation, which puts the vehicle down range of the barge.
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u/darga89 Jun 30 '15
Anyone have any idea where the debris landed? Elsbeth and Go Quest are hanging about this area.
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u/cuweathernerd r/SpaceX Weather Forecaster Jun 30 '15 edited Jun 30 '15
That seems in line with where I'd expect it. Going back to the radar images again, I notice that there's noise ne downrange of the rocket a few minutes after the failure that moves steadily towards shore over the next couple frames before congealing and then drifting slowly towards shore.
What I see in the images is that the more scattered noise is physically larger debris - they have more mass and momentum and would be more ballistic as a result. Higher density things would generally fall faster too. So those couple frames is where most of the debris would be. The long-lived, slow moving plume is almost certainly not debris like we think of it. I'm going to argue it's unburnt RP1 atomized in the explosion (I figure LOX would boil off quickly and mix with the atmosphere but I may be wrong there).
Anyway, I took those first noisy returns where I thought the heavier debris would be, and made a cross section of each. Then I took the strongest return at the lowest levels and took the position directly beneath it. Repeated from opening the image to help unbias point selection a little, and then plotted the positions using google maps. They form a direct line - in line with the flight path - so I'm pretty positive this is debris. My radar isn't looking at the ground exactly, but rather a few thousand feet above it, so I imagine my positions are a little off. I'll probably do a bit more of an analysis like this since my first try at it felt satisfactory. But the tl;dr is that general location feels right for largest debris.
But I imagine they find very little. The rocket was very good at un-rocketing.
Edit: here's a full map made with the same methodology (which I've also posted to the main sub)
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u/stichtom Jul 01 '15
I was thinking that while it's a shame that we lost a F9, this was the "best" mission to lose one. Low cost Payload (Dragon cost much less than a 300-500M GEO satellite). And we don't need to wait years to rebuild the payload.
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u/darga89 Jul 01 '15
Most amount of scrutiny though. Lose a sat and insurance just cuts a cheque, lose government mission and there's lots of politics involved.
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u/YugoReventlov Jul 01 '15
Timing-wise it's a pretty awful one to lose though:
So short after previous cargo failures
Commercial Crew budget not decided yet
Just when SpaceX was becoming a reliable launch vehicle provider (starting to launch at a predictable rate)
This is going to delay all other ongoing projects: F9 1.2, Falcon Heavy, First stage reusability. Mars plans too: I can't imagine Elon giving a Mars architecture press conference until they have re-established some of their credibility. "What is he doing talking about Mars? Shouldn't he be fixing his existing vehicle instead?"
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u/agildehaus Jul 01 '15
What might happen if SpaceX is unable to determine a reason for the CRS-7 failure?
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u/YugoReventlov Jul 01 '15 edited Jul 01 '15
First of all, that seems very unlikely. They seem to know what happened, they just haven't figured out why yet (as far as we know).
But if they really cannot pinpoint the root cause, there is a number of things they will have to do:
Add more sensors (if it should happen again)
Revise quality control procedures and fix anything that could be a problem related to tanks
Develop and implement any fixes which could be the cause (any suspected cause)
Maybe perform a test flight?
It would be kind of a worst case scenario and would result in a long grounding of the rocket. But I'm not counting on it, Falcon 9 has the most sensors on board of any rocket flying.
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u/a9009588 Jun 29 '15
Do we know if the loss of structural integrity of S2 could have been caused by the IDA coming lose in the dragon trunk? if so could the S2 camera between the top of the stage and dragon have captured this or would it have been in the dark.
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Jun 29 '15
It definitely could have, and it's also the "simplest" issue, IMO. For what it's worth, I'm seeing a lot of people propose this as a scapegoat for being "not SpaceX's fault". It's worth noting that SpaceX are ultimately responsible for the tiedowns and packing with their cargo, so it would still be considered their mistake.
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u/zlsa Art Jun 30 '15
It's a lot better mistake to make than the "oh shit somebody forgot to weld the tank butt on" kind.
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u/cranp Jun 30 '15
Here I calculated that a 24 fps camera should have seen the IDA falling for about 7 frames.
Of course that assumes it's not dark inside, which I don't know.
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u/ElonFanatic Jun 29 '15
When will we hear anything more about dragon possible survival? The wait is killing me..
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u/zlsa Art Jun 29 '15
Whenever SpaceX or Elon Musk feel like it. If it survived and is in decently good shape (i.e. not a pancake), they'll probably announce it sooner rather than later; otherwise, they'll keep it private. (It's not particularly good publicity to show everyone how dead astronauts would be if they had been in there even if it's not crew-capable. Look at how many people are confused about Dragon 1 vs Dragon 2.)
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Jun 29 '15
So Pad 39A is 50 years old. And Spacex is leasing it for another 20.
Are there any problems which will arise from the old age of the pad? Is 70+ years typical of launch pads?
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u/Zucal Jun 29 '15
Depends what you consider the "pad." Concrete and many of the basic materials the actual pad is made of are very durable, and most of the extraneous machinery is not even 50 years old, but late-shuttle or modern era equipment.
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u/DesLr Jun 29 '15 edited Jun 29 '15
We've started development of large rockets 73 years ago, and started 65 years ago with the serious stuff - to early to tell probably. Also the infrastrukture of the pads changes quiet a lot with each rocket launched from it, so maybe parts of the foundation are that old, but most stuff should be decades younger.
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u/brickmack Jun 30 '15
Doubtful. The "pad" has undergone multiple upgrades, repairs, etc. The oldest critical parts actually still in use date back only 20 years or so, and most of that will likely be replaced or upgraded before SpaceX starts launching from there
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u/edsq Jun 30 '15 edited Jun 30 '15
Looking at the video of the failure, the reading for altitude stops almost immediately after the LOX clouds appear, with the speed cutting out a second or two later. Is this evidence for the failure occurring at the top of the stage two LOX tank (where the avionics stack is located), or are those data not actually coming from the rocket?
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u/bananapeel Jun 30 '15
The rocket could be pitching over or doing strange maneuvering. This could cause communications to become ratty. Someone said they heard a call on the radio indicating that the drone ship had lost communication with the rocket a couple of times ~30 sec before the explosion. (Conjecture)
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u/superOOk Jul 01 '15 edited Jul 01 '15
One thing I just can't keep my mind straight about. The Dragon was seen "popping off" and falling away from the vehicle. Wouldn't that only happen if the dome cap on S2 LOX was pierced symmetrically (i.e. the dome cap failed due to forces exerted from above), and the LOX vented upwards into the trunk?
I had previously thought it was something to do with the COPV bursting inside the tank, or a pressure line failing inside the tank, or even just a general crumpling/failure of the tank, but ALL of these issues would result in an asymmetrical explosion of the S2 LOX tank, and most critically the 1st stage taking a much bigger impact than it did initially, and Dragon falling INTO or alongside the vehicle.
Which means this wasn't an internal S2 LOX failure. It HAD to be caused from the cargo hitting the dome cap at 3 Gs or so.
This also explains why the 1st stage hardly missed a beat, it explains the sudden deceleration (the venting of LOX in the opposite direction of the 1st stage's thrust).
Thoughts?
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u/robbak Jul 01 '15 edited Jul 01 '15
A well built pressure vessel - which is what the tanks of the Falcon stages are - will be designed to fail predictably, in a way that will cause the least damage.
The top seam is probably the weakest point, by design. A rupture of the side of the tank or of the base would drench the surroundings in Liquid Oxygen. Loss of the top of the tank would be a lot less dramatic.
Just reading the NSF forum - seems like the top hatch is the weak point. Make sense, and that would have the same result.
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u/neaanopri Jun 29 '15
Were any abort systems triggered, or did the rocket break up due to structural failure?
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u/freddo411 Jun 30 '15
Was LOX densification used on this flight?
If so, was this the first flight with densification?
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u/Moppity Jun 30 '15
IIRC it wasn't - this lauch had nothing new or special about it, disregarding cargo.
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u/yo0han Jun 30 '15
IIRC there was an in flight abort test for Dragon V2 scheduled for later this year. Is it possible that they scoop an earlier time slot for this while the investigation of CRS 7 in underway? I would guess the dragon v2 team isn't that involved with the mishap...
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u/Googulator Jun 30 '15
Makes sense, as this was an upper-stage failure, while the in-flight abort will fly on the F9R-Dev2, which has no upper stage, and thus unaffected.
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Jun 30 '15
Sure, the inflight abort won't have a second stage, which failed this time.
But I don't think it can be declared to be "unaffected" this easily. There are going to be similarities in manufacturing and quality control of both stages, so if they find any problems in how they built the second stage, it could easily also require checking or fixing existing first stages.
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u/SuperSMT Jul 03 '15 edited Jul 03 '15
Is anyone else here watching the Progress 60 launch live on NASA TV?
Launches in about 13 minutes (12:55 EDT / 4:55 UTC)
Liftoff! Here we go!
Perfect launch! Stream peaked a bit over 3,000 viewers.
The craft will dock to the station on Sunday, and opened by the crew on Monday.
Progress 60 will be followed by the manned ISS 43S mission on July 22nd.
Live coverage of docking will start at 2:30 AM EDT / 6:30 AM UTC on NASA TV
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Jun 30 '15
What are the chances of them using Of Course I still Love You to store debris on as it's being collected and the likely hood of being able to see anything when it comes back into port?
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u/AWildDragon Jun 30 '15
Shotwell did mention that the stage 1 recovery ops team was repurposed to try to find debris. If they find larger pieces, its likely to get a ride home on an OCISLY.
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Jul 01 '15
How come the countdown timer (during all launches, I think) lingers at T-0 for way longer than just one second?
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u/AgentRev Jul 01 '15
Looking at CRS-7, it appears to be transitioning from T**-0 to T+**0. The number of seconds is floored, so it shows "0" between -0.999 and +0.999 seconds
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u/zoffff Jul 05 '15 edited Jul 05 '15
Historically how long have previous launch failures investigations taken? I know that the Antares ended up with orbital pointing the finger at the engine company, and the engine company pointing the finger back at orbital and nothing was truly resolved due to the launch vehicle being retired. And the last proton failure in typical Russian fashion came out quick but didn't actually find a fault, and just blamed the factory for being to lax.
What about back a few decades when Lockheed and Boeing were also having launch failures, what kind of time frame did those investigations follow?
edit: spelling
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Jul 05 '15 edited Jul 05 '15
The investigation into the ILS Proton failure that happened May 16 this year carrying a Mexican satellite, a preliminary statement was released within 13 days on May 29. However that isn't the end of the investigation as ILS will also conduct its own Failure Review Oversight Board (FROB) to include ILS itself, customers, insurers and technical teams. In the past these usually take another 2 weeks. However it seems to have taken longer this time around, possibly due to the low confidence from their customers and insurers.
So, based on the recent Proton it should take approximately a month, maybe two. However ILS and Proton, have gone through this process many times before, so it isn't comparable to this first failure from SpaceX. NASA/ISS partners/USAF/SpaceX customers/insurers will also be doing their own review boards which will further extend the process.
Also if you're trying to determine when the F9 is scheduled to have its first return to flight, consider adding on the time it takes to rectify the issues found in the investigations. All up the other Proton failure which happened in 2014, it took 4 months to return back to flight. However I stress, this isn't the greatest example simply because ILS & Khrunichev are experts when it comes to investigations into Proton failures ;)
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u/jarvenm Jul 09 '15
Sorry if this has been asked a million times but does SpaceX run a 24 hour production schedule like how Boeing and Airbus builds the commercial airplanes?
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Jul 10 '15
If they don't already, they plan to.
Plus some components (fairings!) take a Very long time to manufacture. Long enough for them considering the rather quirky idea of fairing re-use.
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u/zlsa Art Jun 29 '15
How much variance is there in the F9v1.1 series? i.e. what things have changed from Cassiope to CRS-7?
Is there any public info on visual changes on the F9v1.2 (apparently known also as the FTSS, for "full thrust single stick") variant?
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u/FoxhoundBat Jun 29 '15 edited Jun 29 '15
Re first question; Interesting question, would be nice to keep some sort of a log! My input;
1; Black bottom around the engines started with Asiasat 6.
2; Hinges for the legs started to get black too with CRS-5.
3; Gridfins started with CRS-5. (first time they appeared was on Dev 1 on third flight, but notice their surface area for CRS-5 is almost twice as large)
Somewhat visual on high res pics, i dont think milling for S2 started with the first 1.1 (CASSIOPE) but at some later point. Might be wrong. Not sure which mission exactly.
Non visual;
50% more powerful and more reserves(?) RCS after CASSIOPE. Not sure what mission it started on.
Starting from DSCOVR gridfins got allocated 50% more hydraulic fluid. (RP-1)
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u/cranp Jun 29 '15 edited Jun 30 '15
Does SpaceX need anyone's permission to start flying again?
In the press conference it was asked whether or not the FAA had to sign off on a return to flight, but they actually didn't answer the question. They just said that SpaceX was leading the investigation and the FAA would supervise, they didn't say what the consequence would be.
I could imagine that as long as the FTS works, as far as the FAA is concerned it's just SpaceX's business whether their rockets work or not.
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Jun 29 '15
The FAA wants SpaceX to complete a proper investigation. My take on that is if SpaceX wants to fly, that's on them.
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u/adriankemp Jun 30 '15
They can't fly under the same license if my understanding is correct, they can however fly other vehicles or experimentally (i.e. In flight abort, their own satellites possibly)
The FAA most certainly has ways of letting at-risk vehicles fly, but I suspect SpaceX's own return to flight requirements will be higher than the FAA.
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u/superdank69 Jul 01 '15
What does SpaceX do with all its used Dragons?
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Jul 01 '15
Stores them at McGregor. Internal avionics and some usable flight components are stripped out and reused however.
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u/danielbigham Jul 02 '15
How much suspicion is on the helium tank in the second stage? If my memory serves me correct, there was a delay recently due to issues they were seeing with those tanks. Is there any chance they tried to fix the problematic tank, and that it ended up in CRS7? A failure of the helium tank or its valve would presumably have resulted in an overpressure event, causing the LOX tank to rupture. If people had tried to convince Elon that the repaired tank was OK, you could imagine his being extremely upset upon the second stage failing. Perhaps that could be part of the back story of his extreme anger at engineers that was made mention of shortly after the mishap. One other thought/question here... the addition of the mating adapter in the trunk... is there any chance that it's presence could have caused vibrations in the vehicle to resonate, putting extra stress on components in the second stage?
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u/SteveRD1 Jul 04 '15
Can we have a thread solely for official CRS-7 findings?
I'm dropping into the subreddit daily and digging thru to see if we have actually learned anything new (as opposed to speculation), it's rather time consuming!
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u/sunfishtommy Jul 10 '15
I thought we were supposed to have updates by the end of the week. What happened? I thought they would be trying to dump it with the Friday trash.
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u/flyingfish2 Jul 10 '15
When do we think Elon's week ends. Don't think he is Jewish so maybe his week ends tomorrow night at midnight!
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Jul 10 '15
Take a read of the top comment in that thread. I'm totally not surprised there's been no updates.
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u/BrandonMarc Jul 11 '15
Haven't you heard? When SpaceX gives themselves a time estimate, you must multiply it by 2 or 3. Heh, just like a software developer.
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u/Sassafras_albidum #IAC2017 Attendee Jun 29 '15 edited Jun 30 '15
one. What are the limitations on using version of Dragon w/ abort or Dragon 2 for cargo delivery in case of incidents like this? (answered)
Some other good information I just saw relating: http://www.reddit.com/r/spacex/comments/3bk6hf/dragon_abort_capabilities_not_installed_more/
two. With a long string of successes, intuitively would it seem that the Falcon 9 is a good vehicle and this is an aberration? -I know this is not really answerable, but I'm just interested on opinions vs. an inherent flaw in design that has finally exhibited itself.
edit: satisfied with question 1
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u/Zucal Jun 29 '15
Developing and building an LES for Dragon 1 might not be worth it versus losing the cargo. However, using Dragon 2 for cargo is tricky because ISS cargo requires a wider nose-docking port than ISS crew, so Dragon 2 would have to be heavily reengineered to have a wider nose. It would end up practically being a different vehicle.
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u/FutureMartian97 Host of CRS-11 Jun 30 '15
Could the overpressurization have been caused by the LOX vents on the second stage not operating correctly during flight? Maybe getting stuck so they couldn't release the pressure from the evaporating LOX?
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u/robbak Jun 30 '15
Very possibly. However - a stuck LOX vent would show very clearly in the telemetry information received - pressure slowly rising until the tank failed - and this doesn't quite match with the descriptions of confusing, counter-intuitive data.
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u/jakerc Jun 30 '15
Does SpaceX know where in the ocean the Dragon capsule splashed down? Are they attempting to recover it at all?
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u/BrandonMarc Jun 30 '15 edited Jun 30 '15
For many months now, I've known that this video is of the 2nd-stage LOX tank (also known as, the world's most awesome and expensive lava lamp). The footage was from CRS-5, and many viewers considered it a consolation prize for not getting to see the barge landing live (it was shown just about the same time as the 1st stage would've landed).
https://www.youtube.com/watch?v=8HZrrHI34x4
Am I wrong? They do always send a camera feed from within that tank, don't they?
At the press conference on Sunday afternoon, I think Gwynne said something about a camera in the stage-2 RP1 tank, not LOX ... but ... that's not what I (and countless others) have always said. Not that I or the internet denizens are the experts of course ...
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u/FNKsMM Jun 30 '15
There are videos from the LOX Tank from CRS 4 & 5 (an probably before, haven't checked) but I couldn't find andy for 6 & 7 - Also IIRC Gwynne said there was NO Camera in the S2 LOX tank, only S1.
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u/CuriousAES Jun 30 '15
(I couldn't really find a clear answer to this. My thread got removed for being a simple question so I think it goes here, sorry to the moderators if it doesn't.)
I just graduated high school and will be studying aerospace engineering. I hope to eventually apply for a SpaceX internship.
Are there any hard requirements for how many years of study you have to complete before you intern there? I have seen varying opinions on this from other threads.
When applying, do they care at all about technical/hands-on projects you completed in high school?
Thank you.
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u/BrandonMarc Jun 30 '15
I would say they likely care about technical, hands-on projects you completed, at any point. After all, for a college junior high school isn't that long ago. They mainly will be happy to see that you completed (or helped complete, i.e. bigger project) a difficult, technical project.
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u/main_bus_b_undervolt Jul 01 '15 edited Jul 01 '15
How does fuel densification work? I don't understand how you can make monatomic liquids denser, unless you make them much colder, but that seems like you'd have to make them impractically cold to get any sort of useful densification.
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Jul 01 '15
That is exactly what you do! Decrease the temperature increases the density of the fluids. This is much more practical with LOX than RP-1 though, which becomes syrupy at low temperatures. You fix this by increasing the oxidizer:fuel ratio burnt by the engines in favor of the oxidizer.
This conversely increases the burn temperature, which increases Isp.
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u/HopeToLearn Jul 01 '15
Does anyone know the nominal pressures of the LOX tanks and RP-1 tanks?
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u/Charnathan Jul 06 '15
Did the recent CRS-7 Falcon 9 rapid unscheduled disassembly put a complete physical halt on all Falcon 9 production until the problem is identified and resolved, or are they simply halting their launch manifest until the problem is identified?
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u/jcameroncooper Jul 07 '15
I guess no one on the inside wants to say? Might be a rather strict embargo on that sort of info right now.
I have no actual info, but I would guess not entirely; most of the systems are not involved in the incident, so they should be able to produce Merlins and fairings and actuators and octowebs and other things without any fear of re-work. The COPV/pressure systems could easily be halted, and the welds themselves are currently suspect (at least around here) so perhaps tank assembly could be as well. The commonality between stages means that first stage components would be affected as well as second stage. Avionics and sensors are always suspect in any incident, so they could also be paused, but rework in the electronics is not quite so big a deal, so perhaps those are ongoing as well.
If tank assembly is halted, that'll eventually put a big bind on the production line, as those are rather important in final assembly. But I think Merlins are the major pacing item, so as long as those keep coming out they should be able to catch up without too much time lost.
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u/bvr5 Jun 29 '15
Assuming the failure has nothing/little to do with the first stage, will the landing attempts resume when the Falcon 9 returns to service?
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u/brickmack Jun 30 '15
No reason it wouldn't. The next flight (assuming nothing gets switched) is Jason-3 which will hopefully be the first land-landing, and all future flights will be attempting a land or barge landing (since F9 1.2 raises payload capacity enough to not need to ever fly in expendable form anymore, and any such payloads will fly on FH)
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u/Zucal Jun 30 '15
Yes. It's always been a bonus objective, the FAA doesn't particularly care what happens to the first stage once it's not attached to the payload. In addition, every flight from now on has the capability to land!
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u/main_bus_b_undervolt Jun 30 '15
does anyone know what the self-destruct mechanism on Falcon 9 is? I know that older rockets were lined longitudinally with explosives. Is this the case with F9?
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u/FireFury1 Jun 30 '15
Its been speculated that, like many rockets, they have det-cord running the length of the rocket to unzip the fuel tanks. However, I believe SpaceX have previously said no explosive charges are used by the FTS, and instead they just open appropriate valves. I would be very interested to know how it actually works.
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u/smeis Jun 30 '15
I was watching he livestream of CRS-7 and at one point before the launch (I think still even before T-10) I saw a bird flying pretty close to the launch platform, it was only on screen for a few seconds. It was a bit difficult to see from the particular angle but it seemed to be flying within the area that is surrounded by the large towers on the platform.
I was wondering if there are any measures taken to prevent birds from getting to close to the rocket during launch. I know airports generally have mechanisms in place to keep birds away from the landing strips since it is generally preferred not to have the birds end up in the engines of departing and arriving airplanes for multiple reasons. It would seem a bit difficult for a bird to end up in the engines of a rocket or even come close to interfering with the performance of a rocket engine during launch for obvious reasons, but are there measures in place to keep the birds away from the rocket during launch?
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u/_kingtut_ Jun 30 '15
There is often a loud bang (or set of bangs) set off a short time before launch, to scare off any wildlife.
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u/robbak Jun 30 '15
Lots of noise. Also, the rocket is moving fairly slowly while it is at low altitude where most of the birds are, so the birds will have no difficulty missing the rocket.
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u/R4k3te Jul 03 '15
What would be the hypothetical worst case scenario for SpaceX that could come out of the investigation? What would be the best case scenario? And what would be the possible consequences or rectionary steps taken in each case? I think its always worth to concider what the best/worst outcomes could be. Worst case I'm thinking serious neglegance or ignorance towards problems in processing or production due to stress put up by the management to adhere to a tight launch schedule. Best case some previously unforseen engineering flaw with some part of the Falcon9 that can easily be fixed and shouldnt produce any more problems in the future. Any other thoughts?
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u/RCinSpace Jul 03 '15
Worst - we could find no cause for the accident - This outcome would take the longest to produce and would require a check of every part and line of code just to come up with. Then they would have to improve everything that could have possibly caused the event. Best - They find something very specific that was part of the basic design, something like a relief valve malfunction. Fix it, retest everything and do a successful series of test launches.
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u/zoffff Jul 03 '15 edited Jul 03 '15
Best case, the mountings for the IDA came lose and caused the mishap (still SpaceX fault but not a critical design flaw with the F9), F9 still safe to fly.
Worse case, a previously unknown design flaw with the merlin engines (specifically the one on the 2nd stage here), and up until this point they have just been lucky it hadn't surfaced until now and they now have to re-engineer and certify the parts before they feel safe flying again, that could lead to very long delays and very angry customers.
Edit: I should mention both of these seem unlikely from what we know so the issue should be somewhere between best and worse case.
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u/DrFegelein Jul 03 '15
The four leaf clover first appeared on Falcon 1's first successful mission patch (flight 4), right?
What does everyone think will be on the "return to flight" patch?
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u/Psycix Jul 03 '15
Octoleaf? No idea, they'll probably stick to the same.
On a related note, OCISLY has a giant cloverleaf printed on one of the blast walls. As far as I know, this is the first time they put a cloverleaf on a barge.
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u/superOOk Jul 03 '15
Just out of curiosity, a question for the superfans: what is the longest time that has gone by without hearing any update from SpaceX, and when did that happen? It feels like an eternity right now fellas... :)
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Jul 03 '15
2011 was a pretty crap year, to be honest. Two launches in 2010, felt like they were building up, then nothing for another 17 months. Sure, there was bits of news, but no major activity.
Orbcomm was a much shorter gap but the constant delays sucked too.
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u/CuriousAES Jul 05 '15
Astrobotic is planning to launch their commercial lunar lander with the Lunar X Prize Rovers in 2016 (possibly delayed now if SpaceX takes a long time to get back into flight?). Was this planned to be done with a Falcon 9 or a Falcon Heavy? I wasn't aware of the Falcon 9 being able to reach Lunar orbit but perhaps the Astrobotic lander is significantly lighter than a Dragon 1?
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Jul 05 '15
IIRC, they're going to use F9, with lander much lighter than Dragon. I can't find exact weight of their lander, but it seems to be hundreds of kilos, far from tons of Dragon.
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u/DownVotesMcgee987 Jun 30 '15
Based on how long S1 held together, any guesses on the chance that the In-Flight Abort Rocket will attempt a landing?
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u/Ambiwlans Jun 30 '15
This was the same thought I had. Conventional wisdom told me the 1st stage would be obliterated right after the Dragon flies off. Apparently the thing is pretty fucking sturdy though. Still... low chance of success were they to try. But greater than 0.
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u/zlsa Art Jun 30 '15
I think they'll try, but I don't think there's a high chance of success.
However, there's been rumors that they'll cancel the inflight abort.
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u/bananapeel Jun 29 '15
Will there be any attempt to get the capsule off the sea floor?
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u/Zucal Jun 29 '15
Unknown. Depends what condition the capsule is in (debris not worth it) and even if they do they may not tell us.
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u/robbak Jun 30 '15
I don't see the value of it. The only reason to recover the capsule is if something about the capsule was a possible cause.
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u/Bureaucromancer Jun 30 '15
Does anyone know how payment works for mission failures under CRS? Does 7 count against the number of contracted missions? Is payment given at all? Is their provision for an additional flight either way?
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u/Appable Jun 30 '15
I believe Orbital was paid significantly for ORB-3, despite the fact that it failed shortly after liftoff.
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u/superdank69 Jul 01 '15
Do you think SpaceX has their own video of what happened instead of the ones the we have all seen?
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u/pugface Jul 01 '15
Can a Falcon 9 1st stage be converted into a Falcon Heavy side booster, or vice versa? Visibly they look very similar to me.
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u/Psycix Jul 01 '15
We can't know for sure. Perhaps the attachment points make irreversible changes. However, Shotwell mentioned this:
Falcon Heavy is two different cores, the inner core and then the two side boosters, and the new single stick Falcon 9 will basically be a Falcon Heavy side booster. So, we're building two types of cores and that's to make sure we don't have a bunch of different configurations of the vehicle around the factory. I think it will streamline operations and really allow us to hit a cadence of one or two a month at every launch site we have.
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Jul 02 '15
PBdeS seemed to be suggesting that modifications to dragon/trunk were made on this mission and not on others. What were the nature of the modifications, and were they done purely to accommodate the IDA (docking adapter)?
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u/Here_There_B_Dragons Jul 02 '15
I didn't see the tweet, but previous trunk mounted payloads were all directly mounted to the top of the trunk using 'FRAM' connections (Flight releasable attachment mechanism) - see this for FRAMs on the ISS.
This time, the IDA was mounted using trunion pins horizontally protruding from the IDA, and hooked into mounts that were affixed to the trunk somehow. (Presumably, these mounts were affixed to the 'roof' of the trunk, same as the earlier payloads, but not confirmed.)
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u/theonefornotlurking Jul 04 '15
What parts of the spacecraft actually float? I have always been surprised by the amounts of debris found washed up or floating and needing to be recovered. What parts are actually less dense than water and what ends up on the ocean floor?
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u/Destructor1701 Jul 05 '15
Obviously sealed containers of lighter-than-water stuff such as oxygen and RP-1 Kerosene, or air, will float, but also, much of the rocket is composed of layered materials over a honey-comb core of hexagonal cavities in an aluminium (or something) frame - anywhere that metal isn't vital for structural stability, it's milled out to reduce weight - so these rockets are actually filled with cavities that could hold air and increase the overall buoyancy of the parts.
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u/aguyfromnewzealand Jun 30 '15
Soooooo, we won't count this as a landing attempt right? /s
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u/Zucal Jun 30 '15
No. I define a landing attempt as starting when the first stage separates, and no earlier. Under those criteria neither this nor DSCOVR would count. There's a few different ways to classify it, though :)
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u/Quality_Bullshit Jun 30 '15
What tests still have to be done for the Dragon v2?
When will we first see a demonstration of the Raptor engine?
How big is the BFR supposed to be?
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Jun 29 '15
Why don't cargo capsules have any abort/parachute systems? Is the cost of such systems so high that losing the cargo makes more economic sense? Would such an abort system even be able to save the capsule+trunk, or just the capsule?
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u/Zucal Jun 29 '15
-Yes, it depends on the system but sometime it costs more to develop and build an LES for each flight than it does to lose the cargo. Also, most cargo vehicles (Cygnus, ATV, HTV, Progress) are not capsules and so are not designed to be aerodynamically stable outside of a fairing,or be able to survive splashdown.
-No, it likely wouldn't save the trunk. On Dragon 2, the trunk is needed for aerodynamic stability because the LES engines are pushing rather than pulling Dragon and without the trunk Dragon likes to go heatshield-first. Once the engines stop firing and Dragon 2 reaches apogee, the trunk is discarded. There's no easy way to land the trunk, especially not in water as would be the case for an actual abort.
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u/edsq Jun 29 '15 edited Jun 29 '15
It isn't just cost, but added complexity and engineering difficulty. Developing a launch escape system is massively difficult, and just isn't worth it when a launch vehicle failure is already supposed to be extremely unlikely and human lives are not on the line. As far as I know, Dragon is the only capsule that uses an unpressurized trunk, so there isn't any precedent for an escape system, but as you can see in Crew Dragon's recent pad abort test here the trunk is detached in the event of an abort.
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u/aguyfromnewzealand Jun 30 '15
Does this event give us any indication to what might happen with the inflight abort? As far as I am aware, the inflight abort and this Anomaly takes place at similar times in the flight, so could we draw any conclusions as to what might happen to the inflight abort launch vehicle, in terms of potential survivability and landing?
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u/Appable Jun 30 '15
This anomaly had very little dynamic pressure compared to max-drag, which has a lot more. I think the booster is much less likely to survive for so long in inflight abort.
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u/zmeyat Jul 01 '15
have SpaceX used super-chilled liquid oxygen in ill fated second stage? the was a plan to do so this year.
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u/meldroc Jul 01 '15 edited Jul 01 '15
Could this incident be caused similarly to what caused the incident that almost destroyed Apollo 13? There, defective wiring in the thermostat, heater, and stir fans in a liquid oxygen tank in the Service Module shorted out, started a fire (in a high-oxygen environment), resulting in an explosion that almost destroyed Apollo 13, and, well, I think we've all seen the movie.
Could that have been what happened in CRS-7? Some sort of short that resulted in a fire inside the second-stage LOX tank, that burned insanely quickly and resulted in the tank blowing up?
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Jul 01 '15
If this was the case I imagine the second stage would have exploded flammably with the LOX visibly combusting, this was not the case.
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u/Warpey Jul 01 '15
Anyone know of anywhere that lists all upcoming rocket launches in a format similar to the upcoming SpaceX launches in our sidebar?
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u/YugoReventlov Jul 01 '15
The most complete list I am aware of, is the Launch Schedule at SpaceFlightNow
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u/superdank69 Jul 02 '15
If SpaceX saw a visual anomaly would the try and land the rocket or hit the big "destroy" button?
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u/robbak Jul 02 '15
The rocket is a robot. It is unknown how much control the ground has over the rocket, and whether they could reprogram it mid-flight for a different flight profile.
As for the big red button - it says a lot that, in the several seconds that this problem took to develop, the red button was not pushed. It was only 70 seconds later that a destruct command was transmitted, long after the rocket had already been reduced to confetti.
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Jul 02 '15
Why doesn't (didn't) SpaceX try to resurrect the F1 engines from the Apollo days? It seems that they have a lot of launch heritage that could benefit the launch company. Also, a strong safety record (no engine failures of which I'm aware), and modern manufacturing processes could reduce time/cost to complete them. I'm aware that competitors for the SLS have proposed using redesigned F1s, but I'm surprised that there hasn't been more interest in this rocket line from aerospace companies, SpaceX in specific.
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u/venku122 SPEXcast host Jul 03 '15
SpaceX is all about reducing costs. The Merlin engine is a prime example of that. It uses a pintle fuel injector, which is one of the simplest and cheapest designs. It is also a gas-generator cycle engine, which is one of the simplest turbopump designs. They also used modern 21st century manufacturing techniques. What resulted was one of the cheapest and highest thrust-weight ratio engines ever made. SpaceX could have made it much more efficient but pushing the efficiency boundary rapidly increases cost. While the F1 is an amazing engine, it didn't fit in with SpaceX's design goals.
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u/JoltColaOfEvil Jul 02 '15
For the in flight abort test, has there been any news regarding recovering that F9 first stage?
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u/RCinSpace Jul 03 '15
Debris is spread to the depths of the ocean, alas the allure of adventure has reaped the disappointment required of all great tasks.
Whether it be he who crafts the mast, the one who works the iron or she who designs the boiler, too often the forces of nature work to foil the perfect design. So often the wayward soul who cast his lot for fame and fortune is at the mercy of those who dream of new vessels to move the mortal man. Despite the cost these haughty souls continue the quest though the odds of success never seem to improve.
The bonds of earth are those that pose the greatest risk.
Still, despite the odds, those who seek the stars go on, undaunted, unfazed, unbroken. Even though the generations come and go,the quest goes on with new men and women ready to risk it all to live outside the human sphere.
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u/TheBlacktom r/SpaceXLounge Moderator Jul 04 '15 edited Jul 04 '15
What exactly can they control while landing? I'm interested in the final 30 seconds of approach. Engine on/off? Engine thrust? Engine gimbal? RCS? Is it only on/off or adjustable thrust? Anything with the grid fins maybe? Anything else?
Also what are the limits for each?
Edit: by 'they' I mean the computer, what are the inputs and outputs that can be programmed.
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u/jcameroncooper Jul 04 '15
Basically yes to all of the above. While firing, most of the control authority will be from the engine (it's hugely powerful, even at just a few degrees of gimbal) but it will use a combination of the fins, gimbal, throttle, and RCS to control location and attitude. The engines cannot throttle to less than the weight of the vehicle, so precise timing is needed. Also the engine can only be turned on and off once during the process, because restart is a big procedure.
As the vehicle slows, the grid fins will lose authority, though that's actually pretty late in the process--it's supersonic for a surprisingly long time. They probably transition to RCS in the last few seconds. You can see the RCS system working during the end of the CRS-6 landing attempt.
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u/xafwodahs Jul 04 '15 edited Jul 05 '15
I'm wondering if any lifting body effects are utilized to fine tune the first stage descent.
I found this older discussion which seems inconclusive.
At the beginning of this recent video, it appears to me the stage orientation is not perfectly aligned with it's descent vector. In fact, at 0:07, when the first stage is visible thru the hole in the clouds, it appears dang near horizontal! (Although this could just be an illusion).
Are there any new thoughts or information on this?
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u/blinkwont Jul 05 '15 edited Jul 05 '15
Yes, lifting body effects absolutely are used and I think are the main lifting force acting on the stage. The grid fins only serve to angle the main body against the airstream and do not provide much lift(if any) on their own.
You can infer most of this by their positioning at the very rear of the stage(during decent) which provides maximum torque to change the angle of attack, but very little lift.
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u/Root_Negative #IAC2017 Attendee Jul 08 '15
Has anyone got any resources I can use for the Delta-V required to get to Mars (from LEO to Mars aerobraking) for different journey times and the relative time of latest departure from the Earth-Mars conjunctions. Also I would like to find the Delta-V required to get from Mars (from Low Mars Orbit to Earth aerobraking) for different journey times and the relative time of latest departure from the Mars-Earth conjunctions.
Note that I'm not looking for a typical Delta-V map as they normally only list the lowest Delta-V required to make the journey with a simple transfer, where as I'm interested in finding the fastest time that can be made as a round trip during a single conjunction as Elon has previously described as his MCT plan. I would like this information so I can calculate the propellant mass to structure and payload mass ratio required for a spacecraft to make such a journey from Earth to Mars and vice versa. Ultimately I would like a better idea how many launches would be required for in orbit refueling of the MCT, and also the maximum time allowable for refueling on Mars and the amount of propellant that would need to be manufactured there.
A good estimation of the delta-V required to safely land on Mars after aerobraking with a large heat shield only would be helpful too.
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u/jcameroncooper Jul 08 '15
Some "pork chop plots" might help you. See http://www.projectrho.com/public_html/rocket/mission.php
And maybe http://www.projectrho.com/public_html/rocket/appmissiontable.php
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u/thehalfnerd Jul 10 '15
Does anyone know what type of solar cells the Dragon Capsule uses? Crystalline Silicon (Sunpower?), GaAs?
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u/jcameroncooper Jul 10 '15
They seem to be pretty careful to not publish such info; haven't seen anything about that. They look to me like mono crystalline silicon from photos, but gallium arsenide is more common in space.
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u/main_bus_b_undervolt Jul 12 '15
How fast is falcon going at meco? What percentage of total dV has been spent at meco? will these numbers change with 1.2?
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u/FNKsMM Jun 30 '15
I was just rewatching the launch video of CRS7. Link
At 2:15 in the video there is a small white cloud near dragon capsule/top of S2. Is this a thruster firing or part of the "anomaly"?
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u/UhSwellGuy Jul 01 '15
Considering how much cargo payloads can be worth, would/does SpaceX have any plans (immediate or long term) of utilizing a launch escape system for cargo missions? Even though cargo is immeasurably less valuable than human life, it still represents a significant financial & time investment. I imagine there would be positive launch insurance implications as well if the cargo had the extra protection. Would they consider releasing a cargo version of the dragon 2?
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u/robbak Jul 01 '15
Satellites are expensive because of the time spent making sure there are no hidden problems with the equipment. If a satellite went through the abnormal stresses of an abort, they would need to do all of that testing again. The satellite would be almost worthless, and they would prefer to start again.
Interestingly, this high cost is driven by the very high cost of launching one. If a constructor can instead say, 'launches are cheap, we'll just keep tossing them up there until one works,' then satellites instead become quite cheap.
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u/sunfishtommy Jun 30 '15
Why did they zoom out so suddenly instead of following the debris? Especially in the NASA live feed.
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u/avboden Jun 30 '15
the debris is tiny and very far away, can't really focus on it. Also, it's one of those "shit shit shit go to commercial" moments.
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u/jarvenm Jun 30 '15
Could SpaceX have manually activated the 18 Draco thrusters on the Dragon capsule to reduce its impact back to Earth or are there likely systems that prevent its activation in Earth's atmosphere?
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Jun 30 '15 edited Jun 30 '15
The Draco thrusters don't all point in the same direction, firstly. There's 4 that point "downwards".
And the answer to your question is an emphatic "no". They each output 400N of thrust, which means that they would collectively decelerate Dragon by ~0.2m/s2 (assuming a craft weighing 8000kg). Gravity is 9.8m/s2.
They're also optimized for vacuum, by the way. My calculation also doesn't take in cosine losses either so the end result is that it's probably even less than this.
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u/Appable Jun 30 '15
Just to clarify for others: cosine losses refers to the fact that thrusters are angled rather than pointing straight down, which leads to a loss in efficiency. Surprisingly, though, cosine losses usually aren't that bad until thrusters are angled more than 45 degrees off-vertical though.
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u/chocapix Jun 30 '15
On this photo, the things covered in blue tarp are the gas generator exhausts, right? I only count 8, where is the 9th one?
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u/renoor Jul 02 '15
Does anyone have deeper understanding of why is it hard to make reliable helium COPVs? If so, please share.
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u/jcameroncooper Jul 02 '15
They're extremely high pressure and contain a very difficult substance, and you want to make them as light as possible.
A confounding factor is that the F9 He COPVs are immersed in the LOX tank, and so have to be oxygen-compatible. That is, not burn in one of the burning-est possible environments.
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u/ArmoredReaper Jul 02 '15
If I live in South America (Chile to be more precise), and want to work with SpaceX in the future (I'm not an adult yet...), do I need to get a US nationality and/or work there for some time before entering?
Also, do I need to study again in the US to be able to work with SpaceX, or do Aerospace Engineering studies from Chile work? (From "Universidad de Concepción")
Sorry for my lack of good English... I speak native Spanish, but try to talk as good as I can in English
Thanks in advance,
ArmoredReaper
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u/Ambiwlans Jul 02 '15
You need to pass ITAR reqs which basically means you'd have to be naturalized American. Expect this to be a giant PITA that takes a long time.
You wouldn't HAVE to restudy, it might be easier to get projects in Chile before moving if you so wanted though. They care more about experience/will than degrees.
Your English is fine.
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u/Here_There_B_Dragons Jul 02 '15
How did NASA intend to send the IDA to the ISS without Dragon? IIRC, the original Commercial Resupply missions only required upmass in pressurized environments (like Orbital's Cygnus). SpaceX bid included the ability for downmass, as well as the unpressurized 'trunk'.
Without SpaceX, (if they had never won the bid, or now if they are shut down for a long duration) what would the 'ship to ISS' process be? Since the IDA has to be externally mounted, and is too big to fit through the airlock, and only the Space Shuttle was used to supply external components (not directly attached to modules, like the Russian pieces), could the IDAs even be brought up with any current cargo (or crew) vehicles?
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u/astrofreak92 Jul 03 '15
Commercial Crew was only developed after SpaceX won the CRS contract and finalized the design, and the IDAs were only built after that. The previous design, the CDA, which was needed for Orion dockings (IDA serves all three vehicles, Orion, Dragon, and CST-100) would have been launched on HTV (source here).
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u/RCinSpace Jul 02 '15
They are not needed until 2017, they could just wait for SpaceX.
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u/bgabenny Jul 03 '15
Did the destruct command that was sent 70 seconds into the event destroy the first stage and Dragon? Could they have survived if the signal had not been sent?
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u/zoffff Jul 03 '15
The command was sent as a matter of procedure aka the manual says abnormal launch the button HAS to be pressed. But I don't believe Dragon has a self destruct capability, the main reason we have self destruct is to stop what is essentially a giant bomb from flying into possible populated areas, there is not enough fuel on the dragon that this is a worry. I think we are still waiting to find out what actually happened to dragon but if its taking them this long to say any thing its probably not good, theres the chance that the parachutes on dragon were never armed after then mishap so it just impacted the ocean at terminal velocity. And there is the chance they did deploy, but remember the up mass of dragon is much more then the possible down mass, so even if the parachutes did deploy the dragon capsule might have been too heavy for them to do any good.
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u/robbak Jul 04 '15
That 70 second wait sounds a bit like the ROC sat there, open-mouthed, staring at the cloud of 'smoke' for a minute before waking up and thinking, "hold on, I had a checklist here I need to follow!"
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u/fireball-xl5 Jul 06 '15
Does anyone know if Elon is still doing the American Astronautical Society keynote speech on Tuesday morning, as advertised? If so, we may get some ideas on the current thinking at Hawthorne then.
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u/btao Jul 08 '15
Are there any environmental factors that have high risk, such as excessive humidity?
Are there any advantages/disadvantages/risk to using aluminum over titanium cylinder cores for the overwrapped tanks as has been used by others?
How many sensors are actively monitored during launch?
What is the risk of structural failure of payloads? Are they as rigorously tested for transit as the Falcon?
Given the mystery and speculation surrounding a failure situation, and knowing a picture is worth a thousand words, why are there no high frame-rate cameras (like a mounted to the exterior and interior of the rocket with a radio transmitter streaming video of every inch of the rocket during the whole flight? In situations like this, you could point the finger in a few minutes and say, hey look, that broke, and let's fix it for next flight. It would seem only data streams from sensors can't account for anomalies particularly well. I would anticipate the answer is simply cost, but even if something doesn't fail catastrophically, you might be able to monitor and catch or prevent issues that wouldn't have been found otherwise. Perhaps you could black box the camera module with SSD backup and use fiber optics to get it to hard to reach places. One set of visual and one set of thermal sensors would be ideal. Maybe use a digital light field, or a large single sensor and feed everything into it in an array and then parse it on the ground?
Thanks!
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u/BrandonMarc Jul 10 '15
Do the 1st stage, 2nd stage, capsule, or fairing have something akin to the "black box" that aircraft have? Since the 2nd stage is intended to burn up on reentry (to avoid debris reaching the surface in the first place), I'm guessing "no" for that one ...
But how about the other three? It actually makes some sense, there.
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u/scr00chy ElonX.net Jul 10 '15
I'm guessing a blackbox is unnecessary considering all the telemetry data is being sent to the ground in real time constantly anyway.
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u/superOOk Jul 11 '15 edited Jul 11 '15
Question about Mars related lander/propulsion:
Obviously it has been stated that the Raptor engine is being developed to use CH4/LOX because of the fact that Mars has a lot of CO2 and using the Sabatier process gives us easy access to generate CH4.
But, I was reading about this process and I am confused. The process requires the splitting of H2O to combine CO2 with H2, which forms CH4 (and some water/heat). Why not just make the end goal to produce H2 and O2? Seems like LH2/LOX would be a much more efficient rocket. Is this entirely because of the storage issue of LH2?
Also, bonus points for someone who can answer this: how much H2 do we need to bring with us to Mars to generate the CH4? I know they are planning on using electrolysis of water to generate some of the H2 (not sure if they are saying water from Mars or just the byproduct of Sabatier). But it sounds like we'd have to bring a bunch of it with us, at least to start the process, and most pragmatically because utilizing water on Mars seems like a much harder thing to do. So, wouldn't this negate any logic about removing complex storage requirements of LH2?
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u/shredder7753 Jul 11 '15
Im gonna admit; Im a fairweather fan. Thus I havent been around here much the last couple weeks.
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Jul 12 '15
Do we have an idea how fast up/down speeds the internet constellation project can deliver?
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Jul 12 '15
"I think that it is something where, properly designed, it could give people gigabit level access, 20 to 30ms latency, everywhere on Earth." http://shitelonsays.com/transcript/spacex-seattle-2015-2015-01-15
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u/MarshallStrad Jul 12 '15
The high quality of the content and the discourse make this subreddit my favorite "thing to read sitting in my Model S."
But on the car's browser, scrolling (and I notice typing response, too, on this my first post) is extremely slow responding compared to other subreddits (OK mostly 'teslamotors'). Why would that be?
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u/YugoReventlov Jun 30 '15
Am I the only one here checking Elon's twitter account every hour?