SpaceX Falcon 9/Dragon CRS SpX-1 MISSION GENERAL DISCUSSION

[mlindner]

Thanks for the welcomes. I'm currently a university student in computer engineering and I work in University of Michigan's cubesat building lab. (Look up M-Cubed and RAX, I worked on the former.) I have two friends/coworkers that were previously SpaceX interns and I know people who work there, but don't have direct contact with them. One friend interned over this past summer, and one the summer before that. And I'm trying to become one myself. Although I've yet to get much information out of either them that isn't already publicly available.

I have heard from them, and elsewhere on the net that there was kevlar between the engines/on the engines protecting other engines against a possible engine explosion. Is there any kind of publicly available design document around that actually specifies this or has this all been propagated through word of mouth?

[woods170]

I believe woods170 was concurring, Jim.  He's stating that not only is Falcon 9 autonomous through launch and payload release, but that even Dragon is autonomous through (at least) solar array deployment.

No, I was not. I was just saying that (IMO) new member mlindner had an interesting post. And with 'he' I hope you mean mlindner, because I never stated that Dragon is autonomous etc...

[Jim]

But, Joffen's proposal (from so long ago) was to make the contingency burn a circularization of the orbit to the apogee of the post-release orbit, as a can't-lose maneuver.  This orbit can be pre-approved without knowing the exact starting situation, since a circle is a circle is a circle.

No, not really.  Still too many things to analyze, including overburn

[meekGee]

No, not really.  Still too many things to analyze, including overburn

Can you explain?   The orbit itself, I understand from your reply, is ok so does not have to be re-approved.

The question that remains is whether the stage can hit that orbit.

If we're circularizing an orbit, my logic says that as long as the nav system is intact (which HAS to be assumed since we just relied on it for all the decisions so far, including mitigating the first stage under-performance), the only thing that can go wrong is another underperformance (e.g. insufficient propellant) and then the resultant orbit is still apogee-limited.

The only way to get an over-burn is if the stage itself is unreliable, but if that's the case, might as well have shut it down on the first sign of an anomaly.

[Comga]

No, not really.  Still too many things to analyze, including overburn

Can you explain?   The orbit itself, I understand from your reply, is ok so does not have to be re-approved.

The question that remains is whether the stage can hit that orbit.

If we're circularizing an orbit, my logic says that as long as the nav system is intact (which HAS to be assumed since we just relied on it for all the decisions so far, including mitigating the first stage under-performance), the only thing that can go wrong is another underperformance (e.g. insufficient propellant) and then the resultant orbit is still apogee-limited.

The only way to get an over-burn is if the stage itself is unreliable, but if that's the case, might as well have shut it down on the first sign of an anomaly.

Agreed:  We're going under the assumption that the insertion orbit has been obtained within tolerances and the controller is comparing the calculated fuel and oxidizer levels to their thresholds.  Meeting the thresholds allows the restart to begin and to raise the insertion orbit perigee to the new 760 km apogee.

The current branch for not meeting the required levels is to not restart the second stage engine.  Given all the above assuptions, in a condition SpaceX knew could occur, could the autonomous decision be to burn to the delta V that circularizes the orbit, instead of raising the apogee above the ISS?

[smoliarm]

It's probably a silly question, I'm a novice here, sorry.

Earlier in this thread I saw somebody posted something like "Falcon is grounded..."
In the news, however, I only found statement
>>SpaceX and NASA have jointly formed the “CRS-1 Post-Flight Investigation Board.”

Does the first follows from the second automatically? Or, was there an announcement that they stop Falcon flights?

Another question:
As I understand, SpaceX plans to recover and re-use first stages in future, but for now they are expendable. Does anybody know if they recovered and examined any of 1st stages from previous launches? Was there anything on this in the news?

[edkyle99]

It's probably a silly question, I'm a novice here, sorry.

Earlier in this thread I saw somebody posted something like "Falcon is grounded..."
In the news, however, I only found statement
>>SpaceX and NASA have jointly formed the “CRS-1 Post-Flight Investigation Board.”

Does the first follows from the second automatically? Or, was there an announcement that they stop Falcon flights?

Another question:
As I understand, SpaceX plans to recover and re-use first stages in future, but for now they are expendable. Does anybody know if they recovered and examined any of 1st stages from previous launches? Was there anything on this in the news?

It is a given that NASA will not sign off on the next flight until the Investigation Board completes its work and recommended steps are enacted.  That doesn't necessarily mean that the next flight will be delayed for an extended time.  I expect a month or three delay from current plans at most, but of course it does depend on the results of the investigation. 

SpaceX has not recovered any Falcon 1 or 9 stages, because they have essentially burned up or disintegrated upon reentry.  I believe that the company has stopped trying to do parachute-only type recoveries and has moved on to propulsive velocity reduction research with Grasshopper instead.  It is one of those things that looks easy on paper. 

 - Ed Kyle

[cordor]

But, Joffen's proposal (from so long ago) was to make the contingency burn a circularization of the orbit to the apogee of the post-release orbit, as a can't-lose maneuver.  This orbit can be pre-approved without knowing the exact starting situation, since a circle is a circle is a circle.

Staying few days longer on orbit will only disrupt other space launches, and looks more like insurance flaw. orbcomm still doesn't get a functional satellite in the end.

[meekGee]

But, Joffen's proposal (from so long ago) was to make the contingency burn a circularization of the orbit to the apogee of the post-release orbit, as a can't-lose maneuver.  This orbit can be pre-approved without knowing the exact starting situation, since a circle is a circle is a circle.

Staying few days longer on orbit will only disrupt other space launches, and looks more like insurance flaw. orbcomm still doesn't get a functional satellite in the end.

Might be true, but we were discussing second stage capabilities, not what the best policy was in Orbcomm's case.

There are situations where a month in orbit will allow much more complete testing than 3 days in orbit, or that a satellite can lift itself to orbit if it were not dragging so bad at perigee.

[Joffan]

But, Joffen's proposal (from so long ago) was to make the contingency burn a circularization of the orbit to the apogee of the post-release orbit, as a can't-lose maneuver.  This orbit can be pre-approved without knowing the exact starting situation, since a circle is a circle is a circle.

Staying few days longer on orbit will only disrupt other space launches, and looks more like insurance flaw. orbcomm still doesn't get a functional satellite in the end.

It wouldn't disrupt other launches at all. I don't understand what you mean by insurance flaw. And weeks of extra testing time in orbit would certainly have been valuable; the satellite's own propulsion could have been better evaluated, for example. This was a test satellite, not intended as part of the functional fleet.

[cordor]

But, Joffen's proposal (from so long ago) was to make the contingency burn a circularization of the orbit to the apogee of the post-release orbit, as a can't-lose maneuver.  This orbit can be pre-approved without knowing the exact starting situation, since a circle is a circle is a circle.

Staying few days longer on orbit will only disrupt other space launches, and looks more like insurance flaw. orbcomm still doesn't get a functional satellite in the end.

Might be true, but we were discussing second stage capabilities, not what the best policy was in Orbcomm's case.

There are situations where a month in orbit will allow much more complete testing than 3 days in orbit, or that a satellite can lift itself to orbit if it were not dragging so bad at perigee.

og2 is kinda low density, it's going to lose momentum very quick, maybe it can last couple more days with 300km circular orbit.  That's about the same for all other secondary payloads, cheap and lightweight. There is really no point to salvage the satellite given that the LV was already partial failure,  secondary burn risks maybe as high as crashing into one of the 100M satellites.  Too much to lose and too little to gain.

[Joffan]

og2 is kinda low density, it's going to lose momentum very quick, maybe it can last couple more days with 300km circular orbit.  That's about the same for all other secondary payloads, cheap and lightweight. There is really no point to salvage the satellite given that the LV was already partial failure,  secondary burn risks maybe as high as crashing into one of the 100M satellites.  Too much to lose and too little to gain.

There's a huge difference between a perigee over 300km and one under 200km.

http://www.lizard-tail.com/isana/lab/orbital_decay/
Model the Orbcomm as 100kg and 2m^2 area, and you'll get over 3 weeks at 300km. At 330km you get over 7 weeks. Go down to 220km and you get a couple of days.

There aren't satellites to crash into at that altitude, precisely because of orbital decay.

[cordor]

og2 is kinda low density, it's going to lose momentum very quick, maybe it can last couple more days with 300km circular orbit.  That's about the same for all other secondary payloads, cheap and lightweight. There is really no point to salvage the satellite given that the LV was already partial failure,  secondary burn risks maybe as high as crashing into one of the 100M satellites.  Too much to lose and too little to gain.

There's a huge difference between a perigee over 300km and one under 200km.

http://www.lizard-tail.com/isana/lab/orbital_decay/
Model the Orbcomm as 100kg and 2m^2 area, and you'll get over 3 weeks at 300km. At 330km you get over 7 weeks. Go down to 220km and you get a couple of days.

There aren't satellites to crash into at that altitude, precisely because of orbital decay.

It's going to be 2m^2  X 4.

Of cause there are satellites everywhere, may not be at your "300x300km circular orbit". But who is going to say second burn will place og2 there? There is no way to ensure stage 2 status after stage 1 accident, second burn  may just shoot og2 directly into dragon or ISS.

[Comga]

og2 is kinda low density, it's going to lose momentum very quick, maybe it can last couple more days with 300km circular orbit.  That's about the same for all other secondary payloads, cheap and lightweight. There is really no point to salvage the satellite given that the LV was already partial failure,  secondary burn risks maybe as high as crashing into one of the 100M satellites.  Too much to lose and too little to gain.

There's a huge difference between a perigee over 300km and one under 200km.
http://www.lizard-tail.com/isana/lab/orbital_decay/
Model the Orbcomm as 100kg and 2m^2 area, and you'll get over 3 weeks at 300km. At 330km you get over 7 weeks. Go down to 220km and you get a couple of days.

There aren't satellites to crash into at that altitude, precisely because of orbital decay.

It's going to be 2m^2  X 4.

If you use that calculator, a mass of 142 kg, and altitude of 250 km (average of 200 and 300, although it this is NOT linear), the area has to be set to 1.5 square meters to yield a 10 day lifetime, which I think is what happened to Orbcomm-2.

If the altitude is set to 300 km for a circularized orbit this model predicts that the lifetime rises to 43 days.

If the perigee was raised to just below the ISS and the new average altitude was 350 km, this model predicts a lifetime of 173 days.

There was a lot of life to be gained with even a small raising of the perigee.  There may be a good reason this was not incorporated into their plans, and I would like to learn them.

[Joffan]

It's going to be 2m^2  X 4.

Of cause there are satellites everywhere, may not be at your "300x300km circular orbit". But who is going to say second burn will place og2 there? There is no way to ensure stage 2 status after stage 1 accident, second burn  may just shoot og2 directly into dragon or ISS.

The picture of an OG2 shows that its maximum area is under 4m^2 (when the solar wing is facing directly in the direction of travel), and minimum is less than 1m^2. 2m^2 is a reasonable modelling figure. (One metre is typically just a little more than nose-to-fingertip - scale from the man in the photo. And I love the use of plastic piping and plumbing fittings for the mast support frame.)

The upper stage of the Falcon 9 knew where it was and what orbit it was in - it had already delivered Dragon to its target orbit. Otherwise, it could not possibly have been tasked with inserting the secondary payload into the desired orbit, or with making the go/nogo decision that it did. There is every reason to expect that it could make a burn to put the satellite into the desired circular orbit, since it was in an expected orbit at the time and there was no problem with that stage.

Your ignorance on the location of satellites requires no response. To be honest, I'm not sure why you keep insisting that there was no possibility of getting a few more weeks out of the prototype OG2.

I do not blame anyone for not setting up a circularization burn option. But I do think it is a fallback that should be considered for future secondaries on ISS missions.

[manboy]

You got me curious. Looking at the images and their embedded EXIF data, there were some odd choices in camera settings - small apertures and as a result either high ISO's (causes graininess) or long exposures (chance of motion blur) to compensate.

The astronauts do get some instruction in photography, but not certainly not enough to become pros, so naturally those who enjoy it as a hobby are bound to do better than those for whom it's one of the less interesting tasks they perform.

Thanks for looking into the EXIF data, that does conform my suspicions. Tweaking all those camera settings is fine if you are an experienced photographer - otherwise you should just leave it in 'P' mode. (or whatever the Nikon equivalent is called) And that probably would have made these shots turn out better.

I realize that all the astronauts do not have the time or interest in learning all fields, so I certainly understand... Or they just goofed. (I have certainly blown quite a few pictures myself by accidentally putting my DSLR in the wrong mode) I just hope they had an off day, and get better shots of the departure.

Well they will also be at a crew of six which means there will be a lot more crew members not in the middle of doing critical tasks.

[iamlucky13]

     Being a keen amateur snapper, I have reluctantly come to realize over the years that you can put the most sophisticated camera in the hands of some people and still run a 50:50 chance of a chimpanzee doing better.  Some folk just don't get how to do it

I'd even say in the hands of most people. Photography is an art with a fairly deep technical basis...hence part of why, I suspect, it's naturally appealing to many nerds like you and me.

Most people want to be able to just point and click, but professional cameras like the D3 and D2Xs are designed for people who need to control the exposure settings themselves. It's very easy to change things without understanding what you just did.

[woods170]

https://twitter.com/Astro_Suni/status/258628475722809344

On unloading #Dragon, we found a very thoughful and timely gift from our friends @SpaceX - fall apples! http://twitpic.com/b5164y

Jim will have a field day over this one.
Love the picture. That other 'unlisted' gift shows in the back.

[woods170]

and they didn't pay for them... so they must be free fall apples.

Ha! Good one! So true in more than one way.

[Ben the Space Brit]

You know, on long-duration sea voyages during the age of sail, fresh fruit was a life-support necessity and stocks were secured almost as well as gunpowder.  Not the case when you're orbiting Earth but still...

and they didn't pay for them... so they must be free fall apples.

What can a man say except "Ba-da-dum-tish?"