Author Topic: LIVE: SpaceX Falcon 9/Dragon CRS-2 (SpX-2) LAUNCH and FD-1 UPDATES (Read 278945 times)

Jim · « **Reply #340 on:** 03/01/2013 05:35 pm »

Quote from: AJA on 03/01/2013 05:32 pm

If they were down, how effectively did this happen?

Thrusters are not used for stage separation.

mlindner · « **Reply #341 on:** 03/01/2013 05:36 pm »

Quote from: Targeteer on 03/01/2013 05:33 pm

Per DPC, coelliptic burn delayed one rev to 1700 but there is not a go yet for the burn. If the burn occurs planned timeline tomorrow is intact.

1700 what? Can't be 1700 UTC its already 1836.

Longhorn John · « **Reply #342 on:** 03/01/2013 05:37 pm »

Quote from: Targeteer on 03/01/2013 05:31 pm

Quote from a Bill Harwood update

"After Dragon achieved orbit, the spacecraft experienced an issue with a propellant valve," a SpaceX spokeswoman said. "One thruster pod is running. We are trying to bring up the remaining three. We did go ahead and get the solar arrays deployed. Once we get at least two pods running, we will begin a series of burns to get to station."

That's just the SpaceX PAO comment posted on here pages ago. A lot of people are posting these things as new news. That was 90 minutes ago.

Targeteer · « **Reply #343 on:** 03/01/2013 05:39 pm »

Quote from: mlindner on 03/01/2013 05:36 pm

Quote from: Targeteer on 03/01/2013 05:33 pm
Per DPC, coelliptic burn delayed one rev to 1700 but there is not a go yet for the burn. If the burn occurs planned timeline tomorrow is intact.

1700 what? Can't be 1700 UTC its already 1836.

Must have been 1900...

Chris Bergin · « **Reply #344 on:** 03/01/2013 05:53 pm »

L2 digging has Dragon with "only one working quad and no attitude control" as of - if I've worked out the timing correctly - the planned TIG for coelliptic burn, but I've got a lot of people (NASA and such) who say the only info they are getting is via Elon's now silent twitter feed (heh).

Suggests SpaceX are in info lockdown.

JimO · « **Reply #345 on:** 03/01/2013 05:54 pm »

Quote from: psloss on 03/01/2013 05:17 pm

Apparently still possible with different schedule of burns to make it tomorrow; not sure, though, and not sure how long that would remain a possibility.

I wish somebody would show me that different schedule because I'm skeptical. On the rendezvous you are modulating your phase angle change rate -- the degrees of orbital travel the chaser and target are separated by -- by altering your altitude. You launch with a planned stepwise altitude increment plan, and you launch so that this plan modulates the approach rate to arrive at zero range at a desired time. You give yourself a little flexibility in this altitude raise schedule so you can handle launching over a range of phase angles, which you have to be able to do since the driver on launch time is the planar difference -- you gotta go when and only when it's near zero difference.

But once you launch, you gotta follow that altitude profile pretty close or else your phase angle difference gets bad fast -- and it cannot be quick-fixed by just thrusting directly at the target [just ask Jim McDivitt]. Once you break that plan you can easily develop a new plan -- either go higher/slower as Liss said, or do a full orbital overlap over a period of days. But you spend 'time' to keep the maneuvers within your prop budget.

What you can't do is stop and retrace your steps. No U-turns in orbit.

They do seem to have plenty of 'time'. No space sequester or cliff. I expect they'll work it out, but by now, I'd be surprised to see them be able to do it by tomorrow.

A one-rev delay is within the slack, let's hope they get it off.

mdo · « **Reply #346 on:** 03/01/2013 05:56 pm »

Quote from: JimO on 03/01/2013 05:06 pm

What are the periods of the Dragon and ISS orbits, and then compute their lap time. L = lap time, D and I are the periods,

Propagating the latest available TLEs indicates that Dragon will pass the ISS tonight at around 21 UTC, unless it manoeuvres, of course. In terms of phase angle the two spacecraft currently approach each other at a rate of about 7.8 deg/hour or 185 deg/day (in terms of revs/day: EDIT ~~ISS 16.04, Dragon 15.52~~ ISS 15.52, Dragon 16.04). Hence, once Dragon passed the station the relative orbital constellation will repeat itself roughly every other day. So, one could infer from this that the timeline might shift in increments of about 2 days until the issue can be resolved or Dragons orbit gets significantly altered one way or another.

MarekCyzio · « **Reply #347 on:** 03/01/2013 05:56 pm »

Do we know how much atmospheric drag Dragon encounters on the current orbit?

Robotbeat · « **Reply #348 on:** 03/01/2013 05:56 pm »

Quote from: JimO on 03/01/2013 05:54 pm

Quote from: psloss on 03/01/2013 05:17 pm
Apparently still possible with different schedule of burns to make it tomorrow; not sure, though, and not sure how long that would remain a possibility.

I wish somebody would show me that different schedule because I'm skeptical. ...

It is what folks said on the ISS live feed, giving an update to the ISS crew.

Space Pete · « **Reply #349 on:** 03/01/2013 06:00 pm »

One thing we've all forgotten about: When was the GNC bay door supposed to open, and has/will this be delayed? When does it need to be open by in order to begin rendezvous with ISS?

JimO · « **Reply #350 on:** 03/01/2013 06:01 pm »

Quote from: mdo on 03/01/2013 05:56 pm

Quote from: JimO on 03/01/2013 05:06 pm
What are the periods of the Dragon and ISS orbits, and then compute their lap time. L = lap time, D and I are the periods,

Propagating the latest available TLEs indicates that Dragon will pass the ISS tonight at around 21 UTC, unless it manoeuvres, of course. ....

Excellent data, thanks. Yeah, a two-day overlapping repetition rate seems reasonable.

If they pass in two hours, by your calculation, the near-future phasing burn would have to follow Liss's suggestion and go higher than normal. But propellant reserves are loaded for just such needs.

Nickolai · « **Reply #351 on:** 03/01/2013 06:01 pm »

Doug Messier of parabolicarc has a good summary/timeline, hopefully it will help clear up some of the "who said what when" issues.

http://www.parabolicarc.com/2013/03/01/dragon-reaches-orbit-but-is-experiencing-a-problem/

Nickolai · « **Reply #352 on:** 03/01/2013 06:02 pm »

Quote from: Space Pete on 03/01/2013 06:00 pm

One thing we've all forgotten about: When was the GNC bay door supposed to open, and has/will this be delayed? When does it need to be open by in order to begin rendezvous with ISS?

AFAIK, the GNC bay hides the star tracker and grapple fixture, but without thrusters both of those seem irrelevant, so I'm not sure if there's much of a point in opening that door?

JimO · « **Reply #353 on:** 03/01/2013 06:03 pm »

Quote from: Space Pete on 03/01/2013 06:00 pm

One thing we've all forgotten about: When was the GNC bay door supposed to open, and has/will this be delayed? When does it need to be open by in order to begin rendezvous with ISS?

I would guess that the first phasing burn is ground targeted and does not require on-board navigation. But I have not inspected their actual plan.

I don't think air drag is a significant issue at this point. Insofar as it slightly lowers and speeds up the Dragon, it helps get through a full orbit 'lapping' sooner and line up again for a nominal approach profile.

Jason1701 · « **Reply #354 on:** 03/01/2013 06:03 pm »

Quote from: Nickolai on 03/01/2013 06:02 pm

Quote from: Space Pete on 03/01/2013 06:00 pm
One thing we've all forgotten about: When was the GNC bay door supposed to open, and has/will this be delayed? When does it need to be open by in order to begin rendezvous with ISS?

AFAIK, the GNC bay hides the star tracker and grapple fixture, but without thrusters both of those seem irrelevant, so I'm not sure if there's much of a point in opening that door?

It was supposed to open just before the coelliptic burn.

joncz · « **Reply #355 on:** 03/01/2013 06:08 pm »

Quote from: mdo on 03/01/2013 05:56 pm

... In terms of phase angle the two spacecraft currently approach each other at a rate of about 7.8 deg/hour or 185 deg/day (in terms of revs/day: ISS 16.04, Dragon 15.52).

Shouldn't these be reversed? ISS - 15.52 revs/day, and Dragon 16.04? Otherwise, how is Dragon overtaking ISS?

JimO · « **Reply #356 on:** 03/01/2013 06:09 pm »

Just advised by JSC friend: "The last burn opportunity to ensure an on-time rendezvous with ISS will be about 1pm CST".

That's now, and passed. Looks like tomorrow's opportunity is gone.

mlindner · « **Reply #357 on:** 03/01/2013 06:09 pm »

Quote from: Jason1701 on 03/01/2013 06:03 pm

Quote from: Nickolai on 03/01/2013 06:02 pm
Quote from: Space Pete on 03/01/2013 06:00 pm
One thing we've all forgotten about: When was the GNC bay door supposed to open, and has/will this be delayed? When does it need to be open by in order to begin rendezvous with ISS?

AFAIK, the GNC bay hides the star tracker and grapple fixture, but without thrusters both of those seem irrelevant, so I'm not sure if there's much of a point in opening that door?

It was supposed to open just before the coelliptic burn.

Because of the thruster activation inhibit it likely means the entire automatic startup sequence got stopped there. It is likely that until things are restored to nominal state that most things will be manually commanded.

Galactic Penguin SST · « **Reply #358 on:** 03/01/2013 06:10 pm »

I heard on the ISS update feed that SpaceX is making progress in recovering the propellant system, but will not make it in time for making burns for rendezvous tomorrow.

mlindner · « **Reply #359 on:** 03/01/2013 06:11 pm »

Quote from: Galactic Penguin SST on 03/01/2013 06:10 pm

I heard on the ISS update feed that SpaceX is making progress in recovering the propellant system, but will not make it in time for making burns for rendezvous tomorrow.

I've seen several people talking about this feed, but I haven't seen a link for it. Could this be linked?