SpaceX Falcon 9/Dragon CRS-2 SpX-2 MISSION GENERAL DISCUSSION

[yg1968]

Here is an intersting take on the Falcon 9 and Dragon glitches:
http://cosmiclog.nbcnews.com/_news/2013/03/06/17201079-why-its-good-for-spacexs-private-spaceships-to-rise-above-the-glitches

[Lurker Steve]

I have an issue just 3 paragraphs in.

Are you sure the "value" of a mission is less than the cost of a more reliable spacecraft ? What value is he assigning to the science experiments that are being ferried to the ISS ?

Sure, the value of the basic consummables is easily measured, and as long as there are multiple cargo ships available, those can be replaced. Even the grapple-fixtures in the trunk aren't absolutely necessary today, although they might be, later in the life of the ISS.

But what about the team that has been waiting to get their science payload aboard the ISS ? Are those experiments just discarded, never to happen again ?  How likely would an experiment aboard a failed CRS flight get a second chance to fly to the ISS ?

[baldusi]

But what about the team that has been waiting to get their science payload aboard the ISS ? Are those experiments just discarded, never to happen again ?  How likely would an experiment aboard a failed CRS flight get a second chance to fly to the ISS ?

Experiments with problems in CSR-1 (was an astronaut's accident, I believe) were reflown. that's the idea, behind that concept.
Instead of one 97% reliable flight, you do five 90%. Of course this only works if your payload is cheaper. Which is the case with current types of experiments. You simply have to assume a 20% chance of having to re do the experiment. Please remember that in some failure modes, you might get back your experiment.
This is not a good solution if your are actually building the station, which is so expensive and has unique parts. But for cargo and experiments, it allows a lot more science.
There's a second point, too. And is that fly early fly often means that you have a lot more flight history. Off nominal situations are expected. That the corrective measures are taken and that the lessons are learned is what's important. Thus, flying a lot will result in a very reliable service in the future. Just think how all this experience and system validation will help if they ever launch crew. If they had been transporting astronauts, it would probably have been quite a situation. Just a big scare, but a very public one.

[john smith 19]

There's a second point, too. And is that fly early fly often means that you have a lot more flight history. Off nominal situations are expected. That the corrective measures are taken and that the lessons are learned is what's important. Thus, flying a lot will result in a very reliable service in the future. Just think how all this experience and system validation will help if they ever launch crew. If they had been transporting astronauts, it would probably have been quite a situation. Just a big scare, but a very public one.

The question of course is how much Crewed Dragon is like cargo Dragon so the performance statistics can be "inherited."

I wonder if people really understand how big a lead this gives Spacex over SNC or Boeing in terms of safety prediction?

[oiorionsbelt]

Does anyone have any insight into the mechanism, for holding the HRSGF,s to and then releasing them from the trunk?

[mr. mark]

There's a second point, too. And is that fly early fly often means that you have a lot more flight history. Off nominal situations are expected. That the corrective measures are taken and that the lessons are learned is what's important. Thus, flying a lot will result in a very reliable service in the future. Just think how all this experience and system validation will help if they ever launch crew. If they had been transporting astronauts, it would probably have been quite a situation. Just a big scare, but a very public one.

The question of course is how much Crewed Dragon is like cargo Dragon so the performance statistics can be "inherited."

I wonder if people really understand how big a lead this gives Spacex over SNC or Boeing in terms of safety prediction?

I fully understand. I also understand that if SpaceX launches Astronauts in 2015, 2 years before the NASA contract kicks in they will have that flight experience as well. The lead is way more than people realize.

[Lurker Steve]

But what about the team that has been waiting to get their science payload aboard the ISS ? Are those experiments just discarded, never to happen again ?  How likely would an experiment aboard a failed CRS flight get a second chance to fly to the ISS ?

Experiments with problems in CSR-1 (was an astronaut's accident, I believe) were reflown. that's the idea, behind that concept.
Instead of one 97% reliable flight, you do five 90%. Of course this only works if your payload is cheaper. Which is the case with current types of experiments. You simply have to assume a 20% chance of having to re do the experiment. Please remember that in some failure modes, you might get back your experiment.
This is not a good solution if your are actually building the station, which is so expensive and has unique parts. But for cargo and experiments, it allows a lot more science.
There's a second point, too. And is that fly early fly often means that you have a lot more flight history. Off nominal situations are expected. That the corrective measures are taken and that the lessons are learned is what's important. Thus, flying a lot will result in a very reliable service in the future. Just think how all this experience and system validation will help if they ever launch crew. If they had been transporting astronauts, it would probably have been quite a situation. Just a big scare, but a very public one.

But isn't there limited "bandwidth" due to the allocation of rack space, power, human interaction, etc that must be factored in when scheduling ISS experiments ? If a set of experiments doesn't get delivered, then there is less science during the period of that missed CRS mission, and any re-flight just gets added to a queue of ISS experiments that are waiting to happen. What is the current backlog of ISS experiments ? That is the reason the ISS exists, for the science, not to provide a destination for commerical cargo and crew flights.

[baldusi]

But isn't there limited "bandwidth" due to the allocation of rack space, power, human interaction, etc that must be factored in when scheduling ISS experiments ? If a set of experiments doesn't get delivered, then there is less science during the period of that missed CRS mission, and any re-flight just gets added to a queue of ISS experiments that are waiting to happen. What is the current backlog of ISS experiments ? That is the reason the ISS exists, for the science, not to provide a destination for commercial cargo and crew flights.

You fill the pipeline of waiting experiments with margin for failed deliveries. You give priority to time sensitive experiments and fill a buffer with long expiration time experiments. It's about keeping 100% utilization. Might worsen latency, but improve total output.

[Kaputnik]

Does anyone have any insight into the mechanism, for holding the HRSGF,s to and then releasing them from the trunk?

I was wondering about that too.
Does Dragon have to actively disengage from the trunk payload? Or does the SSRMS, or the payload itself, handle that?

[e of pi]

I was wondering about that too.
Does Dragon have to actively disengage from the trunk payload? Or does the SSRMS, or the payload itself, handle that?

A tweet from a SpaceX engineer yesterday:

We just released the CRAP out of that cargo! High fives, all around! ...What do you mean, "Overfocusing on minutiae because I worked on it?

So I guess the release was on the Dragon side?

[Jim]

The question of course is how much Crewed Dragon is like cargo Dragon so the performance statistics can be "inherited."

I wonder if people really understand how big a lead this gives Spacex over SNC or Boeing in terms of safety prediction?

It doesn't, they will be too different.  Much like F9 1.0 and 1.1.

[edkyle99]

I was wondering about that too.
Does Dragon have to actively disengage from the trunk payload? Or does the SSRMS, or the payload itself, handle that?

A tweet from a SpaceX engineer yesterday:

We just released the CRAP out of that cargo! High fives, all around! ...What do you mean, "Overfocusing on minutiae because I worked on it?

So I guess the release was on the Dragon side?

Of course.  Dragon has to have a way to firmly hold the payload during launch and transit, and a way to cleanly release it when it is time to do so.  Shuttle Orbiters had something called "Payload Attach Fittings" in the payload bay (if I'm remembering correctly) that had a motorized portion to allow things to be clamped down or unclamped.  Things like this are simultaneously simple and complex, especially with the temperature extremes an vacuum of orbit, and I'm sure some SpaceX people were very pleased to see these items work as designed.  We won't see details of these items though.

 - Ed Kyle

[psloss]

Shuttle Orbiters had something called "Payload Attach Fittings" in the payload bay (if I'm remembering correctly) that had a motorized portion to allow things to be clamped down or unclamped.

Yes, Payload Retention Latch Assemblies (PRLA).

[Kaputnik]

Thanks for the info.
This might be impossible to answer, but is it likely that SpaceX will have to design/modify a new payload release system for every external payload?

[Space Pete]

Thanks for the info.
This might be impossible to answer, but is it likely that SpaceX will have to design/modify a new payload release system for every external payload?

Maybe for some unique items such as the BEAM, but for the most part, Trunk payloads will be standard ISS Flight Releasable Attachment Mechanism (FRAM) attachments, which will be removed from the Trunk via the driving of bolts on the FRAM itself, actuated by Dextre.

[CLmason]

Hi all,

First post, complete noob, please be kind. I searched but could not find anything on this topic

My Question, when Dragon is at the ISS, does NASA consider it an emergency escape craft for the astronauts?

Thanks!

[QuantumG]

Hi all,

First post, complete noob, please be kind. I searched but could not find anything on this topic

My Question, when Dragon is at the ISS, does NASA consider it an emergency escape craft for the astronauts?

Welcome to the forum!

This is an UPDATE thread, so I placed a reply to your question here:

http://forum.nasaspaceflight.com/index.php?topic=30385.msg1025267#msg1025267

[Lars_J]

(Sorry if someone already posted this)
New pictures have appeared on the NASA ISS mission pictures, showing some of the goodies (veggies/fruit) that the Dragon brought up:

http://www.spaceflight.nasa.gov/gallery/images/station/crew-34/inflight/ndxpage33.html

They can also be seen in the "Nasa2Explore" Flickr stream:

http://www.flickr.com/photos/nasa2explore

[simonbp]

Those are some totally unprofessional bell peppers right there...

[guckyfan]

The way they are packed, I am surprised that they did not get squashed during launch.

But I can imagine, they are happy with those.