COTS D Minus

[Jim]

You're saying that meeting these shuttle safety requirements is harder and more expensive than developing an automated docking system with propulsion system?

1.  A docking system is not required, only a berthing system.  It can be berthed like HTV, Dragon and Cygnus will be.  A shuttle launched vehicle would have the same system
2.  A propulsion system is needed for leaving the station and entry.  it only needs more propellant to get to the ISS
3.  There are going to be many automated rendezvous systems available.  Orbital express, Orion, ATV, HTV, Dragon and Cygnus

[antonioe]

Slight mod on Jim's description: a COTS-D prime (I hate the "D-minus" label, even if I'm guilty of using it...) has to be able to depart ISS even if the arm is non-functional; on the other hand, "un-berthing", especially in a contingency situation, is a lot less demanding than docking: you release the CMB, and use thrusters to back up; if you're abandoning Station, the slight risk of damaging said Station (from, say, RCS impingement) is probably deemed acceptable as long as the lifeboat itself is not damaged (from, say, a violent recontact).

So Jim's comment is basically valid.

[Jose]

ELV wouldn't have to be human-rated either.  It's almost off the shelf.  I'm afraid it makes so much sense that it'll never happen.

One question on the impingement on the station issue.  Wouldn't you care about it if the lifeboat had to be cycled periodically like Soyuz?  Is it feasible to build a spacecraft with unlimited shelf life docked to the station?  Is this a requirement of the D minus project?  (Sorry Dr. Elias, I love the name.  I'm a fan of irony.)  OK, so that's really three questions.

[HMXHMX]

ELV wouldn't have to be human-rated either.  It's almost off the shelf.  I'm afraid it makes so much sense that it'll never happen.

One question on the impingement on the station issue.  Wouldn't you care about it if the lifeboat had to be cycled periodically like Soyuz?  Is it feasible to build a spacecraft with unlimited shelf life docked to the station?  Is this a requirement of the D minus project?  (Sorry Dr. Elias, I love the name.  I'm a fan of irony.)  OK, so that's really three questions.

I believe it is eminently feasible to build a lifeboat that would have nearly unlimited "shelf" life (i.e., ten years or so, the likely lifetime of the ISS).  Soyuz on-orbit life limits were originally due to issues with propellant seals.  If one uses burst discs and explosive valves to isolate propellants, there should be no other significant life limits. (Soyuz couldn't do this since it needed those thrusters to reach their docking target.  I'd use one set of propulsion for ascent rendezvous and berthing and a sealed system for emergency return.)  Ordnance, parachutes, etc., have all be qualified for long life already, and those test can be used as existence proofs for a rescue capsule.

Obviously, I tend to favor the t/Space "Corona" design for such an application, but there are several alternatives.

[William Barton]

What about cold-gas thrusters for very limited OMS (just enough to back away from ISS at a reasonable rate) and solid-fuel retrorockets (a la Mercury and Gemini)? You could use something like Freon III in the thrusters (nonpoisonous, won't support combustion, relatively large molecule) and I assume since ICBMs can sit around for years and still be trusted to fly away on cue, there are storage-tolerant solid fuels. This is assuming you wanted it to be delivered to ISS as cargo (on, frx, STS), rather than flying on its own.

[HMXHMX]

What about cold-gas thrusters for very limited OMS (just enough to back away from ISS at a reasonable rate) and solid-fuel retrorockets (a la Mercury and Gemini)? You could use something like Freon III in the thrusters (nonpoisonous, won't support combustion, relatively large molecule) and I assume since ICBMs can sit around for years and still be trusted to fly away on cue, there are storage-tolerant solid fuels. This is assuming you wanted it to be delivered to ISS as cargo (on, frx, STS), rather than flying on its own.

I designed cold gas thrusters into the t/Space vehicle specifically for prox ops.  I believe others are planning similar options. 

I don't like solids for a number of reasons.  But the best reason for avoiding them is the inability to tailor the de-orbit impulse.  A simple biprop liquid gives you the ability to trim velocity to hit your landing zone precisely.

[iamlucky13]

What would a COTS D minus entail? Would it be possible for a previous competitor to bypass the need for a commercial launch vehicle by using STS to put the lifeboat at the station? Just curious.

Aside from the proven ability of the shuttle to rendezvous, I'm not clear what such a scheme would provide over using an existing ELV, assuming ULA wants to make a proposal or Falcon or Taurus aren't ready in time.

Could EADS be a participant if they wanted to speed development of their Advanced Return Vehicle or would this be US-only? The ATV seems like the most mature new western spacecraft design.

ATV is great for what it was built for, but I'm not sure how it's mature for the COTS D CRV role.  There are a few sub-systems that could be reused (but repackaged), but otherwise a new project (even behind Orion in planning)

In some areas it's behind, in some areas it's way ahead. Capsule design work is basically nil, but the launch, propulsion, power, and docking systems have already been built and fully tested.

Supposedly the Cargo Advanced Return Vehicle derivative is being planned for 2013. That's a very major amount of the capability needed to return crew, and they might be able to accellerate that.

[antonioe]

Is it feasible to build a spacecraft with unlimited shelf life docked to the station?  Is this a requirement of the D minus project?

O.K., guys, there is no COTS D-minus (or whatever) project - just a bunch of speculation on what we would do iff Shuttle continued at two/year, Soyuz lifeboats were INKSA-ed (wow!) out, etc. etc.  Therefore, there are no requirements!

I believe it is eminently feasible to build a lifeboat that would have nearly unlimited "shelf" life

Possible?  Definitely yes.  Desirable?  Well, the Soyuz designers were no dummies, and a company that knows a lot more about designing human space capsules than I do thinks that 210 days is feasible using existing components but anything longer starts to have major flight assurance cost consequences.  I suspect there is a trade line where it becomes more life-time-economical to replace entire units.

Having said that, *I* don't know where that trade line is.

[A_M_Swallow]

Possible?  Definitely yes.  Desirable?  Well, the Soyuz designers were no dummies, and a company that knows a lot more about designing human space capsules than I do thinks that 210 days is feasible using existing components but anything longer starts to have major flight assurance cost consequences.  I suspect there is a trade line where it becomes more life-time-economical to replace entire units.

Having said that, *I* don't know where that trade line is.

Items for use in space stations, Mars transfer vehicles, Moon/Mars bases and rovers have to be designed to last for several years.  With some thoughtful systems engineering the ACRV may be able to share parts.

Since it returns to Earth the ACRV could be used to test how these parts survive in a real space environment.

[Peter NASA]

Sorry Dr, but you're wrong. I had a letter in front of me today with the wording COTS D- Capability. It is part of the assessment study for Shuttle requirements in an INKSA waiver denial situation, so that is what you mean, as it's not initiated yet. Saying it's "speculation" is a frabrication, please be very careful with your wording.

[HMXHMX]

Is it feasible to build a spacecraft with unlimited shelf life docked to the station?  Is this a requirement of the D minus project?

O.K., guys, there is no COTS D-minus (or whatever) project - just a bunch of speculation on what we would do iff Shuttle continued at two/year, Soyuz lifeboats were INKSA-ed (wow!) out, etc. etc.  Therefore, there are no requirements!

I believe it is eminently feasible to build a lifeboat that would have nearly unlimited "shelf" life

Possible?  Definitely yes.  Desirable?  Well, the Soyuz designers were no dummies, and a company that knows a lot more about designing human space capsules than I do thinks that 210 days is feasible using existing components but anything longer starts to have major flight assurance cost consequences.  I suspect there is a trade line where it becomes more life-time-economical to replace entire units.

Having said that, *I* don't know where that trade line is.

I don't know where the trade is, either, but I do know the primary Soyuz constraint was originally due to the H2O2 mono-propellant (whether regarding seals or just decomposition rate, I am not sure) and for the "T" version I believe it is related to seals on the N2O side of the biprop system.  Maybe someone who knows the Soyuz can elaborate or correct this if it is mistaken.  The only other obvious constraint is the leakage of cabin atmosphere across the hatch seal, and there are several ways to deal with that, too.

And I do agree, the Soyuz designers were very clever.  Would that we were half as clever in the design of Orion.

[antonioe]

I don't know much about the Soyuz design, either historical or present, but there is a myriad of tiny little things: battery cycles, micrometeorite protection thickness, radiation hardening vs. exposure, usage of atmosphere scrubbing canisters, etc. etc.) that would affect any human-carrying craft's on-station docked time vs. cost relationship, either directly or via mass/size (for the same size crew).  Mass increases also "leak" to launch cost.

It's not the ostrich flying overhead and dropping an egg on you that hurts, it's all that nibbling by the geese.

[HMXHMX]

I don't know much about the Soyuz design, either historical or present, but there is a myriad of tiny little things: battery cycles, micrometeorite protection thickness, radiation hardening vs. exposure, usage of atmosphere scrubbing canisters, etc. etc.) that would affect any human-carrying craft's on-station docked time vs. cost relationship, either directly or via mass/size (for the same size crew).  Mass increases also "leak" to launch cost.

It's not the ostrich flying overhead and dropping an egg on you that hurts, it's all that nibbling by the geese.

I don't want to be contrary, and neither of us should be doing the trades on-line when we each have other ducks "chewing" on our respective legs, but I'd offer:

Thermal batteries could be used, and of course many spacecraft have proven very long on-orbit life (>15 years) with conventional batteries; I wouldn't expect many charge-drain cycles for a rescue vehicle.  If you tested the systems once per month, that's only 120 cycles.

TPS has been shown to be relatively long-life as well, though I don't believe we have anything like decade-long experience.  But I'd bet SIRCA or PICA will be functional after long on-orbit storage. (And since this is a down-mass-only vehicle the entire spacecraft could be designed to rest in a shroud until use, though I think that may be overkill.  But it would also address the debris/micrometeorite issue.)

Once again, our current GEO and LEO spacecraft experience addresses the issue of radiation exposure.  Most electronic radiation exposure is worse when systems are powered up, and rescue vehicle systems should be quiescent for the most part.

CO2 scrubbing would be turned off and the canisters sealed while berthed.  There would be plenty of time after separation to open canisters and activate fans.

Bottom line for me is the Soyuz is a remarkable vehicle in which I'd be happy to fly, but it was not designed for the quite different task of on-orbit rescue.  In fact, when the Russians looked at using a Soyuz re-entry module for just such  task, they found it to be fairly straightforward to adapt to longer life.  The lifetime on orbit was to be five years.  We never adopted it, favoring the X-38 instead.    See:

http://www.astronautix.com/craft/alpeboat.htm

[Jose]

Chris Bergin sez:

...the issue of a US-controlled 'lifeboat' is also being evaluated on several fronts, especially in relation to opening discussions with COTS (Commercial Orbital Transportation Services) partners on providing such a vehicle.

Known as 'Capability D-minus', several companies have noted the ability to make available a lifeboat vehicle from 2012 (names and details currently embargoed due to ongoing discussions).

So maybe "discussions" d.n.e a "project", fair enough.  But it's safe to say that it's more than idle speculation at this point.

Wouldn't you want to cycle these lifeboats periodically just as a sanity check?  Make sure that your extrapolations about the on-orbit life of materials and components are correct?  Hopefully these spacecraft are relatively inexpensive anyway.  Also, recovery of an unmanned vehicle doesn't have to be a big navy-warship deal.  Maybe it can be more like the routine recovery of Shuttle SRBs.

[William Barton]

Chris Bergin sez:

...the issue of a US-controlled 'lifeboat' is also being evaluated on several fronts, especially in relation to opening discussions with COTS (Commercial Orbital Transportation Services) partners on providing such a vehicle.

Known as 'Capability D-minus', several companies have noted the ability to make available a lifeboat vehicle from 2012 (names and details currently embargoed due to ongoing discussions).

So maybe "discussions" d.n.e a "project", fair enough.  But it's safe to say that it's more than idle speculation at this point.

Wouldn't you want to cycle these lifeboats periodically just as a sanity check?  Make sure that your extrapolations about the on-orbit life of materials and components are correct?  Hopefully these spacecraft are relatively inexpensive anyway.  Also, recovery of an unmanned vehicle doesn't have to be a big navy-warship deal.  Maybe it can be more like the routine recovery of Shuttle SRBs.

If the hypothetical lifeboat needed to be cycled periodically, it could be loaded with whatever downmass was on tap (lab animals, experimental results, whatever) so as not to waste the trip any more than necessary.

[Blappy]

Chris Bergin sez:

...the issue of a US-controlled 'lifeboat' is also being evaluated on several fronts, especially in relation to opening discussions with COTS (Commercial Orbital Transportation Services) partners on providing such a vehicle.

Known as 'Capability D-minus', several companies have noted the ability to make available a lifeboat vehicle from 2012 (names and details currently embargoed due to ongoing discussions).

So maybe "discussions" d.n.e a "project", fair enough.  But it's safe to say that it's more than idle speculation at this point.

Wouldn't you want to cycle these lifeboats periodically just as a sanity check?  Make sure that your extrapolations about the on-orbit life of materials and components are correct?  Hopefully these spacecraft are relatively inexpensive anyway.  Also, recovery of an unmanned vehicle doesn't have to be a big navy-warship deal.  Maybe it can be more like the routine recovery of Shuttle SRBs.

Or just land it on a runway!   

[bad_astra]

Chris Bergin sez:

...the issue of a US-controlled 'lifeboat' is also being evaluated on several fronts, especially in relation to opening discussions with COTS (Commercial Orbital Transportation Services) partners on providing such a vehicle.

Known as 'Capability D-minus', several companies have noted the ability to make available a lifeboat vehicle from 2012 (names and details currently embargoed due to ongoing discussions).

So maybe "discussions" d.n.e a "project", fair enough.  But it's safe to say that it's more than idle speculation at this point.

Wouldn't you want to cycle these lifeboats periodically just as a sanity check?  Make sure that your extrapolations about the on-orbit life of materials and components are correct?  Hopefully these spacecraft are relatively inexpensive anyway.  Also, recovery of an unmanned vehicle doesn't have to be a big navy-warship deal.  Maybe it can be more like the routine recovery of Shuttle SRBs.

Or just land it on a runway!   

There's no point in designing a lifeboat vehicle that will stay docked for months or years on end, to have wings. Several shapes of reentry craft are already well understood aeorodynamically, unless we are talking resurrecting the X-38 (which is not COTS hardware of course). They also benefit from not having to be piloted in the event of an injured or ill crewmember(s).

Wings just aren't needed. Then there's the whole payload shroud for it.

[Jim]

Or just land it on a runway! 

Not viable for an emergency spacecraft.  It would limit deorbit opportunities

[antonioe]

John Muratore, where aaaare youuuu....?

Seriously, anybody hear about John?  How is he doing?

[JSC Phil]

John Muratore, where aaaare youuuu....?

Seriously, anybody hear about John?  How is he doing?

He was "moved sidewards" about two, three years ago, after an "incident/argument" with another manager. That's all I should say.