Commercial Crew Spacecraft Competition

[DaveH62]

NASA to Announce New Agreements for Next Phase of Commercial Crew Development.
Is this THE announcement of the 2.5 Comm Crew Providers?

http://spaceref.com/news/viewpr.html?pid=38013

[Go4TLI]

I don't know where all this reboost stuff is coming from. The LAS engines are likely not throttleable.  And something that is intended to get one off an exploding rocket as quick as possible would also destroy ISS if fired while docked.

Shuttle reboosted ISS with 25 lbf thrusters

[cleonard]

The amount of boost that a Dragon can give to the ISS will be limited.  The Dragon is so much smaller.  To be useful for abort the deltav will need to be in the 500 m/s or more range.  The deorbit burn for the Dragon will be around 100 m/s to 120 m/s depending on the exact situation.  There is some other maneuvering and reserves so lets say a Dragon has 300 m/s extra. 

When you are pushing a 420mT ISS that 300 m/s will only do so much.  If you go most optimistic and say that 300 m/s is for a max weight Dragon at 10mT, when you combine masses you get a deltav on the order of 7 m/s.  It's better than zero, but it's not going to boost the ISS all that much.

I see mentions of using the Super Draco to boost the ISS.  It would not be done that way.  That's too much force.  A longer lower thrust burn of an attitude control Draco is how it would be done.   

EDIT:
If I'm doing this right that 7m/s should boost a 320km low ISS orbit to a little under 330km.  I think that the ISS operates between 320km and 350km or so.  That makes it a useful boost, but not a real big boost.

[pathfinder_01]

I don't know where all this reboost stuff is coming from. The LAS engines are likely not throttleable.  And something that is intended to get one off an exploding rocket as quick as possible would also destroy ISS if fired while docked.

Shuttle reboosted ISS with 25 lbf thrusters

The propellant for reboost could be used by either LAS thrusters or other thrusters. CST-100 plans two differnt types of thrusters that could use the same propellant.

[Orbital Debris]

How come the CST-100 suffered from bloat that didn't effect Dream Chaser? 7 crew, life support, abort system, docking hatch, power for 60 hours of free flight. Then add the weight of wings and wheels for landings.

How do they fit all that on Atlas 402? I'm sceptical.

Dragon & CST look to be built the right way looking towards being on time/budget even if they might be a little heavier. Aluminium pressure vessel and small round simple heat shield.

I wonder if Boeing would want to change to Delta IV if it becomes the sole customer on Atlas V.

Isn't that upper stage being man rated anyway for SLS?

DEC might not be needed in that case. 

I also like the money that Bigelow/Musk invested in those 2 spacecraft and that is one of the things CCDev was trying to do.

Bigelow did not invest money in either Dragon or CST-100. 

[spectre9]

I don't know where all this reboost stuff is coming from. The LAS engines are likely not throttleable.  And something that is intended to get one off an exploding rocket as quick as possible would also destroy ISS if fired while docked.

Shuttle reboosted ISS with 25 lbf thrusters

The propellant for reboost could be used by either LAS thrusters or other thrusters. CST-100 plans two differnt types of thrusters that could use the same propellant.

The SM supplies prop to both abort engines and the OMAC thrusters. There are 24 of them. I'm sure there is a way to give ISS a little push.

[erioladastra]

I don't know where all this reboost stuff is coming from. The LAS engines are likely not throttleable.  And something that is intended to get one off an exploding rocket as quick as possible would also destroy ISS if fired while docked.

Shuttle reboosted ISS with 25 lbf thrusters

The propellant for reboost could be used by either LAS thrusters or other thrusters. CST-100 plans two differnt types of thrusters that could use the same propellant.

The SM supplies prop to both abort engines and the OMAC thrusters. There are 24 of them. I'm sure there is a way to give ISS a little push.

CST-100 will use the RCS for reboost.  The OMAC and LAE are too powerful.  Not it still remains to be seen how much total delta V will be available to see if worth it.

[Orbital Debris]

CST-100 Reboost will be important for Bigelow.  They need every spare m/s that they can get.

[Robotbeat]

Really, ANY of the commercial crew vehicles could be used for reboost, since all have maneuvering thrusters. Some are better than others. (And some surely have thrusters in better spots for the burn.) And no, in no case would the high-thrust abort motors be used for reboost for any of the vehicles. The only vehicle that has talked about it is the CST-100. But the others could do it, too (though DC would be less efficient, since it is using a lower Isp monopropellant for RCS/ACS). Though of course, the exact arrangement of thrusters and which docking port is used will matter. I think CST-100 has more options in this regard.

[Prober]

CST-100 Reboost will be important for Bigelow.  They need every spare m/s that they can get.

News on Bigelow, also some links to SpaceX, SNC

http://www.lvrj.com/business/nasa-contracts-benefit-north-las-vegas-outfit-164988796.html

[docmordrid]

So they're hiring again. Good.

[Nomadd]

If I'm doing this right that 7m/s should boost a 320km low ISS orbit to a little under 330km.  I think that the ISS operates between 320km and 350km or so.  That makes it a useful boost, but not a real big boost.

ISS has been around 390-400 km since ATV-2 last year.

 Is that where they'd like to be, or will it go higher in the future?

[erioladastra]

If I'm doing this right that 7m/s should boost a 320km low ISS orbit to a little under 330km.  I think that the ISS operates between 320km and 350km or so.  That makes it a useful boost, but not a real big boost.

ISS has been around 390-400 km since ATV-2 last year.

 Is that where they'd like to be, or will it go higher in the future?

They may go as high as 410 km during the upcoming solar maximum. They will not go much higher than that because Soyuz and Progress have a "ceiling" of 425 km and ISS needs some "wiggle room" for debris avoidance.

Actually, Progress can reach 460 km, hence why 1130 requires that the CCVV be able to reach that.  It is a contingency case, likely only to be used if ISS had to be unmanned and put in a parking orbit for safe keeping.

[Robotbeat]

If I'm doing this right that 7m/s should boost a 320km low ISS orbit to a little under 330km.  I think that the ISS operates between 320km and 350km or so.  That makes it a useful boost, but not a real big boost.

ISS has been around 390-400 km since ATV-2 last year.

 Is that where they'd like to be, or will it go higher in the future?

They may go as high as 410 km during the upcoming solar maximum. They will not go much higher than that because Soyuz and Progress have a "ceiling" of 425 km and ISS needs some "wiggle room" for debris avoidance.

Actually, Progress can reach 460 km, hence why 1130 requires that the CCVV be able to reach that.  It is a contingency case, likely only to be used if ISS had to be unmanned and put in a parking orbit for safe keeping.

+1, Informative.

[Zed_Noir]

Just out of curiosity, what's the operational ceilings of the 3 commercial crew vehicles in their current configurations?

[erioladastra]

Just out of curiosity, what's the operational ceilings of the 3 commercial crew vehicles in their current configurations?

Not really the right question.  Given a big enough booster these companies can all readch very high altittudes and get back.  I think what you are getting at is how high could they reboost.  Depends on how much delta V they can produce.  Also a factor, is even a small reboost won't be useful for ISS (different story for Bigelow) if they also don't have enough prop to swing the large ISS around so you can do the burn in the right direction, burn and swing back.  If you have to use a lot of RS prop and only getting a really small burn that doesn't help.  of course we now have the Optimized Prop Manuever that helps.

[Zed_Noir]

Just out of curiosity, what's the operational ceilings of the 3 commercial crew vehicles in their current configurations?

Not really the right question.  Given a big enough booster these companies can all readch very high altittudes and get back.  I think what you are getting at is how high could they reboost.

Not about ISS reboost. Just what is the maximum altitude can the commercial crew vehicles can get to in their current stack configuration. Someone might want to operate some sort of facility/platform higher up than the ISS requiring visits in the future.

[Lars_J]

Just out of curiosity, what's the operational ceilings of the 3 commercial crew vehicles in their current configurations?

Not really the right question.  Given a big enough booster these companies can all readch very high altittudes and get back.  I think what you are getting at is how high could they reboost.

Not about ISS reboost. Just what is the maximum altitude can the commercial crew vehicles can get to in their current stack configuration. Someone might want to operate some sort of facility/platform higher up than the ISS requiring visits in the future.

It also depends on how heavily loaded the spacecraft will be. A lightly loaded spacecraft with 2 crew would be able to higher than a fully loaded spacecraft.

For example, the SpaceX C2+ mission got themselves extra delta-V by flying a lighter load of cargo than they could have flown.

[Prober]

thats a good layout and glad Apollo got in there for reference.

Blue Origin and DC fans how about some input?

back in the game....

[docmordrid]

http://www.flightglobal.com/news/articles/spacex-completes-system-requirements-review-for-crewed-launches-378446/

SpaceX completes system requirements review for crewed launches 
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