CEV development cost rumbles

"Jorge R. Frank" writes:

(Derek Lyons) wrote in
:
If you are doing EOR, then being able to ship significant sized pieces
back for repair/refurbishment becomes attractive.

We are starting to see that now with ISS, in fact. ISS has lost one of its
four CMGs and there is a growing suspicion that the failure mode may be
generic. NASA would *really* like to get that failed CMG on the ground to
determine the root cause, but the shuttle is the only existing vehicle
capable of returning it.

Certainly it would be useful to be able to return failed equipment to
earth, especially for analysis of the failure. However, I'm not sure
we really need something as big as the shuttle to do this. Certainly
you want the ability to return pieces bigger than a CBM hatch, but
hopefully, smaller than an entire module. You ought to be able to
meet this requirement without building another vehicle with a 15 foot
by 60 foot payload bay.

Jeff
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"Kim Keller" writes:
Remember that spacecraft design is driven by *mission requirements*. Had
NASA specified some key mission requirement that could only be handled by a
WV, then that's what you would have seen the teams move forward with. Winged
vehicles have their advantages and disadvantages, just as capsules do.
Attempts to rank one above another mean nothing without stating what the
mission requirements are.

Note that NASA has, in the past, written mission requirements that
appeared to lead directly to a winged vehicle (large cross-range, low G
re-entry, and etc), without much justification for those requirements.

One notable example is emergency crew return from ISS. Winged
vehicles had been NASA's preference for this role for many years,
despite the fact that the only vehicle now performing this role is a
capsule. If this were a *real* requirement, NASA would never accepted
Soyuz as an interim emergency return vehicle.

We all know how Soyuz sometimes doesn't land where you'd expect (they
now carry satellite phones on Soyuz for just such an emergency). We
also know that the retro-rockets don't always work, leading to a very
hard landing that can injure the crew.

Jeff
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(Derek Lyons) writes:

Agreed. The ultimate problem with our current space transportation
system is that it's built around a mini-van towing a camping trailer.
There is no Ford Escort, no 18-wheeler, no buses....

Actually, the mini-van is permanently welded to the camping trailer.
Because of this, you're stuck taking your camper along on missions
that only need the mini-van and vice-versa. If you could decouple the
two and fly them independently...

Jeff
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In message , Hallerb
writes

The decision was made on the basis of safety, not worth the effort, according

to the Administrator of NASA who made the decision. Senior officials stated
that they had the money to support the mission.

So, it appears that you are against a safety-based decision.

--
rk, Just an OldEngineer


A hubble flight is no less safe than a ISS one. ANY ISS flight may have a abort
to orbit, where it gets to orbit but cant reach ISS. In such a case a stand
alone repair capability will be needed.

Hubble service and a stand aklone repair might well save a ISS orbiter one day.

I think Buashes goal was electioneering and setting the stage to gut nasas
manned space capability. While saving as mucgh $$$ as possible. His plan scraps
too much

If Bush was TRULY dedicated to his program why no follow up or even mentioning
it?
Let's see now. By your own admission, you can't be bothered to take the
trouble to spell correctly when you post to this group.
So why should we bother listening to you?
--
Save the Hubble Space Telescope!
Remove spam and invalid from address to reply.

John Doe wrote:
[...]
TPS is not a "show stopper". There are a number of TPS solutions available
now.

Apart for what is used on the Shuttle, what other technologies exist ?

If one were to build Shuttle mark II, how different would the TPS system be ?
Same materials, but larger tiles due to better manufacturing techniques
allowing more complex 3d shapes ?

Well, I may be misquoting Ray Schmidt, but IIRC the TPS for X-33 was
an improvement on STS TPS, but not enough to avoid the large standing
army. This is a serious issue for a 2nd gen WV.


Remember that spacecraft design is driven by *mission requirements*.

Alpha isn't the first, nor will it be the last LEO space station. Heck, even
Star Trek has space stations and ship assembly in orbit :-)

The US space station isn't even finished yet and there is already a need to
bring back stuff other than rubbish. That need will grow. And if you start
building a ship to mars, you'll also need bidirectional transport because
during building, stuff will fail and you will want it analysed to make sure
that you fix the problems before the ship departs for its long voyage.

NASA specified some key mission requirement that could only be handled by a
WV, then that's what you would have seen the teams move forward with.

Well, you mentioned that contractors have internal pressures to use EELVs
(probably because one solution fits both NASA and commercial launches). Sounds
to me like there is a lot of brainwashing being done to smear Shuttle style
approach and NASA is just gulping it all in, believing it all.


Space craft design, like automotive engineering (Wankels, anyone?) and
bridge design, is subject to fads. But I don't think the discussion
that has led to capsules being first in line *at this time* was a
"smear Shuttle style approach".

Heck, I grew up with Rocket Ship Galileo and Have Spacesuit Will
Travel, so I'd like to have a finned needle sitting in my backyard,
but sometimes one doesn't go directly to one's goal.



Winged
vehicles have their advantages and disadvantages, just as capsules do.
Attempts to rank one above another mean nothing without stating what the
mission requirements are.

Well, that brings the big question which NASA seems to have really avoided:
WHAT ARE THE REQUIREMENTS ?????

Since a trip to Mars is being discussed, does anyone really think that they
could launch it all in one piece and that assembly and a shakedown would not
be required in orbit prior to the trip actually starting ?

Can NASA develop automated docking on hatches the size of CBM (they learned
from MIR that smaller russian hatches are not good enough). ? Will truss
structures assemble themselves automatically ? Will an arm fly by itself and
attach itself to the station automatically ?

If you're going to limit yourslef to camping trips to the moon, to re-enact
Apollo, then yes, capsules are all that you need. But if you are going to move
forwards, you need a truck to bring your materials to space for intelligent
assembly. And during the shakedown, you need to bring back failed pieces for analysis.


Yeah, but you need more up-tracks than down-trucks, so why pay to use
wings 50 times instead of 5 times? Hmmm, it just occurred to me that
one way to avoid having the weight penalty of wings on lift-off is to
assemble them in orbit from material left over from the DSV assembly.
Not that you'd have a lot of properly shaped silicate tiles on hand if
you tried that, though.

And I suspect that a good Mars design will probably have
ease-of-assembly as a design criteria, so that automated docking and
robotic assets will pay a big part. And while the current ISS shape
is heavily influenced by the shape of the Shuttle's payload bay, the
basic idea of modular constuction is supported by other launch
vehicles as well. Mir and ISS have taught us a great deal about
assembly; we still have more to learn, but I think we could handle
assembling a Mars DSV using largely expendable launches. There is a
case to be made for HLVs to make it easier, but it appears that at
least most of the tasks can be done using existing expendable
launchers.

And what about an HL-20 to bring back CMGs?

/dps

(Derek Lyons) wrote

I find it unlikely that a space vehicle for an 18 month
flight will be more complex than a Trident submarine. Which
submarine does all it's monitoring, all it's combat operations,
all it's everything with the equivalent of about 6-8 386's.

That's an interesting point which might deserve a bit of discussion.

Doubtlessly for Classical Age spaceships, maybe even ones up to
the Discovery of 2001, that's probably true (no HAL needed). But
these are perhaps different days, and it might be worthwhile to
consider what somewhat pervasive computation could do for a Mars-
or Jupiter-ship. Active and continuous control of flexible structure,
active and continuous control of the life-support system/ecosystem,
maybe a really closely monitored power and propulsion system,
continuous monitoring of the details of the space environment, etc.
-- maybe those would lead to a superior space vehicle.

"John Doe" wrote in message ...
What motivation was behind that "internal pressure" ? Doesn't that mean
that
the contractors had vested intetests that perhaps didn't match NASA's real
needs ?

No. The pressure was that brought on by the competition itself, something
that is always true of competition. All teams knew thatlife-cycle costs were
going to have to be low in order for their design to have a shot at winning.
That meant making every possible effort to keep their design weight down so
they could use the smallest possible (thus,cheapest) variant of the two
EELVs.

Using capsule designs met that
need. Both teams also found that a capsule design would provide 100%
abort
capability during ascent, something not true of the WVs they had
developed.

Is this a winged vs capsule issue, or a reusable vs not reusable issue ?

This particular issue turned out to be winged vs. capsule. The teams found
(independently) that there were several points during ascent when successful
abort could not be achieved with their winged designs.

What if a winged vehicle were mounted on top of a stack instead of
attached to
its side ? Wouldn't that give it the same abort capabilities ? (In an
abort
scenario, must a reusable vehicle be completely saved or is it acceptable
to
lose it, while saving occupant's lives ?

No. Early in the ascent, and at one or two other points during ascent, the
probability of a successful abort was severely diminished because of the
handling properties of the vehicle. (All winged concepts were mounted on the
nose of the boosters)

In an abort scenario, it is realistic to even assume that a normally
reusable
vehicle would be intact enough to be reusable ?

That is questionable, depending on the design of the vehicle, the dynamic
environment at the moment of abort and the subsequent loads the vehicle must
endure to reach a safe landing.

TPS is not a "show stopper". There are a number of TPS solutions
available
now.

Apart for what is used on the Shuttle, what other technologies exist ?

More mature developments of them, plus newer materials that offer better
durability. There are also expendable ablative solutions that can be
applied, even on a reusable vehicle.

If one were to build Shuttle mark II, how different would the TPS system
be ?
Same materials, but larger tiles due to better manufacturing techniques
allowing more complex 3d shapes ?

Either metallic TPS or more advanced ceramics.

Remember that spacecraft design is driven by *mission requirements*.

Alpha isn't the first, nor will it be the last LEO space station. Heck,
even
Star Trek has space stations and ship assembly in orbit :-)

The US space station isn't even finished yet and there is already a need
to
bring back stuff other than rubbish. That need will grow. And if you start
building a ship to mars, you'll also need bidirectional transport because
during building, stuff will fail and you will want it analysed to make
sure
that you fix the problems before the ship departs for its long voyage.

That is true. However, the mission requirement for OSP did not specify
return of anything bulky, i.e., if it didn't fit through the crew hatch it
wasn't going home. Remember that, originally, OSP was to be a complement to
STS, not a full-blown replacement. STS would have continued to handle the
return of bulky items. We don't know yet what the mission requirements will
be for CEV, so I can't make any real predictions regarding what return
capacity it may have.

NASA specified some key mission requirement that could only be handled
by a
WV, then that's what you would have seen the teams move forward with.

Well, you mentioned that contractors have internal pressures to use EELVs
(probably because one solution fits both NASA and commercial launches).
Sounds
to me like there is a lot of brainwashing being done to smear Shuttle
style
approach and NASA is just gulping it all in, believing it all.

No. NASA specified that OSP must be able to ride either EELV. It knew that
it did not have enough money to develop a new booster just for OSP.

Winged
vehicles have their advantages and disadvantages, just as capsules do.
Attempts to rank one above another mean nothing without stating what the
mission requirements are.

Well, that brings the big question which NASA seems to have really
avoided:
WHAT ARE THE REQUIREMENTS ?????

NASA provided Level I & II requirements which laid out in sufficient detail
the mission requirements for OSP. The contractors were then given free reign
to develop any system they could think of that would fit those requirements.
The requirements had been released to the public, but with the end of OSP I
don't know of a valid site where you can read them. Perhaps someone else
does.

Since a trip to Mars is being discussed, does anyone really think that
they
could launch it all in one piece and that assembly and a shakedown would
not
be required in orbit prior to the trip actually starting ?

I certainly don't.

Can NASA develop automated docking on hatches the size of CBM (they
learned
from MIR that smaller russian hatches are not good enough). ? Will truss
structures assemble themselves automatically ? Will an arm fly by itself
and
attach itself to the station automatically ?

If you're going to limit yourslef to camping trips to the moon, to
re-enact
Apollo, then yes, capsules are all that you need. But if you are going to
move
forwards, you need a truck to bring your materials to space for
intelligent
assembly. And during the shakedown, you need to bring back failed pieces
for analysis.

I agree. We'll just have to wait and see how this part of the future
unfolds.

-Kim-

dave schneider wrote:

Yeah, but you need more up-tracks than down-trucks, so why pay to use
wings 50 times instead of 5 times? Hmmm, it just occurred to me that
one way to avoid having the weight penalty of wings on lift-off is to
assemble them in orbit from material left over from the DSV assembly.
Not that you'd have a lot of properly shaped silicate tiles on hand if
you tried that, though.

Wings are rather complicated, so this seems to be a nonstarter.

If you want a reentry system that uses space-available materials,
consider a transpiration cooled heatshield, using water mined
on the moon (or elsewhere in space).

Paul

(Allen Thomson) wrote:

(Derek Lyons) wrote

I find it unlikely that a space vehicle for an 18 month
flight will be more complex than a Trident submarine. Which
submarine does all it's monitoring, all it's combat operations,
all it's everything with the equivalent of about 6-8 386's.

That's an interesting point which might deserve a bit of discussion.

Doubtlessly for Classical Age spaceships, maybe even ones up to
the Discovery of 2001, that's probably true (no HAL needed).
But these are perhaps different days, and it might be worthwhile to
consider what somewhat pervasive computation could do for a Mars-
or Jupiter-ship.

Quite a bit. But very little of that pervasive computation really
needs heavy horsepower for extended periods. Most people assume that
since they need complex expensive hardware so that $POPULAR_PC_GAME
runs at a decent speed that the 'obviously' more complex spacecraft
control system *must* be orders of magnitude more powerful than their
home PC. T'ain't so.

Most folks don't realize what a heavy penalty Windows and a graphics
heavy application/game impose on their system. They also don't
realize that spacecraft control systems *don't* have those penalties.
For example, the hardware and software will be tightly bound. No need
for a zillion driver hooks and translations. For another, the
application and OS software will be more tightly integrated, which
reduced the required computational load.

Active and continuous control of flexible structure,
active and continuous control of the life-support system/ecosystem,
maybe a really closely monitored power and propulsion system,
continuous monitoring of the details of the space environment, etc.
-- maybe those would lead to a superior space vehicle.

Active and continuous monitoring of the life/support ecosystem could
probably be done with a 286 or maybe a 386. Ditto for the propulsion
system, unless it's *really* horridly complex.

D.
--
Touch-twice life. Eat. Drink. Laugh.

rk wrote:

In retrospect, it appears as if the forces on the oil in zero gravity caused
it to seek different locations than in one-g where full lubrication was
possible. Since fluid flow In zero-g is not yet fully understood, it appears
prudent to design a system with positive control.

Yep. But according to many 'space experts', there is no need to go
around and around in Earth orbit to research these issues. We can
boldy go on years long missions to Mars without any experience in LEO.

I'm not saying that ISS is actively researching these issues, but that
it *should* be doing so. (Once it's complete.)

D.
--
Touch-twice life. Eat. Drink. Laugh.