CEV PDQ

Rand Simberg wrote:

But in the case of the Shuttle-derived one, we already have most of the
cost covered in the development arena.



A lot of it, but not "most," particularly if they go with an in-line
design (which would make a lot more sense).



It would be better- but the perfect is the enemy of the good enough;
and the side cargo pod is a lot simpler from the design viewpoint.



Building a new cargo pod would be around as difficult as building a new
third stage for the Saturn V, particularly now that we have the RS-68 to
use.



Nope. It's a new launch system, using existing propulsion elements.
And this doesn't take into account the additonal (relative to using
EELV) standing army needed to support it and its pads. It will still
have heavy fixed annual costs, even if they're lower than Shuttle.



Actually, it would be 2/3rds a stock shuttle stack, with the new
motor/cargo pod stuck on the side- and yes, the long term costs are
high, but this is something that can be done fairly quickly with things
on hand.
And they do seem to be in a rush about all this.



The only payloads that exist in sufficient volume to justify high
flight rates of anything are humans. They're unlikely to go on a
Chinese-made rocket, unless there's no domestic alternative.



They don't generate much long term income for the companies that launch
them, unlike a comsat.



The obvious counter-argument is to launch the parts of the U.S. Mars
ship on the Chinese made booster; that presupposes that the Chinese
would launch our Mars ship on their boosters....rather than launch
_their_ Mars ship on their boosters. ;-)



If they want to do Mars missions with their boosters, more power to
them. It will bankrupt them to no useful purpose, just as Cheng He's
treasure fleet did.



What, pray tell, will be the difference if we do it with _our_ boosters?
Remember, under this week's take on Chinese Marxism "To Be Rich Is
Glorious!" :-)

Pat

Rand Simberg wrote:

If you put enough slack in the schedule. If not, launch windows to
Mars occur relatively frequently. This discussion presupposes much
more routine capability to get things into orbit (as well as doing
orbital assembly) than we have today. Developing that kind of
capability would have much greater long-term value for our prospects
in space than a heavy lifter.

This also assumes that the partially-assembled craft can withstand an
extended delay if a serious problem with the booster surfaces. Even if
you plan to launch consumables at the very end of the assembly sequence,
you need to provide for (for example) sufficient delta-v to provide for
maintaining the assembly's orbit.

At some point, an interplanetary craft being assembled orbitally needs
to be considered a "self-propelled" space station, and manned accordingly.

--
Reed Snellenberger
GPG KeyID: 5A978843
rsnellenberger-at-houston.rr.com

In message
"Frank Scrooby" wrote:

"Henry Spencer" wrote in message
...

BAe's Multi-Role Capsule design, done in the mid-80s, with a capacity
of four people for normal flight and six in a lifeboat configuration,
almost entirely reusable (including propulsion), had an estimated launch
mass of 8t including escape tower.

I seem to recall you've mentioned this (the BAe M-R capsule) before, Henry.

Do you have more info on this design?

The only reference I could get through Google is you:

http://www.spacebanter.com/q-t_5821-...aceflight.html

However, using some manual labor I found this:
http://www.astronautix.com/craft/mulpsule.htm ?

They're both pointing you at the same edition of JBIS which, as far as
I'm aware, is the only place you'll find anything extra short of knowing
who to ask at BAe. Try your local library, or see if the BIS will do you
a back issue or photocopy of the article.

Anthony

On Tue, 10 May 2005 08:53:02 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

Neil Gerace wrote:



Whereas Saturn V carried all components up with it, ensuring that if one
component went tits up, all of the others would too - including the crew.


If the odds are even as regards the possibility of a individual vehicle
failure (say 90 percent reliability, which was probably what Saturn V
was good for), and you need all the parts for a successful mission, then
the fewer launches, the better.

Not if a replacement part can go up on another cheap (something that
heavy lift will never be at planned usage rates) ) launch. There's an
old saying about eggs and baskets...

On Tue, 10 May 2005 09:04:32 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:



Rand Simberg wrote:

So? We end up with a lot of launches (assuming we can't get
propellant from the moon). Big deal.

Last time I had a house built, I don't recall demanding that it be
delivered assembled on a giant truck.



Assuming that your component parts go up on rockets that have around 95%
reliability (which is around what most have, particularly the larger
ones) and you've got to assemble something from say 20 or more
parts...then you can be pretty sure of losing a part of it along the
way....and that means building back-up parts for all the parts if you
want to be fairly sure that you have all the components you need to
assemble it, which won't be cheap.

Of course you should have backups for all the parts. It's not like
you're only going to go once.

The cost of building a lunar base to extract propellant for the ship
would be far more than any savings accrued from not bringing it up from
Earth, at least if only a flight or two to Mars is intended.

It would be nutty to go to Mars at all if only a flight or two is
intended.

On Tue, 10 May 2005 15:01:11 -0500, Rand Simberg wrote
(in article ):


On Tue, 10 May 2005 11:46:28 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

But in the case of the Shuttle-derived one, we already have most of the
cost covered in the development arena.



A lot of it, but not "most," particularly if they go with an in-line
design (which would make a lot more sense).



It would be better- but the perfect is the enemy of the good enough;
and the side cargo pod is a lot simpler from the design viewpoint.

But sufficiently limited in its diameter as to make the thing probably
unworthy of building (one of the reasons that Shuttle-C never
happened).

I'd like to see a cite for that proposition. It all came down to
money, not payload diameter.

--
Herb Schaltegger, GPG Key ID: BBF6FC1C
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." - Benjamin Franklin, 1759
http://www.individual-i.com/

Rand Simberg wrote:

At some point, an interplanetary craft being assembled orbitally needs
to be considered a "self-propelled" space station, and manned accordingly.


I've no problem with that. You don't think that a Mars ship will be
"manned accordingly"?

Of course it would -- my point is that at some point early in the
assembly sequence (which might require several months or more), we'd
want to have a full-time crew on board to do maintenance, support, and
additional assembly (module links, etc) on the developing craft. During
that time, the ship is (essentially) just a space station...

The assembly of the Mars ship wouldn't be all that different than the
ISS assembly process, when you think about it.

--
Reed Snellenberger
GPG KeyID: 5A978843
rsnellenberger-at-houston.rr.com

In article , Frank Scrooby wrote:
BAe's Multi-Role Capsule design, done in the mid-80s, with a capacity
of four people for normal flight and six in a lifeboat configuration,
almost entirely reusable (including propulsion), had an estimated launch
mass of 8t including escape tower.

I seem to recall you've mentioned this (the BAe M-R capsule) before, Henry.
Do you have more info on this design?

Not online, I fear. The Feb 1989 issue of JBIS (the Journal of the
British Interplanetary Society) was a set of papers on MRC, and that's the
main reference for anyone seeking info on it. Check a university library,
if you've got one handy.

However, using some manual labor I found this:
http://www.astronautix.com/craft/mulpsule.htm ? Is this the beastie, you are
referring to, Henry?

Yep, that's it.

Apollo CM...
Now given that this is 1960s technology (and some of its was 1950s tech),
and given that the CM could apparently have accomodated 5 couches instead of
three if used purely for LEO ops, why is NASA even thinking about granting
contracts for a CEV?

Note that the 5-couch configuration was an emergency-lifeboat version,
which sacrificed land-touchdown capability in particular. (Coming down on
land would likely have resulted in serious injury for the crew.) You
wouldn't want to use that for routine operations.

I know this is not a new idea but why not just dust off the boilerplates and
blue prints for the CM?

The idea is not ridiculous, but note that it wouldn't save you much money.
You'd want to rework a lot of things, and you'd have to re-test everything
anyway -- since all the old production tooling and expertise is gone, you
have to rebuild the production base, and you can't just rely on the new
stuff being close enough to the old that the old test results still apply.

There would be some awkward questions of just how much you revise the
design:

+ Do you use 14.7psi air instead of the old 5psi oxygen? Without that,
you can't board it quickly from ISS; indeed, using a 5psi spacecraft on
ISS would be a major headache. This affects structure, hatches, etc. as
well as life support.

+ Do you plan for land touchdown? The practical advantages of being able
to come down on land are large, but it's also a design headache. You'll
need to add braking rockets.

+ Do you enlarge the docking hatch and tunnel to match the ISS hatches?
Ideally you'd match the ISS berthing interface that the MPLMs use -- since
its hatch is big enough to pass a standard ISS equipment rack -- but there
are major practical advantages to at least matching the ISS docking
interface, which is what the shuttle uses. It's not a small change, alas.

A new Apollo capsule should sit nicely on top of the Atlas V (with its five
meter maximum diameter fairing) and the Atlas van deliver 12,500 kgs to a
185 km orbit at 28.5 degrees (someone can tell me whether this is
ISS-compatiable).

That's a maximum-payload parking orbit, not at all close to the ISS orbit.

Assuming that the 4m fairing is the closest equivalent (you do take some
payload hit for the 5m fairing), a no-solids Atlas V puts 10.3t into the
ISS orbit.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Pat Flannery wrote:


Rand Simberg wrote:

Not necessarily. It's a lot easier to do a mission to Phobos for an
initial mission than it is to land on the planet, and a lot of good
science could still result.



After the amount of time it would take to get to Mars and back is
considered, getting that close and not landing would be pathetic.

Pat

Less pathetic than getting that close, landing, and not taking off,
though... baby steps, baby steps...

--
Reed Snellenberger
GPG KeyID: 5A978843
rsnellenberger-at-houston.rr.com

In article ,
Jorge R. Frank wrote:
the DIV has to fly an odd trajectory (due to structural
concerns) that means that there are points in the ascent when abort is
*not* survivable.
Is that bad? Seems to me that it happens to STS as well.

No. That's due to not being able to terminate the SRBs safely, not due to
trajectory as is the case with the D-IV.

If memory serves, it is still the case that there are "black zones" in
the shuttle ascent trajectory where a multiple SSME failure is not
survivable, because the orbiter is too high and too slow to reenter at
an acceptably shallow angle.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |