CEV PDQ

On Tue, 10 May 2005 12:45:08 -0500, Reed Snellenberger wrote
(in article ):

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

Actually, you would hope very much that it would require less EVA
assembly and ideally none. The need for EVA on ISS is the result of a
number of design decisions that hopefully will not be repeated for an
interplanetary spacecraft as opposed to an LEO station.

--
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/

"Frank Scrooby" wrote:
[ an updated Apollo]
The design is already proven, just update the parts you can't get
anymore or know you can safely replace with something better.

The problem is... The design you propose *isn't* already proven
beyond the aerodynamics.

You are going to end up replacing virtually every interior component,
which means you incur the (very non trivial) costs of testing,
qualification, and integration. You'll have to re-do virtually all of
the interior structure, which will also have to be designed and
verified.

I know reviving a 40 year old design is not as sexy (and probably
not as lucrative) as designing and building a new vehicle,

The problem is... You aren't reviving an old design. In practice you
are designing a totally new vehicle that happens to have the same
moldline.

Maybe NASA should get its money back if its contractors fail
to perform ;-). Isn't that the way it works in the REAL WORLD.

Only if you define 'real world' to exclude 'activities that do occur
in the real world, and are high risk, high payoff'.

Get ISS (and NASA) and alternative, safe and expandable crew and
cargo delivery system and then start thinking about how to extend
it's usefulness to lunar missions.

Thats a sure and certain way to make the craft *more* expensive, not
less.

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

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

(Henry Spencer) wrote:

In article .com,
Ed Kyle wrote:
To me this brings to mind another question: Does the CEV
need to be twenty tons? Soyuz was designed in the 60's and weighs
seven metric tons.

Kliper, proposed as a Soyuz replacement, but able to carry
up to six, is projected to weigh 13-15 tons...

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.

Of course a company with very little experience in designing manned
spacecraft will design one with less weight than any comparable
machine... And it will *never* grow in weight in moving from paper to
operational metal.

You are very selective in your examples Henry.

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

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

On Tue, 10 May 2005 16:08:10 -0500, Rand Simberg wrote
(in article ):


It came down to value for the money. Shuttle-C was constrained to the
same diameter as the Orbiter payload bay, and pretty much the same
volume (though I think that the payload could have been eighty feet,
instead of sixty). That meant that it would save very few assembly
flights to SSF, and waste much of its lift capacity because it was
volume rather than mass limited.

Actually, you're incorrect about this. Few if any of the
U.S./European/Japanese segment for ISS have been truly volume limited.
They've all been mass-limited, especially at the inclination chosen for
ISS.

The U.S. modules were reduced in length from 40 racks to 24 and even
then they had to be launched on semi-outfitted. These decisions were
made well before the change to the ISS orbital inclination. Had
Shuttle-C and OTV been available, fully-outfitted 40-rack modules could
have been launched to the "proper" SSF inclination, saving many
logistical and operational headaches, not the least of which have been
the UF flights necessary to outfit the modules after launch.

Breaking out of this constraint
would have meant major mods to the RSS and LC-39, which were verboten
because it had to continue to support Shuttle flights. That was why
it never happened.

See above.

--
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/

Pat Flannery wrote:

The lifting body design gives the vehicle great cross range, which is
said to be in the interests of safety, and to avoid water landings.
Given the present administration's desire for military space control,
one can wonder if the great cross range requirement had a similar origin
to that of the Shuttle's, with its delta wings- something the military
wants for a military derivative of the CEV.

Presumably the designers lack your propensity to see a conspiracy
around every corner and an equal propensity to blame every ill on the
current administration.

Equally presumably they have done what many have not - studied the
Shuttle's operations and noted the flexibility that a wider cross
range allows in landing windows and abort opportunities.

Admitting the last requires many space enthusiasts to think outside of
the box - and to admit to themselves three things that are Heresy to
every Right Thinking space enthusiast; 1) That the military
requirements may have provided (whatever the cost) a useful
capability. 2) That the dinosaurs have actually thought about what
makes a spacecraft useful. And 3) we can learn something from the
Shuttle other than "two legs bad, four legs good".

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

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Pat Flannery wrote:

Rand Simberg wrote:

Or subcool the propellants and insulate the tanks properly...

Still, how long would one have to get it all stuck together? Days or weeks?
The Soviet's did a stage (Block D) that used an insulation sunshade for
it LOX/Kerosene propellant on Proton-Zond and N-1:
http://www.myspacemuseum.com/l1s_2.jpg
But do we have any experience with this sort of thing? The closest we
came was the canceled Shuttle boosted Centaur stage.

Of course... we shouldn't try *anything* we don't have experience
with. We might depart from the One True Path as shown by the mighty
Apollo, blessed be His Name.

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

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

h (Rand Simberg) wrote:

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...

Assuming that the cheap booster is available in a reasonable time
frame, and a complete second set of hardware is sitting around checked
out and ready to go in a reasonable timeframe.

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

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

On Tue, 10 May 2005 10:27:06 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

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...



I was concerned about the cost of the parts themselves- which could be
more than the rocket that carries them.

Could be, but it's still better than losing an entire mission with a
single loss, and you can pay for a lot of lost pieces with the
development cost savings for the unneeded HLLV.

The big problem is needing replacements for ones that may get lost
during launch.
With our unmanned planetary missions we have many times used dual
spacecraft in case one was lost for some reason.

If you have to build a complete back-up modular Mars ship that will be
expensive; the other concern is the launch window- can you get the
replacement component for the lost one up and docked while the launch
window is still open?

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.

On Tue, 10 May 2005 10:36:58 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:

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



To Mars? With all that entails? There'll be a very long time interval
between the first manned flight for the prestige factor and the second
one...for whatever reason it is done.

If it's going to be flags and footprints, as you imply, then we
shouldn't do it at all.

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



Remember the Bush administration suggested a manned flyby flight of Mars
with no manned landing- which is about the nuttiest, most pointless
thing I ever heard suggested in the field of spaceflight outside of the
Soviet Voskhod test EVA by a dog. :-)

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.

Herb Schaltegger wrote:
On Tue, 10 May 2005 12:45:08 -0500, Reed Snellenberger wrote
(in article ):


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


Actually, you would hope very much that it would require less EVA
assembly and ideally none. The need for EVA on ISS is the result of a
number of design decisions that hopefully will not be repeated for an
interplanetary spacecraft as opposed to an LEO station.


I've actually been pleasantly surprised at how little EVA work has been
required for the station (apart from the truss components, which are
unlikely to be used in a ship). The CBM design seems to have worked out
very well...

Since they won't be going up in the Shuttle, it will be a lot simpler to
pre-install the armor & EVA handholds on the ground. I imagine the
biggest demand for EVAs during the trip would be to change out the
(inevitable) interstellar solar wind, gas, & micrometeorite experiments...


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