CEV PDQ

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

Reed Snellenberger wrote:

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...

And require additional launches to support the interim crew.(Or a
larger amount of supplies/spares stowed in the infant ship/station in
the first place.)

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

It's an interesting design problem to be sure. I'd be tempted to go
with a 'parasitic' and self supporting module (group) for the assembly
crew.

As a side note: USN practice is to man ships under construction with a
minimal crew of key people fairly early on. (They are however
housed/officed separate from the ship.) As construction progresses
more and more people report, but they don't move aboard until very
late in the assembly sequence. Systems responsibility follows the
same pattern - they belong to the building yard until fairly late,
then are turned over to the crew for operation/maintenace.

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

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

Herb Schaltegger wrote:

They've all been mass-limited, especially at the inclination chosen for
ISS.


....or center-of-mass-limited in the abort case -- once again, not as
much of a problem for a not-Shuttle.

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

On Tue, 10 May 2005 10:49:07 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:



Andrew Gray wrote:

So, what you do, is you build one flight's worth of hardware in advance,
so there's always a spare of each part "in stock" (this also protects
you against manufacturing accidents, or the like)... which then gets
used for the next flight, anyway. A little more sunk cost at the
beginning, trivial increases for storage through the life of the
program, and (possibly) some non-trivial savings on your final flight.



If we are talking Lunar flights, that makes sense.
But if you think that the Apollo flights got truncated due to lack of
public interest and the perceived high cost, wait till you see how fast
manned Mars missions get ditched after the first one... especially
considering the time factor involved for each flight.

That's why it's important to build the infrastructure necessary to
make it affordable to privately fund it. Heavy lift definitely
doesn't do that.

Derek Lyons wrote:

And require additional launches to support the interim crew.(Or a
larger amount of supplies/spares stowed in the infant ship/station in
the first place.)


Yep. Until it leaves Earth Orbit, it's just ISS/USS (take your pick) #2


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


It's an interesting design problem to be sure. I'd be tempted to go
with a 'parasitic' and self supporting module (group) for the assembly
crew.


It doesn't make much sense to build out a separate set of module (group)
when the thing you're building is designed to be a long-duration habitat
(that moves) -- particularly when the construction period gives you an
opportunity to flight-test the pieces. I imagine you'd have a series of
"Assembly" crews whose training focused more on EVA & system startup,
and a Flight crew who's more focused on "run and maintain" and the
science (but there'd be no reason why at least some of the Flight crew
wouldn't spend some time on board during assembly).

As a side note: USN practice is to man ships under construction with a
minimal crew of key people fairly early on. (They are however
housed/officed separate from the ship.) As construction progresses
more and more people report, but they don't move aboard until very
late in the assembly sequence. Systems responsibility follows the
same pattern - they belong to the building yard until fairly late,
then are turned over to the crew for operation/maintenace.


It's a sensible model for things that you can live aboard that take a
significant time to build. You could even plan for a reasonably long
"shakedown mission" (LEO or even Lunar) to convince yourself that the
ship could hold up well on the Mars mission. You just have to plan for
things like on-orbit consumables replenishment (including propellant)
between missions.

For that matter, there's no reason why the core of a well-designed ship
couldn't make the trip more than once...

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

On Tue, 10 May 2005 11:04:07 -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:

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.


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).

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.

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.



But it also means an expanded civilian as well as military and
governmental demand to get the high volume of payload into orbit that
would justify a high launch rate capability for medium lift vehicles. So
far that hasn't happened, and if it does happen I wouldn't be surprised
to see a lot of those payloads going up on a Chinese-made rocket that
offers far lower cost than a U.S. one.

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.

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.

On Tue, 10 May 2005 13:53:14 -0500, Reed Snellenberger wrote
(in article ):

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...

If you only knew how many headaches the CBM's were to design from a
mechanical and fluid/electrical standpoint! There are so many
connectors that had to be run through the vestibules you wouldn't
believe how hard it was to get them all to fit and still meet the
various micro-g/on-orbit human factors design requirements. It's NOT
simply a matter of "plug-in the module and let's go!" It's more like,
"Plug in the module, pressurize the vestibule, draw a sample of the
vestibule atmosphere to ensure nothing nasty got in there. Test the
sample for several of the most likely nasties. Open the first hatch.
Connect a whole hell of a lot of fluid and power/data jumpers, draw
samples of the next module's own atmosphere. Test those samples for a
much wider variety of nasties due to contamination, off-gassing and/or
out-gassing. Open that hatch." Repeat this process for as many
modules as necessary. If the modules are not internally pressurized,
you'll have to design and implement a series of automated
power/data/fluid connecting devices for each module. The more heavily
instruments and interconnected you wish each module to be, the more
complicated the interface mechanisms become and the more failure
mechanisms there will be.

--
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/

On Tue, 10 May 2005 17:01:02 -0500, Rand Simberg wrote
(in article ):


On Tue, 10 May 2005 13:31:14 -0500, in a place far, far away, Herb
Schaltegger made the
phosphor on my monitor glow in such a way as to indicate that:

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.

I'm referring to Shuttle-C, not Orbiter.

And if you'd actually read my post you'd see that your typically
snarky one-liner is a non sequitur. You're bitching that Shuttle-C is
volume limited, just like an STS orbiter and I'm pointing out that
Station modules have been mass-limited, not volume limited so your
argument that Shuttle-C is deficient due to volume limits is
irrelevant.

--
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/

On Tue, 10 May 2005 11:19:05 -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:

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.

Your opinion is noted. That doesn't mean that it's necessarily
shared.

On Mon, 09 May 2005 21:46:15 -0700, Ed Kyle wrote:

It's about time Russia accepted Zenit for what it
is - maybe the world's most perfectly conceived
(if not perfectly executed) space launcher. It is
the rocket that NASA would like to have for CEV -
kind of like an Atlas V on steroids - able to boost
a 14-15ish ton payload to low earth orbit with no
solid booster augmentation. It is the capability
Russia is trying, unneccessarily, to copy with its
Angara program. China and Japan would like to have
such a rocket, but they don't. Europe had to work
hard to get its Zenit (Ariane 5G) working.

Ukraine and Russia have had the perfect machine
for nearly 20 years. They just haven't used it.

Ukraine can't afford a space program of its own,
and Russia, I suspect, cares more about keeping its
own launch capacity local than the US does (since the
DoD's required-to-be-US-manufactured EELV wound up
with engines made in Ukraine).

I'm beginning to wonder how much modification it would take
to modify Zenit so that it was only made-in-Ukraine...

pgf