CEV PDQ

Rand Simberg wrote:
On Tue, 10 May 2005 19:14:32 GMT, in a place far, far away, Reed
Snellenberger made the phosphor on my
monitor glow in such a way as to indicate that:


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


Only in a very gross sense. It's not designed for weightless
research, for example. The only requirements it shares with ISS are
the ability to support some number of people for several months.
Also, it's likely to have nuclear power, even if the reactor doesn't
get activated until after departure.

Even in a detailed sense, it's like ISS...

Until it leaves Earth Orbit, it'll be identically equal to ISS (a
habitat orbiting a planet), with the same requirements (zero-g
facilities, among other things). Even if we assume a continuous 1-g
boost to Mars & back (unlikely), there will be long periods when the
ship will be both occupied and in a microgravity environment while it's
in Mars orbit. While in orbit around Mars, it will be ISS/USS-Mars.

The transit from Earth to Mars (and back) won't be filled with endless
X-box tournaments, either -- the areonauts (I'll claim coinage on that,
if it hasn't already been) will be assigned to do interplanetary
research on both themselves, the interplanetary environment, and
whatever else can be dreamed up to keep them busy -- and facilities to
do that research will be included on the ship.

Whether or not it uses nuclear power isn't relevant to whether it's like
ISS or not -- unless you're reminding me that the Mars ship will have a
significant amount of truss in its design devoted to power and thermal
management... in which case it's *even more* like ISS in its design. :-)

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

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).

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.

Too much so, in my opinion.



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.

That remains to be seen.

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?

Nothing, actually, except that, unlike the Chinese, we can afford to
waste money on such things.

On Tue, 10 May 2005 11:34:02 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in
such a way as to indicate that:



Rand Simberg wrote:

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.



Flyin' to Mars ain't like dusting crops, boy! :-)
Bill Gates could probably afford to finance the whole kit and kaboodle
right now if he felt like it... but he hasn't done it yet.

If he did, I'd hope that he'd be smart enough not to do it with heavy
lifters. Elon Musk, who wants very much to go to Mars, seems to
understand this...

Herb Schaltegger wrote:
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.


I can believe that the CBMs were a design challenge (and a half). And
I've read online copies of the checklists for connecting modules that
went into the process in *excruciating* (and very interesting) detail.
(incidentally, does anyone have a link to that again -- I think it used
to be at spaceref.com, but it's been a while...)

But the thing is... even if you're willing to endure the design & weight
overhead of purely automated interconnects (with the liklihood that
you'll need to have the excruciating procedure in your hip pocket for
when the automated procedure craps out), you're still going to have to
do all of those testing steps *anyway*.

And once you're done -- you're done. I can't remember hearing about any
problems with the CBM-based connection in the U.S. segments since they
were installed. Of course, there are only two of the hard-connected CBM
joints installed at this point (Node 1-Lab, Node 1-Airlock) -- I'm not
counting the MPLM or PMA joints...


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

On Tue, 10 May 2005 16:56:32 GMT, in a place far, far away, Reed
Snellenberger made the phosphor on my
monitor glow in such a way as to indicate that:

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.

That's not an assumption--it's a design requirement...

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.

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

"Pat Flannery" wrote in message
...
You are going to end up with a lot of launches if you try to do it with
anything smaller than some of the proposed souped-up Delta IV heavy
variants from the viewpoint of crew life support requirements alone.

Seriously? The last time I remember looking into this, it took surprisingly
little mass to keep a person alive for a day.

In this article there is a chart for this:
http://www.space.gc.ca/asc/eng/educa...system-edu.asp

Their conclusion of nearly 25 kg per person per day is absolutely silly.
They budget nearly 7 kg for clothes washing, but disposable clothes, as they
use on ISS, would weigh less than washing clothes and reusing them. They
also budget 13 kg for "urine flush". What's up with that? I seriously
doubt you need that much water per day in order to vent urine out to
vaccuum.

If you take those silly values off, you're left with about 5 kg per person
per day. You could sustain a crew of four for two years for about 15,000
kg. Since a Delta IV Heavy can loft 23,000 kg to LEO, you'd only need a
single launch to get a cargo module containing your consumables into LEO.
I'd hardly call that "a lot" and I hardly think it justifies a "souped-up
Delta IV Heavy variant".

Besides, consumables (O2, H2O, food, fuel, oxidizer, and etc), are easier to
launch in smaller pieces than people. ;-)

Seriously though, we really didn't need a rocket the size of Saturn V to get
us to the moon if we'd adopted Earth Orbit Rendezvous instead of Lunar Orbit
Rendezvous. Why would we need a launch vehicle approaching that size today?

Jeff
--
Remove icky phrase from email address to get a valid address.

"Rand Simberg" wrote in message
.. .
On Tue, 10 May 2005 14:28:12 -0500, in a place far, far away, Herb
Schaltegger made the
phosphor on my monitor glow in such a way as to indicate that:
If you only knew how many headaches the CBM's were to design from a
mechanical and fluid/electrical standpoint!

Yes, it's a shame that all of the effort/millions invested in this
didn't go instead into decent EVA equipment.

Unless we plan on exploring the Moon and Mars from inside the lander, you'd
think that better EVA hardware would be a long term goal of the Moon/Mars
program.

Canceling the development of better space suits for the space station
program, and then subsequently spending quite a bit of time, effort, and
money trying to reduce EVA time, seems to have been a very short sighted
decision.

Jeff
--
Remove icky phrase from email address to get a valid address.

On Tue, 10 May 2005 18:36:47 -0500, Rand Simberg wrote
(in article ):

On Tue, 10 May 2005 14:28:12 -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 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!

Yes, it's a shame that all of the effort/millions invested in this
didn't go instead into decent EVA equipment.

Once again your one sentence reply ignores everything of substance.
The CBMs were designed the way they were in response to a set of
specific design requirements. Perhaps you don't realize that?
Alternatively, you do realize that, and you realize as well that
advanced EVA equipment was considered and then cut from separate
portions of the budget, and you realize as well that the current EVA
equipment is sufficient for most purposes, and you realize as well that
the U.S./European/Japanese segments of ISS were designed for EVA
assembly using current EVA equipment which works just fine for those
purposes.

Of course, that makes for a much less pithy one-sentence reply though,
doesn't it?

--
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/

"Derek Lyons" wrote in message
...
h (Rand Simberg) wrote:

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.

You mean like how we had a *complete* backup Skylab along with a *complete*
backup Saturn V? We also had backup CSM's and Saturn IB's for all of the
Skylab missions and for ASTP.

If you stop and think about it, having backup hardware isn't that expensive
if you're talking about a *sustained* program where you're going to have
many missions. The backup hardware for mission 1 just becomes the flight
hardware for mission 2 and so forth and so on. If you accept that your last
mission may fail, you don't need a backup for that mission at all.

Now the question becomes, if you've got a launch success rate that's fixed
at 95% or so, would you prefer to have more or less launches required for a
mission? Now you need to know more, like do you really want to fly your
missions on time? If so, what percentage of hardware loss can you absorb
for a single mission and still expect to fly your next mission on time?

Jeff
--
Remove icky phrase from email address to get a valid address.

On Tue, 10 May 2005 18:35:44 -0500, Rand Simberg wrote
(in article ):

On Tue, 10 May 2005 14:30:42 -0500, in a place far, far away, Herb
Schaltegger made the
phosphor on my monitor glow in such a way as to indicate that:

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

No, I'm pointing out that Shuttle-C is volume limited, *unlike* an STS
orbiter.

Go back and re-read your own posts. You're not making any sense.

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.

It would seem that your argument is the one that's irrelevant. The
point is that Shuttle-C would not have reduced the number of assembly
flights enough to make it worth the money, which (one more time) is
why it wasn't built.

No, *I* stated it wasn't built due to money, in response to your
comment that volume limitations (irrelevant volume limits, by the way)
were a main reason (which they were not).

--
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/