NASA Exploration Systems Architecture Study Final Report (DRAFT) released

NASA has released the ESAS Executive Summary - First Installment, on
Dec. 22.
Some of it is reprinted on the NASAWATCH website:

"NASA Exploration Systems Architecture Study Final Report (DRAFT)"

http://www.spaceref.com/news/viewsr.html?pid=19066
http://www.spaceref.com/news/viewsr.html?pid=19067
http://www.nasawatch.com/archives/20...repo.html#more
http://www.nasawatch.com/

It's interesting to compare the ESA ATV stats with the CDV
unmanned/unpressurized
ISS Cargo version.

ESA ATV webpage
http://www.esa.int/SPECIALS/ATV/ESA4ZJ0VMOC_0.html

See Figure 1-17 for CDV stats
http://www.spaceref.com/news/viewsr.html?pid=19067


Rusty

ATV and CDV look quite similar to my untrained eyes. ATV can carry a
bit more than the CDV (7667 kg vs 6000 kg), but is a bit heavier (20750
kg vs 19112 kg). The cargo to weight ratio is better for ATV. And the
ATV cargo bay is pressurized.
Jules Verne wins?
Cyrille

In article . com,
Rusty wrote:
NASA has released the ESAS Executive Summary - First Installment, on
Dec. 22...

Some interesting bits of data there, not all of them obvious.

Note, in particular, that in the proposed Mars-mission profile, the
capsule has to go up to meet the MTV (Mars Transfer Vehicle) "in a
circular orbit of 800- to 1200-km altitude". Why so high?!? There's only
one reasonable answer: the MTV uses nuclear propulsion, and must start in
a "nuclear-safe" orbit, high enough that orbital life in the event of a
failure exceeds 10kyr.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

On Wed, 28 Dec 2005 14:02:23 -0600, Cyrille V wrote
(in article .com):

ATV and CDV look quite similar to my untrained eyes. ATV can carry a
bit more than the CDV (7667 kg vs 6000 kg), but is a bit heavier (20750
kg vs 19112 kg). The cargo to weight ratio is better for ATV. And the
ATV cargo bay is pressurized.
Jules Verne wins?
Cyrille


Different mission priorities, different launchers, different launch
sites - of course the results will be different.

Recall that conceptually, CDV is simply CEV minus crew couches and it's
still launched from KSC.

--
Herb

There ain't no such thing as a free lunch.
~ RAH

Henry Spencer wrote:
In article . com,
Rusty wrote:
NASA has released the ESAS Executive Summary - First Installment, on
Dec. 22...

Some interesting bits of data there, not all of them obvious.

Note, in particular, that in the proposed Mars-mission profile, the
capsule has to go up to meet the MTV (Mars Transfer Vehicle) "in a
circular orbit of 800- to 1200-km altitude". Why so high?!? There's only
one reasonable answer: the MTV uses nuclear propulsion, and must start in
a "nuclear-safe" orbit, high enough that orbital life in the event of a
failure exceeds 10kyr.

The report also tells how the commitee ruled out use of
ET-only-based concepts (like the "Spencer" you discussed
a few weeks ago). They were "briefly considered", but were
ruled out on the basis of schedule and cost.

'Sounds like serious handwaving to me. The concepts were
not detailed in the report, not included in any tables, etc.
Someone might have mentioned an ET-based crew launch
in a meeting, perhaps, but I see no evidence of rigorous
analysis.

- Ed Kyle

On Wed, 28 Dec 2005 16:25:49 -0600, Ed Kyle wrote
(in article . com):

Sounds like serious handwaving to me. The concepts were
not detailed in the report, not included in any tables, etc.
Someone might have mentioned an ET-based crew launch
in a meeting, perhaps, but I see no evidence of rigorous
analysis

Bear in mind that there is clearly a great deal of background study
material (including the Appendices) which have not yet come to light.
Just look at the designations for various architectures - "LVxx" where
xx is up in the twenties for some of these options.

I suspect much of what you accuse as "handwaving" is contained within
that material.

--
Herb

There ain't no such thing as a free lunch.
~ RAH

On Wed, 28 Dec 2005 20:04:56 GMT, (Henry Spencer)
wrote:

Note, in particular, that in the proposed Mars-mission profile, the
capsule has to go up to meet the MTV (Mars Transfer Vehicle) "in a
circular orbit of 800- to 1200-km altitude". Why so high?!? There's only
one reasonable answer: the MTV uses nuclear propulsion, and must start in
a "nuclear-safe" orbit, high enough that orbital life in the event of a
failure exceeds 10kyr.

....Henry, I've got an alternative theory: Wouldn't a gravity-assist
TMI trajectory designed to reduce transit time drastically begin from
such an altitude?

OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let's face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[

Henry Spencer wrote:


Note, in particular, that in the proposed Mars-mission profile, the
capsule has to go up to meet the MTV (Mars Transfer Vehicle) "in a
circular orbit of 800- to 1200-km altitude".


That's high enough to start worrying about the inner Van Allen belt.

Why so high?!? There's only
one reasonable answer: the MTV uses nuclear propulsion, and must start in
a "nuclear-safe" orbit, high enough that orbital life in the event of a
failure exceeds 10kyr.



It might not use nuclear propulsion, but rather nuclear electrical power
generation, which for a manned Mars mission would seem to be almost a
necessity. Of course their might be a Timberwind engine lurking out
there somewhere...for as excited as the military got over that thing it
seemed to vanished awfully quickly.
Of course knowing the current administration it will probably use the
Orion drive. Why? Simple, that breaks a treaty, and that's always fun to do.

Pat

Herb Schaltegger wrote:
On Wed, 28 Dec 2005 16:25:49 -0600, Ed Kyle wrote
(in article . com):

Sounds like serious handwaving to me. The concepts were
not detailed in the report, not included in any tables, etc.
Someone might have mentioned an ET-based crew launch
in a meeting, perhaps, but I see no evidence of rigorous
analysis

Bear in mind that there is clearly a great deal of background study
material (including the Appendices) which have not yet come to light.
Just look at the designations for various architectures - "LVxx" where
xx is up in the twenties for some of these options.

I suspect much of what you accuse as "handwaving" is contained within
that material.

The ET-only idea was studied, but not during the ESAS
study. Instead, the idea was ruled out back in 2004
during a series of trade studies by the Exploration
Systems Mission Directorate (ESMD).

"http://images.spaceref.com/news/2005/cev.33.l.jpg"
"http://images.spaceref.com/news/2005/cev.32.l.jpg"

But these studies were performed during the pre-Griffin
era, back when CEV was going to be done in "spirals".

- Ed Kyle

In article ,
OM wrote:
"circular orbit of 800- to 1200-km altitude". Why so high?!? There's only
one reasonable answer: the MTV uses nuclear propulsion...

...Henry, I've got an alternative theory: Wouldn't a gravity-assist
TMI trajectory designed to reduce transit time drastically begin from
such an altitude?

Not if everything has to be boosted up to that altitude first. The point
of a gravity-well maneuver is that it helps to do your departure burn at
the lowest possible altitude. But if your launchers drop you off in a
parking orbit just above the atmosphere -- as they invariably do -- you
just stay there until departure time. Moving up for the sole purpose of
coming back down simply wastes fuel.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |