ESAS draft report is out!

[nacnud]

Space ref has the low down.<br /><br />Executive Summary (Introduction): NASA Exploration Systems Architecture Study Final Report (DRAFT) October 2005<br /><br />In includes mission senarios for cargo to ISS and Moon as well as upto six month stays on the moon, and the best bit - the proposed Mars missions.<br /><br />

 

[nacnud]

And more from NASA watch: http://www.nasawatch.com/archives/2005/12/esas_final_repo.html<br />

 

[Swampcat]

I read the reports in spaceref.com, but thanks for the nasawatch.com link. <br /><br />I noticed that the spaceref.com stuff is just an executive summary and nasawatch.com reports that the full report is 793 pages. Sure would be nice to get a look at that. <br /><br /> <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[jamie_young]

Nacnud, I think you missed one, but I'm not sure which. I see you are on nasaspaceflight forum logged in, so go through http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=1086&start=1 again.<br /><br />KCowing is Keith Cowing, he goes on that forum and let us have a first look at those pages yesterday, but I'm sure there's another you have missed. He posted three links yesterday. <br /><br />He's going to post more after Xmas. He's cool to talk to.

 

[Swampcat]

I definitely need to spend more time at nasaspaceflight.com. I'm a member, but I just haven't spent enough time there. I'm making it a New Year's Resolution to do so...after I'm a Star <img src="/images/icons/smile.gif" />.<br /><br />The karma here at Uplink is getting too weird for my taste. <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[nacnud]

Oops yes I ment to post the Nasaspaceflight link as well, my mistake, I was being forceably removed from my PC to go Christmas shopping at the time <img src="/images/icons/crazy.gif" />

 

[jamie_young]

I meant there are three links that Keith posted over on nasaspaceflight. One of nasawatch.com and two of spaceref.com. So I think there's another one to be posted here, a spaceref.com page, which is the missing link I was talking about.<br /><br />http://www.spaceref.com/news/viewsr.html?pid=19067 Ah, found it, that's what was missing. I know what happened, Keith posted this link at the same time, but on a new thread.

 

[JonClarke]

Interesting archiecture. Conjunction class, split mission, with a descent ascent spacecraft that I have not seen before. No mention of ISRU.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[mattblack]

Perhaps no ISRU is just a backup in case the technology takes longer to develop than planned (doesn't most of it in the space business?)<br /><br />The architecture proposed has some slight clumsiness to me. <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[mattblack]

Post deleted by mattblack <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[krrr]

One detail:<br /><br /><font color="orange">[...]while the MTV loiters in a circular orbit of 800- to 1,200-km altitude.</font><br /><br />Why does the MTV have to wait in such a high orbit? After all, at 500 or 600 km atmospheric drag becomes negligible.<br /><br />One explanation would be that they consider nuclear-thermal propulsion for the Mars mission. They should forget about that.

 

[nacnud]

Well if you need a fast transpher nuclear would be one way to go. Another possible reason for such a high orbit is that it is easier to get out of the <br />Earths gravity well from there.

 

[henryhallam]

It does seem a little odd, since ~1000km is about where you start having to worry about Van Allen belt radiation. Perhaps it is something to do with balancing dV requirements between SDHLV, EDS/MTV and CLV? There's a significant difference (something like 200m/s at a rough guess) between a 500km and a 1000km circular orbit.

 

[JonClarke]

I don't think the architecture is clumsy, it is a fairly typical of long stay, conjunction class split missions.<br /><br />180 day transfers don't need nuclear. Chemical is quite adequate for this, and even 140 days. Less than this and some sort of nuclear stuff gets very attractive.<br /><br />The high orbit suggests that the TMI stage is an NTR, high departure orbits like this are typical of NTRs, which is one reason why in practice they will be less efficient than theory suggests.<br /><br />ISRU is contraversial to some, but the advantages are significant for mission mass, safety, and exploration capability. At fist glance it does not offer any more development risk than NTR, for example, for the DAV, and probably less.<br /><br />The other question is whether the DAV is reusable. Unlike some other elements in the overal ESAS archiecture it does not specifically say it is expended. If it is reusable then I can't see it being anyothing other than a SSTO, not can I anyway round either bringing the propellant for it from earth, or having ISPP on the surface. A non-resuable DAV might be not unlike the Rockwell MEM of the 60's. <br /><br />Does anyone know when the full report will be available?<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[lampblack]

<font color="yellow">Does anyone know when the full report will be available? </font><br /><br />Keith Cowing posted notices on his main web sites (both NasaWatch and SpaceRef) saying he would start putting up the remainder of the report after the holiday is out of the way. It looked like he meant Tuesday.<br /><br />It was interesting: he also strongly encouraged all the rest of us to spend the next few days focusing only on the important stuff: playing with children, enjoying meals with family, and whatnot. <img src="/images/icons/smile.gif" /><br /><br />Of course, the report may well be floating around somewhere else in plain view -- but I haven't stumbled across it.<br /> <div class="Discussion_UserSignature"> <font color="#0000ff"><strong>Just tell the truth and let the chips fall...</strong></font> </div>

 

[JonClarke]

"he also strongly encouraged all the rest of us to spend the next few days focusing only on the important stuff: playing with children, enjoying meals with family, and whatnot."<br /><br />Let's see, I've got family dinner tonight, church, then presents in the morning and friends round for a meal tomorrow. In between I can fantasise about mission architectures <img src="/images/icons/smile.gif" /><br /><br />Jon<br /><br /> <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[vt_hokie]

I guess I should be excited, but until this country develops a true space shuttle replacement - something along the lines of a modern Lockheed "Starclipper" - I think I'll forever be disappointed with the failure to advance beyond STS, even if we do send humans back to the moon with the "CEV".

 

[JonClarke]

Sorry, I can't understand that at all. How can a new space plane be more interesting than returning to the moon with vastly improved technology for much more seriosu exploration?<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[mattblack]

DITTO!! <div class="Discussion_UserSignature"> <p> </p><p>One Percent of Federal Funding For Space: America <strong><em><u>CAN</u></em></strong> Afford it!!  LEO is a <strong><em>Prison</em></strong> -- It's time for a <em><strong>JAILBREAK</strong></em>!!</p> </div>

 

[subzero788]

Yes I can't understand why you would prefer another spaceplane that can't go beyond LEO to a craft that can get us to the moon and help us on our way to mars. Can you give your reasons why, vt_hokie? Or is it just something to do with the Starclipper looking so much cooler than the CEV? <img src="/images/icons/smile.gif" />

 

[gunsandrockets]

Thanx for the news!

 

[gunsandrockets]

"Why does the MTV have to wait in such a high orbit? After all, at 500 or 600 km atmospheric drag becomes negligible." <br /><br />"One explanation would be that they consider nuclear-thermal propulsion for the Mars mission. "<br /><br />Bingo.<br /><br />Reading the history of the Soviet nuclear powered RORSAT (Radar Ocean Reconnaisance Satellite) program is instructive.<br /><br />http://www.astronautix.com/project/rorsat.htm<br /><br />The earlier RORSATS had a 1/2 tonne disposal stage to boost the one tonne spent reactors into higher 1,000 km altitude orbits, where it would take hundreds of years for the orbit to decay. It was one of these RORSATS which crashed into Canada in the late 1970's. The later RORSATS with the more powerful TOPAZ nuclear reactors did away with the disposal stage because the RORSAT itself was placed in the higher orbit.<br /><br />That the MTV begins in a 1,000 km Earth orbit is too much of a coincidence. The MTV must have nuclear rocket engines. That also explains why the MTV does not use ISRU for return to Earth.<br /><br />That this is the case should surprise no one. NASA administrator Griffin has remarked on numerous occasions that NTR is neccessary for manned missions to Mars.

 

[gunsandrockets]

"180 day transfers don't need nuclear. Chemical is quite adequate for this,.."<br /><br />Ah, but the slower cargo-prepositioning missions would be perfect for NEP. The NEP tug could even be reusable. Prior to Mars arrival the cargo detaches and course corrects for aerocapture at Mars. The tug shorn of it's cargo does a Mars flyby gravity assist to begin the trip back towards Earth.<br /><br />"The high orbit suggests that the TMI stage is an NTR, high departure orbits like this are typical of NTRs, which is one reason why in practice they will be less efficient than theory suggests."<br /><br />But henryhallam says, "There's a significant difference (something like 200m/s at a rough guess) between a 500km and a 1000km circular orbit. "<br /><br />200 m/s seems like an insignificant price to pay for double the ISP of chemical rockets.<br /><br />"The other question is whether the DAV is reusable. Unlike some other elements in the overal ESAS archiecture it does not specifically say it is expended. "<br /><br />By using ISRU for refueling, a reusable DAV might enable the mission crew to explore several different locations on Mars during their stay, maybe even visit the moons of Mars.

 

[gunsandrockets]

"I meant there are three links that Keith posted over on nasaspaceflight. One of nasawatch.com and two of spaceref.com. So I think there's another one to be posted here, a spaceref.com page, which is the missing link I was talking about."<br /><br />Very very interesting link! <br /><br />Did you catch this bit about returning from Mars and direct Earth reentry of the CM?<br /><br />"As the MTV approaches Earth upon completion of the 1.5- to 2.5-year round-trip mission, the crew performs a pre-undock health check of all entry critical systems, transfers to the CEV, closes hatches, performs leak checks, and undocks from the MTV. The CEV departs 24 to 48 hours prior to Earth entry, and the MTV then either performs a diversion maneuver to fly by Earth or recaptures into Earth orbit. After undocking, the CEV conducts an onboard-targeted, ground-validated burn to target for the proper entry corridor, and, as entry approaches, the CEV CM maneuvers to the proper Entry Interface (EI) attitude for a direct-guided entry to the landing site. Earth entry speeds from a nominal Mars return trajectory may be as high as 14 km/s, compared to 11 km/s for the Block 2 [lunar mission] CEV. The CEV performs a nominal landing at the primary land-based landing site and the crew and vehicle are recovered."<br /><br />14 km/s! Yowch! That reminds me of what Lockheed had to say back in May when promoting their lifting-body CEV design...<br /><br />"[Cleon] Lacefield [vice president and CEV program manager] said the lifting body shape would broaden the rescue envelope across the entire flight profile by eliminating "black zones where we could not recover the crew because of g-loads. When we were looking at the reentry profiles from both the Moon and Mars, and ...at our abort profiles, [we saw] some pretty high gs...on the crews, for example the Apollo capsule coming in was around 8gs. With just a little bit of lift that we're talking about, to go from a 0.3 to 1.0 lift-to-drag took the gs from 8 [to 3

 

[vt_hokie]

I guess I care more about routine access to space. I want to see us make access to/from LEO safer, more affordable, and more routine before we worry about going beyond. With the right infrastructure in place, then we can start doing some real exploration at an affordable cost, instead of spending NASA's entire budget to send 4 people to the moon two or three times per year. <br /><br />Also, a lot of you differentiate between "going in circles" in LEO and "actually going someplace" by returning to the moon. Well, to me, it's going in circles either way. You're still orbiting the Earth on the moon, after all! <img src="/images/icons/smile.gif" /><br /><br />And yes, maybe it's also partly because a space plane is so much cooler than a retro-style ballistic reentry capsule sitting on top of a solid fuel rocket! <img src="/images/icons/wink.gif" /> I find it ironic that we're looking at continued use of SRB's, when the use of solid propellant was always one of the main criticisms of STS. Also, to me, parachutes are something to use as backup, not something to use as the primary method of landing! I really dislike the primitive "float down in a tin can with a parachute" approach to returning crews to Earth.