Prometheus smothered...

[crix]

http://timesunion.com/AspStories/story.asp?storyID=398580&category=BUSINESS&BCCode=HOME&newsdate=9/14/2005<br /><br />Nevermind nuclear-thermal, now we're not even putting money into nucler-electric. Maybe this will somehow bring about nuclear-thermal propulsion earlier?<br /><br />It's disappointing news.

 

[radarredux]

> <i><font color="yellow">We can not do everything.</font>/i><br /><br />"Focusing is about saying 'no'." -- Steve Jobs<br /><br />"If you chase two rabbits, both will escape." -- Chinese Proverb</i>

 

[mikejz]

It was really really slick, but then again---it was the sort of project that you do once you already have heavy-lift.

 

[spacefire]

we can only do what Bush 'proposed' <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[yurkin]

Disappointing but not unexpected.<br />I think a good move in the long wrong.<br />

 

[mattblack]

Losing nuclear propulsion for Marsflights would be dissapointing, but not a major blow. But Marsflights MUST have nuclear reactors for the long stay!!<br /><br />No nukes; no ISRU fuel plants or crews staying on Mars for 600 days. Period.<br /><br />Damn... <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>

 

[thermionic]

<br />That's sad. Personally, I'd rather see a good deep space motor developed first, then put people on board to really cover some ground. I know we can get to Mars with chemical engines, but think of what could have been! Ah well, maybe my kids will get to see it happen, if not I.

 

[mikejz]

Just wondering, do we even have enought Xenon on earth to support a large number of missions?

 

[kdavis007]

or service the Hubble...

 

[john_316]

I hate to say this but we may see the funding brought back to Prometheus in the near future as we will undoubtedly have a "TAX" increase because we cannot weather these large catastrophies year in and year out. <br /><br />I see this coming by 2007....<br /><br />Hate to say it but its a commin just like the draft may as well too...<br /><br /><img src="/images/icons/smile.gif" /><br />

 

[yurkin]

JIMO exceeded the world’s production of xenon gas by 2 years. So we don’t even have enough gas for one mission let alone multiple ones.

 

[nacnud]

They arn't as heavy and therefore not as effiecent but does anyone know what the performance loss would be to use Krypton or Argon. Then again Xenon is present in the atmosphere at about one part in twenty million so it might just be a case of building another plant or three.

 

[gunsandrockets]

"Then again Xenon is present in the atmosphere at about one part in twenty million so it might just be a case of building another plant or three."<br /><br />Xenon is produced by liquifying air. Since Xenon has a relatively high temperature for the liquid state it is easy to generate and store. So I think fears of a Xenon shortage are overblown.

 

[gunsandrockets]

"Nevermind nuclear-thermal, now we're not even putting money into nucler-electric. Maybe this will somehow bring about nuclear-thermal propulsion earlier?"<br /><br />I think the scaling back of nuclear-electric is a mere reordering of nuclear priorities. Griffin has stated in testimony to Congress the importance of nuclear-thermal rockets. Odds are a space nuclear reactor for lunar base power will get moved to the number one nuclear development spot.<br /><br /> The requirements of moon missions seem to be crowding out everything else from NASA plans. I much rather see nuclear thermal rockets and nuclear electric rockets developed than throw away 5 to 10 billion dollars developing a new HLV. But NASA seems fixated on the HLV, the better to put up a massive LH2/LOX Earth Departure Stage for moon missions. What a waste.<br />

 

[JonClarke]

"No nukes; no ISRU plants or crews staying on mars fo5 600 days. Period."<br /><br />Not true. You can design an ISRU plant for a Mars mission using only solar power provided you are happy with low to moderate latitudes and a semi-direct architecture for similar of less mass than an equiavlent nuclrear plant. <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>

 

[radarredux]

> <i><font color="yellow">You can design an ISRU plant for a Mars mission using only solar power</font>/i><br /><br />I remember Zubrin talking (writing?) about this, and he mentioned sending someone out with a broom from time to time to sweep the dust from the solar panels. Taking a lesson learned from the MERs, maybe they should just look for a place with lots of dust devils <img src="/images/icons/smile.gif" /></i>

 

[cuddlyrocket]

"The requirements of moon missions seem to be crowding out everything else from NASA plans."<br /><br />A nuclear power plant is also a requirement of both Mars Direct and NASA's Mars Reference Mission. As you need such a plant anyway for lunar missions (which will come well before missions to Mars) it's hardly surprising that it's given priority over nuclear propulsion, which is not needed yet.<br /><br />Nuclear power gets the nod over solar power sources because of its greater reliability, and therefore safety factor. A dust storm like the one that greeted Mariner 9 would drastically reduce the output of solar panels. And the power is needed for the ISRU propellant factory that has to operate without humans present for long periods (no brooms!). Solar power will be useful later.

 

[JonClarke]

Brooms would work, so would compressed air jets, maybe even small fans to keep a constant flow of air over the panels. <br /><br />Perhaps the biggest engineering surprise of the MERs is that the panels are periodically cleaned naturally. This is an unexpected bonus. Both MERs landed in the traditional dark areas of Mars, which are known to be less dusty than the bright areas. I suspect that any solar powered spacecraft in these aeeas would be kept clean by dust devils or wind gusts.<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>

 

[JonClarke]

It depends what you mean by "reliable". Fission reactors offer the prospect of compact sources of power, a power rich environment working environment makes many things a lot easier. But a lot of practical issues to do with operating nuclear reactors in space get swept under the carpet.<br /><br />Operationally solar cells are much more mature technology than fission reactors for space applications. We know they can function of Mars for the periods of time required for human missions. They are far simpler and easier to maintain than fission reactors, and are extremely resistant to failure.<br /><br />Fission reactors in space do not have a good reliability record to date, and would require extensive development to become as reliable as solar panels. Both MD and DRM implicity recognise this as they both use solar panels as a back up power source. If you are going to ship solar panels anyway in sufficent quantifites to provide a backup power supply you might as well simply everything and use it as your main source.<br /><br />The only real drawback of solar panels is the need to collect enough power for night time and have a sufficient reserve for dust storms. Even with these caveats solar panels supply more power for greater reliability and less mass than nuclear.<br /><br />People often forget that nuclear reactors will need extensive cooling as most of the energy they produce is wasted as heat. Thus there will be a need for extensive radiator arrays. The performance of these also will also be degraded by dust accululation. The reactors will also need to be deployed at least 1, possibily 2 km away from the main base. As a result a 2 km high voltage armoured cable will need to be carried and laid.<br /><br />This is all without considering the launch safety and security issues. Don't get me wrong, I am not opposed to nuclear power in space. But it needs to be used only for those missions that actually need it. Initial human Mars missions, at least those that use s <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>

 

[JonClarke]

Record stuck again?<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>