Advanced Plasma Rocket Tested in Costa Rica

[Boris_Badenov]

Advanced Plasma Rocket Tested in Costa Rica <br /><br />Aviation Week & Space Technology, 02/19/2007, page 17<br /><br />Edited by Frank Morring, Jr.<br /><br /><br />Ad Astra Rocket Co. expects to begin operating a 200-kw. "flight-like" engine prototype in ground test by the end of the year. Ad Astra is a Houston-based company that grew out of research into Variable Specific Impulse Magnetoplasma Rocket (Vasimr) technology conducted at Johnson Space Center by seven-time shuttle astronaut Franklin Chang-Diaz. The company has opened a facility in Costa Rica, where Chang-Diaz was born, for life-cycle testing that started at lower power levels in December 2006. Next up is a test series with a 100-kw. unit already in early checkout. Assembly of two flight variants of the engine is set for early next year, with in-space testing targeted for 2011. The company, which has an exclusive license to the original Vasimr patents under a privatization agreement with NASA (AW&ST Jan. 30, 2006, p. 12), has added new intellectual property in the past year. The Vasimr engine uses radio waves to heat propellant gas to extremely high temperatures, producing exhaust velocities in the 40-50-km./sec. range. <br /><br /><font color="yellow">(the link requires a subscription that I don't have, I swiped the article from another message board) </font>/safety_wrapper> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[docm]

Just goes to show that if you really want it developed go private. Otherwise the govt. paperwork & bureaucratic BS will bury it. Now to get the thing spaceborn. <div class="Discussion_UserSignature"> </div>

 

[qso1]

Good news. <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[gunsandrockets]

"Ad Astra Rocket Co. expects to begin operating a 200-kw. "flight-like" engine prototype in ground test by the end of the year... Next up is a test series with a 100-kw. unit already in early checkout. Assembly of two flight variants of the engine is set for early next year, with in-space testing targeted for 2011."<br /><br />I am very curious.<br /><br />What possible spacecraft in 2011 will have 100 kWe available to power the VASIMR? Or is the 'flight variant' VASIMR a much smaller scale test device?<br /><br />And I am also very curious about the performance numbers for the VASIMR engine. Okay, at top end the engine could crank out 5,000 seconds ISP. But how does it compare to the NSTAR when the VASIMR is adjusted to 3,000 seconds ISP? How does it compare to a Hall plasma thruster when at 1,500 seconds ISP?<br /><br />The basic concept of variable ISP rocket propulsion I heartily agree with. But I am very skeptical that a pure electric propulsion system is the way to achieve that. What kind of thrust to weight ratio does the VASIMR have at the bottom of it's ISP scale? Even pure electro-thermal propulsion systems have lousy T/W. <br /><br />Instead of pure NEP, I think a mixed mode propulsion system utilizing two different rocket engines is the best way to achieve variable specific impulse propulsion. As in a ship using NTR for low ISP propulsion then switching to NEP for high ISP propulsion. Since the high thrust phases of a mission could be covered by the NTR engines, the NEP of a mixed mode ship could get by with much lower power -- perhaps only one megawatt, in contrast to a pure NEP ship which could require 6 megawatts or more.

 

[docm]

Point of reference: Deep Space 1 delivered 92 millinewtons from 2.1 kw using 2.5 kw SCARLET panels.<br /><br />VASIMR "gears" (exhaust velocity -- thrust in newtons) @10 MW<br /><br />VASIMR (high gear) 294,000 -- 40 <br />VASIMR (med gear) 147,000 -- 80<br />VASIMR (low gear) 29,000 -- 400 <br /><br />Best thought for a 200 kw supply in short term is a reactor. Maybe even a TPV (thermophotovoltaic) generator. They work like a super-RTG but using IR photocells instead of thermocouples. Toyota & NASA are researching them as is the military for silent field power generation. <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

I've been doing a little more research on VASIMR since my last post. Supposedly the ISP can range from 1,000 to 30,000 sec.<br /><br />http://en.wikipedia.org/wiki/Variable_specific_impulse_magnetoplasma_rocket<br /><br />You inform me...<br /><br />"VASIMR (low gear) 29,000 [m/s? exhaust velocity] -- 400 [newtons thrust]"<br /><br />Hmm...10 mWe power to generate 400 Newtons of thrust. That's about 9 lbs thrust per megawatt, about the same as a Hall effect plasma thruster operating at the same ISP.<br /><br />Does the ISP vs thrust tradeoff scale the same way down at 1,000 sec ISP? 1,200 N @ 1,000 sec ISP? And has such VASIMR performance been validated with experimental testing?<br /><br />Even if the 1,200 N figure is true, that's only 300 lbs of thrust from an enormous 10 mWe power system. That is an inadequate thrust to weight ratio to support quick propulsive braking into Mars orbit. It seems to me the VASIMR would still have to employ the slow deceleration spiral typical of pure electric propulsion spacecraft which all suffer from low thrust. <br /><br /><br />

 

[Boris_Badenov]

Guessing only here;<br /><br /><font color="yellow"> Does the ISP vs thrust tradeoff scale the same way down at 1,000 sec ISP? 1,200 N @ 1,000 sec ISP? And has such VASIMR performance been validated with experimental testing? </font><br /><br /> I don't think they've gone that far in the testing yet. I think this one was just a sub scale test engine that sat on a stand. As they build them larger & larger they will get a better feel for what they will be capable of. I'm also willing to bet they will need a nuclear reactor to power the in space test engine, & it will be a real butt-kicker. <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[vogon13]

I have also read that it is possible the exhaust from the VASIMIR engine will arc back around and contact the vehicle, thus negating all or a portion of the thrust.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[docm]

That's what space tests are for. <div class="Discussion_UserSignature"> </div>

 

[vogon13]

Space would be a helluva spot to find out the bloody thing don't work at all.<br /><br />All the development money could have gone into something else.<br /><br /> <br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[docm]

Same as designing a sub, car or plane; at some point you have to get off the computer & test stand and hit the real world. All this matter of arcing can only be proven or disproven in a flight test. <br /><br />If the thing arcs then they can evaluate if it's fixable or not. <br /><br />If it doesn't then it's time to evaluate scaling up and production engineering.<br /><br />In MoTown we say 'that's where the rubber hits the road.' <div class="Discussion_UserSignature"> </div>

 

[vogon13]

{an aside:<br /><br />actually, over the months, I have become a teeny bit optimistic it might actually work, there might be enough stray neutralizing electrons and/or protons in the solar wind to make it work. Could be a problem scaling it up though.}<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

And if it does work because of the neutralization, then we have yet another coffin nail for the electric universe concept.<br /><br /><br />{like we needed yet another one}<br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[docm]

Try convincing the guys at IEEE of that <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>