Why the VASIMR hype?

[mlorrey]

Folks:

Franklin Chang Diaz gave a UHCL lecture Friday night here in Houston and he disclosed that by the time the VF-200 VASIMR flight engines flies to the ISS, the development cost for Ad Astra Rocket Company will be over $150 million.  I wonder what investors were willing to wait for such a long shot return on their investments, and a fairly large investment at that.

Second item, I asked Franklin during the Q&A session what the VASIMR engine power level was for planning his proposed 200 MW manned mission to Mars project, and he stated that it was something in the range of 20-to-40 MW per engine.  That implies 5-to-10 engines would be used for this 39 day mission senario tied to three nuclear reactors.  Each engine would be consuming something on the order of 40 kW/Newton, so each of the 40 MW VASIMR engines would be producing ~1,000 Newtons.

Thanks for the report, good numbers. Have they disclosed who any of their investors are?

[Zachstar]

On the other hand with approximately a third the power (492/1321 = 0.372) it will take the VASIMR longer to reach inter-planetary velocity.

Note Mars gravity is 1/3 of Earth's so in fact it will take the same amount of time to escape the shallower gravity well on 1/3 of the power.

Then continue accelerating until about 2/3 of the way back.  The timings of the two transfer orbits is a nice problem for the orbital guys.

Meh even an Xbox could calculate that mission quickly. There is an MFD for Orbiter already that can calculate burns for Ion type engines.

I still think that in a situation of solar to mars we would end up not using the full potential of the array for the start and would do so during the return.  There is a real reason for this anyway because you want to be able to have full needed current to do an emergency return. Think about it. There might actually be a scenario where the craft would end up further away from the sun than mars. You would need the full power possible in such a situation in my opinion.

In the more near term tho the issue of degrade is going to have to be seriously addressed. A lunar base supporting tug is going to have to be able to function quite a number of years before replacement of its large solar systems.

[8900]

On the other hand with approximately a third the power (492/1321 = 0.372) it will take the VASIMR longer to reach inter-planetary velocity.

Note Mars gravity is 1/3 of Earth's so in fact it will take the same amount of time to escape the shallower gravity well on 1/3 of the power.

Then continue accelerating until about 2/3 of the way back.  The timings of the two transfer orbits is a nice problem for the orbital guys.

Meh even an Xbox could calculate that mission quickly. There is an MFD for Orbiter already that can calculate burns for Ion type engines.

I still think that in a situation of solar to mars we would end up not using the full potential of the array for the start and would do so during the return.  There is a real reason for this anyway because you want to be able to have full needed current to do an emergency return. Think about it. There might actually be a scenario where the craft would end up further away from the sun than mars. You would need the full power possible in such a situation in my opinion.

In the more near term tho the issue of degrade is going to have to be seriously addressed. A lunar base supporting tug is going to have to be able to function quite a number of years before replacement of its large solar systems.

math is simple, we don't even need supercomputer to do the calculation, a high end PC game graphic card's GPU will do, the tricky part is to make it actually work

[JonSBerndt]

Folks:

Franklin Chang Diaz gave a UHCL lecture Friday night here in Houston and he disclosed that by the time the VF-200 VASIMR flight engines flies to the ISS, the development cost for Ad Astra Rocket Company will be over $150 million.  I wonder what investors were willing to wait for such a long shot return on their investments, and a fairly large investment at that.

Second item, I asked Franklin during the Q&A session what the VASIMR engine power level was for planning his proposed 200 MW manned mission to Mars project, and he stated that it was something in the range of 20-to-40 MW per engine.  That implies 5-to-10 engines would be used for this 39 day mission senario tied to three nuclear reactors.  Each engine would be consuming something on the order of 40 kW/Newton, so each of the 40 MW VASIMR engines would be producing ~1,000 Newtons.

Thanks for the report, good numbers. Have they disclosed who any of their investors are?

I vaguely recall a discussion and photo of the visit of a Swiss investor or potentially interested party (is that correct, Star-Drive?). There are a fair number of articles linked in one way or another from their web site (http://www.adastrarocket.com/aarc/).

This lecture was one of a series you can read about here:

http://www.spacecenterlectureseries.com/index.html

There is a video of a VASIMR engine firing there, too, I believe, as well as some images.

Jon

[Star-Drive]

Jon:

As Dr Chang Diaz noted during his Friday lecture, he was not at liberty to divulge any of the company's investors at this time.  Sadly I have nothing to add to that state of afairs other than what is available from the below Google hits.

"AARC (formerly Ad Astra Technologies, Inc.) was incorporated on Jan. 14, 2005 and officially organized on the Jul. 15, 2005. Former Space Shuttle astronaut Franklin R. Chang Diaz serves as company President and CEO. Chang Diaz invented the VASIMR concept and has been working on its development since 1979, starting at The Charles Stark Draper Laboratory in Cambridge Massachusetts and continuing at the MIT Plasma Fusion Center before moving the project to the Johnson Space Center in 1994. In the development of the VASIMR engine, Ad Astra Rocket Company is teamed with NASA JSC, Oak Ridge National Laboratory, University of Texas at Austin, University of Houston and other various government space and research centers, industrial companies and academia including foreign universities."


http://www.adastrarocket.com/EXECUTIVE%20SUMMARY051109.pdf

[isa_guy]

Some new info from ad astra site http://www.adastrarocket.com/aarc/VF200.

[Zachstar]

Getting it to the station is going to be a royal PITA but it looks like a sane design in my view and they diddnt try to claim it was going to keep that station up. Bravo!

[Star-Drive]

"Getting it to the station is going to be a royal PITA but it looks like a sane design in my view and they diddnt try to claim it was going to keep that station up.  Bravo!"

The current VF-200 VASIMR delivery baseline to the International Space Station (ISS) is via an Orbital Sciences Taurus-II COTS rocket.  I hardly think that will be a PITA issue. 

As to the capability of the VF-200 VASIMR engine neutralizing the ISS drag, if it works as advertised, it could.  Provided it had a dedicated ENTECH or equivalent 200 kW, 8X stretched lens concentrator array using EMCORE triple junction photovoltaic cells feeding it power.  That also might be doable if NASA is willing and can find the money for same.  Right now the Russians are paying for and taking care of ISS reboost via delivered propellant on their Progress resupply ships.

[mlorrey]

"Getting it to the station is going to be a royal PITA but it looks like a sane design in my view and they diddnt try to claim it was going to keep that station up.  Bravo!"

The current VF-200 VASIMR delivery baseline to the International Space Station (ISS) is via an Orbital Sciences Taurus-II COTS rocket.  I hardly think that will be a PITA issue. 

As to the capability of the VF-200 VASIMR engine neutralizing the ISS drag, if it works as advertised, it could.  Provided it had a dedicated ENTECH or equivalent 200 kW, 8X stretched lens concentrator array using EMCORE triple junction photovoltaic cells feeding it power.  That also might be doable if NASA is willing and can find the money for same.  Right now the Russians are paying for and taking care of ISS reboost via delivered propellant on their Progress resupply ships.

One would think that the same amount of propellant would last 20 times as long used on VF-200 for the same amount of boost per day. VF-200 is going to be run 15 minutes a day apparently off its battery pack that is trickle charged. How much boost is that compared to the existing thrusters?

I also am wondering what the stations orientation is versus its direction of travel. It looks like VF-200 is to be mounted near the end of a truss with thrust pointing along the booms axis or slightly upward from it. Does the ISS travel with the truss pointing in the direction of travel or perpendicular to it?

[A_M_Swallow]

According to this Ad Astra webpage the VASIMR VX-200 can produce approximately 1 lbf at an Isp 5000.
http://www.adastrarocket.com/aarc/Technology

The current mass of the International Space Station is 344,378 kg (759,222 lb).
http://en.wikipedia.org/wiki/International_Space_Station

[mlorrey]

According to this Ad Astra webpage the VASIMR VX-200 can produce approximately 1 lbf at an Isp 5000.
http://www.adastrarocket.com/aarc/Technology

The current mass of the International Space Station is 344,378 kg (759,222 lb).
http://en.wikipedia.org/wiki/International_Space_Station

Ok so 2533 lb mass / lbsec thrust, per day. What is the measured drag imposed on the station?

[GuessWho]

"Ok so 2533 lb mass / lbsec thrust, per day. What is the measured drag imposed on the station?"

By my calcs, at 5000 sec Isp, 200 kWe power input, and assuming a 60% efficiency on the EP thruster, thrust level is 1.045 lbf.  A 15 minute burn would use 0.085 kg of propellant producing approximately 1.2 cm/sec delta-V.

Best number I could find for measured drag on ISS was about 4 micro-g's (circa 2004 kinda number).  The 15 minute burn of VASIMR yields about 1.4 micro-g's of acceleration.  If these numbers are reflective of reality, then VASIMR would need to operate for 45 minutes per day just to counter drag.

[A_M_Swallow]

A daily 45 minute burn is definitely doable.  That is about half of an orbit around the Earth and the electric power could be feed directly from new solar arrays. 

Depending on how long it takes to trickle charge 3 off 15 minute burns a day could be used.  Since the ISS already uses its power regular trickle charging would still require new solar arrays.

[Star-Drive]

It's beginning to look like the VF-200 module will be fired from the end of the ISS robotic arm so its plasma plume doesn't scorch any of the ISS solar arrays or thermal radiators.  Charging of the VF-200 battery pack would be performed back at a charging station on the ISS truss.  That power port is limited to ~2,300 watts, so charging a 200kW capable battery pack that can store enough energy for the 15 minute firing AND the concurrent superconductive cooling loads will take several days per charge dependent on other ISS load demands.  Looks like they may have to have a dedicated ~300 kW SLA for their power supply if NASA were to choose to use VF-200 for replacing the Russian ISS reboost capabilities.  Just send money...

[Robotbeat]

"Ok so 2533 lb mass / lbsec thrust, per day. What is the measured drag imposed on the station?"

By my calcs, at 5000 sec Isp, 200 kWe power input, and assuming a 60% efficiency on the EP thruster, thrust level is 1.045 lbf.  A 15 minute burn would use 0.085 kg of propellant producing approximately 1.2 cm/sec delta-V.

Best number I could find for measured drag on ISS was about 4 micro-g's (circa 2004 kinda number).  The 15 minute burn of VASIMR yields about 1.4 micro-g's of acceleration.  If these numbers are reflective of reality, then VASIMR would need to operate for 45 minutes per day just to counter drag.

That is 1.4 micro-gees for 15 minutes, not averaged over the whole day! According to your calculations, you'd need about a 600kw Vasimr just to counter the drag (or run at a lower ISP).

I heard that (very optimistically on a good day) the ISS decays in orbit about 20 meters per day, which works out to roughly 13 m/s per day, which is about 15 microgees. Am I wrong? (It's very possible I am wrong, and I hope I am.) If this is the case, then the ISS needs about a 2MW vasimr to counter drag.

[Star-Drive]

I was told today by one of the ISS project managers that the average net drag force on the ISS amounts to ~0.70 Newtons.  Since the VF-200 can produce ~5.0 Newton at full power, it looks like it could perform the re-boost function if one where fire the VF-200 thruster for about 3.4 hours per day at full power along the appropriate thrust vector.  Of course that does still require the procurement and installation of that new ~250kW SLA solar array...

[Robotbeat]

I was told today by one of the ISS project managers that the average net drag force on the ISS amounts to ~0.70 Newtons.  Since the VF-200 can produce ~5.0 Newton at full power, it looks like it could perform the re-boost function if one where fire the VF-200 thruster for about 3.4 hours per day at full power along the appropriate thrust vector.  Of course that does still require the procurement and installation of that new ~250kW SLA solar array...

A 250 kW Stretched Lens Array (SLA) flown in orbit would be a great, empowering technology demonstration on its own. Together with VASIMR, and you have everything tested for an orbital tug (the only thing untested would be Van Allen belt passing). You could design standard upper stages that use SLA and VASIMR for interplanetary probes, and you could make a cargo tug whenever you wanted.

[Nomadd]

 Part of the attraction of VASIMR or ion station keeping would be the ability to maintain a gravitational sweet spot where they wanted. That would require constant thrust.
 I'm a little confused as to why you'd want VASIMR for station keeping anyhow. A Hall effect ion engine can deliver a Newton of thrust with about 1/3 the electricity of a VASIMR.

[Robotbeat]

Part of the attraction of VASIMR or ion station keeping would be the ability to maintain a gravitational sweet spot where they wanted. That would require constant thrust.
 I'm a little confused as to why you'd want VASIMR for station keeping anyhow. A Hall effect ion engine can deliver a Newton of thrust with about 1/3 the electricity of a VASIMR.

Because there's potentially a longer lifetime if there's no grid to erode?

[A_M_Swallow]

It is simpler if the port and starboard solar arrays use the same design but it is not necessary.  Keeping the ISS in orbit until 2020 would allow a 6 - 7 year soak test of rival designs.


From the above figures

20 metres per day for 7 years = 20 * 365.25 * 7 = 51,135 metres

A 15 minute VASIMR burn uses 0.085 kg of propellant and 3.4 hours per day are needed.  15 minutes = 0.25 hours
Total propellant = (0.085/0.25) * 3.4 * 365.25 * 7 = 2,956 kg

Assume solar array is 150 W per kg UltraFlex BOL and 300 kW is needed
300,000/150 = 2,000 kg

Allocate mass of VASIMR thrusters, power converters, cables and cooling system to the experiment.  Extra mass is 2,956 kg + 2,000 kg = 4,956 kg.
With 10% mass reserve 5.5 mT.

It will be interesting to know the mass and cost difference of using chemical fuel for the station keeping.