VASIMR - Solar Powered?

Antius · 2017-04-07 13:14:17

How about butane? At -1C its vapour pressure is 1bar.

Do you not need to pressurise tanks anyway to prevent cavitation at turbopump inlet? Propane has a vapour pressure of about 9bar at room temp, so would seem to be the ideal hydrocarbon.

Oldfart1939 · 2017-04-07 13:58:43

The density of these fuels is a disadvantage. The Isp is OK in both cases, but the Id is low. Need bigger (and thus, heavier) tankage for a given amount of Enthalpy.

Antius · 2017-04-07 14:29:59

Styrene perhaps?

http://www.engineeringtoolbox.com/liqui … d_743.html

https://en.m.wikipedia.org/wiki/Styrene

Density = 903kg/m3 even better than kerosene (820kg/m3). Only problem with an alkene is that small amounts of oxygen can serve as free radical catalysts for polymerization. A problem with ethylene that has caused accidents. Not so sure how big a problem this would be with styrene.

The reason I chose methane was that there already exists a space rated engine in the right thrust range for the 100te lander. But in hindsight, a reusable engine for a lunar lander would probably need to be pressure-fed anyway. Otherwise, you need a fresh turbopump for every new landing. It would however be quite an experience carrying out the EVA needed to change it 60 miles above the surface of the moon.

Last edited by Antius (2017-04-07 14:41:24)

Oldfart1939 · 2017-04-07 15:03:21

Styrene? NOOOOOO! This could readily thermally polymerize in the cooling lines! This stuff is the WORST possible choice. Also, as an aromatic hydrocarbon, is very prone to coking. Oxygen is actually a polymerization inhibitor. The final 15 years of my professional career were spent synthesizing various substituted styrenes.

SpaceNut · 2017-04-07 19:40:47

Here are some slides which have the thruster stuff and
http://images.spaceref.com/fiso/2015/05 … -20-15.pdf

http://spirit.as.utexas.edu/~fiso/telec … -13-13.pdf
http://spirit.as.utexas.edu/~fiso/telec … -29-15.pdf

Original links from the site were moved but I did find them once again based on this next key
For 2007-2009 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist07-09.htm
For 2010-2012 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist10-12.htm
For 2013-2015 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist13-15.htm

Terraformer · 2017-04-08 03:35:03

For powering an electric thruster, how about leaving the solar system behind and using microwave beams to get the power to the ship?

Antius · 2017-04-08 03:40:21

SpaceNut wrote:

Here are some slides which have the thruster stuff and
http://images.spaceref.com/fiso/2015/05 … -20-15.pdf
http://spirit.as.utexas.edu/~fiso/telec … -13-13.pdf
http://spirit.as.utexas.edu/~fiso/telec … -29-15.pdf
Original links from the site were moved but I did find them once again based on this next key
For 2007-2009 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist07-09.htm
For 2010-2012 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist10-12.htm
For 2013-2015 presentations, go to http://spirit.as.utexas.edu/~fiso/archivelist13-15.htm

Thanks Spacenut. I will give these a read. The second of the PDFs gives delta-V to lunar orbit and back as 8km/s with impulsive thrust. This suggests that delta-v from LEO to lunar surface is 6km/s. If lunar oxygen is available at a base on the lunar surface, it should therefore be possible to build a methane-oxygen fuelled crew cycler that would complete a journey from LEO to lunar surface and back refuelling only with methane in LEO. As LOX is about 80% of propellant mass, refilling with LOX on the lunar surface prevents the mass ratio from becoming ridiculous. The same type of vehicle could be used to ferry cargo between LLO and the lunar surface, taking on payload and methane from the SEP tug in LLO. These vehicles would spend their entire lives cycling between lunar surface and LLO.

Lunar colonisation would be possible by mass-producing three classes of vehicles. (1) An Earth-launched vehicle who's function is to transport crew and material to LEO; (2) An SEP tug, conveying cargo from LEO to LLO and back; (3) A methane-oxygen reusable vehicle that will be specialised to (a) Convey human beings between LEO and lunar surface and (b) Carry cargo between LLO and lunar surface. It would be best to use separate vehicles for a and b, although the same basic design of vehicle could be used.

In the short-term, methane and argon would need to be supplied from Earth. If lunar materials can be used to manufacture SEP and chemical propellants, the effective payload fraction delivered to the lunar surface would at least double. This could be done for example, if it became possible to electromagnetically launch bulk materials from the moon. This would then serve as propellant for the SEP tug and silicon could be converted into silane using lunar regolith based hydrogen.

If we develop that capability, manufacturing other items in Earth orbit using lunar materials would be a natural extension. For orbital altitudes above 1000km, circular orbits have a lifetime of millennia, even if not actively maintained.
http://www.spaceacademy.net.au/watch/debris/orblife.htm

Last edited by Antius (2017-04-08 03:50:22)

tahanson43206 · 2020-11-08 20:55:42

It's been a while since anyone posted about VASIMR

Here is part of an article July, 2017, just after Antius posted last in this topic ...

https://www.spaceflightinsider.com/conf … s-39-days/

In Arthur C. Clarke’s classic science fiction novels and movies 2001: A Space Odyssey and 2010: Odyssey Two, the spaceships Discovery and Alexei Leonov make interplanetary journeys using plasma drives. Nuclear reactors heat hydrogen or ammonia to a plasma state that’s energetic enough to provide thrust.
In 1983, seven-time Space Shuttle Astronaut Franklin Chang Diaz turned Clarke’s speculations into reality with an engine known as the Variable Specific Impulse Magnetoplasma Rocket (VASIMR).
An electric power source ionizes hydrogen, deuterium, or helium fuel into a plasma by stripping away electrons. Magnetic fields then direct the charged gas in the proper direction to provide thrust.
“A rocket engine is a canister holding high-pressure gas,” Chang Diaz explained. “When you open a hole at one end, the gas squirts out and the rocket goes the other way. The hotter the stuff in the canister, the higher the speed it escapes and the faster the rocket goes. But if it’s too hot, it melts the canister.”
The VASIMR engine is different, Chang Diaz explained, because of the fuel’s electrical charge: “When gas gets above 10,000 [kelvins], it changes to plasma – an electrically charged soup of particles. And these particles can be held together by a magnetic field. The magnetic field becomes the canister, and there is no limit to how hot you can make the plasma.”

The article includes graphics showing the operation of the design (Note Chang Diaz).

Edit#1: Here is a link to an article by Dr. Zubrin casting buckets of ice water on the VASIMR concept.
https://spacenews.com/vasimr-hoax/

The VASIMR Hoax
by Robert Zubrin — July 13, 2011

In looking for current status of VASIMR, the most recent article I could find was from 2018 ...

https://www.fromspacewithlove.com/vasimr/

– News of August 15, 2017 –
Ad Astro Rocket has just passed the second stage of a contract with NASA. Indeed, in 2015 NASA has invested $ 10 million for Ad Astra Rocket so that the company carries out extensive testing of its VASIMR engine. The objective is to carry out in 2018 a test of continuous operation of the VASIMR plasma engine with a power of 100 kilowatts.
One of the major challenges ahead is VASIMR’s power supply. In its current design, the engine is designed to operate optimally at a power of 200 kilowatts. But even the huge solar panels of the international space station can not provide a power greater than 120 kilowatts. A nuclear reactor identical to those of the aircraft carriers would be sufficient. Like many means of propulsion, VASIMR is limited by the unavailability of such sources of energy.
Image by NASA; Posted in Public domain, via Wikimedia Commons
By From Space With Love

One of the ** really ** large buckets of ice water tossed by Dr. Zubrin was the size of the nuclear power plant. The quote above appears to concede the point. I liked the reference to a nuclear power plant from an aircraft carrier.

I asked Google about that, and received this:

A1B reactor - Wikipediaen.wikipedia.org › wiki › A1B_reactor
Using A4W data with a 25% increase in thermal power, the A1B reactors likely produce enough steam to generate 125 megawatts (168,000 hp) of electricity, plus 350,000 shaft horsepower (260 MW) to power the four propeller shafts.
People also ask

I would imagine a VASIMR could produce decent thrust with a reactor producing 125 MW of electric power. However, the mass of the reactor and shielding would (presumably) take up a large part of the thrust.

(th)

tahanson43206 · 2021-08-05 18:16:52

Almost exactly one year ago, I posted a reminder to the VASIMR topic ...

I've had a year to think about the problem of supplying power to VASIMR.

During that year numerous members of the NewMars forum have provided inspiration by talking about entirely unrelated topics, but here an there I picked up hints of ideas that might help to address the VASIMR power problem.

In particular, Quaoar led the forum in an exploration of the physics of driving an intergalactic exploration probe using power developed at Mercury.

It came to me then that it is not necessary to wait until we are ready to send an intergalactic probe to use the basic idea.

A ship travelling to Mars is as good a target for focused energy as any that might be proposed.

The posts above quote power levels in the 100-200 kilowatt range ....

I see no reason at all why a power transmitter based on the Moon could not deliver power to a vessel headed away from Earth, whether inbound to Venus or outbound to Mars or the outer system.

Likewise, I see no reason at all why Phobos could not provide a similar service for vessels inbound to Mars or heading out for other destinations.

I'd like to invite members with posting privileges to consider the math involved.

Questions to be addressed include what kind of receiving array is most effective for the space craft over Earth-Mars distances, and what kind of equipment on the Moon is needed to deliver power reliably to a vessel in transit for weeks or months if necessary.

The Sun can be counted upon to provide energy for the venture, and the Moon can be counted upon to hold steady in its course.

It's up to humans to work out the details of how this could and would be done.

(th)

SpaceNut · 2021-08-05 18:44:42

The electromagnetic spectrum diffuses with distance and would require refocusing the beam of energy with distance such as to keep power levels as close as possible to the starting point. With each recombining of the beam there will be losses.

tahanson43206 · 2021-08-05 19:02:49

For SpaceNut re #110

Thank you for your important reminder!

Can you (would you if you have time) find precise numbers for diffusion of laser beams as compared to focused beams?

My understanding is that parabolic mirrors are able to achieve focus on a single star light years away.

Presumably a light transmitted from such a mirror to the distant star would arrive at the star as a single point of light.

I understand that laser beams ** do ** spread, but (apparently) the spread is less than is true for an ordinary beam of light.

A single photon does NOT spread (as I understand the situation). If an operator is wanting to send a supply of photons to a remote vessel, I would imagine the operator would want to arrange things so that each photon transmitted arrives at the target without having taken a side trip to somewhere else.

Your point in Post #110 is an excellent starting point for what I hope will be a productive discussion that might lead to a solid recommendation for the developers of the VASIMR engine.

(th)

SpaceNut · 2021-08-06 18:52:37

Lasers are collimated light using lenses to shape the beam for distance of projection and it will spread out once more with enough distance. I am sure that one can google for function but its about the numbers for the beam focus that matter not just power.
If one could supply the solar array with the beam over distance its still going to be the efficiency of the panels to storage rate that will be the issue for making use of the stored energy for the VASIMR engine.

tahanson43206 · 2021-08-06 19:46:56

For SpaceNut re #112

Thanks for keeping this concept for VASIMR going for at least one more round ....

It sounds as though you are ready to accept that photons can be delivered to distant targets with appropriate technical adjustments.

Regarding efficiency .... The recent post in another topic about use of nanometer scale antenna and rectifier systems offers hope that efficiency of a receiving antenna at a VASIMR vessel can approach or exceed 50%. Even the 50% that is NOT captured by the antenna need not be lost, but instead can be collected by suitable heat sensitive material. With the deep space cold on the back side, such panels should be able to achieve at least 20% thermal efficiency in generating electricity.

Todo: Find thermal efficiency of Seebeck effect with 100 Centigrade on front and 0 Kelvin on the other.

(th)

tahanson43206 · 2022-01-26 12:39:22

The recently revisited post of C M Edwards, about using chemically stored energy to power a plasma engine, inspired me to ask Wikipedia for an update on the subject.

The Wikipedia article was last updated: This page was last edited on 17 January 2022, at 22:49 (UTC).

Based on that update date, I conclude not much has changed from the previous status.

The system is (apparently) less efficient than an ion engine, and it (apparently) requires much more mass to operate.

On top of that it (apparently) requires superconducting magnets that themselves are energy hungry (assuming they require cooling).

That is a detail that may be discussed in the Wiki. I scanned the article, so may have missed it.

In any case, as nearly as I can tell, VASIMR is no closer to practical use than it was 10 years ago, and that was essentially Zilch.

This topic is entitled VASIMR - Solar Powered ....

The topic accumulated 4 pages before it entered hibernation. Perhaps someone in all those posts found a way to collect solar power in a way that did not add massive structures to the space vessel, and corresponding great mass, which would further weaken the limited effect of the engine.

(th)

tahanson43206 · 2023-12-25 14:31:05

It may be time to take another look at VASIMR...

Per Google:

One of the biggest concerns for the VASIMR project in general is that, to be able to travel to Mars in a short amount of time, it needs a nuclear power system that is capable of delivering 200 kW to the engine.
Plasma, Ion-Thrusters, and VASIMR
University of Colorado Boulder
https://www.colorado.edu › kantha › content › pla...
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200 Kw seems modest compared to the 1 megawatt target of the shipping container power pod under discussion in other topics.

Update later: In looking back over the topic, I see that various sizes have been proposed for VASIMR, and 200 Kw appears to be at the low end.

(th)

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#101 2017-04-07 13:14:17

Re: VASIMR - Solar Powered?

#102 2017-04-07 13:58:43

Re: VASIMR - Solar Powered?

#103 2017-04-07 14:29:59

Re: VASIMR - Solar Powered?

#104 2017-04-07 15:03:21

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#105 2017-04-07 19:40:47

Re: VASIMR - Solar Powered?

#106 2017-04-08 03:35:03

Re: VASIMR - Solar Powered?

#107 2017-04-08 03:40:21

Re: VASIMR - Solar Powered?

#108 2020-11-08 20:55:42

Re: VASIMR - Solar Powered?

#109 2021-08-05 18:16:52

Re: VASIMR - Solar Powered?

#110 2021-08-05 18:44:42

Re: VASIMR - Solar Powered?

#111 2021-08-05 19:02:49

Re: VASIMR - Solar Powered?

#112 2021-08-06 18:52:37

Re: VASIMR - Solar Powered?

#113 2021-08-06 19:46:56

Re: VASIMR - Solar Powered?

#114 2022-01-26 12:39:22

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#115 2023-12-25 14:31:05

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