Notes & Queries 9/29/07

by Paul Gilster on September 29, 2007

Franklin Chang-Diaz, astronaut and CEO of Ad Astra Rocket Company, intends to test the VX-200 VASIMIR prototype in January. VASIMIR (Variable Specific Impulse Magnetoplasma Rocket) offers much greater fuel efficiency than conventional chemical rockets, working with hot plasma heated by radio waves and controlled by a magnetic field. Technology Review talks to Chang-Diaz about the prototype and the flight version to follow in this interview.

And here’s where Chang-Diaz see us going in the long-term:

I think lots of people are going to be moving into space. I think we will be populating the moon, building enclaves of research and even money-making ventures there. Just last month, Ad Astra signed an agreement with Excalibur Exploration Ltd., a British company, to mine asteroids [when the time is right]. I believe there will be a huge demand for resources, particularly water, from asteroids and comets, because taking water from the earth is going to be very expensive. We’re probably going to supply the moon and the habitat on the moon with water from comets.

Thus Earth as a place humans come back to; think of it as a kind of national park. Chang-Diaz rightly worries about redundancy in case something happens to our planet. Coupling the commercial space sector with next generation propulsion technologies may expand our options.
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And speaking of potential catastrophes, consider the work of Stephen Petranek, who argues that there are plausible ways to surmount almost any disastrous scenario you can mention. Is this the first time in history that humans have had a shot at controlling many of the greatest threats to their survival? View his absorbing presentation on ten ways the Earth could end at the annual TED (Technology, Entertainment and Design) Conference here. A former editor-in-chief at Discover, Petranek is now working on a book on the dangers of climate change.
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What’s the best way to explore an asteroid? If the object’s diameter is something less than eight kilometers, a bad step could put an exploring astronaut into orbit or worse. Even much larger objects present the problem of trying to maneuver on a surface without bouncing yourself into completely new trajectories. A possible solution is a tether out of MIT that would be unwound from a spool (deployed by remote-controlled rocket) to completely encircle the asteroid, establishing a roped path along which crews could work. A homely idea, to be sure, but a first step toward making on-site human exploration of Earth-crossing objects possible.

Robin Goodfellow September 30, 2007 at 13:45

VASIMR is a great technology. Unfortunately, like other electric drives it’s only half a propulsion system, it still requires a very beefy electric power source (most likely a sizeable fission reactor). This tends to put the technology a bit out of our grasp for the immediate future. On the plus side, there are lots of uses for high output electric power sources in space so there is and will be a substantial force behind their development.

The fascinating thing about VASIMR is that in many ways it is a technology born of failure. VASIMR is essentially a fusion rocket without the fusion. The design comes from looking at all the work that has been going on in fusion research and seeing that while we haven’t been able to produce self-sustaining fusion reactions which provide net energy production (except with thermonuclear weapons) we have developed many plasma confinement and heating technologies. By ignoring the fusion issue completely we can use those same technologies to create high temperature, magnetically confined plasmas using almost any gas (not just fusion fuels). If you can manage to come up with a power source for VASIMR then you end up with a technology that offers extraordinarily high Isp in combination with high thrust, which makes it perfect for deep space manned spaceflight missions.

Adam September 30, 2007 at 21:35

Hi Robin

What do you think of the prospects for beaming power to a VASIMR rocket? Would be a good way to boost it out of orbit, for example, even if low-thrust high-Ve mode was powered by a reactor or BIG concentrator arrays.

Robin Goodfellow October 1, 2007 at 23:14

On the receiving end, beamed power tends to look like solar power, only stronger, realistically this gets you up to an order of magnitude more power than straight solar power, at least with near-term technologies. That being said, VASIMR still very much needs multi-megawatt power sources, which can pretty much only be delivered by fission reactors or RTGs using fuels so exotic (e.g. Th-228, Cf-248, Po-210, etc.) that they would be almost as dangerous as nuclear weapons if they were to fall into the wrong hands.

ljk November 29, 2007 at 10:52

Vasimr engines plus 200 MW of nuclear “batteries” =
39 days to Mars

A proposed portable nuclear reactor (simplified solid core)
is the size of a hot tub and will be able to generate 27MW.
It is in funded development. A 200 KW version of the Vasimr
engine is being ground tested in 2008 and a flight version is
being readied for 2010.

Seven of the nuclear generators would provide 200 MW of
power to enable 39 day one way trips to Mars. Two technologies
that are both in funded development and with no major feasibility
questions could revolutionize space travel.

Full article here:

http://advancednano.blogspot.com/2007/11/vasimr-engines-plus-200-mw-of-nuclear.html

ljk April 29, 2008 at 10:59

Vasimr 200KW almost flight ready in 2008 and the solar electric sail like a Dandelion seed

I will look at two near term space systems the Vasimr and the solar electric sail. Both could provide a significant increase in the performance of various space missions. Both have their advantages and would be welcome improvements in the capabilities of space systems. Vasimr can go up to higher power levels that are limited by the Vasimr system and the power system. The Solar electric sail uses no propellant while the Vasimr is ten times or more efficient than current chemical systems. Both could be in space flight tests in the next year or three.

The 200 kilowatt VX200 Vasimr system is almost ready for flight tests and the type of missions impacts it would have are discussed. The solar electric sail system which I reviewed last week is discussed again. Comparison is made to dandelion seeds and how the multiple parachute configuration could be used to combine the propulsion of several solar electric sails to move larger objects.

Full article here:

http://nextbigfuture.com/2008/04/vasimr-200kw-almost-flight-ready-in.html

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