Testing on the space station[edit]On December 8, 2008, Ad Astra signed an agreement with NASA to arrange the placement and testing of a flight version of the VASIMR, the VF-200, on the International Space Station (ISS).[24] As of June 2012, its launch is anticipated to be in 2015;[25] the Antares rocket has been reported as the "top contender" for the launch vehicle.[26] Since the available power from the ISS is less than 200 kW, the ISS VASIMR will include a trickle-charged battery system allowing for 15 min pulses of thrust.Testing of the engine on ISS is valuable because it orbits at a relatively low altitude and experiences fairly high levels of atmospheric drag, making periodic boosts of altitude necessary. Currently, altitude reboosting by chemical rockets fulfills this requirement. The VASIMR test on the ISS may lead to a capability of maintaining the ISS or a similar space station in a stable orbit at 1/20th of the approximately $210 million/year present estimated cost.[12]Ad Astra held a formal PDR for the VF-200 with NASA on 26 June 2013
The problem with even-lower-thrust engines than VASIMR is that burn times get really long. So you are not in zero-G anymore. Which may or may not disturb some of the scientific experiments which are done in the ISS for precisely that environmental factor.
Quote from: Muska on 05/21/2014 08:55 amOne question: What are the advantages of untested VASIMR engine compared to well tested array of Hall thrusters? This is salient in the ISS's role as a laboratory.
One question: What are the advantages of untested VASIMR engine compared to well tested array of Hall thrusters?
{snip}Sidenote, I missed this before: The plans Ad Astra have for testing on the ISS involve a miniscule plane-change maneuver, 15 minutes at a time(once per day?) for 6 newtons, not actual drag-cancelling propulsion. So long as this is their mode of operation, the ISS will require the same degree of chemical fuel for station-keeping. As such, VASIMR and an array of more conventional ion thrusters are not mutually exclusive.
Zubrin has in theaccused VASIMR of being essentially a "Wait until advanced propulsion is ready" perennial excuse to delay a Mars mission...
. VASIMIR or some other advanced technology is absolutely necessary. Can it be done with out it? Of course,
Quote from: bad_astra on 05/22/2014 05:49 pm. VASIMIR or some other advanced technology is absolutely necessary. Can it be done with out it? Of course, These statements are inconsistent. I don't think there's a problem with using chemical rockets (EDIT: and just accepting long travel times) if you a) bring a solar flare shelter and b) are willing to accept a few percent (like 5% I think) increase in cancer risk decades down the road (by which point medical technology may well mean the risk is much less significant). Also, I think those risks are calculated with the linear-no-threshold model of radiation cancer risk (that's the normal 'regulatory' one) which may well be far too pessimistic.
1) The microgravity experiments they do are sort of a joke. Make-work stuff that doesn't really achieve much. The pointful part of having them up there is to further develop the engineering capacity for human spaceflight.2) The ISS is already a very vibration-prone structure, due to the number of humans bumping around in it.
If NASA really does actually really truly want to focus on the asteroid missions for the near term, I'd love to see a VASIMR concept on the front stage with Dr. Chang Diaz organizing the whole show.
Wow! Didn't Werner von Braun play that role... which is designer and administrator?
Quote from: Mr. Scott on 05/27/2014 05:02 amWow! Didn't Werner von Braun play that role... which is designer and administrator?von Braun was never NASA administrator. http://en.m.wikipedia.org/wiki/List_of_Administrators_and_Deputy_Administrators_of_NASAbut IIRC he was the first director of Marshall.