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SBird

Banned

Registered: 2004-03-10

Posts: 490

Re: LEO to TMI - discuss

Although this thread has wandered a bit from the original intended purpose, I think some interesting infro has come up.

Since it appears that we've gone ahead and started discussion of the entire LEO to LMO portion of transportation, let's talk about technologies that are useful for the Earth-Mars Transit.

One idea that I've found to be particularly intriguing is the M2P2 drive.  It's basically a magnetic field pumped up with plasma.  The original ida is to use it as a solar sail replacement.  The force generated is small but the equipment weight and power requirements are quite low.

In terms of a fast Hohmann trajectory, the propulsive benefit of an M2P2 drive are minimal.  However, the protective properties are interesting.  Basically, the M2P2 can deflect most or all of the incoming solar wind.  I'm not certain how well it could handle the impact of a CME but it should work quite well to reduce or eliminate the non-cosmic ray component of the radiation.

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: LEO to TMI - discuss

I would lump this one in with the solar sail really, at least until somebody tests it on a scale bigger than a few inches. The antiradiation properties of a magnetic field are interesting, but I have reservations of putting the whole ship under such a high level magnetic flux. Keeping the magnet running would also require superconductors that would need to be kept cold.

Coincidentally, one of the advantages cited for the VASIMR engine is that it would have a smiliar albeit less powerful effect, since it operates by confining plasma with magnetic fields.

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[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

dicktice

Member

From: Nova Scotia, Canada

Registered: 2002-11-01

Posts: 1,764

Re: LEO to TMI - discuss

Keeping things cold, when you have all of free space to radiate to--as well as your vehicle to shade radiators from the sun--can't be all that difficult to do.

SBird

Banned

Registered: 2004-03-10

Posts: 490

Re: LEO to TMI - discuss

I really doubt that the magnetic fields involved with an M2P2 will affect and ship systems.  It's a non-dynamic field and so really has no effect upon electronic systems which are highly resistant to magnetic fields anyway.  After all, computers can operate in close proximity to NMR and MRI systems with no problem. 

Also, the field strengths used by M2P2 aren't that big.  The present M2P2 models generate a plasma bubble a few meters in diameter with a coffee-can size electromagnet.  My understanding is that the field could be much larger but is limited by the walls of the test chambers.  The estimates I've seen is a few tens of Kw being sufficient to create a 30 km diameter plasma bubble.  Obviously, we don't need something that strong so the power requirements can be lower, in the order of a few Kw which is easily provided by solar panels. 

M2P2 does need a space shakedown but since it operates under the same principles as planetary magnetospheres, we know the basic principle is sound. 

Assuming a total thrust of 10 milliNewtons from, say, a 1 km M2P2 shielding system and a 100 MT spacecraft on a 180 day Hohmann trajectory, the total deltaV ends up being a whopping 2 m/s.     This estimate is actually an order of magnitude lower than Winglee's estimates and more in line with what his critics predict.  Nonetheless, the low power requirements to block the solar wind make this an attractive system.

bolbuyk

Member

From: Utrecht, Netherlands

Registered: 2004-04-07

Posts: 178

Re: LEO to TMI - discuss

Two things make me that I am somewhat carefull to be fond of new technologies if we want to send humans to Mars, especially when it comes to TMI.

1. High-ISP/Low-thrust (solar sail/ion engine) needs long acceleration times and monitoring from earth will last long. Also will there be problems with keeping the spacecraft vital.

2. Development will ask big sums to create new propulsion-technologies.

I think immediately after LEO-insertion there should be a transfer to a high, strongly elliptical EO (delta-V about 3 km/s), rather easily obtaineble with LO2/LH2. In this orbit, the spacecraft can membered by a small Apollo-like capsule.
For TMI just some hundred m/s is required. :realllymad:

SBird

Banned

Registered: 2004-03-10

Posts: 490

Re: LEO to TMI - discuss

I largely agree with you.  However, it should be noted that ion drives are a fairly mature technology and being pursued for other reasons anyway. 

As for the highly eliptical launch orbit, O2/H2 does suffice for this but you still need all the delta V to get up to that eliptical orbit.  It all depends upon how perishable the cargo is.  If you're moving people or low-shelf life goods, chemical or NTR is the way to go as it minimizes transit time.  For cargo that is non-perishable, you're much better off going the slow way.  Using all the tricks available (ions drives, cycling space tugs to L1, 0-energy trajectories, etc) your MArs arrival mass approaches the LEO mass.  That's about a 4-fold increase in the total mass, saving huge amounts of money in terms of launch costs.

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,267

Re: LEO to TMI - discuss

maybe worth a bump since Nuclear and NASA articles started to show up in the news again

The Nuclear Thermal Rocket That Could Get Us to Mars in Just 45 Days
https://www.yahoo.com/lifestyle/nuclear … 00960.html

NASA and the U.S. Department of Defense’s Defense Advanced Research Projects Agency (DARPA) contracted Lockheed Martin to design, build, and test nuclear thermal rocket technology

Mars_B4_Moon

Member

Registered: 2006-03-23

Posts: 9,267

Re: LEO to TMI - discuss

'We could have been on Mars 30 years ago'

Can Starship Take Us To Mars?

https://www.youtube.com/watch?v=GZHKYTRPXRo