Can Starship Take Us To Mars?
]]>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
]]>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.
]]>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:
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.
]]>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.
]]>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.
]]>I agree that something like a GCNR for fast transit would be great for human flights. However, if we get teh technology perfected, there's no reason to not use it for all our missions. The high Isp means that your fuel expenses are minimal. You could send crew via high-speed flat trajectories and cargo standard high speed Hohmann trajectories.
I think that the Mars SSTo would have to be sent as a kit or lander or something. The facilites to build such a craft on Mars won't exists for a long time.
]]>If there is going to be a ten-ton-payload class DC-X style SSTO rocket on Mars, then the ease of maintenance does depend on how well its built, but I wonder if when this stage of development is reached - where you can make gobs of fuel and have at least some surface infrastructure - could a TransHab style pressurized hanger be built? The only part that wouldn't be collapsable for transport would be the hatch and the handling gear.
]]>I think that the only reason to have a pilot is to load and unload cargo. Even that can be largely circumvented by using standardized cargo loading/unloading proceedures that are compatible with automated pilots.
In fact I was thinking about cargo loading/unloading as well, but as you say, maybe human presence isn't so important to get the job done anyway.
The mass ratio of an SSTO will be lousy enough as it is, and adding the extra room and mass and reliability/escape option for pilot(s) doesn't make much sense to me for a tanker. The archaic 1960's Progress cargo hauler doesn't need a pilot, why should the SSTO?
Can't really argue with that, but on another note how do you picture passenger operations between MLO to Mars surface? If done by SSTO, should that include pilots in your opinion?
There should be a great deal of difference as regarding the negative implications of a crew for Mars SSTO's in comparison with Terra SSTO's. Delta-V to MLO is only 4.0 km/s with a mass ratio of 2.9 for CH4/O2. Basically, this tells me that if for any reason you wanted to include a pilot you'll have mass to spare.
]]>The mass ratio of an SSTO will be lousy enough as it is, and adding the extra room and mass and reliability/escape option for pilot(s) doesn't make much sense to me for a tanker. The archaic 1960's Progress cargo hauler doesn't need a pilot, why should the SSTO?
If somthing does go wrong with the automated controls, thats why you have a second set driven by remote control from the ground. Extra computers don't weigh as much as a crew cabin...
Getting people to and living on Mars will be hazardous enough as it is without putting them in make-work pilot roles on freighter rockets. An unessesarry risk.
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