To Mars And Back In 90 Days...

[qzzq]

From Universe Today:<br /><br /><ul type="square">Mars and Back in 90 Days on a Mag-Beam<br /><br />Summary - (Oct 14, 2004) Researchers from the University of Washington have been funded by NASA to develop a magnetized-beam plasma propulsion system (or mag-beam). Selected as part of NASA's recent Advanced Concepts study, the system would involve a space-based satellite that would fire a stream of magnetized ions at a spacecraft equipped with a magnetic sail. The researchers think they could get a spacecraft going fast enough that it could make a round trip to Mars in 90 days, as long as there was another station at Mars that could slow the spacecraft down again.<br /><br />...<br /><br />Under the mag-beam concept, a space-based station would generate a stream of magnetized ions that would interact with a magnetic sail on a spacecraft and propel it through the solar system at high speeds that increase with the size of the plasma beam. Winglee estimates that a control nozzle 32 meters wide would generate a plasma beam capable of propelling a spacecraft at 11.7 kilometers per second. That translates to more than 26,000 miles an hour or more than 625,000 miles a day.<br /><br />Mars is an average of 48 million miles from Earth, though the distance can vary greatly depending on where the two planets are in their orbits around the sun. At that distance, a spacecraft traveling 625,000 miles a day would take more than 76 days to get to the red planet. But Winglee is working on ways to devise even greater speeds so the round trip could be accomplished in three months.<br /><br />But to make such high speeds practical, another plasma unit must be stationed on a platform at the other end of the trip to apply brakes to the spacecraft.<br /><br />"Rather than a spacecraft having to carry these big powerful propulsion units, you can have much smaller payloads," he said.</ul> ( More at <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[rogers_buck]

Interesting. What's wrong with aerobraking? Might take a few dozen dips through the atmosphere and take a while, but you could drop a payload on the first dip.

 

[Aetius]

Every time you aerobrake a payload at Mars, you are taking a chance that your models of the Martian atmosphere were incorrect in some great or small detail. Humans at least should not be subjected to a dozen reentries just to lose enough angular momentum for orbital capture.<br /><br />I love the possibilities which may be created by this propulsion concept. Outer solar system colonization could even become a reality, without 'Battlestar Galactica'-sized fusion rockets.

 

[scottb50]

That first dip would have a lot of velocity left and I doubt you could "drop" a payload and land it in one piece.<br /><br />Spacester makes a good point on the other thread in pointing out the relative positions of the Earth and Mars for that period of time and the amount of deltaV that would be required. <div class="Discussion_UserSignature"> </div>

 

[rogers_buck]

Humm, you'd definatly be going fast. I wonder how effective aerodynamic conrol surfaces might be at ultrahigh velocities and ultrathin atmospheric conditions. Actually fly around mars in the sparse upper atmosphere doing manuevers to loose energy as heat. Each lap of the planet the altitude gets lowered into thicker air as the velocity goes down. Too deep and you burn, too shallow and you blow through and are lost in space. Climbing and diving between the night and day side. That would be interesting to model.

 

[Aetius]

It sure would save a heck of a lot of fuel and infrastructure wear and tear, if it could be done the right way.

 

[qzzq]

<i>What's wrong with aerobraking?</i><br /><br />Nothing wrong with it at all. I suggest we use it to slow down the probe that will deliver the Martian plasma unit! <img src="/images/icons/smile.gif" /><br /><br />Anyway, 90 days...When was Around the World in 80 Days written again? In 1873 that seemed like a real challenge. Now, 131 years later, almost just one human life time, we're seriously considering going to Mars and back in about that time span. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[odysseus145]

The same subject is being discussed here.<br /><br />Strange though that both qzzq and shuttle_guy posted the same thing at the exact same time. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[rogers_buck]

Perhaps they are entangled. (-;<br />

 

[qzzq]

odysseus145,<br /><br />Yes, strange, hadn't noticed shuttle_guy's post yet. Indeed exactly the same time and date...weird. ( whistling tune from the Twilight Zone...)<br /> <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[qzzq]

stevehw33<br /><br />I think the purpose of the announced funding is to get answers to your questions and probably many others through research. If we don't look into it, there never will be hard science. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[nexium]

The magnetic field needs to be stronger than we can produce with present nitrogen temperature super conductors, perhaps stronger than we can presently produce with liquid hydrogen cooled super conductors. (The humans and equipment can likely be protected from the magnetic field) Liquid hydrogen would increase the mass and cost prohibitively, but we can keep the super conductor at liquid nitrogen temperature by shading it from sunlight. For a manned mission the circumfrence of the super conductor coil needs to be many miles. The beam needs to deliver several megawatts to the magsail continously for weeks. The craft and the shade for the superconductor loop will acquire a very high voltage charge, which can be nuetralized by ions from another power beam of opposite polarity. If the destination is Mercury or Venus, the sun likely provides enough ions to decelerate the mag sail if we are willing to take a year or so to get to Venus.<br /> If we can accelerate, then decelerate at 0.02 meters per second per second: S = 1/2 at squared = 0.01 times one trillion = 10 billion meters = ten million kilometers in one million seconds = 277hours = 11 days V=at = 0.01 times a million = 10,000 meters per second = 10 kilometers per second = 18 kilometers per second if we start from LEO =low Earth orbit. We will loose some of that speed coasting half way to Mars or Venus, then start gaining speed as we approach our destination. We need to start breaking about 11 days before arrival at our destination so as to minimise the areo braking needed. The math is much more complicated, but I think this is an approximation. At an average speed of 10 kilometers per second = 36000 kilometers per hour = 864,000 kilometers per day, it takes several months to reach Mars or Venus, depending on the path length which will likely exceed 100 million kilometers. 48 million kilometers is very optimistic. Neil

 

[Grok]

After 90 days of weightlessness would the astronauts be able to walk on the surface of Mars? With less gravity on Mars, I'm assuming so. How do they get back? Do they carry a beam machine with them to beam them back?