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To Mars and Back in Ninety Days
paltemalte writes "A new means of propelling spacecraft being developed at the University of Washington could dramatically cut the time needed for astronauts to travel to and from Mars and could make humans a permanent fixture in space. In fact, with magnetized-beam plasma propulsion, or mag-beam, quick trips to distant parts of the solar system could become routine, said Robert Winglee, a UW Earth and space sciences professor who is leading the project."
Isn't this similar to VASIMR? Variable Specific Magnetoplasma Rocket.
I barely got the page to load... here's the article text: A new means of propelling spacecraft being developed at the University of Washington could dramatically cut the time needed for astronauts to travel to and from Mars and could make humans a permanent fixture in space. In fact, with magnetized-beam plasma propulsion, or mag-beam, quick trips to distant parts of the solar system could become routine, said Robert Winglee, a UW Earth and space sciences professor who is leading the project. Currently, using conventional technology and adjusting for the orbits of both the Earth and Mars around the sun, it would take astronauts about 2.5 years to travel to Mars, conduct their scientific mission and return. "We're trying to get to Mars and back in 90 days," Winglee said. "Our philosophy is that, if it's going to take two-and-a-half years, the chances of a successful mission are pretty low." Mag-beam is one of 12 proposals that this month began receiving support from the National Aeronautics and Space Administration's Institute for Advanced Concepts. Each gets $75,000 for a six-month study to validate the concept and identify challenges in developing it. Projects that make it through that phase are eligible for as much as $400,000 more over two years. 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. 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. 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. "Rather than a spacecraft having to carry these big powerful propulsion units, you can have much smaller payloads," he said. Winglee envisions units being placed around the solar system by missions already planned by NASA. One could be used as an integral part of a research mission to Jupiter, for instance, and then left in orbit there when the mission is completed. Units placed farther out in the solar system would use nuclear power to create the ionized plasma; those closer to the sun would be able to use electricity generated by solar panels. The mag-beam concept grew out of an earlier effort Winglee led to develop a system called mini-magnetospheric plasma propulsion. In that system, a plasma bubble would be created around a spacecraft and sail on the solar wind. The mag-beam concept removes reliance on the solar wind, replacing it with a plasma beam that can be controlled for strength and direction. A mag-beam test mission could be possible within five years if financial support remains consistent, he said. The project will be among the topics during the sixth annual NASA Advanced Concepts Institute meeting Tuesday and Wednesday at the Grand Hyatt Hotel in Seattle. The meeting is free and open to the public. Winglee acknowledges that it would take an initial investment of billions of dollars to place stations around the solar system. But once they are in place, their power sources should allow them to generate plasma indefinitely. The system ultimately would reduce spacecraft costs, since individual craft would no longer have to carry their own propulsion systems. They would get up to speed quickly with a strong push from a plasma station, then coast at high speed until they reach their destination, where they would be slowed by another plasma station. "This would facilitate a permanent human presence in space," Winglee said. "That's what we are trying to get to." Love, Tripptdf
after actually /reading/ the article, they have a plan in place to "slow down" the approaching spacecraft...namely another plasma shooter at the other end. I don't know how I feel about that. Maybe if there was a conventional backup solution like thrusters or something...I dunno. Thrusters might slow you down enough to navigate into orbit, but a highspeed orbit would probably be dangerously close to the atmosphere...
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What Would Kirk Do?
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A new means of propelling spacecraft being developed at the University of Washington could dramatically cut the time needed for astronauts to travel to and from Mars and could make humans a permanent fixture in space.
In fact, with magnetized-beam plasma propulsion, or mag-beam, quick trips to distant parts of the solar system could become routine, said Robert Winglee, a UW Earth and space sciences professor who is leading the project.
Currently, using conventional technology and adjusting for the orbits of both the Earth and Mars around the sun, it would take astronauts about 2.5 years to travel to Mars, conduct their scientific mission and return.
"We're trying to get to Mars and back in 90 days," Winglee said. "Our philosophy is that, if it's going to take two-and-a-half years, the chances of a successful mission are pretty low."
Mag-beam is one of 12 proposals that this month began receiving support from the National Aeronautics and Space Administration's Institute for Advanced Concepts. Each gets $75,000 for a six-month study to validate the concept and identify challenges in developing it. Projects that make it through that phase are eligible for as much as $400,000 more over two years.
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.
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.
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.
"Rather than a spacecraft having to carry these big powerful propulsion units, you can have much smaller payloads," he said.
Winglee envisions units being placed around the solar system by missions already planned by NASA. One could be used as an integral part of a research mission to Jupiter, for instance, and then left in orbit there when the mission is completed. Units placed farther out in the solar system would use nuclear power to create the ionized plasma; those closer to the sun would be able to use electricity generated by solar panels.
The mag-beam concept grew out of an earlier effort Winglee led to develop a system called mini-magnetospheric plasma propulsion. In that system, a plasma bubble would be created around a spacecraft and sail on the solar wind. The mag-beam concept removes reliance on the solar wind, replacing it with a plasma beam that can be controlled for strength and direction.
A mag-beam test mission could be possible within five years if financial support remains consistent, he said. The project will be among the topics during the sixth annual NASA Advanced Concepts Institute meeting Tuesday and Wednesday at the Grand Hyatt Hotel in Seattle. The meeting is free and open to the public.
Winglee acknowledges that it would take an initial investment of billions of dollars to place stations around the solar system. But once they are in place, their power sources should allow them to generate plasma indefinitely. The system ultimately would reduce spacecraft costs, since individual craft would no longer have to carry their own propulsion systems. They would get up to speed quickly with a strong push from a plasma station, then coast at high speed until they reach their destination, where they would be slowed by another plasma station.
"This would facilitate a permanent human presence in space," Winglee said. "That's what we are trying to get to."
Trolling using another account since 2005.
Working Mirrordot link .
.: Max Romantschuk
there's particles travelling high speed that might hit you, no matter what speed you're going yourself.
and as such, high speed in this case wouldn't necessarely be 'increased risk'.
if anything, it would be less risk of that(because the trip itself would take less time..).
though, with this and the gazillion other "how to get to mars" plans there's holes in it that haven't been filled.
world was created 5 seconds before this post as it is.
It's not actually that fast. Mars is only about 50 million miles away from us; that means the capsule would need to travel at an average speed of 23,148 miles per hour to achieve this. Assuming acceleration and deceleration were continous, you'd need a peak speed of twice that. Your acceleration figure works out to be about 0.3 miles per hour every minute. You'd hardly feel it.
The big "breakthtrough" here is to decouple the propulsion system (the plasma beam) from the spacecraft. That makes the craft smaller and lighter since it doesn't have to move all that fuel around.
HOWEVER...
This system requires having another plasm beam generator to "catch" the spacecraft and slow it down with another plasma beam. That means not only sending the generator platform to Mars, but also all of the material from which to make the plasma (most likely nitrogen or one of the heavier noble gases). The generator platform needs a power source capable of sustaing the creating and acceleration of the plasma beam, which means nuclear, and a fission nuclear reaction, not radiothermic generation. All of that means a technically complex space station, with people to keep it running. To have such a system in Earth orbit would be tough enough. The cost and difficulty of shipping all of that material out to a Mars orbit, and maintaining it so it will be ready to deccelerate an incoming spacecraft would be Absolutely Enormous.
The man who does not read good books has no advantage over the man who cannot read them. - Mark Twain
Early space related centrifuge tests performed at WADC
In 1952, E. R. Ballinger, leader of the research program at Wright-Patterson, conducted one of the earliest series of centrifuge tests directed expressly toward the problem of g forces in space flight. Ballinger found that 3 g applied transversely would be the ideal takeoff pattern from the physiological standpoint, but he realized that the rocket burning time and velocity for such a pattern would be insufficient to propel a spacecraft out of the atmosphere. Consequently he and his associates subjected men to gradually increasing g loads, building to peaks of 10 g for something over two minutes. Chest pain, shortness of breath, and occasional loss of consciousness were the symptoms of those subjected to the higher g loads. The tests led Ballinger to the conclusion that 8 g represented the acceleration safety limit for a space passenger.
They will have to spread the acceleration and deceleration down over a few miles
And no, spacecraft right now are NOT beer cans. They contain an outer shell, and several layers of different material to prevent micrometeriods from penetrating the pressure hull. Windows are specially designed, and if you pay attention to photographs from spacecraft you would see tons of scratches on the outer surface.
Guess what they are from?
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
D'oh. Round trip, not single direction. Double my figures; 0.6 miles per hour per minute.
For perspective, to the Moon and back in a day with plenty of time to have a picnic.
It's allready done. Go to http://www.mirrordot.org Have fun!
A NERVA, starting from LEO could match that speed with a mass ratio of 2.7 or thereabouts.
In other words, it's not really terribly fast by the standards of the solar system.
"I do not agree with what you say, but I will defend to the death your right to say it"
Nuclear Salt Water (this seriously needs to be developed!)
I had to look it up. Looks like a good candidate for in-space propulsion. If its as cheap as it is simple, then its definately worth looking into. I doubt it'll get the go-ahead for launchpad stuff... all that plutonium spewing out the back would freak people out.
A nuclear salt-water rocket is a type of rocket designed by Robert Zubrin that would be fueled by water bearing dissolved salts of plutonium or U235. These would be stored in tanks that would prevent a critical mass from forming by some combination of geometry or neutron absorption. The rocket would be powered by a nuclear-thermal reaction when the water was injected into a reaction chamber.
Calculations show that this rocket would have both very high thrust and a very high specific impulse, a rare combination of traits in the rocket world.
Who says you can't feather your way out of orbit? There most certainly is atmosphere up there. What do you think caused Skylab's orbit to decay? Bad karma?
You can tell a great deal about the character of a man by observing those who hate him.
Not quite. It is in fact the kinetic energy of the plasma that is being transferred to the spacecraft; the electrical interaction is just the transfer mechanism. So, yes, the space station will be pushed back in a fashion more or less prescribed by Newton's 3rd Law. However, as mentioned above, the acceleration produced by the conservation of momentum is proportional to the mass, so if the space station is massive enough, this won't be a problem. Plus, I'm sure some corrective measures can be taken with orbits to minimize the effect.
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
It's a form of welfare. More socialist countries don't beat around the bush and hand out cheques. Socialism and welfare are taboo in the US, so it has to be done this way...
Try a different allotrope, like carbon nanotubes. Unfortunately very hard to manufacture at the moment.
It'll be a long time until any of the (former) X Prize teams get anything into orbit, and when they do it won't be very similar to the purpose-built vehicles they've been working on up until now.
You're forgetting that Scaled Composites (Burt Rutan's company) was heavily involved with both the McDonnell-Douglas Delta Clipper and Lockheed Martin Venture Star programs. Though these programs were not complete successes, it does mean Scaled Composites has actual experience in building real spacecraft and that means Rutan has a pretty good idea of the engineering needed to build a spacecraft to reach low Earth orbit (LEO) at reasonable cost.
Just a few nits - the Space Shuttle Main Engine has an Isp of ~430, and still throws away a lot of stuff! Most Hydrogen/Oxygen engines have Isp in the 400 range, while the 300 range is typically hydrocarbon such as kerosene. I would have difficulty believing that a 200 Isp engine would make it to orbit, if it hadn't already been done. (Pretty amazing engineering, that!) The mass ratio required goes up exponentially with Isp, and at 200 it is ~90:1 (so for every kg in orbit, you launched with 90 kg!).
As for your other comment, about how high Isp devices seem to always have low thrust, that is because to a first approximation we are limited by the power available. Engine power is proportional to thrust x Isp, so assuming the same power source increasing Isp decreases thrust. Going from a dense power source (chemical fuel) to a non-dense power source (solar panels) only makes that worse!
while (sig==sig) sig=!sig;
Have you ever read Henry Ford's writings on business organization? He was a far more ardent critic of international finance than me.
From what I know of Ford, I can only assume that "international finance" is a code-word for "The Jews".
--grendel drago
Laws do not persuade just because they threaten. --Seneca
No, thats not actually why DeBeers is so keen to do that.
Diamond is one of the most common gemstones in the world. It would have virtually no value if a) DeBeers hadn't pulled the greatest marketing spinjob in history convincing people today that diamond rings are a centuries old wedding tradition, not a decades old one and b) they didn't warehouse them.
DeBeers has warehouses of bins, floor to ceiling of diamonds they keep off the market to artificially inflate their value. By controlling access to virtually all the mines that are econimical to exploit, they ensure competitors with access to diamond deposits will not flood the market with cheap ones.
Basic physics, trip to mars accellerating at 1G tll half-way then decellerating at 1G.
Time taken for total trip = 6 days 10 hours.
"Wouldn't a moon-based launch only be about 1/6th more doable?"
Surface gravity isn't the correct measure for the difficulty of leaving the Earth or its moon.
The escape velocity from here is 4.7 times that of Luna, and the energy required (one half mass times velocity squared) is 22 times as much.
a,e,i,o,u and sometimes w and y (at be if of up cwm by)
We actualy have from 3-5 moons. The Moon that you know of is the fifth largest in the whole solar system. Kinda big, infact it is more of a planet with a shared orbit than it is a moon. It is to big, and affects earth to much (1/3 the size of earth) to be considered a satalite. However, since people have the "earth is flat" syndrome, people will always know earth has one moon, etc.
e m/ second_moon_991029.html
http://www.space.com/scienceastronomy/solarsyst
The spirit of resistance to government is so valuable on certain occasions that I wish it to be always kept alive
http://www.ess.washington.edu/Space/magbeam/
The station is propelled backwards a small amount due to the KINETIC energy it imparts to the plasma beam, but that level of energy is INSIGNIFICANT. The station also imparts MAGNETIC energy to the plasma beam, but that does not propel the station backwards at all.
The ship is propelled forwards primarily due to the MAGNETIC energy in the plasma beam, not the KINETIC energy. It does this by creating an electromagnetic shield that repels all magnetically charged particles. This force is much stronger than the KINETIC energy.
Newton's 2nd law is preserved. The shield pushes the magnetized plasma particles away with enough force to accelerate the ship to high speed. Turn the shield off, and it won't go very far.
And anyone who thinks this plasma beam could scorch the Earth doesn't realize just how much energy the Sun blasts the Earth with constantly. The Earth has its own magnetic shield, and what little of the solar wind does get in is scattered in the upper atmosphere (i.e. auroras). Even though it's a more focused beam, the beam would be spread thin before it came close to the ground.
The biggest problem with this method is not being able to slow down if there's a problem at the other end. Even if there's not a problem at the other end, it would be like trying to throw a rock from here to Mars and expecting to hit a very small target precisely when it got there. Without course corrections on the way, it will miss by hundreds of miles. Even with corrections, it will very likely miss on the scale of hundreds of yards.
IMHO, they should use this only for acceleration. Add ion thrusters to the craft, and it can help accelerate the craft as well as decelerate it as it approaches Mars (making continuous course corrections if necessary). The last step would be a gravity-assisted deceleration to put the craft in orbit. It can meet up with the mag-beam station later, which will help to send it back to Earth quickly.
The ion thrusters would also be insurance against the station on the other side breaking down. It may take a few extra months to get home, but ion thrusters can provide continuous acceleration for years. You could put extra rations in the station itself. If and when it breaks down, the rations can be transferred to the ship for the longer ride home. If it doesn't break down, then the ship remains lighter and will be easier to send home.
I've never understood why a shuttle takes off from a completely vertical position. I mean, doesn't it take the greatest amount of force to set an object in motion, rather than keep it going?
I'm not sure where this idea comes from.
Any given acceleration requires the same amount of force no matter how fast you're going. F = ma.
When you're moving in an atmosphere, you have to add force to counter air resistance as well, which goes up roughly as the square of airspeed.
The shuttle boosts upwards to get out of most of the atmosphere as fast as it can. Then it thrusts sideways, because it's sideways velocity that puts you in orbit. Taking off at an angle would just mean there'd be that much more atmosphere to plow through.
Aerodynamic craft with air-breathing engines _might_ be able to derive benefit from being in the atmosphere, but the shuttle's a brick strapped on to a bigarsed rocket booster, so it doesn't.
Can anyone give a quick calculation of how much material from space can be brought back to Earth before adversely affecting our orbit? "An unfathomable amount" doesn't count.
If the rockets bringing the material to us match Earth's velocity before dropping the material off, an infinite amount (or at least, up to 10-20% the mass of the _Sun_, before the center of mass of the Earth-Sun system changes enough to affect our orbit).
You could pile on at least the current mass of the Earth before gravity increased enough to be a serious problem.
If you're asking "how big an object could smack into earth before its orbit is affected", the answer is "more than big enough that far smaller objects would reduce the surface of the earth to a magma field and maybe give us a new moon or two in the bargain". Motion induced by Earth's gravity doesn't count, because the centre of mass of the system is still pretty much the same - this refers to something plowing into Earth from an asteroid belt transfer orbit without being slowed down first. Nobody's going to do that, because we don't want to reduce the planet's surface to a magma field. The actual amount of mass you'd need depends on the impact velocity, but is at minimum comparable to the mass of the moon (about 1% Earth's mass).
In summary, for any reasonable asteroid-recovery scheme, there is zero effect on Earth's orbit.
NASA has this page explaining the physics and why it granted the money to the UWash research team. And the NASA page responds...The UWASH page pointed to by the article is somewhere behind a cloud of smoke coming out of their poor slashdotted server. 350 comments later, I still cant raise it.
SLASHDOT: news for people who can't concentrate on work or have no life at all and got tired of yelling back at the TV.
Cassini
Apollo 12
Apollo 13
Apollo 14
Apollo 15
Apollo 16
Apollo 17
Pioneer 10
Pioneer 11
Voyager 1
Voyager 2
Galileo
Ulysses
Viking 1
Viking 2
Nimbus
Transit
Les
All of the above carried highly radioactive Plutonium into space. The above list does not include Russian launches, nor does it mention missions (like the Mars Exploration Rovers) which used plutonium heaters to prevent mechanical damage from low temperatures.
Linky
Javascript + Nintendo DSi = DSiCade
Correct me if I happen to be mistaken, but what physics and maths I attended state that the greek Delta translates in equations as the phrase "change in".
So, therefore, Delta-V = change in V (or change in Velocity).
If, "Delta-V for rockets is all about the final velocity obtained".
Why is the symbol Delta used instead of one for maximum?
"Secrecy is the keystone of all tyranny. Not force, but secrecy
Then say that and dont be sarcastic.
:-)
I agree we need to slow human growth and otherwise learn to me more efficient with the earth we have.
I dont see how that means that space, both near and far will not be *part of* a solution to overcrowding.
I dont agree that we will run out of land and resources before we can send *some* people off to space colonies. At least not if we *begin* sometime soon. If we wait, then yes, we may run out.
Also, there are other benefits to having a human population in space.
A: Catastrophies happening to earth dont wipe out the human race. ( debate on wiping out the human race being a good thing can begin now
B: All the manufacturing that is so polluting here on earth need not be so in space. Not to mention the raw materials that would be available to us without having to damage the earth.
I would guess there are other benefits I am not seeing right now.
So, in my opinion, the solution is
here on the ground,
in near space,
in deep space.
All of the above.
emt 377 emt 4
Any given acceleration requires the same amount of force no matter how fast you're going. F = ma.
That would be true if it wasn't for gravity and aerodynamics adding to F. Imagine a spaceplane with wings and with engines that can indefinitely deliver 1G of acceleration: If it tried to launch straight up, it would never make it off a launch pad, but taking off from a runway it could reach orbit, because it's lift to drag ratio (even hypersonically) could be much larger than 1.
This doesn't apply to the shuttle, though; the shuttle's L/D ratio is larger than 1, but the L/D for the stack as a whole is pretty much zero.
This is where you are confused....
If a shuttle takes off like a plane it doesn't have to fight against gravity to gain velocity.
Once it has a solid velocity it can work just like a plane and take off while starting to go at an angle and ultimately straight up. There would be a tremendous amount of energy savings doing it this way, think of how long those rockets are going before the shuttle even lifts off a couple of feet, that would be bypassed by doing it this way.
To answer the other question for why the shuttle wasn't designed like this is simple. Think of the shuttle as a brick with paper wings taped to it. Quite simply they could just throw a larger rocket on this brick and shoot it up into space without having to worry about taking it from a horizontal to vertical position and actually having to fly this thing while increasing altitude. Sure it can "glide" or rather "fall" back to earth somewhat in control, but taking it back up in the same way is quite harder. When these things were on the table it was more of a race to get to the moon, and I would venture that adding in the horizontal take-off would have tacked on another couple of years. Sure it would have been better now had that method been chosen, but could have ended our enthusiasm in the space program had we lost the race to the moon.
Plus, going horizontally does no good unless you're using "wings" or an airfoil to give you some lift. Otherwise you're just fighting gravity that much longer.
Though the shuttle does have wings, they're not going to do much when weighed against the mass of the large boosters and fuel needed for launch.
Question: which weighs more, the heat shielding and structure required to survive re-entry at orbital velocities or the fuel required to brake then re-enter at a low velocity?
The fuel weighs more, by far. You'd need as much fuel to get out of orbit without aerobraking as you needed to get into orbit in the first place.
(Another question, at high altitudes, does the atmosphere rotate with the Earth?)
Yes.
Having been corrected on this, I often feel a need to pass it on.
The moon is:
just over 1/4th of earth's diameter (27%)
roughly 1/6th of earth's gravity, (17%)
roughly 1/81st of earth's mass (1.2%).
roughly 3/5th of earth's density.
The mass part is one of the highest in the solar system, but I believe that Pluto/Charon have us beat by a comfortable margin. Of course, a lot of people want to have Pluto rescheduled as something besides a planet, but that's an argument for another thread.
Wake up - the future is arriving faster than you think.
I've gotten curious enough about this stuff that I've started learning a little bit about orbital mechanics. I've written some Python code to do the calculations for this stuff. Here's the asteroid's orbit:
This needs my libraries for physical units and orbits, and produces these results:WWJD for a Klondike Bar?
This is where you are confused....
If a shuttle takes off like a plane it doesn't have to fight against gravity to gain velocity.
If it's _climbing_, it sure does.
If it's flying level, it has to overcome atmospheric drag, which is rather substantial even below the speed of sound, and is ludicrously high at near-orbital speeds. There's a reason a 747 has to carry jet fuel.
Once it has a solid velocity it can work just like a plane and take off while starting to go at an angle and ultimately straight up. There would be a tremendous amount of energy savings doing it this way
Virtually all of the delta-v for the shuttle is that needed to accelerate the rocket tangentially (horizontally). Orbital velocity is 8 km/sec. Delta-v required to climb to orbital _altitude_ is far lower (look at the X prize for an example, though anything orbiting at 100 km would still have enough atmospheric drag to de-orbit very quickly).
In summary - what takes the fuel is horizontal acceleration, mostly outside the atmosphere. All other parts of the course are optimized to burn as little fuel as possible _getting_ to a place where the orbital burn can be done.
I am ignorant of the forces used in this technology, but if I am correct...
You have a space plasma generator orbiting the sun that will push payloads into a Mars-intercepting trajectory. OK, fine and dandy.
Now, if it's shooting all this high energy plasma out one end, won't there be a reaction of its own in the opposite direction, effectively causing the force on the payload to be cut in half, while also shooting itslef way the heck out of the original "stationary" orbit? I'm sure someone smarter than me has already thought of this, I just can't see the solution.
The Van Allen Radiation belt would kill you if you stayed in it for a few hours. This is relatively inconsequential if you are moving at a rapid pace through it. I've seen it reported that our guys who landed on the moon received 1% of a fatal dose. Presumably this method is faster, and they'd receive a fraction of a percent.
Still a concern, but the grandparent was off on the facts.
Your design is a variant of a device I've heard called the Forward Slingshot some links. Which I first heard described by Robert L. Forward. Congrats are in order for co-inventing and possibly improving upon such an original concept.
I also feel that this is one of the most practical means of getting things into orbit.
An alternative means of powering the slingshot is to deliver mass (cargo) down the energy well, though you'll have to deliver enough cargo to overcome the cost of raising the next outbound payload along with all of the air friction losses on both transfers. If you're taking apart a second asteroid for raw materials, however, you'll probalby be able to find enough mass to make this practical (and it radically increases the safety of deorbiting the inbound payload, helping the practicality of that enterprise as well). A third advantage of this approach is improved stabilization of the tether during the descent phase.
Regards,
Ross
We have three moons.
The first moon is the largest, aka Luna.
The second moon is named Cruithne and has roughly a 5km diameter.
The third moon hasn't gotten a cool latin/celtic name name and is known as 2002AA29. It's only about 100m in diameter.
My thinking is that we could move Cruithne into an orbit that would suit our needs for a space elevator.
Yes Francis, the world has gone crazy.
It comes from the myth of "escape velocity". People figure, hey, why not just fly horizontally until you hit escape velocity, and then up you go, instead of trying to reach escape velocity vertically.
Actually, thrusting horizontally is the perfect way to reach orbit (and this is largely what the shuttle does now). Orbital velocity is tangential; an escape trajectory is a very different beast (can be thought of as the limiting case of a parabola or a hyperbola as perigee (backtracked along the course) approaches the centre of the earth).
What puzzles me is people who think flying horizontally is free, or lets you climb for free, or magically reduces by some large fraction the delta-v required to reach orbital velocity.
More of a problem, I think, is what happens to the mag-beam generator? Is someone forgetting Newton's Laws?
If the generator is shooting off a beam that's able to propel the space ship, then the generator is propelled BACKWARDS. So you probably want big rockets or something on the generator to stop it de-orbiting itself. So why not just cut out the middle man, put the rockets on the space ship and be done with it?
Cruithne and 2002AA29 are co-orbital objects, not exactly moons (depending on your definition of moon).
At any rate, the energy required to normalize their orbits into standard elliptical/circular orbits around the Earth (as opposed to Cruithne's 385-year orbit which only happens to include the Earth due to eccentricity in the orbit, or 2002AA29's horseshoe orbit which is even stranger) is extremely high.
---
Mod me down, you fucking twits. Go ahead. I dare you.
(I read with sigs off.)
I think a more interesting list would be the list of launch accidents involving spacecraft with nuclear materials onboard.
Transit
Nimbus
Apollo 13
The above list does not include the Russian RTG accidents. (They were nice enough to burn up plutonium over Canada.)
Linky
Javascript + Nintendo DSi = DSiCade
Of course, once we can run a settlement on the moon that is productive enough to build and launch a Mars mission (keeping in mind that we can't even do that on Earth yet), then things change. But only slightly. It's still only a profitable enterprise for the Moon-people (Lunans?). If you live on the moon, and want to go to Mars, you're in luck - you can do it cheaper than the Earthlings can. But if you live on Earth, the moon is still a pointless stop-over. It's like flying New York to L.A., with a stop-over in Australia.
But let's just say for the hell of it that we're past all that, and we've got a moon city that can build and launch interplanetary voyages. There are two more issues that come to the fore:
- if we can build a moon city starting from earth-launched resources, then we can do the same with Mars. The journey to Mars is harder, but the place itself is more hospitable. So once we've built our Moon city, there is really no point in using it as a spaceport to Mars. We're probably already on Mars, using the same technology.
- Given (1), the Lunans are left in a position of competing for the Earth-system-to-Mars-system interplanetary transport. The Lunans have a much lower launch cost, so they are very competitive on that score, but only if the stuff being shipped originates from the moon. But if the Lunans can produce it from scratch on the moon, then the Martians can surely do the same. And if the Lunans can't produce it from scratch, then you're importing crap from Earth and doing the whole Australian stop-over thing again.
Ultimately the whole idea only becomes feasible if the moon somehow becomes a sovereign entity with its own specialized science and technology base, and a monopoly on whatever useful technologies spring from that. Then and only then will anybody have a valid economic argument to go to the moon. But how do you get to that point if there is no valid economic argument to lay the stepping stones to get there?