Slashdot Mirror
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."
How would you accelerate and decelerate from such speeds without the human inside being crushed?
"Rather than a spacecraft having to carry these big powerful propulsion units, you can have much smaller payloads,"
.sig, but I'm not going to give it to you.
If the station fails at the remote end, will it take 40 years to get back to earth?
I have a great
I hate to be a buzzkill, but is there ANY realistic reason why sending people to Mars is good science?
It seems that if we spend the money that it would take to develop the spacecraft & lifesupport required to send people that far on better and more reliable robots, a lot more actual research would get done. Heck, we might even have enough left over to fix the Hubble.
Let's work on practical reasons to send people into space at all... then maybe the moon. Billions of tax dollars shouldn't be blown on a project of little scientific validity just because "it's cool."
In Capitalist America, bank robs you!
Wave a plan near congress and they're sure to kill it before breakfast.
Sure they will. The aliens don't want our crap in outer space at least until we can handle our problems like adult persons instead of reacting emotionally to every single difference between us. So, what's better than keep tabs in the govment of the only country that can fund such stuff?
It's better to be the foot on the boot than the face on the pavement. ~~ tkx Kadin2048
Need I remind you that the asteriods are rich with a host of rare metals that only exist in trace amount here on Earth. Indeed, one of the reasons mobile phones can't get any cheaper is that one part requires an obscenely expensive metal for the tuner.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
"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."
Would not it also push the space-based station the other way? The whole action-equal-reaction thing they teach in physics?
With a space elevator, of course ;)
Has anyone gleaned from the article how the beaming stations are maintained in place?
I got that nuclear and solar power would be used to generate the beam, but generating the beam would impart thrust to the station.
Did I miss something?
The REAL jabber has the user id: 13196
What you do today will cost you a day of your life
..or at least the brakes. It's not a new plan, though it might be a new flavor. Nivens was talking about laser-based launching stations back in the 70s and he was just taking the most probable solution.
Of course Newton's laws interest me. If you fire an energy beam able to move a 1000kg probe at 11.7km/s, your 10,000kg station is going to be moving 0.117km/s. (261mph)
Then there's the power issue. Exactly what are these orbital launcher going to use for power? I don't see the green club letting enough fissionable materials get up there and otherwise we're looking at a biiiiig solar array tied to some form of energy storage (water/hydrogen/fuelcell?)
I've been on slashdot so long I'm starting to get out of touch with the cool stuff if it ain't on slashdot.
That should be "at what Delta-V?" More Delta-V == faster.
If, by "Delta-V" you mean "change in velocity," then that would indeed be acceleration -- which doesn't necessarily mean faster.
Think about it: I drive my car from 0 to 60mph in 3 seconds, while yours only goes from 0 to 60mph in 12 seconds. At the end of that time, we're both going the same speed (assuming we stop accelerating once we hit 60mph), but my acceleration was much quicker than yours (4 times as fast, in fact).
More likely outsourced to the asteroid belt, where there are plenty of usable minerals without a gravity well to fight.
Maybe even mine the moon for water (for deuterium), package, and send over by railgun to defeat the much smaller pull.
Don't think we'll see anything other than essentials being pulled up from Earth, if and when we can help it.
Interestingly, Harry Harrison uses this as a reason to consider war as being unlikely in space itself, since it would cost too much to lift the ordnance - battles presumably fought purely on surfaces with weapons made from local materials.
>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.
This ignores Newton's law that for every action there is an equal and opposite reaction.
According to Newton if the transitter unit isn't fixed to something big and heavy (i.e. a planet) it would also propel itself backwards (and out of position) at an inversely proportional acceleration rate to the spaceship.
2: How are you going to point it? Minute differences in direction on launch will determine whether you go into orbit around Mars or crash into Jupiter.
3: Not all planets have substantial magnetic fields (such as Venus)
4: The acceleration that would result if you could get this working would liquefy any human.
5: Sound != electromagnetic radiation.
Not exactly correct. None of them were working on getting to orbit. All the different spaceships were designed specifically to go straight up to 100km and come back down. Not one of them was designed or planned to do any more than the bare minimum to win the X Prize. The ten million dollars and the fame was the goal (then at least), nothing more.
Orbiting, and particularly de-orbiting (without burning up), is quite a bit harder, and would require massive changes for some of the designs (beyond just bigger fuel tanks and heat shielding). 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.
They've got to have a serious stash of fuel on board for the "Holy $@%^%$%! There's an asteroid at 12:00" times. You can't expect to cruise through space and not come across some floating debris, can you?
If, by "Delta-V" you mean "change in velocity,"
Yes.
then that would indeed be acceleration -- which doesn't necessarily mean faster.
No. Delta V is the desired change in velocity. How fast you accelerate has nothing to do with that. So I could thrust toward Mars at 1/100 gravities and still obtain the same Delta-V (for the same fuel!) as someone who thrusted at 2 gravities.
In other words, Delta-V for rockets is all about the final velocity obtained. Thus a slower thrusting craft that obtains a higher delta-V over time is still likely to beat out a high-thrust craft that only burns for a few minutes.
Javascript + Nintendo DSi = DSiCade
Otherwise there won't be any slowing down at Mars , just a big splat. Unless the ship carries conventional thrusters too of course, but the fuel required to slow down would be immense and then we're back to square one.
Does that picture remind anybody else of the sail ship that they used in the movie Tron? Were they ahead of the game -again-?
There's a buffalo and a carrier pigeon outside, they'd like a word with you.
We've already developed a plan for, errr, developing the cosmos. Never underestimate the power of exponential growth. I'm sure that we'll find a way to despoil the universe if we don't off ourselves first.
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
Please cite any source that claims a 30 minute-long fatal exposure dose for any near-Earth location.
As I understand things, from (among other books) Zubrin's "The Case For Mars" as well as ample proof from the ISS and our own Apollo moon missions, merely being in space does not mean fatal radiation doses are inevitable.
Rather, space travel does involve higher doses than one would receive on the ground, or (say) in a mineshaft. But that doesn't mean these doses are fatal, or even that they significantly impact long term health.
I remain interested if ANYONE can cite specific data (hopefully from a reputable source) saying that radiation doses in space are near fatal in the time frame envisioned for a Mars mission or, or any other popularly conceived-of mission aside from a manned mission to Jupiter, which does have significant radiation belts.
Unitarian Church: Freethinkers Congregate!
I'm not going to analyze every single item on your list...
But the Printing Press? Did you think this through? Do you really think Johann Gutenberg's motivation was profit??? Have you ever read Henry Ford's writings on business organization? He was a far more ardent critic of international finance than me.
I think you need to read a little more about the people who invented the items you are discussing. Most were invented by men who followed their dreams and were hardly concerned with financial gains. More importantly, financial concerns did not dictate whether or IF they pursued that dream.
I don't read or respond to AC posts
Not wanted a well designed nuclear reactor on the ground may qualify as "Chicken Little"-ish. Being glad the Challenger and Columbia weren't loaded up with plutonium when they exploded doesn't. Until you can show that you can get radioactive materials into orbit with a damn close to 0% probability they will turn into a really big airborne dirty bomb, people will be uncomfortable with the idea. Even people who wouldn't worry about living near a power plant.
Don't blame me; I'm never given mod points.
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've seen prototypes on NASA's site for a shuttle that takes off like a plane. Wonder why it hasn't gotten off the ground yet.
Sounds like a winner IMO.
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
The problem with using a celestial body's magnetic field as a force is that in many cases, the field is far too weak or nonexistent. The moon and Mars lack magnetic fields, for instance, and the earth has a magnetic field of about 0.5 gauss. In comparison, powerful magnets used in NMR generally are in the 10-20 Tesla range (100,000-200,000 gauss). Which is to say, the earth's magnetic field is great for turning compass needles and deflecting the solar wind, but not nearly strong enough to repel magnets at reasonable velocities. The overall energy of the earth's magnetic field is of course enormous- we're talking about 100 billion billion tons of iron acting as a dynamo, but the field strength- perhaps better called the flux density is not very high- lines of magnetic force are spaced too far apart. Despite being many orders of magnitude weaker in terms of absolute force strength, gravity predominates over electromagnetism as the major force we encounter from a planet. The problem is that almost every object in the universe that produces a gigantic magnetic field is also extraordinarily massive, so that the attractive force of gravity competes with the magnetic field- and dipole magnetic field strength falls off as the third power of distance versus gravity, which follows an inverse square law.
Your idea might actually work around a neutron star, which can produce a field in the 100,000,000 Tesla range, which might be enough to escape the immense gravity. You probably would not be able to survive this, however.
Also, while such a design would not use an fuel in the manner that a rocket would, you would need to expend energy to create the very powerful field required. Frankly, given the requirements of the scenario, which demand an object with very strong magnetic field and a ship that can produce a very strong magnetic field, there are better options. If you have an object like the sun putting out a solar wind, solar sails are a possibility. If you have an enormous electromagnet at your disposal, well, an idea like the one the story proposes, an ion drive of some sort, a railgun system- lots of options.
"FDA staff reviewers expressed concern about the number of patients who were left out of the study because they died."
These cause braking, like the oceans.
I wouldn't be too surprised if there was a (smallish?) frictional component caused by the Earth's precession - it is moving away from part of the atmosphere and pushing some of it ahead.
These would probably be relatively small but continuous, so I would expect some retardation on the upper atmosphere.
The solar wind may even have a slight effect.
I'm an engineer.
If you put me in charge of a Mars mission here's the only proper way to do it.
#1 what we did in the sixties, whistle stop one pass visits, are pointless, if you're going to go then go, don't fuck around.
#2 we have the perfect platform for solar system operations right on uor doorstep, Luna, that and the L1 and L2 largrange points in lunar orbit for stuff that the moon's 1/6th gravity will make difficult or expensive.
#3 all space vehicles will need enough delta vee to decelerate to matching velocity with the target, whether that target is Mars, another planet, or an asteroid, that's no big deal we can use MHD which will efficiently generate low braking thrust for long periods.
#4 all space vehicles and this includes "materiel" of any kind, including "lego" style construction sets and so on, can be given practically any velocity you like by launching from a lunar linear accelerator, these work REALLY well in a vacuum.
SO top priority will be getting mebbe 500,000 tons of mass up to the moon to buind a nearly self sufficient base.
Best way to do that is a two pronged approach.
1/ Develop REALLY heavy lifters, nuclear salt water is cool as a starting point, first step need to be throw everything at perfecting Fusion until it's as doable as fission power plants.
2/ Develop (materials) for the space elevator.
The united states spends 450 BILLION dollars every year on the military, if that lot was thrown at this project you could adopt a JFK / Apollo sort of timescale and we'd have a viable and working moonbase by 2020 AD easy.
If the USA doesn't do this, there will be a moonbase by 2050 at the latest, and it will be Chinese.
When that happens the entire might of every military on the planet, IN CONJUNCTION, will be as effective as wet toilet paper agauinst a
Who knows, I may even live long enough to see it.
http://slashdot.org/~GuyFawkes/journal
I saw a talk, by this group, when they ventured across the state to my University. Despite the fact that all researchers are convinced that their new way of doing something is so much better than the other ways, this group really seems pragmatic about the whole thing.
They admit that the difficulties in getting this to work are tremendous. But from a cost standpoint (as opposed to nuclear methods, the only other energy source we can work with right now that provides enough energy density -- antimatter has a much higher energy density, of course, but we haven't any way of carrying it with us!), the UW method is the best I've seen so far, and it doesn't really screw around with the tricky issues of getting a nuclear source up in the atmosphere, where a problem can cause BIG problems for those of us on the ground. His charts showed that among all the methods out there (including some -- I don't remember seeing some of the parent poster's suggestions -- of Orion, Nuclear Salt Water, etc.), this dealie from his group sort of lies on a critical line between expense, availability, and ability to develop it to a useful stage.
Technical, very tricky engineering is required to get their "induction coil" out there, and have it be strong enough, but once it's deployed, the basic physics behind the thing is really pretty foolproof (as far as I can see).
I *did* ask him during the colloquium whether the accelerations provided would be enough for a long manned spaceflight -- they're SO much less than 1g. He said that for (far-in-the-) future flights, they have found a way to couple the fields' angular momentum to the "sail", thus spinning the spacecraft about the axis of translation, so that you could essentially have a spinning ring of which sci-fi writers are so fond. However, the efficiency of this is pretty low, so to spin the thing up, you might want to use chemical rockets, and let the plasma thingy do its job in the other direction.
But with a horizontal launch you could keep the speeds down until after you achieved a higher altitude and recduced the air pressure.
Remember that drag increases at v^2
Very true.. but then you are essentially combining the two vehicles I mentioned before into one. This is basically a single stage to orbit system where white knight and spaceshipone used more of a two stage system for it's suborbital hop.
I still believe you'd expend more energy but you bring up an interesting point because you do it gradually which makes it much more practical for "safe" launch systems. It would require at least two engine systems on the vehicle or a really good way to throttle a single rocket engine to avoid too rapid of an acceleration. i.e. conventional jet to get you up to the high altitude (like white knight) and a rocket to push the rest of the way (like SpaceShipOne).
Planetes
"One World, One Web, One Program" - Microsoft Promo Ad
"Ein Volk, Ein Reich, Ein Fuhrer" - Adolf Hitl
Nanotubes aren't difficult to manufacture. It's nanotubes of appropriate length and consistency that are hard to manufacture. The current record is a mere 4cm, a little too short to reach orbit, even when wound as a cable. It's still several times longer than the previous record. If we can keep up this pace, we might be able to get nanotubes with lengths of tens or hundreds of centimeters soon, and those might be enough to wind into a cable. Imagine someone suspending himself from the ceiling with something the diameter of thin-guage fishing line.
Heh... Imagine catching a marlin with the same line.
Anyway, we still have some things to do, but we may be getting close to the point where we're not trying to peer over the horizon because the next major port is in view.
You can never go home again... but I guess you can shop there.
So here's an idea. Put a captured asteroid into an elliptical orbit. Perigee is at about 200 miles, going about 10 km/sec, apogee is at about 18000 miles going about 1900 km/sec. As the asteroid approaches perigee, it lowers a cable (made of space-elevator rope) into the upper atmosphere. As the cable gets into the atmosphere, the asteroid starts paying it out very fast, so that the end moves slow enough to be grabbed by a high-altitude airplane and attached to a spaceship. Once attached, the asteroid pays out cable slower and slower, accelerating the spaceship to the asteroid's velocity, and very slightly slowing the asteroid in its orbit. Eventually the asteroid starts reeling in the cable faster and faster, accelerating the spaceship further.
The spaceship only needs to be accelerated a little past the asteroid's velocity to reach escape velocity. There are a few possible ways to correct the energy loss of the asteroid's orbit. The simplest is for the airplane to attach a fuel tank to the cable along with the spaceship so that after the spaceship detaches, the asteroid can reel in the fuel and do a burn to pump its orbit back up.
Of course there's a big PR battle to be fought, to make people feel good about a big rock in a relatively low orbit over the earth. But if it worked, it would use a lot less rope than the space elevator, and it would get you into space quicker.
WWJD for a Klondike Bar?
Mmm, well it's a big moon compared to the size of the Earth, but the common centre of mass of the Earth Moon system is still inside the Earth, so I'd say that's a pretty clear statement of who's the daddy in the Earth-Moon system.
Why not put the second plasma beam generator on the spacecraft itself? They could build/maintain/operate it themselves, deploying it ahead of the craft when they arrive. Total energy expenditure is about the same - you're just sending one package instead of two - and it sounds a whole lot easier than matching orbits with the thing at nightmarish velocities.
qntm.org
One of the concerns of Freeman Dyson, one of the originators of Orion was that the radiation placed into the atmosphere by a single launch produced a statistical guarantee that 10 people somewhere in the world would get cancer who otherwise would not have.
But that wasn't what killed the project. What killed the project was the Nuclear Test Ban treaties of the 1960's. The Orion team actually felt that they could reduce the fallout further, potentially to levels where no one would die from a launch. This was due to the fact that the Orion actually attempted to contain its explosions rather than the military goal of causing the maximum damage possible.
Truth be told, if Red Mercury really does what it's supposed to (the Russians ARE selling the stuff), we may have a way of making Orion launches 100% safe. Of course, our government claims that Red Mercury is a hoax all the while other countries are buying the stuff up. Hmm...
Speaking of which, does anyone know what the heck Mercuric Pyro-Antimonate is useful for besides "creating" Red Mercury? There appears to be a whole bunch of the stuff on the open market, but no documents actually stating what it's useful for.
Javascript + Nintendo DSi = DSiCade
For generating the plasma, Focus Fusion looks like a real possibility. Could even be light enough to carry onboard for power and backup propulsion.