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Space Science Technology

Riding an Ion Drive to the Asteroid Belt 141

Posted by samzenpus from the to-infinity-and-beyond dept.
Iron Condor writes "JPL is now close to embarking on another of its trademark, one-of-a-kind missions, this time to the heart of the asteroid belt: The Dawn mission is being prepared for launch this summer from Kennedy Space Center. Dawn will explore Ceres and Vesta, the two largest known asteroids in our solar system, which lie in the vast expanse between Mars and Jupiter. In the process, the mission will make history on several fronts. Besides being the first spacecraft to orbit a main-belt asteroid and the first to ever orbit two targets after leaving Earth, Dawn will be the first science mission powered by electric ion propulsion, the world's most advanced and efficient space propulsion technology."
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Riding an Ion Drive to the Asteroid Belt More

Riding an Ion Drive to the Asteroid Belt

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  • "Electric ions"? (Score:5, Insightful)

    by CarpetShark ( 865376 ) on Thursday June 07, 2007 @07:59AM (#19421959)
    Aren't ions charged (or charge-stripped) particles? Do we really need to say "electric ions"? Is there another kind?

    • Re:"Electric ions"? (Score:5, Informative)

      by cnettel ( 836611 ) on Thursday June 07, 2007 @08:12AM (#19422021)
      The propulsion is electric, as in the energy source being electricity, although some mass is still needed for the actual thrust, hence the ions.
      • I was under the impression that ion drives used electricity to accelerate some inert gas ( xenon? ) so you still have to have a tank of propellant. I'm not griping, as this is damned cool, but it's not some sort of sci-fi pure electric space-drive.

        • Re: (Score:3, Informative)

          by ArieKremen ( 733795 )
          The European Space Agency (ESA) has recently sent a satellite to the moon using ion propulsion. (http://www.esa.int/SPECIALS/SMART-1/SEMLZ36LARE_0 .html [esa.int])

        • Re:"Electric ions"? (Score:5, Interesting)

          by MyLongNickName ( 822545 ) on Thursday June 07, 2007 @09:32AM (#19422611) Journal
          Ummmmm... by definition ions require some type of propellant. There are thoughts on some kind of mass driver that would take advantage of the sparsely populated atoms in space for thrust, but nothing past the drawing boards as far as I know.

          That being said, ion drives are many, many times more efficient than traditional chemical propellants. If my memory serves, about 3 orders of magnitude more efficient. This yields a much smaller propellant tank. Especially when you consider that the tanks must also be dragged around.
          • They are energy and mass efficient compared to rocket engines. However, they are not powerful enough - one of the first ion drives was able to accelerate its ship at a thousand of a g.

            • Re: (Score:3, Informative)

              by account_deleted ( 4530225 )
              Comment removed based on user account deletion
              • It's all about mass expenditure - as one must get the reaction mass all the way out of Earth's gravitational well (it means accelerating it to more than 11km/s) and energy (solar power at least) is pretty much free (even if not strong) once you have the solar panels up there, the most costly thing is the reaction mass. The ion drive (which ejects its reaction mass at speeds much higher than a rocket engine) uses less mass for the same delta V

          • Re:"Electric ions"? (Score:5, Informative)

            by Rei ( 128717 ) on Thursday June 07, 2007 @11:36AM (#19424211) Homepage
            The Isp (specific impulse) on ion drives varies considerably depending on the type of drive and its operational situation. Chemical rockets are typically 300-450 sec. Ion drives (depending on how broadly you accept the term "ion drive") usually range from 1,000 to 20,000 sec. Of course, Isp isn't the only factor to consider -- you also need to consider thrust, mass (including voltage regulation hardware), and efficiency.

            There are some really neat drives on the horizon that combine the best of thermal and ion drives, such as VASIMR. The particles are heated with radio waves to extreme temperatures (like in some fusion apparatuses), but since they're ionized, they're affected by magnetic fields. The fields collaminate them into a spiralling plasma, converting their chaotic energy distribution into a directed flow. A magnetic nozzle then redirects this out the back. Moderate thrust plus high ISP -- a nice combination.

            My favorite "long range" design is the dusty fission fragment rocket. Most of the energy of fission reactions is contained in "fission fragments" -- basically, the fission of your fissionable fuel blasts microscopic fragments of the fuel at high speeds. In a normal reactor, these bump into the rest of the fuel or the moderator and are "thermalized"; the heat is then converted into electricity lossily. In a fission fragment reactor, the design is such that the fragments (where are inherently ionized) are allowed to escape the core; they can then be A) decelerated to produce electricity, or B) redirected with a magnetic field and vented out the back to produce a ridiculously high ISP thrust. You can do that with ionized particles. :) The "dusty" part comes from the reactor design. The fuel is nanoscale particles of enriched uranium mixed with graphite. Fission reactions automatically ionize the particles, so to keep them suspended at an even distance from each other, all you have to do is ionize the walls of the reactor. Since the particles are so small, their surface area to volume ratio is incredibly large, making radiative cooling realistic. The radiated heat itself can be turned into extra electricity (and even a bit of extra thrust)

      • Re: (Score:3, Insightful)

        by Bromskloss ( 750445 )

        The propulsion is electric, as in the energy source being electricity, although some mass is still needed for the actual thrust, hence the ions.

        Exactly, human language needs more of parentheses, like in mathematics, so it's "electric (ion propulsion)" rathern than "(electric ion) propulsion". :-)

    • Re:"Electric ions"? (Score:5, Funny)

      by Dystopian Rebel ( 714995 ) on Thursday June 07, 2007 @08:43AM (#19422181) Journal
      To the true geek, it's all Impulse Power.

      Move along, there's no warping to see here.

      • Re: (Score:2)

        by Ucklak ( 755284 )
        Next thing you know, we'll find some starship with our ion power spaceship and take a brain from the smartest person on the starship and use the brain as our central computer.

      • Re: (Score:3, Informative)

        by Rei ( 128717 )
        Specific impulse (Isp) is a very real, very important term in rocketry. The standard unit is "seconds" (sec), and is the velocity of the exhaust divided by the acceleration of gravity at the surface of the Earth (9.81m/s^2). Isp and thrust are the two most cited stats for rocket engine performance.

        Of course, the velocity of the exhaust itself is more useful in calculations (who needs Earth's gravity factored in?), but that's just how things go. :)

    • Re: (Score:1)

      by elguap0 ( 758827 )
      At least they didn't call the spaceship a pilotless drone. [sfgate.com]

  • Not the first ion thruster propelled spacecraft (Score:5, Informative)

    by thue ( 121682 ) on Thursday June 07, 2007 @08:02AM (#19421971) Homepage
    From the summary: Dawn will be the first science mission powered by electric ion propulsion

    No, a quick Wikipedia check says otherwise: http://en.wikipedia.org/wiki/Ion_thruster#Missions [wikipedia.org] . For example, Deep Space 1 [wikipedia.org] used electric ion thrusters.

    • Re: (Score:2, Funny)

      by kickedfortrolling ( 952486 )
      Perhaps its the first science mission

      we all know deep space 1 was just a NASA trip to get more doritos that got a bit out of hand

    • Re:Not the first ion thruster propelled spacecraft (Score:5, Informative)

      by TheRaven64 ( 641858 ) on Thursday June 07, 2007 @08:24AM (#19422087) Journal
      I believe you could make a distinction between science and technology missions. To my knowledge, all previous missions involving ion propulsion have been for the purpose of testing ion drives, while this one is expected to perform scientific exploration and happens to use an ion drive.
      • Wouldn't testing an untested/less tested piece of technology be considered a scientific experiment. In it's intended environment, that would be called a "field test" which is very much science. Without such tests, you are still in philosophy and mysticism. Testing is the major difference between those two fields and science.

        • Re: (Score:2)

          by LWATCDR ( 28044 )
          That depends on how you define science and engineering.
          Testing the ION drive wasn't an experiment. There was no theory to prove. They knew that an ION drive could work. What they where testing was if the DS-1 ion drive was built correctly. So yes they are different categories. And if there is one thing scientists love to do categorize things.

      • Re: (Score:1, Insightful)

        by Anonymous Coward
        Even if you use that "bad" argument, there is still Hayabusa [wikipedia.org], which does have a very scientific goal.

      • Re:Not the first ion thruster propelled spacecraft (Score:4, Interesting)

        by Brett Buck ( 811747 ) on Thursday June 07, 2007 @11:49AM (#19424425)
        >To my knowledge, all previous missions
        >involving ion propulsion have been for
        >the purpose of testing ion drives,
        >while this one is expected to perform
        >scientific exploration and happens to
        >use an ion drive.

              Not even that; The Russians have been using them for decades for various spacecraft, and at least some current US comsats use them as well. I am working on another one right now, a comsat that uses it for orbit raising and on-orbit stationkeeping/repositioning.

              I read TFA and it's mostly a load. I don't see why JPL has to jump on the same "we did it first" (except for all the other people who did it before us) bandwagon. I expect that sort of nonsense from ESA but JPL shouldn't have to pump themselves up, since they actually did do a lot of legitimate "firsts".

                  Brett

                    Brett

      • Firsts-O-Matic (Score:2, Interesting)

        by Tablizer ( 95088 )
        I believe you could make a distinction between science and technology missions.

        But they are slicing thin to create new "firsts" in general. Being the first to orbit asteroids in the *main belt* is also kind of a yawner because Eros, outside the belt, was also orbited IIRC. Being inside the belt is almost like saying, "Pioneer X is the first probe to pass Jupiter while Earth was between a 30 and 50 degrees angle relative to the Sun". It is easy to make up records and firsts if you combine enough factors. S

    • Re: (Score:2)

      by mbone ( 558574 )
      Science versus engineering.

      Deep Space 1 and the various other previous ion tests by NASA were engineering missions, not science missions. This distinction is mostly important to the program officers.

      Where they really fell down is not incluidng the Japanese asteroid mission, Hayabusa, which was certainly a science mission, just not from NASA.

    • Re: (Score:1)

      by swanchr ( 660220 )

      The Deep Space series of spacecraft are technology demonstrations. Some many carry science instruments but the primary focus is to test technologies for use in later missions.

    • From the summary: Dawn will be the first science mission powered by electric ion propulsion

      No, a quick Wikipedia check says otherwise: http://en.wikipedia.org/wiki/Ion_thruster#Missions [wikipedia.org] . For example, Deep Space 1 [wikipedia.org] used electric ion thrusters.

      you're tripping over intent. DS1 was a mission solely to test the engine as a viable propulsive technology for future missions. This mission is the first for a real science mission.
      I wonder if that's true for the JSA and ESA missions that other /.ers have mentioned? Just a guess on that...
      The concept it akin to the early Apollo missions for example; as we all know Apollo 11 was the first to use the LM for what it was intended, it was tested several times before that on other missions.

      By the way, i

    • There's several different types of ion engies. The Dawn mission is using electrostatic ion thrusters of the same design from the Deep Space 1 mission. The Smart-1 mission, and I'm pretty sure the Hayabusa mission as well, used Hall effect ion thrusters. The differences are small and each has a few advantages and disadvantages. So the submitter would have technically been more correct if they said "electrostatic" instead of "electric." The parent's link also has links to descriptions of each type.

      Addition

  • Not the first to use ION Propulsion (Score:3, Informative)

    by jmoo ( 67040 ) on Thursday June 07, 2007 @08:05AM (#19421977)
    Nasa's Deep Space 1 first used ION Propulsion several years ago. http://nmp.nasa.gov/ds1/tech/sep.html [nasa.gov]

  • We're doomed! (Score:5, Funny)

    by Timberwolf0122 ( 872207 ) on Thursday June 07, 2007 @08:07AM (#19421987) Journal
    Sir, the possibility of successfully navigating an asteroid field is approximately 3,720 to 1.

  • acceleration with patience (Score:5, Interesting)

    by one_who_uses_unix ( 68992 ) <glen.wileyNO@SPAMgmail.com> on Thursday June 07, 2007 @08:07AM (#19421991) Homepage
    I enjoyed the article - take a look at the FAQ. The author(s) mention that ION drive is "acceleration with patience" - it will take 6 years of accelerate to change the spacecraft's velocity by 10KM/s but will use a fraction of the weight of propellant that conventional chemical propulsion would.

    Space exploration and the related technology are still in their infancy, it is really exciting to to see the stuff of decades old sci-fi making into reality. Who can predict what non-conventional propulsion systems will look like in 50 years?

    • Re: (Score:2, Interesting)

      by arivanov ( 12034 )
      Solar sail will be one of them. Various forms of nuclear drive - another.

      • Re: (Score:2)

        by JDevers ( 83155 )
        Nuclear drives, all the benefit of current electricity generated ion drives without that pesky waiting time (at least in their larger and most grand forms...).

      • Re: (Score:3, Interesting)

        by JudgeSlash ( 823985 )
        I'm voting for VASIMR (variable specific impulse magnetoplasma rocket). They are meant to be able to "change gears" from high thrust, low specific impulse to low thrust, high specific impulse and vice-versa. In theory you could use the same engine to climb out of Earth's gravity well, coast on the flat space-time bits inbetween, and then come wail on those pesky martians from the top of their gravity well. Suckers.

        http://en.wikipedia.org/wiki/Variable_specific_imp ulse_magnetoplasma_rocket [wikipedia.org]

      • Re: (Score:1)

        by Yoozer ( 1055188 )
        Why not build a mass driver (aka rail gun) on the Moon so it can be given a nice sling? At least you can give it a few years of acceleration in advance.

    • Re: (Score:3, Interesting)

      by morgan_greywolf ( 835522 ) *
      I'll take a stab.

      Propulsion systems will likely be driven by some sort of nuclear energy. The theory of operation of these systems will probably revolve around some set of quantum effects, maybe even superposition. These will be early systems based on this technology and, as such, may be prone to various difficulties imposed by the limits of an unrefined technology. They will be capable of traveling at unprecedented speeds using amazingly small amounts of fuel.

      While there will definitely be privately-fund
      • Propulsion systems will likely be driven by some sort of nuclear energy

        Every once in a while I drift back to Doc Smith on the bookshelf. Although his space suits were made of Bakelite, some of his thoughts were rather far-seeing (thinking for example of the replicated logic units of his Skylark electronic brain) considering he wrote in the 30's, where Einstein's mass-energy equation hadn't yet been popularised. Pre-atomic era. He thought that with enough energy you could turn energy directly into matter

        • Although his space suits were made of Bakelite, some of his thoughts were rather far-seeing

          Okay, so bakelite wouldn't be the answer, but space travel would be more or less impossible without plastics, many of which were invented for the space program in the first place... Which certainly includes space suits.

          And of course, sooner or later we will get around to using full-hardsuits, which only make sense.

  • Two targets? (Score:4, Interesting)

    by Atheose ( 932144 ) on Thursday June 07, 2007 @08:10AM (#19422005)
    One thing that surprised me was the fact that it will be the first spacecraft to orbit two seperate targets after launch. For some reason I did not think that this was a difficult thing to do, though now that it has been brought to my attention I can understand why.

    • One thing that surprised me was the fact that it will be the first spacecraft to orbit two seperate targets after launch. For some reason I did not think that this was a difficult thing to do, though now that it has been brought to my attention I can understand why.

      Well, most of the Apollo missions orbited both Earth and the moon. The Lunar Module orbited the moon on two separate flights, before descent and after ascent.

      • Re: (Score:2)

        by Atheose ( 932144 )
        Well yes, but the article says that it's the first time a single craft has orbited two targets, the earth not included. And most would agree that the part of the LVM that left the moon was a seperate craft, since it had different engines than the one that landed on the moon.

        Here's a good video of it leaving the moon: http://youtube.com/watch?v=3fOSTfGXVN4 [youtube.com]

    • Re:Two targets? (Score:5, Informative)

      by Anonymous Coward on Thursday June 07, 2007 @08:33AM (#19422143)
      It's not difficult to do if the two objects are in approximately the same orbital path. So, perhaps, we might soon get a probe looking at Phobos and Deimos.

      Of course, most probes orbit the Earth for a while after launch, before injection into their transit path. All the early moon probes orbited both the earth and the moon, and the manned ones then orbited the earth again after return. So you could say that three targets have been orbited before, back in the '60s. This was just the project team looking for a 'first' to impress Americans with.

      I suppose the difficulty levels go:

      Orbit your base
      Orbit your base and your target
      Orbit your base, then gravity assist from other object, then orbit your target
      Orbit your base, then gravity assist, then swing by one target, then orbit final target (typical multi-planet probe)
      Orbit your base, then gravity assist, then orbit one target, then orbit another.

      In fact, I was most impressed with the few probes which altered their trajectories in mid-mission to do swing-bys of targets of opportunity. You need flexible fuel provision to do that!

      • Re: (Score:2, Informative)

        by Anonymous Coward
        A small correction: The Apollo spacecrafts came straight in from the moon with no orbiting the Earth. See the movie Apollo 13.

      • Re: (Score:2, Funny)

        by RendonWI ( 958388 )
        "In fact, I was most impressed with the few probes which altered their trajectories in mid-mission to do swing-bys of targets of opportunity. You need flexible fuel provision to do that!" So this thing runs on E85?

      • Re: (Score:2)

        by bmgoau ( 801508 )
        "In fact, I was most impressed with the few probes which altered their trajectories in mid-mission to do swing-bys of targets of opportunity. You need flexible fuel provision to do that!"

        And very good math!

      • It's not difficult to do if the two objects are in approximately the same orbital path. So, perhaps, we might soon get a probe looking at Phobos and Deimos.

        Too late, I understand there's already a UAC base established there, as well as a brigade of marines (which has a curiously high ratio of sargeants to grunts).

    • The US and Russian moon missions orbited two targets 50 years ago.

      • Re: (Score:2)

        by Atheose ( 932144 )
        The article says "not including the earth".

        I assumed people would RTFA first but I guess slashdotters would rather quickly point out what they think is an error.
    • Its also not true.
      For example, Giotto visited at least one other target after halley.
  • I'm not using Ion Drives until the TIE fighter goes into production.

    • Re: (Score:1)

      by f8l_0e ( 775982 )
      They went into production a long time ago ... in a galaxy far, far away. (queue brass symphony)
  • This mission would (as far as I'm aware) also be the first man-made object to orbit a dwarf planet at any time, even before the dwarf planet designation was created. Which reminds me: should Ceres still be referred to as an asteroid, as it has been named a dwarf planet recently?

  • Correction (Score:5, Informative)

    by FrostedWheat ( 172733 ) on Thursday June 07, 2007 @08:59AM (#19422273)

    Dawn will explore Ceres and Vesta, the two largest known asteroids in our solar system

    Correction: Ceres is now the smallest dwarf planet.

  • At least three previous space probes used ion engines. JAXA launched Hayabusa, now returning a sample of a asteroid to earth, The European Space Agency launched SMART-1, a lunar orbiter and NASA built Deep Space One.

    http://en.wikipedia.org/wiki/Hayabusa [wikipedia.org]
    http://www.space.com/missionlaunches/smart-1_orbit _041116.html [space.com]
  • Dear god that sounds cool. I want one.
  • This one [nuclearspace.com] for liftoff from Earth (exhaust is not radioactive), and in-system work, and this one [washington.edu] for deep-space missions. We can move thousands of tons around with these, cheaply and safely. (Note: neither of these is an Orion type, which is another option.)

  • You are attempting... (Score:5, Funny)

    by foodnugget ( 663749 ) <eric-slashdot@NOSpAm.ericfeldman.com> on Thursday June 07, 2007 @09:32AM (#19422609)
    Dawn is attempting to explore Vesta. Cancel or Allow?
  • But wouldn't a stream of charged particles from the engine mess up the data collected?
  • Manned missions are launched from Kennedy - this is being launched from Cape Canaveral Air Force Station. They are different facilities.

  • American exaggeration...? (Score:2, Insightful)

    by Anonymous Coward
    Reading below, this is NOT the:

    First to visit an asteroid
    First to orbit two targets
    or First to use an Ion Drive

    and, in fact, space probes are now becoming sufficiently common for the launches to be a yawn in the press. The Europeans are dropping probes on Titan, for christsake!

    What is it with us? This kind of trumpeting makes the rest of the world assume we're so insecure that we need to keep pretending that we're the best...... Oh wait, maybe that's true??

    • Re: (Score:2, Insightful)

      by swanchr ( 660220 )
      So... you might want to check your facts. The Americans (Cassini spacecraft) dropped the European Probe (Huygens) on Titan. The press release is somewhat U.S. centric but the first to orbit two separate Planetary bodies is probably a valid claim.
    • No space launch is ever "routine." While the world (especially the Russians and the US) are roughly fifty years past the days of rockets usually exploding rather than flying, there is still a great deal of risk involved whether the payload is a satellite for cable tv, a manned mission to orbit the Earth or even a robotic mission to another celestial body.

      People seem to forget the number of failures exploring Mars. The Americans lost the Observer, the Climate Orbiter, Deep Space 2, and the Polar Lander sin
  • Have you ever looked at where the asteroid belt lies? maybe we'll prove once and for all that there was a planet that
    had an orbit between mars and jupiter.
  • The first thing the Dawn probe transmits apon arriving at the asteroid belt:

    "My position is correct, except...no, Alderaan!"
    "It ain't there. It's been totally blown away!"

  • About time (Score:3, Insightful)

    by huckamania ( 533052 ) on Thursday June 07, 2007 @12:06PM (#19424719) Journal
    It's nice to see well thought out and efficient science experiments like this one. The asteroids in our solar system are probably more valuable to us in the short term than any of the planets or moons, with the exception of our own moon. I remember an estimate of how much iron is in the asteroid belt once and its enough to cover the earth several times over.

    As scary or foolish as it may seem, our only future is to get off this rock and learn to live in space. Mars is El Dorado, worthless except in the minds of poets and dreamers. There may be hope for purchase on some of the moons, but to get to them or Mars we'll have to have already adapted to space.

    I don't think it will work with out fusion, but if they find gold or oil in one of those rocks, who knows what could happen.

    • Re: (Score:2)

      by Intron ( 870560 )
      More likely they will figure out a way to do precision acceleration of big chunks of rock onto specific targets on Earth. Military uses drive space budgets.

    • Re: (Score:2)

      by Amouth ( 879122 )
      exactly how are they going to find Oil - a product of organic decomp...

    • Re: (Score:2, Insightful)

      by Loke the Dog ( 1054294 )
      As unromantic as it might sound, water will probably be the first stuff mined from asteroids, and the only stuff for a long time.

      The thing is that bringing asteroids to the surface of the earth isnt easy, and even gold isnt really THAT expensive on earth. You have to launch mining equipment, mine the asteroid, bring the stuff to earth and then land it on earth. Add those things up, and it might not be worth it. Lastly, finding gold on an asteroid is unlikely.

      Water on the other hand has many advantages. It c
  • I dunno, it seems to me that a mission to the asteroids is precisely the WRONG field to employ an ion-emission engine.
    Ion engines are low thrust, long duration power - meaning very^2 slow to accelerate. Certainly, as a
    cruising engine, it's great. But in the asteroid belt, I'd suspect that to be an environment where it's (relatively) cluttered, and somewhat quick accelerations in any sort of direction might be required. Maybe it's a relative thing, and an asteroid field is actually less cluttered then a
    • The asteroid belt isn't really all that crowded.
      I found a scientific american article [sciam.com]that has some interesting bits.
      • Maybe the parent poster should read up on astronomy instead of recalling scenes star wars.
        • Maybe this poster should double-check what the term "relatively" means.

          My point was not that it's a "Star Wars" style dodgem...my point is that
          a) at the speeds traveled, even a marble-sized piece of debris would be enough to severely damage a spacecraft.
          b) in a given volume of space, that of the "asteroid belt" is likely to be RELATIVELY more cluttered than that of interplanetary space.

          The Pioneer spacecraft passed almost through the belt, and had very few hits. Likely this would be the case for any probe.
  • "...Dawn will be the first science mission powered by electric ion propulsion, the world's most advanced and efficient space propulsion technology."

    Oh? [wikipedia.org]
  • Last October, My children and I attended a great NASA sponsored presentation about the Dawn mission given by John Ristvey of MCREL that had was very entertaining, and had wonderful participation activities for the kids. He had one activity where he had kids holding various fruit to illustrate differences in the asteroids. One was a grapefruit (large, smooth, has moisture) another, a raisin (small, irregular, dry). It's a great presentation suitable for your scout, science, or astronomy group. At the time

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