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Space Technology

Boeing Readies For First Ever Conjoined Satellite Launch 67

Posted by samzenpus from the two-by-two dept.
Zothecula writes Boeing has successfully joined two of its 702SP satellites in a stacked configuration in preparation for a launch scheduled for early 2015. Aside from being the first involving conjoined satellites, the launch will also put the first satellites to enter service boasting an all-electric propulsion system into orbit. "Designed by Boeing Network & Space Systems and its defense and security advanced prototyping arm, Phantom Works, the 702SP (small platform) satellites are an evolution of the company's 702 satellite. Operating in the low- to mid-power ranges of 3 to 9 kW, instead of chemical propulsion, the satellites boast an all-electric propulsion system that Boeing says minimizes the mass of the spacecraft and maximizes payload capacity."
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Boeing Readies For First Ever Conjoined Satellite Launch More

Boeing Readies For First Ever Conjoined Satellite Launch

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  • "Conjoined?" Good.

    TBF, given globalization, part of it, even marginally, was probably actually built in Siam. So it wouldn't be a stretch to call it Siamese...

  • I'll be the first to admit "I'm no rocket scientist", but I'm curious how this works.

    I assume this is a very limited amount of thrust, and can be powered by solar ... but just how much can they do with this?

    Always cool to see they're still doing new stuff, even if I don't know what it means. :-P

    • ion drives, probably
      but those still require ions to work, so there will probably be a tank of hydrogen onboard

      • although, i suppose you could use a PEM fuel cell, and have it eject water vapor

      • Re:So, ion drive or something??? (Score:5, Informative)

        by ubergeek2009 ( 1475007 ) on Friday November 14, 2014 @01:44PM (#48386899)

        According to wikipedia the 702SP uses xenon.

        • Re:So, ion drive or something??? (Score:5, Informative)

          by K. S. Kyosuke ( 729550 ) on Friday November 14, 2014 @01:59PM (#48387019)
          And it seems to have [l-3com.com] a 4.5 kW power input, a specific impulse of 34 kNs/kg (insert an anti-Imperial rant here), and gives a thrust of up to 165 mN, which is fairly decent, Dawn has to do with about a half of that.
      • IANARS (as is obvious from this question), but If it requires a tank of H, how is this ion engine more efficient than just squirting a small amount of pressurized gas out of the tank instead?

        • Re:So, ion drive or something??? (Score:4, Insightful)

          by iggymanz ( 596061 ) on Friday November 14, 2014 @01:53PM (#48386969)

          Ion engines fire ions at tens of thousands of meters per second, your squirt would have a few meters per second. The momentum change of the ion rocket firing same mass of gas is thus greater by factor of ten thousand or more

        • Re:So, ion drive or something??? (Score:5, Informative)

          by jehan60188 ( 2535020 ) on Friday November 14, 2014 @01:56PM (#48386995)

          good question, the efficiency comes from the speeds achievable
          squirting pressurized gas out of a nozzle into space results in an exit velocity of ve = sqrt(C), where C is some clever arrangement of specific heat, R, T, etc (it's been a while since i've study nozzle design)
          Basically, the exit velocity is limited by mostly the chemical's temperature; quadrupling the absolute temperature would only double the speed, so a lot of energy would be needed

          ions are different (bare with me, I'm not an electrical engineer), because you just need to create them (chemical reaction, heat, etc), and then control them (static field, magnetic field). it's a lot lower power, and a lot greater impulse (over a lot longer time) than what ejecting molecules in to space can provide

        • Re:So, ion drive or something??? (Score:5, Insightful)

          by necro81 ( 917438 ) on Friday November 14, 2014 @02:10PM (#48387101) Journal

          how is this ion engine more efficient than just squirting a small amount of pressurized gas out of the tank instead

          It has to do with how quickly you can throw the propellant - how much momentum you can impart to it, which in return imparts a certain change in momentum to the rest of the satellite (delta-v). With conventional satellite propulsion, like fuel+oxidizer rockets or monopropellant thrusters, the energy available to impart that momentum is chemically based. That is, the propellants undergo a chemical reaction, get hot and/or change phase into a gas, and nozzles force that gas to exit at some velocity. Details vary with engine and nozzle design, but there are limits on how much thrust you can get each fuel type. Mass in, reaction energy, mass*velocity (momentum) out. Rocket designers measure this "efficiency" with a quantity called specific impulse [wikipedia.org] (measured in units of seconds) For a given mass of fuel, you can pretty quickly calculate what the total delta-v the satellite has available to it.

          Ion engines [wikipedia.org] can impart much higher velocities to the "fuel" than chemical rockets, in part because they are using electrical energy (of which there is an arbitrarily large supply) rather than whatever you can get from chemical reactions. Again, the details vary based on the design, but ion engines tend to have specific impulses much higher than chemical rockets. The actual thrust (i.e., total force) from an ion engine tends to be miniscule, but is provided very efficiently, and can be produced for days or weeks at a time.

        • Re: (Score:3)

          by Dunbal ( 464142 ) *
          Uses far less fuel mass for the same amount of thrust. Like the other poster said, an important component of a rocket engine is not only the amount of mass you can throw out of an engine but also the velocity at which that mass leaves the engine. In fact velocity is far more important (KE = 1/2m v SQUARED). So an ion engine uses tiny, tiny masses at amazingly high speeds. You don't get much kick out of one, but if you're not in a hurry and run it for weeks and months, then you'll get where you need to go ev

    • Re:So, ion drive or something??? (Score:5, Informative)

      by tomhath ( 637240 ) on Friday November 14, 2014 @01:45PM (#48386917)
      Yes, ion thrusters [spaceflightnow.com]. Used to adjust from the original elliptical orbit to the final circular one (and yea, it takes a long time to do that compared to a conventional booster). They've been using these to maintain position for almost 20 years.

      • Could be a new ion design considering the originals were developed by Hughes Space back in the 90's.

        1st time: no
        New: maybe.

        • Re: (Score:2)

          by khallow ( 566160 )
          I think the new part is the "conjoined satellite" part. I think one engine places the two satellites, one after the other.

  • So these [wikipedia.org] don't count?

  • Great (Score:2)

    by PPH ( 736903 )

    Now they can lose two satellites at once when their surplus Russian rocket engine blows up.

    • That was a different company all together. Orbital Sciences had a launch failure shortly after it left the pad. This launch is going to performed by Boeing.

      • In addition, this is just the payload package - not the launch vehicle. Apparently this is compatible with the Delta IV, Atlas V, Ariane 5, Proton, and Sea Launch.

    • Half as many launches means half as many chances to blow up.

      • Half as many launches means half as many chances to blow up.

        And twice the loss if it does.

        • That was the original point that PPH made. My counter-point was meant to show that it's not so simple as "oh, no, twice the loss" when there are other variables to consider.

          To be explicit, doubling the payload adds no additional risk if all other things are equal. Assuming a 1 in 10 launch failure, 10 launches of a single payload rocket would give you 9 satellites boosted and 1 destroyed vs 18 boosted and 2 destroyed. The ratio is exactly the same.

          So if the success ratio is the same and you roughly halve yo

    • Re: (Score:2)

      by Dunbal ( 464142 ) *
      This is why you buy insurance. Rockets are tricky remember?

    • Re: (Score:3)

      by hernick ( 63550 )

      Wrong. These satellites will not be launched by Lockheed-Martin's russian-powered Atlas V rocket, nor by Orbital Sciences soviet-powered Antares.

      These two american-built satellites will launch on the Falcon 9, an all-american rocket, which is powered by 10 american engines.

      Also, if any of the 9 first stage engines were to blow up in a mild fashion that didn't cause too much damage, the Falcon 9 would in fact be able to complete the mission using the remaining engines.

  • Conjoined satellites with solar panels and two ion engines? I've seen that somewhere before...

    http://img3.wikia.nocookie.net... [nocookie.net]

  • Lots here... (Score:3)

    by Zoxed ( 676559 ) on Friday November 14, 2014 @02:21PM (#48387173) Homepage

    Do none of these count as "conjoined" http://en.m.wikipedia.org/wiki... [wikipedia.org]? Does SMART1 not count as electric propulsion? Or is that all too European ;-)

    • Re: (Score:1)

      by Anonymous Coward

      conjoined, meaning that the space vehicles htemselvs are connected, instead of using an adapter. SMART1 used chemical propulsion for the transfer burn; this is planned to use only electric propulsion, including the transfer burn. (actually, with it's low total thrust, it's several "burns" for these.

    • Re: (Score:3)

      by nojayuk ( 567177 )

      The Ariane V has been launching two geosync large satellites simultaneously for quite some time but the upper satellite is carried on a frame/shield called SYLDA that fits around the lower satellite. Usually the two satellites being launched are different sizes and shapes. In this case it appears the Boeing satellites are roughly identical and docked together in their launch fairing saving on the weight and volume of the carrier. However the lower satellite has to cope with the mass of the upper satellite d

  • we are V.ger

  • Um ... so then what was STEREO? [wikipedia.org] (launched in 2006)

    There are pictures of them stacked together [zimbio.com]

    It was even launched from a Boeing Delta II [nasa.gov], so they can't claim it was their first conjoined launch. (which caused major launch delays ... due to the Boeing strike, then the batteries in the second stage being de-certified ... then once the strike was over, the Air Force kept cutting in line for launch pads)

    Disclaimer : I work for the Solar Data Analysis Center. which operates the STEREO Science Center.

    • Um ... so then what was STEREO? [wikipedia.org] (launched in 2006)

      There are pictures of them stacked together [zimbio.com]

      It was even launched from a Boeing Delta II [nasa.gov], so they can't claim it was their first conjoined launch. (which caused major launch delays ... due to the Boeing strike, then the batteries in the second stage being de-certified ... then once the strike was over, the Air Force kept cutting in line for launch pads)

      Disclaimer : I work for the Solar Data Analysis Center. which operates the STEREO Science Center.

      The same is true for the Van Allen Probes (formerly RBSP): http://en.wikipedia.org/wiki/V... [wikipedia.org]

      Perhaps this is just the first time that Boeing has stacked two satellites?

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