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What, um, impact will this have on the space weapons debate?

AP: Pentagon to shoot down broken spy satellite. A press conference is scheduled for 2:30 pm EST to discuss this, with the deputy national security advisor, vice chair of the Joint Chiefs, and NASA administrator Mike Griffin in attendance.

31 comments to What, um, impact will this have on the space weapons debate?

  • After due deliberation, my considered comment is: “hoo ha.”

    The simplest, most straightforward interpretation is very, very interesting. And all the others are fascinating.

  • Charles in Houston

    Pentagon Fans –

    Who thought of this idea? A missile shot from a Navy ship would not “shoot down” anything – at best it would fragment the satellite so it would break apart into smaller pieces, higher in the atmosphere.

    I just hope that we do hit the darn satellite, it would be embarrassing if we missed it. The word Missile describes it’s tendency, it is not called a Hittile for good reason.

    If we shoot and miss, will the Missile Defense Initiative be cancelled? Or will they just find a good reason to explain this away? Remember, that this target does not have a beacon to home in on, unlike many of our MDA targets.

    Charles

  • How, after a year of outrage since China did basically the same thing, does the US think we can do this?

    I’m sure the military will spin this in terms of the weaponization of space by saying that the missile is being launched from the ground and thus not technically a space-based weapon, but come on. Only a week after both China and Russia approached us about working together to keep weapons out of orbit, we do this?
    They are willing to further degrade our relations with China and Russia, not to mention all the other countries that have satellites in orbit, to eliminate the minuscule chance of a piece of a spy satellite surviving re-entry and landing somewhere on solid land where it might be recovered by a foreign power. The arrogance of the military, not to mention those elected to provide oversight of them, continues to astound me.

  • If we shoot and miss, will the Missile Defense Initiative be cancelled?

    Why would they announce a failed attempt?

  • How, after a year of outrage since China did basically the same thing, does the US think we can do this?

    Because it won’t leave a mess up there, as the Chinese test did.

  • NASA TV carried the DoD briefing; I’m summarizing what was said in the last hour here, here and here.

  • libs0n

    If we shoot and miss, will the Missile Defense Initiative be cancelled?

    Why would they announce a failed attempt?”

    Can they keep it a secret? After all, they’ve made a big to-do about the safety reasons involved, how can they keep from the press now the fate of the satellite in the event the shoot down succeeds or fails? Are any other nations capable of monitoring the events of the shoot-down?

  • Habitat Hermit

    If they pull this off nicely everyone smarter than Rosie O’Donnell will realize the difference to the Chinese ASAT test and it will be a feather in the hat for the US.

  • MarkWhittington

    “If they pull this off nicely everyone smarter than Rosie O’Donnell will realize the difference to the Chinese ASAT test and it will be a feather in the hat for the US.”

    For one thing unlike the Chinese test, this operation seems to be designed to prevent a mess, by breaking open the hydrazene tank, causing the toxic fuel to burn up in the atmo.

  • Go

    I don’t get it. If there is too much hydrazene on board, why not gradually expend it through station-keeping or maintaining a higher orbit over the next 10 years? That way, the satellite won’t fall down for a long time, and when it does, it won’t have any hydrazene left.

    Or, is the satellite so screwed up that they can’t even command it to expend the hydrozene?

  • Marcel F. Williams

    If the US had a real space station equipped with an orbital space tug capable of retrieving satellites in low Earth orbit for repair, none of this would be necessary.

  • Because it won’t leave a mess up there, as the Chinese test did.

    Less of a mess, I can imagine: time the attempt so the target is as low as possible, but not yet experiencing enough drag to make it unpredictable. But no mess? No fragments of sat or impactor end up with trajectories and velocities that keep them up longer?

    I ask not argumentatively, but out of genuine curiosity. If we have a genuine “no mess” solution, I’d love to know more about it.

  • CitizenE

    It would be interesting to see the cost benefit analysis of this. The benefit can be calculated by dividing the Earth’s surface area by two football fields and them multiplying by the probability of someone being at that spot at the wrong moment times the medical cost of treating their possible lung damage. In other words as near zero as most calculators permit. On the other side is the cost of a SM-3, its modifications and the mission. Could it be that the value of a “free” target and the chance to extend and test the envelope of the Aegis/SM-3 system might balance the equation?

  • Spacecraft Engineer

    re: repairing it at ISS (a la Marcel) —

    Bad idea.

    You’ve haven’t got an on-orbit serviceable spacecraft bus–digging into the bus could be highly damaging if not impossible without screws and nuts and perhaps even carefully aligned sensors floating around all over the place. The bus is likely to be tumbling errantly and uncontrollably without a solid grapple point on it. You’d be without the specific tools and test software that this bus was built and tested with in place at the ISS–most satellites are not built with flyable hardware. Finally, you’d be putting precious astronauts at risk working around a fully-fuelled, very toxic bird in a thermal environment that could drive many components to temperatures well outside of their design capabilities.

    Assuming that this spy-sat is in polar orbit, the propellants needed to meet orbit maneuvering requirements to get it to ISS orbit and back into a working orbit would be overwhelming. Remember that each pound of payload in orbit, including fuel, costs a great deal of cash. Add to that, the costs of planning and engineering and effecting a repair mission.

    It all adds up to a repair mission that would be of high enough risk as to be completely unsellable. Even with some basic repair capability designed into the ISS.

  • CitizenF

    I kinda doubt that any nominal Aegis devices are capable of an orbital intercept, even with some software tweaks. If this is a real effort, and not just some sort of exercise, it is more likely a test of a true anti-satellite device.

    I would think that the orbital debris community is doing some heavy calculations right now deciding if they should throw a huge fit or not. What is the cost of some amount of new orbital debris vs. the benefit of a heroic demonstration of our military’s anti-satellite prowess? That’s the cost-benefit trade off that should be going on right now.

    Or perhaps that tradeoff has already been done. After all, the latest debris rentry and demise models could always use more real data to help verify their veracity. Or maybe there’s only a little bit of new debris likely to stick around, assuming the strike happens at a low enough altitude.

  • I ask not argumentatively, but out of genuine curiosity. If we have a genuine “no mess” solution, I’d love to know more about it.

    We really do, yes. I explained it at my blog yesterday.

    Because the orbit is already low, any energy imparted to pieces will either bring them in immediately, or raise their apogee (but most likely lower their perigee as well, which means they come in half an orbit later). The satellite was going to come in in a couple weeks anyway, and pieces of it will only come in faster. The only way to significantly extend the orbital life of a piece beyond that of the satellite itself would be to dramatically increase its orbital energy such that it spent a lot of time outside of the high-drag environment, but it will still come in eventually (a pretty unlikely event, since it requires an addition of velocity exactly in the direction of the satellite’s motion). There’s no way to actually raise the orbit (both apogee and perigee) of a piece with a single collision, and that’s the only way, really, to make a long-term mess. The Chinese satellite was different, because it was at a much higher altitude with a long life.

  • Charles in Houston

    Colleagues –

    This is actually a facinating situation – with lots of things to learn and things that could go wrong.

    First, the satellite is in a polar, high inclination orbit. Launched from Vandenberg AFB. It never turned on and has been just slowly losing altitude since launch. So there is no way to have it use it’s engines to reboost or deboost.

    The intercept dynamics could easily propel significant pieces into higher, longer lasting, more threatening orbits. A Direct Ascent intercept adds a lot of energy that would push pieces into larger orbits, and would do unknown things to it’s inclination as well. If they could trick the missile (let’s be realistic and not call it a Hittile yet) into intercepting from “behind” along the negative velocity vector much less mass would tend to be pushed into larger orbits. Easier would be to try to go “beak to beak” but then the closing velocities would be far higher and it would be harder to arrange the meeting.

    What happens to the energy stored in the (probably substantial) hydrazine tank? Could push fragments into larger orbits pretty easily.

    Where would they try to intercept? Probably would want to do it above a capable space track site, over water (duh, launching from a ship) so they can’t do it over some of the US tracking sites. Maybe they could do it over Kwajelein, there are lots of high frequency tracking radars there.

    But regardless of where they do it, there is no way to hide the fact that you tried. The interceptor would be launched from a ship full of people eager to get on TV to describe their role in the attempt. We are really incapable of keeping secrets in this country.

    Almost certainly, the “best” thing to do would be to just hope that the darn thing breaks up high in the atmosphere (the Columbia broke up real low, and it was a LOT larger, and it had hydrazine, and no one was hurt), and people find some burned, twisted fragments that are sold on eBay.

    But if we shoot and miss, it could provide a lot of ammo for opponents of the Missile Defense Initiative. Even if we shoot and hit it could have little affect and still attract a lot of attention to MDI.

    Charles

  • Charles in Houston

    Fans Of Orbital Mechanics –

    This is pretty unique, I find myself correcting Rand Simberg.

    He said: Because the orbit is already low, any energy imparted to pieces will either bring them in immediately, or raise their apogee (but most likely lower their perigee as well, which means they come in half an orbit later).

    and probably he is thinking about the classical orbit change, where you boost in the velocity vector at apogee (to get a larger orbit). Without being pedantic, boosting at apogee is the efficient, easily calculated way, to raise the perigee. Or more correctly, periapsis. Boosting at perigee is the classical way of reducing, probably to circularize, an orbit. Depending on which way you push of course.

    Can you raise both apogee and perigee by imparting energy at a single point? YES. If you give a piece of mass a large amount of energy at a single point in it’s orbit – you can easily increase both apogee and perigee.

    It may not be efficient. It may not be easily calculated. It could easily come from, say, an explosion.

    Charles

  • Charles in Houston

    Oops –

    Let me modify that note about modifying an orbit at a single point.

    If the energy was imparted essentially within a few seconds the point where the energy was imparted would become the new perigee for the resulting pieces (those which did happen to increase in specific mechanical energy). With a near circular orbit, the difference between apogee and perigee is minor.

    Potentially, if the energy was imparted over a longer time (say from a venting tank) the perigee would be fixed by the end of the period of thrusting (when the resulting piece goes into an inertial path).

    My, well camoflaged, point was that the satellite would not necessarily be engaged at perigee. But the orbit must be quite circular so the difference is minor.

    Sorry for appearing to be nit picking, better has proven to be the enemy of good enough.

    Charles

  • Can you raise both apogee and perigee by imparting energy at a single point? YES. If you give a piece of mass a large amount of energy at a single point in it’s orbit – you can easily increase both apogee and perigee.

    Sorry, no. You can’t only not do it “easily,” you can’t do it at all, regardless of the amount of energy you put into it.

    Any new (non-escape) trajectory you give a particle from a point in an orbit is going to pass through that point (or, with precession, through that altitude) sometime during the new orbit, which is a smooth ellipse. This means that, unless the flight path is tangential to the horizontal at that point (in which case there is no change in periapsis), the periapsis has to be lower. If you think that you can raise both periapsis and apoapsis with a single impulse, you have to explain how it makes that angled turn.

    The only way for this to occur would be from a secondary explosion, some time after the impact, which could then raise the perigee (like a circularization burn).

  • D’oh!

    Yes, I was assuming an initial circular orbit for the above. Since that is pretty close to what we have here (it’s slowly spiraling in), my analysis holds. Clearly if you’re in a non-circular orbit, you can raise both with a single burn. But, to first order, we’re not.

  • Space Tug:

    Total delta V for the suggested transfer (there and back, and there and back) from the ISS orbit (51.5 deg) to the satellite’s orbit (58 deg) adds up to ~12K ft/sec. That would have to be one mother of a space tug. Plus all the inherent dangers cited.

    Orb Mech: Rand is correct. It’s going to be in a circular orbit by now. Only pure posigrade delta V imparted along the velocity vector could raise your altitude without some lowering of altitude elsewhere (and, as he notes, you’ve GOT to fly back through the impact site/altitude or the universe doesn’t work the way we think). Retrograde would lower it everywhere, making the impact site your new apogee. Radial in & out delta V would shift the line of apsides, creating an apogee AND perigee…so any gain in altitude gets a corresponding lower dip into the atmosphere on the other side of the Earth.

  • Total delta V for the suggested transfer (there and back, and there and back) from the ISS orbit (51.5 deg) to the satellite’s orbit (58 deg) adds up to ~12K ft/sec.

    That’s the best case, assuming that the nodes are properly aligned. It’s a job for a low-thrust, but high-Isp transfer.

  • Good clarification. Always making those assumptions… Where’s that nuclear tug when you need it?

  • Thread Hijacker

    The problem with orbital debris is that secondary and tertiary and higher order collisions will eventually create a cloud of smaller debris particles that are impossible to track and avoid and that are just as hazardous to a pressurized volume as their larger progenitors. So, as the altitude of intercept decreases, the increased atmospheric drag at the new perigee will help to bring the pieces back to earth more quickly, but only after the new highly elliptical orbits of the particles have first been circularized by that drag. During that circularization time in orbit, subsequent collisions can occur and thereby lead to the creation of the aforementioned cloud or clouds.

    Alas, this thread diverges from the original intent…

    It will be very interesting to see how the Chinese spin this. There’s just no way they won’t take some advantage of it to try and make their ASAT test blunder less offensive. Will they wait ’til after the missle launches? Probably, but who knows.

  • …as the altitude of intercept decreases, the increased atmospheric drag at the new perigee will help to bring the pieces back to earth more quickly, but only after the new highly elliptical orbits of the particles have first been circularized by that drag. During that circularization time in orbit, subsequent collisions can occur and thereby lead to the creation of the aforementioned cloud or clouds.

    Any piece that has a new apogee high enough to cause a problem of this nature would have a perigee so low that it will come in on the first pass through the atmosphere.

  • Chinaman

    Maybe the Chinese will decide to take a pot shot at it first.

  • Charles In Houston

    Fellow Topic Divergers –

    This topic has many angles to examine it from – orbital mechanically, politically, possibly artistically…

    But sticking to my expertise, Thread Hijacker stated: The problem with orbital debris is that secondary and tertiary and higher order collisions will eventually create a cloud of smaller debris particles but one point to remember is that the debris-debris collisions will not bring new energy into the system. An intercepting missile would bring new energy. Lots of new energy. So second order collisions will not alter even the short term fate of the products.

    Oh if we could delve deeply into the orbital mechanics of collisions… But I fear that some of our gentle readers (who do NOT ordinarily exhibit tendencies towards thin skinniness) might get pushed too far today.

    Charles

  • ISS alum

    The facts were presented pretty well in the press conference. They’ve done the math on this and there is no downside to attempting the intercept. All fragments from a collision should re-enter within a few weeks.

    This results in part because smaller objects tend to have a higher drag to mass ratio. Any higher velocity fragments still have perigees low enough for drag to deorbit them.

    The case for the attempt rests on a finding that the hydrazine tank will reach the surface intact. The hydrazine is frozen solid and won’t completely melt on the way down. The tubing will be ripped off, so it will vent as the hydrazine melts, creating a hazard in a radius of about 50 meters.

  • […] Le ragioni per dubitare che il satellite rappresenti un pericolo reale sono varie. Per esempio, che l’abbattimento non garantisce una distruzione completa, ma produce frammenti, di dimensioni certamente minori del satellite intero, ma comunque non controllabili, e in orbite tutte da stabilire (qui c’è tutto un dibattito di meccanica orbitale in merito). […]

  • For those not versed in Italian (like myself), here’s a rough translation of the previous guest’s post:

    […] The reasons to doubt that the satellite represents a real danger are several. For example, [the attack] does not guarantee a complete destruction, but it [may] produce fragments smaller than the entire satellite, but [which] however are not controllable and are all in established orbits (here there is an orbital mechanics debate of merit). […]

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