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ESA Launches GOCE To Map Earth's Gravity

Posted by kdawson on from the go-see dept.

DSG2 sends in an ESA press release which reads in part: "This afternoon, the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite developed by the European Space Agency was lofted into a near-Sun-synchronous, low Earth orbit by a Rockot launcher lifting off from the Plesetsk cosmodrome in northern Russia. GOCE is the first of a new family of ESA satellites designed to study our planet and its environment in order to enhance our knowledge and understanding of Earth-system processes and their evolution, to enable us to address the challenges of global climate change. In particular, GOCE will measure the minute differences in the Earth's gravity field around the globe." One consequence of mapping the planet's geoid in finer detail is that ocean currents can be limned more accurately. This BBC article from 2007 goes into some detail about this application.

81 comments

  1. Whoa, this is heavy by MrEricSir · · Score: 4, Funny

    There's that word again; "heavy." Why are things so heavy in the future? Is there a problem with the earth's gravitational pull?

    --
    There's no -1 for "I don't get it."
    1. Re:Whoa, this is heavy by Anonymous Coward · · Score: 0

      Want to know what's really heavy? The positive bias /. first posts receive. Now that's heavy.

  2. I'd be happy to wander around and weigh myself by Anonymous Coward · · Score: 0

    I can probably wander around the world and weigh myself at various locations and twitter the results in for a lot less $$$ than they spent on the satellite!

  3. height by Silm · · Score: 3, Interesting

    what really interests me is the fact that this satellite in such a low orbit that it actually has wings and an aerodynamic body to cope with the small amounts of air on that height. Those wings combined with the ion motor's onboard make it almost a plane/ satellite hybrid.

    1. Re:height by TorKlingberg · · Score: 4, Informative

      It actually flies "sideways" though. The upper side of the two big wings always face the sun. The two smaller wings at the back are for aerodynamic stability.

      While I'm here, there is more information at the ESA GOCE sites.

    2. Re:height by AikonMGB · · Score: 1

      The atmosphere remains a fairly significant factor in satellite design up to altitudes of about 1000km (depending on where you are in the solar cycle; as Sun activity increases, the atmosphere expands). However, your premise remains.. 250km is a VLEO (Very Low Earth Orbit).

      Aikon-

  4. "GOCE" by weirdcrashingnoises · · Score: 0, Redundant

    Hmmmm, this sounds vaguely familiar on the interwebs...

    --
    sigs... don't talk to me about sigs....
    1. Re:"GOCE" by Anonymous Coward · · Score: 0

      Ok, wait.. wait.. please don't make an ass out of yourself and spoil it for the rest of us.

      That would be rather.. malodorous.

    2. Re:"GOCE" by Anonymous Coward · · Score: 0

      OGOCE would be textually obscene, I guess.

  5. this and that by girlintraining · · Score: 3, Interesting

    Article title: ESA Launches GOCE To Map Earth's Gravity
    Article quote: ...to enable us to address the challenges of global climate change.

    Great. Now we're going to have to start ejecting people into orbit because they stayed under their carbon credits quota, but they had too much gravitational pull and that's damaging the environment. I can just see the green movement in five years: "Stop warping spacetime! Excercise! And screw the whales."

    --
    #fuckbeta #iamslashdot #dicemustdie
    1. Re:this and that by Anonymous Coward · · Score: 0

      The PR filters are obligated to affix some mention of "climate change" to many things. The physicists attempting to (re)measure minute changes in Earth's gravity field are probably oblivious to whatever state the atmosphere might be in. If they can actually detect the mass of the atmosphere, they'll probably consider it 'error' and attempt to factor it out. Putting "climate change" mantra in all their press releases keeps the funding flowing. One more expensive project they can tally up in the 'for the climate' column. Basically it's academia lying to itself to getting funding for something other than 'climate change'.

    2. Re:this and that by maeka · · Score: 1

      The PR filters are obligated to affix some mention of "climate change" to many things. The physicists attempting to (re)measure minute changes in Earth's gravity field are probably oblivious to whatever state the atmosphere might be

      No, rather the non-minute changes in water/ice distribution causes significant differences in the created geoid model.

  6. Yeah... by dwiget001 · · Score: 0, Troll

    Climate change.

    The climate changes in short, long and very very long time cycles.

    Hotter, colder, etc.

    Of course, that completely obliterates the "Man Made Global Warming" myth.

    Which makes one wonder: When did "Global Warming" become politically incorrect and "Climate Change" became politically correct?

    1. Re:Yeah... by Anonymous Coward · · Score: 0

      Of course you're right! I'll turn my heater off now, as I clearly can't change the local climate in my house.

    2. Re:Yeah... by girlintraining · · Score: 3, Insightful

      When did "Global Warming" become politically incorrect and "Climate Change" became politically correct?

      When they realized they might be wrong.

      --
      #fuckbeta #iamslashdot #dicemustdie
    3. Re:Yeah... by vadim_t · · Score: 2, Informative

      You can have both global warming and local cooling.

      For instance, one possible effect is that while the average temperature over the whole planet does rise (global warming), the melting of the ice will shutdown the gulf stream and make some countries like Britain colder.

    4. Re:Yeah... by DMUTPeregrine · · Score: 1

      The average global temperature has been going up, much more so in recent years. Thus the term "global warming." When some scientists predicted that if the earth gets hot enough there might be a catastrophic rebound and another ice age the term "climate change" began to be used. It's more accurate, since the warming may lead to extreme cooling.

      --
      Not a sentence!
    5. Re:Yeah... by Anonymous Coward · · Score: 0

      When some scientists predicted that if the earth gets hot enough there might be a catastrophic rebound and another ice age the term "climate change" began to be used.

      [citation needed]

      There is a possibility that overall warming will cause changes in ocean currents, and this will change the climate in northern Europe to something more appropriate for its latitude (e.g. compared to places in Canada or Siberia). I have not heard anything about a "rebound" to a global ice age.

    6. Re:Yeah... by khayman80 · · Score: 3, Insightful

      As a climate scientist, I've seen that shift in wording too. I think it was largely a PR move, designed to combat fundamental misconceptions that laymen have regarding "Abrupt Climate Change" (the officially accepted title).

      1. Most people don't understand the difference between weather (purely local phenomena, hard to predict because it requires extremely complex vector-valued numerical models of the motion of the atmosphere) and climate (purely global phenomenon, easier to predict because it just requires summing energy input and subtracting energy output). They stuck the word "climate" in there to emphasize that today's cold temperatures in Joe Schmoe's town don't "disprove" climate change.
      2. Global warming is a little simplistic. A more accurate description is that our addition of greenhouse gasses has reduced the volume of energy leaving the planet while leaving the energy input constant. As a result, the average energy in the atmosphere is increasing, which allows the system to "explore more of its phase space". More energy means more opportunities for extreme weather- even weather that involves colder temperatures! (Again, note that weather is local.)
      3. The word "abrupt" was added to emphasize that what we're experiencing isn't a natural process. The ice core from Vostok shows that CO2 hasn't risen above 300 ppm in the last half million years. It's at 380 ppm now, which is almost certainly due to human activities. This rapid increase hasn't happened in the hundreds of thousands of years over which we have records. The consequences aren't likely to be pretty. Hence, "abrupt".

      I'm embarrassed to admit it, but climate change has me pretty scared. I might live to see some of the effects (drought, famine, extreme weather) and I wonder if my life will be as comfortable as my parents was. I used to assume that advancing technology would make my life much better, and I'm just now coming to grips with the possibility that it won't.

      But what really scares me is the ostrich-like manner with which people react to the problem. They seem to be in denial, which is understandable. Scientists aren't bringing good news, so it's natural to be resentful. But I figured that some deep survival mechanism would kick in eventually as people looked at the rigorous nature of the modeling, the diverse data sets all leading to the same conclusions, and the myriad positive feedback effects that makes climate change accelerate on its own.

      Instead, people seem to react as though the existence of climate change is somehow a political question rather than a scientific question. They don't seem to be looking at that evidence. Instead, they seem to decide that their political party's position on climate change is "X", so they believe "X". (Note that I'm talking about the existence of anthropogenic abrupt climate change. I realize that our response to climate change is a legitimate political question.)

    7. Re:Yeah... by Anonymous Coward · · Score: 0

      lolling citation:http://www.exitmundi.nl/Iceage.htm

    8. Re:Yeah... by smoker2 · · Score: 1

      Global warming is a consequence of climate change. Global cooling is a consequence of climate change.

      I am not a denier, but I am not about to be told we must halt climate change. This is a phenomenon that is as old as the earth, and to think we can just stop it when we want to is ludicrous. If you want to limit our impact on that change, fair enough. But don't tell me it has to stop, because you make yourselves look like idiots. The climate has changed in cycles, and despite the CO2 lobbys best propoganda, the climate was already on an upward curve regarding CO2 before we even discovered fire. And if you take those same records which are used to promote the current scare tactics, you would see that after it (CO2) goes up, it goes down - way way down. It is cyclic.

      So even if we completely stop producing CO2 now, the cycle will continue. So you are left with politics. The real question is one of adaptation, not prevention. It amuses me when people blame cows for farting too much, completely forgetting there are billions of humans farting too. And as our population continues to increase, we will rely more and more on vegetable matter to survive, and this makes us fart even more. It's us that causes the problem right down to our basic existence.

      So go ahead and do your worst. The only way to stop climate change is to kill the planet. We are better off finding ways to live with it. We are responsible for the crops that will suffer in a warmer world. We helped their colonisation much better than they would have done on their own. We bred cattle. We use fresh water for more things than there is sufficient fresh water to accomplish, and waste it. We over fish the seas, poach wildlife, deforest whole areas and drive animals to extinction. We use chemicals to eradicate species we don't find a use for, even when we don't know what that means for other species in that chain. Then we let chemicals run into the seas killing and mutating who knows what in the process. Worrying about the climate is secondary to all those concerns IMHO.

      But then I've always been a "happy camper". I try not to leave any evidence of my passing. Like grasshopper on the rice paper, you try to leave no mark. The current world seems to care only about what it wants, not what it should do, or how it should do it. Fuck the consequences. Well it seems like in Soviet Russia, the consequences fuck you !

      To be honest, I'll be dead long before this starts to bite and I have no kids, so I'm finding it hard to care too much. On principal I care, but for practical purposes, it's already too late. I live in a one room flat. I use no gas for cooking, only electricity. I don't have central heating or air-con. I have a car (17 years old, 45 mpg, 0.16% volume CO2 [limit is 3.5%])that is used maybe once a week. I'm not obese, I recycle where possible and I resist convenience products. What else can I do anyway ? But senior climate scientists find it acceptable to fly around the world just to have meetings on the serious state of global warming.

      ??????

    9. Re:Yeah... by TheTurtlesMoves · · Score: 1

      IPCC is run by a political origination with an axe to grind. Al Gore, a Politician won a peace prize for little movie campaign. Can you blame people that they say its all politics these days.

      Hell even ask about model details and your slammed with a global warming denier label. You don't get your question answered.

      The science is now so obscured with media and other groups agenda bias that its pretty hard to claim its not all politics. Really what does your emotional state ("I'm pretty scared") have to do with the science?

      I was in fact working with climate scientists for a while, and i was quite shocked that most think its appropriate to misrepresent the certainty of the models because they "know" best. Now tell me again why people shouldn't think that the science is just as politicized as the rest of the debate?

      --
      The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
    10. Re:Yeah... by khayman80 · · Score: 2, Informative

      Global warming is a consequence of climate change. Global cooling is a consequence of climate change.

      I think the term global dimming more accurately describes a separate problem that is sometimes referred to as global cooling. Aerosols decrease the size of cloud droplets, thus increasing the albedo (whiteness) of the clouds. This reflects more sunlight back into space. Its effects have been seen in long-term sunlight brightness studies (in Israel) and in long term evaporation rate measurements (amazingly, evaporation depends on the number of photons hitting the surface rather than just the temperature, so it serves as an independent check of the phenomenon).

      It's not such a big deal anymore because regulations were effective at curbing emissions of these aerosols. Unfortunately, it used to act to counter greenhouse gases like CO2...

      This is a phenomenon that is as old as the earth, and to think we can just stop it when we want to is ludicrous.

      I think we're talking about different things. You're talking about natural variability, and I'm talking about human-caused climate change. Scientists are aware that both phenomena exist, and based on the research I saw at the December 2008 American Geophysical Union conference, I'm fairly confident that we can tell how much climate variability is due to humans.

      The climate has changed in cycles, and despite the CO2 lobbys best propoganda, the climate was already on an upward curve regarding CO2 before we even discovered fire.

      Vostok ice core data confirms that for nearly half a million years, the climate has changed cyclically. But in all that time, the maximum CO2 concentration never went above 300 ppm. (It's hit higher levels millions of years ago, but that was a slow and gradual change. Plus the Earth was essentially a different planet back then, with a different solar luminousity and biosphere so comparisons across that much time are tricky.)

      And if you take those same records which are used to promote the current scare tactics, you would see that after it (CO2) goes up, it goes down - way way down. It is cyclic.

      I presume you're referring to the Vostok ice core data I just linked. You're right to say that natural variations are cyclic- that graph displays variations that are governed by (among other effects) Milankovitch cycles which are caused by periodic variations in the earth's orbit.

      But I'll reiterate the point I made in my original post: CO2 concentrations are at 380 ppm today. That's a level it hasn't hit in the last half million years. If we're seeing natural variability alone, it's quite a coincidence that it occurs right when we started excavating fossil fuels to fuel a billion cars.

      Plus, the Vostok data is a little difficult to analyze in this manner, but it seems like at Vostok the CO2 always increased 600 years AFTER the temperature started to increase. At least, that's the way it used to work. Right now, the CO2 concentration is at an unprecedented level but the temperature is barely above normal. Again, that suggests that we're not facing natural climate change, we're dealing with anthropogenic abrupt climate change.

    11. Re:Yeah... by khayman80 · · Score: 3, Informative

      IPCC is run by a political origination with an axe to grind. ...

      I've read through their reports and rebuttals, and I've not seen any difference between the science they're reviewing and my own work (or the work of my colleagues or my advisor). In fact, some of my personal research results support their conclusions. I guess that means that my dissertation research is just politically motivated claptrap?

      Hell even ask about model details and your slammed with a global warming denier label. You don't get your question answered.

      Wow. If you politely asked a climate scientist for details of their model, and got that reaction then you were talking to a pretty bad scientist. Alas, PhDs cannot be revoked...

      The science is now so obscured with media and other groups agenda bias that its pretty hard to claim its not all politics.

      The science isn't obscured from where I'm sitting, and it isn't for anyone within driving distance of a university library. Those biases you're talking about don't make it into the peer reviewed journals like Geophysical Research Letters. I'd recommend those sources over the secondhand sources that you're reading. They sound like horrible sources of information.

      Really what does your emotional state ("I'm pretty scared") have to do with the science?

      Umm... I'm not writing a scientific journal article right now. It's just an online forum. I definitely wouldn't include statements like that in my article submissions.

      I was in fact working with climate scientists for a while, and i was quite shocked that most think its appropriate to misrepresent the certainty of the models because they "know" best.

      What a coincidence! I, too, work with climate scientists. And my experience with scientists in general is that they're much less likely to overstate their case than other people. Scientists are more likely to add caveats to their statements, and less likely to make statements of certainty when all that the evidence supports is "strong probability". What you're describing is just the normal way scientists act.

      Now tell me again why people shouldn't think that the science is just as politicized as the rest of the debate?

      Show me an experiment from a peer reviewed journal article that you think is politicized. I'll review it and get back to you. On the other hand, if you were talking about Rush Limbaugh's editorial about climate science, then I think we mean different things when we use the word "science".

    12. Re:Yeah... by khayman80 · · Score: 1

      I was in fact working with climate scientists for a while, and i was quite shocked that most think its appropriate to misrepresent the certainty of the models because they "know" best.

      What a coincidence! I, too, work with climate scientists. And my experience with scientists in general is that they're much less likely to overstate their case than other people. Scientists are more likely to add caveats to their statements, and less likely to make statements of certainty when all that the evidence supports is "strong probability". What you're describing is just the normal way scientists act.

      Holy shit, I completely misread that! I thought you said they DIDN'T think it was appropriate. Please post their names and research affiliations so I know who to avoid at conferences!

      (The reason I misread that comment was, I think, because my experience from 10 years in science has been completely opposite to yours. Of course, it's possible that your experience was more representative than mine...)

    13. Re:Yeah... by BoothbyTCD · · Score: 1

      No when they realized that stupid people were getting confused when they got hit by a big winter storm. "Dang it's cold! Guess we don't have none of that librul warmin here." /Cletus the slack-jawed yokel. The idea that destabilizing an equilibrium leads to extremes in both directions is too big a concept for people who can't correctly say how long it takes the earth to go around the sun.

      --
      snig
    14. Re:Yeah... by Anonymous Coward · · Score: 0

      Very well put. I am sorry that I am out of mod points. What I witnessed here is a well informed person explaining away the misinformed opinions of the lazy. They would rather just absorb some talking points from the blind, hidden-agenda media that find the real facts out for themselves.
      Pathetic.

      Hence, this is why there is no retort to your last reply. Well done sir.

    15. Re:Yeah... by TheTurtlesMoves · · Score: 1

      My experience is "anecdotal" evidence. But it is however my experience. They won't put in a journal. But when a reporter is asking....

      --
      The Grey Goo disaster happened 3 billion years ago. This rock is covered in self replicating machines!
    16. Re:Yeah... by girlintraining · · Score: 1

      Instead, people seem to react as though the existence of climate change is somehow a political question rather than a scientific question.

      It became political the moment it became obvious that it would cost something to fix. The evidence may not be in doubt, but like all finite resources, the mindset today is "take what you can now" -- not plan for tomorrow. The collapse of the social security system, medicaid, the global recession, all point to a fundamental lack of interest in the future. Politics globally has aquired a hedonistic taint. The evidence could be indisputable and as solid and proven as gravity but it wouldn't change people's reactions.

      --
      #fuckbeta #iamslashdot #dicemustdie
  7. Truly an amazing machine by Thagg · · Score: 5, Informative

    GOCE is a gravity measuring satellite -- the spiritual successor to the amazing GRACE pair of satellites from a few years ago.

    GRACE works by flying two satellites in the same orbit, one a few dozen miles ahead of the other. By monitoring the distance between the satellites with laser rangefinders, one can measure how strong gravity is -- the more gravity, the faster the satellite goes, so the distance between the satellites grows until the second one reaches the same area. This was the state-of-the-art, and GRACE made some amazing measurements. It was able, for instance, to measure the amount of extra groundwater during flooding along the Mississippi.

    But GOCE does it all with one satellite. Where the baseline for GRACE was many miles, for GOCE it is just 50 cm.

    Now, if you think about it, in any satellite, the amount of gravity you would feel is zero...or at least, very very close to zero, as you are orbiting inertially. But, really, gravity is only zero right at the center of mass of the satellite. You'd feel a tiny amount of acceleration the further you go. As you go toward the center of the earth, you would be in a lower orbit, and you would be pulled down with respect to the satellite.

    GOCE measures this microgravity to rediculous precision. By measuring the difference in gravity affecting two test masses 50 cm apart, it can measure how strong gravity is at that point. It should have much better accuracy, and far better resolution, than GRACE.

    GOCE is amazing in other ways, too. It flies very low, to get better resolution. So, it has fins! A satellite with fins, to keep it pointing along the direction of travel. Because there is some tiny amount of air drag at the altitude it is flying, GOCE has a tiny xenon ion engine pushing it along to keep it at the same altitude, and to keep the air drag on the satellite from overwhelming the gravity measurement.

    Hats off to ESA, this is an amazing machine!

    --
    I love Mondays. On a Monday, anything is possible.
    1. Re:Truly an amazing machine by Randle_Revar · · Score: 0

      >Now, if you think about it, in any satellite, the amount of gravity you would feel is zero...or at least, very very close to zero, as you are orbiting inertially.

      There is plenty of gravity, if there wasn't, the sat would be flying off into deep space.

      --
      Climate Progress - Hell and High Water
    2. Re:Truly an amazing machine by Zoxed · · Score: 1

      > GOCE is a gravity measuring satellite -- the spiritual successor to the amazing GRACE pair of satellites from a few years ago.

      Technically it is not measuring gravity: it measures *variations* in the gravitational field: basically from it's known orbit it detects incredibly small delta-Vs in it's path.

    3. Re:Truly an amazing machine by Anonymous Coward · · Score: 0

      All this is fine and dandy, but we all know that's just a cover that EU uses to get updated geoid profile for military inertial navigation ;)

      High resolution gravity (geoid) data used to be pretty much top-secret. Has that changed somehow? The accuracy of geoid data affects the accuracy of inertial navigation systems. Ballistic missiles can't really rely on GPS, you know.

      Any data from this program, if made available in the 80s and prior, would be at least heavily embargoed, and the highest resolution data was really classified as a national security asset.

      Can anyone elaborate what resolutions we're talking about for navigation vs. GOCE?

    4. Re:Truly an amazing machine by Anonymous Coward · · Score: 0

      Funny thing about Gravity... the Earth's Gravity changes with it's rotational velocity and location and relativistic density in the Solar System. By the time they complete the Gravity map, it'll be "out of date".... Hope they'll have Dynamic data that shows this variation with time, Now That Really would be interesting!

    5. Re:Truly an amazing machine by khayman80 · · Score: 4, Informative

      I am a physicist working with GRACE data, and I feel the need to nitpick. GRACE uses a microwave ranging system, not a laser ranging system. The increased accuracy of a laser ranging system wouldn't be useful because there are so many other sources of noise, but it is being considered for GRACE 2.

      Also, the baseline between the GRACE satellites is more than a couple dozen miles. On average, GRACE A and B are 220 km apart.

      GOCE is an amazing satellite, and its low altitude combined with its ion engine (to precisely compensate for drag) will increase the resolution of our STATIC (i.e. not time dependent) gravity field maps. But it can't replace GRACE's measurements of the changing gravity field. GRACE has provided independent measurements of the Greenland ice sheet melt and helped to correct water storage models, which underestimated the 2005 Amazon drought.

      My research involves pushing GRACE's temporal resolution even further down. Rather than detecting annual signals or slowly varying linear mass changes (like ice sheet melt), I'm trying to measure the gravity changes from ocean tides. My preliminary results show that GRACE can detect gravity fluctuations from twice-daily tides, which means that it can be used to improve our ocean tide models. This helps oceanographers, but indirectly helps all gravimetry because tides are a source of noise even for static measurements of the earth's gravity field. Modelling the tides better can help to reduce this noise.

      GRACE isn't dead yet.

    6. Re:Truly an amazing machine by Anonymous Coward · · Score: 0

      ... the spiritual successor to the amazing GRACE ...

      So the amazing grace was not spiritual enough? What do you want, the holy trinity?

    7. Re:Truly an amazing machine by LarryRiedel · · Score: 1

      The amount of gravity you would feel

    8. Re:Truly an amazing machine by Thagg · · Score: 1

      Thanks...I suppose I was in GOCE rapture this morning when I read about it, and I was more harsh than I should have been. It's good to hear about the work that you're doing, and that you're possibly going to do a GRACE2. What are the other new features of GRACE2 over GRACE?

      I love the apparent simplicity of GRACE -- I say apparent because I know there's a mountain of math between the distance measurements and the geoid data. Congratulations on your work, and keep it up!

      --
      I love Mondays. On a Monday, anything is possible.
    9. Re:Truly an amazing machine by Anonymous Coward · · Score: 0

      GOCE is an amazing satellite [...] But it can't replace GRACE's measurements of the changing gravity field.

      Why not? Isn't time-dependent gravity measurement simply achieved by comparing "static" measurements of the same spot over time?

    10. Re:Truly an amazing machine by Anonymous Coward · · Score: 0

      This is probably an application of Amdahl's law: If public geoid data is now so good that most of the error in inertial navigation systems come from other sources (launch speed and angle, atmospheric variations), then there's no problem in publishing infinitely precise geoid data.

    11. Re:Truly an amazing machine by khayman80 · · Score: 1

      What are the other new features of GRACE2 over GRACE?

      The "drag-free" concept that GOCE is using has been popular at the GRACE Science Team Meetings. This would allow GRACE's altitude to be lowered from its current ~500km (starting) altitude to something more like 200km. Lowering the altitude increases the spatial resolution because from very far away the Earth's gravity field looks exactly like a point mass's. The closer to the surface the satellite gets, the more of the extra features are revealed.

      A laser ranging system is also being considered, but we're having a great deal of trouble getting our noise floor (due to mis-modeled forces on the satellite and errors in modeling known sources of gravity fluctuations such as tides and atmospheric circulation) low enough so that we're actually limited by the reduced accuracy of the microwave system. Until then, it's hard to argue for a more expensive system that doesn't seem necessary.

      I've seen interesting proposals for a more complicated orbit geometry. David Wiese proposed a "cartwheel" orbit where 2,3 or 4 GRACE satellites would revolve around each other as they orbit the planet. Sometimes the satellites would be at the same altitude, at other times they'd be right on top of each other. The laser ranging systems would be continually synced, so measurements of gravity variations could be made along radial directions instead of along the theta (or phi, depending on which spherical coordinate system you prefer) direction. These added degrees of freedom could help eliminate a strange, unexplained error source that we whimsically call "longitudinal striping" (Sean Swenson developed a smoothing algorithm that reduces it, but we still don't really know why it happens).

      Aside from that, we're just trying to make sure that there IS a GRACE 2. Many of our long term measurements are limited by the short (~6 year) timespan of the data. GRACE is slowly falling out of the sky (I think it's projected to burn up in 2012 or so) and it's dangerously low on propellant. We need another mission like GRACE to extend the time series, and it's best to launch the second mission before the first one fails to cross-validate the time series from both satellite systems.

    12. Re:Truly an amazing machine by khayman80 · · Score: 1

      First, it's in a sun-synchronous orbit. That means that it only passes over a certain spot on the earth's surface at a particular time of day, which never changes from day to day. As a result, it can't tell if gravity is different at that spot at a different time of day. Secondly, the GOCE mission is expected to fall out of the sky in 20 months (and that's if the ion engine works well). It just won't be up there long enough to measure a long enough time series for any serious analysis.

    13. Re:Truly an amazing machine by Randle_Revar · · Score: 1

      I would argue that "feel" in the sense of human nerves saying "this way is down" is irrelevant, given that we are talking about a satellite, and the satellite most certainly "feels" the effects of gravity by staying in orbit.

      --
      Climate Progress - Hell and High Water
    14. Re:Truly an amazing machine by techno-vampire · · Score: 1
      By measuring the difference in gravity affecting two test masses 50 cm apart, it can measure how strong gravity is at that point.

      If the two masses are separated by 50 cm, as you say, gravity will pull on the nearer one very, very slightly stronger than it does on the farther one. If the masses were free to move, they'd be in separate orbits, with the outer one moving away from the inner one. As they are (I presume) tethered, there will be a force acting on that tether. This is, in fact, the same thing that causes tides, and that means that what GOCE is doing is measuring the variation in the tidal force generated by the two mass's difference in altitude. Interesting.

      --
      Good, inexpensive web hosting
    15. Re:Truly an amazing machine by Anonymous Coward · · Score: 0

      It's not just human nerves; there's no local experiment you can do inside of the satellite to measure "the force of gravity" acting on it. And if you could, it would be a vector sum of G*m*M/d^2 over the whole universe -- a crazy beast which may not even be well-defined (the sum might not converge). The "gravity you feel" is really the only concept that is usable.

  8. From the ESA website:.. by Star+Particle · · Score: 3, Informative

    For 24 months, GOCE will collect three-dimensional gravity data all over the globe. The raw data will be processed on the ground to produce the most accurate map of the Earth's gravitational field to date and to refine the geoid: the actual reference shape of our planet. Precise knowledge of the geoid, which can be considered as the surface of an ideal global ocean at rest, will play a very important role in further study of our planet and, with any luck, by detecting subtle changes in gravitational potential, it will be able to provide mankind with its first indirect measurement of your girlfriend's mass.

    1. Re:From the ESA website:.. by Anonymous Coward · · Score: 0

      Precise knowledge of the geoid, which can be considered as the surface of an ideal global ocean at rest, will play a very important role in further study of our planet and, with any luck, by detecting subtle changes in gravitational potential, it will be able to provide mankind with its first indirect measurement of your girlfriend's mass.

      Great, I can already hear her asking, "Does this subtle change in gravitational potential make my butt look big?"

    2. Re:From the ESA website:.. by Ontheotherhand · · Score: 4, Funny

      How did you manage a +3 informative for insulting my girlfriend?

    3. Re:From the ESA website:.. by Star+Particle · · Score: 3, Insightful

      Hmmmm... good question. I could launch into a wordy, detailed answer here, but it would inevitably end with me insulting your girlfriend once again.

    4. Re:From the ESA website:.. by Blakey+Rat · · Score: 1

      That would have been much funnier as a "your momma so fat..." joke. Still good though.

      --
      Comment of the year
    5. Re:From the ESA website:.. by ricky-road-flats · · Score: 1

      How did you manage a +3 informative for insulting my girlfriend?

      He made a mistake and fluked it. Obviously, if he'd said it about your mom instead he would have got the full +5 insightful.

    6. Re:From the ESA website:.. by Ontheotherhand · · Score: 1

      My mum has an eating disorder, you insensitive clod!

      besides, this is slashdot. i have an imaginary girlfriend. surely my mum is out of bounds?

  9. Use a terrestrial earthquake method instead . . . by PolygamousRanchKid+ · · Score: 1

    Why not use a unfeasibly massive cloud of Internet grid connected next generation aspect oriented sensors instead? Spam everyone on the Internet, and ask them in which direction gravity is manifesting itself in their part of the world. I think most respondents will reply "down."

    On the serious side, serious scientists have proposed using laptop accelerometers to detect earthquakes: http://www.wired.com/science/planetearth/news/2008/03/quake_network

    Maybe something free on the iPhone App Store could help the gravity folks out? You get a pop-up: "Please drop your iPhone from exactly one meter to the ground. We will now measure the impact time. Thank you."

    --
    Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
  10. Theory by Samschnooks · · Score: 1

    ...knowledge and understanding of Earth-system processes and their evolution,...

    We all know that Evolution and Gravity are just theories and there's no concrete evidence that they exist. Okay? We also need to teach "Intelligent Downward Pull". There may be some intelligent force that really loves us and doesn't want us flying off into space - upon which we'd hit the Sun because it revolves around the Earth.

    1. Re:Theory by JuzzFunky · · Score: 1

      Gravity is a myth...
      The earth sucks.

      --
      Unexpect the expected!
    2. Re:Theory by ChatHuant · · Score: 1

      We all know that Evolution and Gravity are just theories and there's no concrete evidence that they exist. Okay? We also need to teach "Intelligent Downward Pull".
       
        Already done

    3. Re:Theory by Anonymous Coward · · Score: 0

      dude - no offence, but this is not on topic. Find somewhere else to grind your axe.

  11. Re:Use a terrestrial earthquake method instead . . by Anonymous Coward · · Score: 0

    you're not very funny D:

  12. WTF is a ROCKOT? by Anonymous Coward · · Score: 0

    Or did you mean a rocket? What an idiot! You must be a foreigner!!! LOL

    1. Re:WTF is a ROCKOT? by TorKlingberg · · Score: 2, Informative

      http://en.wikipedia.org/wiki/Rockot
      It's a rather small Russian rocket.

    2. Re:WTF is a ROCKOT? by Anonymous Coward · · Score: 0

      It's a rather small Russian rocket.

      Is that a Rockot in your pocket, or are you just slightly pleased to see me?

  13. That's easy by JuzzFunky · · Score: 1

    It's down.

    --
    Unexpect the expected!
  14. Cheap launch by benjfowler · · Score: 0, Flamebait

    Glad they managed to get GOCE to orbit in one piece.

    Cut-price Russian satellite launches don't seem to work out all that often. Probably a good thing for American cities in the case of a nuclear war...

  15. mnb Re:What this information is useful for: by Anonymous Coward · · Score: 0

    Making ICBMs more precise.

    Scared yet?

    Not at all, as current geoid models are accurate world-wide to within 30 meters or so, which is more than adequate as the effects of absolute elevation on horizontal navigation are negligible.
    30 meters might be enough error to cause concern when it comes to altitude of detonation, but to the best of my knowledge no munitions rely on GPS for that role, they all use barometric, radar, or some other more reliable source of altitude triggering.

  16. Now if only we could launch a carbon sat... by xxxJonBoyxxx · · Score: 1

    Now if only we could launch a satellite to keep an eye on carbon...we did? What happened?

  17. Formation of the moon by DigiShaman · · Score: 1

    Would it be possible to pin-point the location of impact to the Earth that formed our Moon? I would think the impacted site would be more dense from compression.

    Then again, I'm no geologist.

    --
    Life is not for the lazy.
    1. Re:Formation of the moon by Anonymous Coward · · Score: 0

      Then again, I'm no geologist.

      And that's no moon.

    2. Re:Formation of the moon by khayman80 · · Score: 2, Interesting

      GRACE has found what many believe to be an ancient impact crater in Antarctica. It might have been responsible for splitting Antarctica away from Australia, and might have been responsible for the Permian extinction. The researchers note that it formed 260 million years ago- around the right time, and it was directly opposite to the usual culprit- the Siberian traps. It's possible that the impact sent shockwaves around the world, which converged on the antipodal point and triggered the Siberian traps.

      But that's a "new" 260 million year old meteorite. What you're talking about is a 3 billion year old impact with something the size of Mars. Plate tectonics have probably erased that evidence. Also, large scale impacts are HARDER to find than smaller impacts because large impactors penetrate the crust, and magma rises up to fill the crater.

      Interesting notion, but I'd be surprised if it's possible...

    3. Re:Formation of the moon by smoker2 · · Score: 1

      When talking about a Mars sized impact, there would be no crater. It would pretty much liquify the crust and homogenize the rock structure planet wide. The moon was probably formed before the earths surface was completely solidified anyway, if you take an impact as the likely formation method. The fact of the moons low density does give credence to the impact theory as it is composed of the less dense rocks that might have been knocked off the earth. The denser stuff like iron was already deeper in the earth and so remained there.

  18. Re:What this information is useful for: by guruevi · · Score: 1

    No. Currently ICBM's are accurate anywhere from 1 to 100 cm. It doesn't really matter if it's off even 5x that amount, the target will get hit or be incinerated.

    --
    Custom electronics and digital signage for your business: www.evcircuits.com
  19. Sounds like by Anonymous Coward · · Score: 0

    It is sad that my mind makes a connection to goatse whenever I hear GOCE.

    *sigh* damn you internet.

  20. Re:Use a terrestrial earthquake method instead . . by TapeCutter · · Score: 1

    Speaking of earthquakes, we had a small tremor a week or so ago here in Melbourne, Australia. We just had another one a short while ago. I'm sure there are people on here who live where they get earth tremors all the time but it's unusual to have two in a short space of time down here.

    --
    And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
  21. Re:What this information is useful for: by Ihlosi · · Score: 1

    Currently ICBM's are accurate anywhere from 1 to 100 cm.

    American and Russian ones, because these nations have their own gravity mapping satellites. (and I believe the number was somewhere around 100m, i.e. the payload has a 50% chance of landing in a circle with 100m diameter of the target).

    Can you say the same about French and British ICBMs? Do the US share all of the significant digits of their gravity maps? Do they keep them up to date, too?

  22. Crap Acronym! by AP31R0N · · Score: 1

    Half of the word in the name are ignored. They just picked a few letters that could make a sound.

    It's a crapronym! (c) 2009 Apeiron

    Crapronym - a kludge of an acronym that ignores the rules of abbreviation

    Look, if you can't give a project a name like, Percy or "The Gravity Observation Thing", at least go with an honest unpronounceable abbreviation. You can leave out the articles and prepositions if helps. But this is just laziness.

    --
    Utilizing the synergization of benchmark e-solutions to pre-workaround action items!
  23. The next big scam: Gravity shortage! by Anonymous Coward · · Score: 0

    But nobody can figure out a way to get the Chinese to use less gravity, so we're really stuck. Unlike global warming... oops... never mind.

  24. Re:What this information is useful for: by dwiget001 · · Score: 1

    Last time I had data on ICBMs (80s?) a miss of 50 or 100 miles by an ICBM was considered a "near miss". /shrug