back to article Goodnight Kepler! NASA scientists lay the exoplanet expert to rest as it runs out of fuel

The Kepler spacecraft has coughed up its last reserves of fuel and is now retired, after helping scientists discover thousands of exoplanets for nearly a decade, NASA announced on Tuesday. “Fuel exhaustion means it has reached the end of its space life,” Charlie Sobeck, a project system engineer at NASA’s Ames Research Center …

  1. Mark 85 Silver badge
    Pint

    Pity there's no gas station around when you need one, but Kepler did a lot of great science in it's lifetime. Well done to NASA and Ames, have a frothy one before you look to the future explorations.

  2. defiler Silver badge
    Pint

    Noooooo!

    Shame. It did well. Very well.

    Here's to the next one.

  3. DCFusor Silver badge

    A song

    About just how much Kepler changed our world...and the search for planets in general.

    https://www.youtube.com/watch?v=gai8dMA19Sw

    Though based on a disney tune, I thought it pretty good.

    1. Ugotta B. Kiddingme
      Thumb Up

      Re: A song

      wow, that was simply outstanding. Thanks for sharing that.

  4. vir Silver badge

    And let's not forget that the design life was 3.5 years, which was up back in September of 2012!

    1. Charles 9 Silver badge

      Not only that, there wasn't any panic. A smooth, orderly wind-up with everything of value obtained in time. As far as "one-way" missions like this go, this is a best-case scenario.

  5. Joe Dietz
    Pint

    Well done

  6. Neil Barnes Silver badge
    Alien

    I hope

    That in a few hundred years or so, when it bumps into a passing alien interstellar probe, and wakes up to full sentience, it won't be *too* angry.

    1. Danny 14 Silver badge

      Re: I hope

      https://xkcd.com/1504/

  7. wt29

    What a bird - it has raised our collective view of the universe immeasurably.

    Well done to everyone involved.

  8. wt29

    RIP Kepler

    What a bird - raised our collective view of the universe immeasurably.

    Well done to everyone involved.

  9. Champ

    Fuel? Why no solar panels?

    I didn't think spacecraft were generally powered by a few gallons of 4 star? Why did Kepler use (exhaustible) on-board fuel, rather than (inexhaustible) sunshine?

    1. hammarbtyp Silver badge

      Re: Fuel? Why no solar panels?

      Even with solar panels you still need something to push out to move. True, they could of used Ion engines which would of reduced the action mass required, but even that would run out eventually (Smaller mass x higher speed). Also Ion engines are slow and steady, and probably would not be capable of moving a satellite like kepler at the rates required. Fine if you want to reposition over a period of months, but I'm not sure anyone is wanting to wait that long

      Finally Kepler has far exceeded its design lifetime, so the engines have done what they needed to do

    2. 0laf Silver badge
      Pint

      Re: Fuel? Why no solar panels?

      I think it's safe to say that the bods at NASA had very good reasons for chosing one form of propulsion over another.

      Yet another mission sadly ends although having greatly exeeded its original targets. Some excellent boffinry has been and is being done in our era. Libations for those white coats and engineers who have and are working on such wonderful projects!

    3. Scroticus Canis Silver badge
      Coat

      Re: Fuel? Why no solar panels?

      Oh it has those too. Don't think they were running a mini genset for the electrics :)

      With the electrically powered gyros bust they had to use fuel to point the comms at earth just to transfer the collected data, doubled the drain probably.

      If they had used imperial gallons it would still have a little life left.

      1. Hopalong

        Re: Fuel? Why no solar panels?

        Solar panels for power, the reaction wheels for fine pointing (powered by the solar panels), then the hydrazine powered RCS for things like unloading the momentum built up in the reaction wheels etc.

        The reaction wheels failed over time so it had to use the RCS to do the pointing, which used more hydrazine.

        So after 9 1/2 years, it had used up its 11.7 Kg of hydrazine. The camera was failing as well, so it was time for Kepler to retire with a job well done.

    4. Destroy All Monsters Silver badge
      Windows

      Can anyone shed light on how the recommendation soundbites are obtained

      I didn't think spacecraft were generally powered by a few gallons of 4 star?

      You now imagine Kepler warming itself by an oil barrel full of burnable material salvaged from abandoned housing in Detroit.

    5. Pen-y-gors Silver badge

      Re: Fuel? Why no solar panels?

      There were good reasons. But with hindsight, given the beast weighed over a ton, couldn't they have gone for an 8-gallon tank instead?

      1. Charles 9 Silver badge

        Re: Fuel? Why no solar panels?

        "But with hindsight, given the beast weighed over a ton, couldn't they have gone for an 8-gallon tank instead?"

        When it comes to launching things into space (and believe me, there's just no easy way around beating the Earth's inertia), weight is a very sensitive matter. We're talking ounce-precise calculations and so on due to the cascading problem that it takes fuel to get things into space...but fuel is weight that must be lifted up as well, which takes more fuel, and so on, and so on...

      2. Kevin McMurtrie Silver badge

        Re: Fuel? Why no solar panels?

        I'd say the gas mileage was pretty good. Doubling the fuel probably wouldn't help. Some components wear out from radiation or use. Making the components more robust could add so much weight that no amount of fuel can compensate for it (the fuel itself becomes too heavy).

    6. DuncanLarge Bronze badge

      Re: Fuel? Why no solar panels?

      It has panels all over it. But you cant use electricity to move a spacecraft (yet). Ion engines are ok for constant acceleration.

      To move a spacecraft you must squirt something out with force. That means you need fuel.

      1. Anonymous Coward
        Anonymous Coward

        Re: Fuel? Why no solar panels?

        To move a spacecraft you must squirt something out with force. That means you need fuel.

        I just use electric propellers on mine - you just need larger solar panels.

      2. Bruce Ordway

        Re: Fuel? Why no solar panels?

        >>electricity to move... NOT (yet)

        Now I wonder if you could use electricity to move a body in space?

        If motion might result from spinning eccentric thing(s)?

        And for fans of SciFi/fantasy, didn't the Stargate run on electricity?

    7. imanidiot Silver badge

      Re: Fuel? Why no solar panels?

      It did have reaction wheels to control it's orientation using electrical power. In which case it only needed the fuel to desaturate (spin down) the reaction wheels every once in a while. These are heavy however and the craft only carried one spare (4 total, needing at least 3 for accurate pointing) However, back in 2012 the second of the 4 wheels failed, requiring NASA to find a different way to keep the craft pointing at the target it was observing. They achieved this by carefully "leaning" the craft into the solar wind, then using the remaining reaction wheels to keep it steady in that position. This worked, but because a nearly constant force input from the remaining reaction wheels is required they need to be desaturated much more often, expending more fuel. (Exact details in the NASA paper here: https://keplerscience.arc.nasa.gov/docs/Kepler-2-Wheel-pointing-performance.pdf)

    8. JK63

      Re: Fuel? Why no solar panels?

      The fuel was for station keeping not for general propulsion. It also has nothing to do with sunshine, which is used to run the platform's electronics packages.

      The design life was 3.5 years. They got almost 10 out of the platform. Sorry that nearly 3x the design life isn't acceptable.

      1. david 12 Bronze badge

        Re: Fuel? Why no solar panels?

        >nothing to do with sunshine<

        The fuel has everything to do with sunshine. Without fuel, they can't keep the panels pointing towards the sun.

  10. Fizzle

    But why were the transmitters shut down?

    Why shut them down rather than just leave them running?

    Can someone explain that to me? What difference would it have made? Was it just housekeeping and was it necessary?

    1. Pen-y-gors Silver badge

      Re: But why were the transmitters shut down?

      I think the fuel may be needed to keep the transmitters aligned, so even if it kept transmitting it's only little green people on Mercury who'll hear it.

    2. Charles 9 Silver badge

      Re: But why were the transmitters shut down?

      "Why shut them down rather than just leave them running?"

      Kessler Syndrome, I think. At least with an orderly shutdown, they can reduce the chances it'll do something crazy and start making more space junk.

      1. Neil Barnes Silver badge

        Re: But why were the transmitters shut down?

        I suspect they shut down the transmitters so it doesn't interfere with anything else out in that direction in the future.

        1. 0laf Silver badge

          Re: But why were the transmitters shut down?

          They do exactly that. It's part of international agreements with space thingies. When they're done switch 'em off to prevent interference.

          Kepler is too far away to be de-orbited but it's also too far away to present much of a problem with regard to Kessler Syndrome. That's a near earth orbit issue.

    3. ilmari

      Re: But why were the transmitters shut down?

      If dead probes weren't shut down, you'd eventually have no frequencies left for new probes to transmit on. So they shut it off, while it's antennas were still pointing close enough towards earth to be able to receive commands.

      A US navy navigation satellite launched in 1964 still wakes up occasionally when it gets sunlight on its panels, and transmits telemetry. At its job of navigation satellite it failed 2 months after launch.

  11. Antron Argaiv Silver badge
    Happy

    Opportunity's last rights?

    Why?

    Can't it turn left?

  12. Michael H.F. Wilkinson Silver badge
    Pint

    Goodbye Keppler, you did brilliantly

    A toast to all those involved in this great space mission. At least the probe's name will live on in countless planets it has helped us find.

  13. imanidiot Silver badge

    Goodbye Kepler

    And thanks for all the exoplanets.

  14. E_Nigma

    A Bit Sad

    On one hand, I'm as sorry as everyone else that this wonderful piece of scientific machinery is now "dead" due to the trivial matter of fuel, but on the other hand, after almost 10 years, maybe it's time for a new telescope?

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