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NASA's MESSENGER Mission To Crash Into Mercury In 2 Weeks

Posted by Soulskill on from the take-that,-mercury dept.

astroengine writes: NASA's MESSENGER spacecraft is in the final days of an unprecedented and unexpectedly long-lived, close-up study of the innermost planet of the solar system, with a crashing finale expected in two weeks. Out of fuel, the robotic Mercury Surface, Space Environment, Geochemistry and Ranging, or MESSENGER, probe on April 30 will succumb to the gravitational pull of this strange world that has been its home since March 2011. The purpose of the mission, originally designed to last one year, is to collect detailed geochemical and other data that will help scientists piece together of how Mercury formed and evolved. "MESSENGER is going to create a new crater on Mercury sometime in the near future ... let's not be sad about that," NASA associate administrator John Grunsfeld said Thursday. The Johns Hopkins Applied Physics Laboratory has an excellent site for looking through the pictures MESSENGER has taken and the science it's done.

12 of 40 comments (clear)

  1. Backro-tastic by Ralph+Wiggam · · Score: 5, Interesting

    Can we take a second and thank the person who came up with the fantastic backronym "Mercury Surface, Space Environment, Geochemistry and Ranging" for MESSENGER.

    For those that don't know, Mercury was the messenger of the Gods.

    1. Re:Backro-tastic by Sique · · Score: 2
      The Mercury probes were never called Voyager before, so why start now?

      The first space probe to pass Mercury was Mariner 10. Mariner 11 and Mariner 12 were supposed to fly to Jupiter and Saturn, but they were renamed to Voyager 1 and Voyager 2.

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      .sig: Sique *sigh*
  2. Re:how Mercury evolved? by Anonymous Coward · · Score: 2, Informative

    Lots of things evidently crash into it:

    MESSENGER Finds Spacecraft Graveyard on Mercury

  3. Re:Interesting.. by Joviex · · Score: 2

    I love reading about this stuff. Space has always been something that amazes me. It will be awesome to see what the future holds as we learn more about what is out there.

    Well I can understand, Space is, after all, a huge subject.

  4. "succumb to the gravitational pull"??? by idji · · Score: 2, Insightful

    When will people stop talking about gravity is it it is in a struggle with object X and eventually it wins. People constantly talk about "Black Holes" sucking in, "inevitable"....
    MESSENGER did NOT run out of fuel and SUCCUMB to the gravitation pull of Mercury. Mercury ran out of fuel and continued on it's gravitationally influenced trajectory which was chosen to crash it. they could have left it in an eternal orbit if they wanted too - and the journalist would probably say it "did not succumb" to gravity - which is equally nonsensical. Gravity did not some get the upper hand because this spacecraft ran out of fuel. That craft will always be influenced by Mercury's gravity, no matter how many fragments it smashes into, unless a fragment gets an upwards speed of more than 4.3km/s, in which case it will ESCAPE Mercury's gravity.

    1. Re:"succumb to the gravitational pull"??? by Tablizer · · Score: 2

      they could have left it in an eternal orbit if they wanted too

      I believe some reaction between the Sun and Mercury gradually degrades orbits of probes in the area. Being that close to the Sun makes the effect fairly large.

      It may be true that if they had a bigger orbit it may have been able to stay in orbit a long time. But, scientists wanted to get closer to the planet for more detailed observations.

      It's probably not a big concern anyhow because the probe would typically run out of instrument orientation fuel after a few years, unless you spend more to launch bigger tanks.

      But, being Mercury is mostly a "dead" world, you are not going to see many new things after a couple of years in orbit such that "lingering" a good while may not be cost effective. If you were studying the atmosphere of say Venus or Jupiter, then lingering makes more sense because the weather patterns are always changing.

      --
      Table-ized A.I.
    2. Re:"succumb to the gravitational pull"??? by Anonymous Coward · · Score: 2, Insightful

      The pull of the Sun perturbing the orbit of something that close to Mercury causes the orbit's periapsis to lose altitute. Seems like he's correct, maybe just worded awkwardly.

    3. Re:"succumb to the gravitational pull"??? by Tablizer · · Score: 2

      I'd qualify that and say NASA decided not to spend (precious) fuel on "parking" it in a more stable orbit. But the trade-off would be either a shorter "active" mission or observations not as close to the planet.

      Obviously getting the most science from the probe trumps other issues such as museum pieces for great great great grandchildren. I'd slap them myself if they shorted current science to "save" the probe for future museums.

      Note that they sometimes decide on a "controlled" crash to reduce biological contamination risk to a planet or moon. But I don't think that's the case here.

      --
      Table-ized A.I.
    4. Re:"succumb to the gravitational pull"??? by Anonymous Coward · · Score: 2, Insightful

      Range of eccentricities and timescales involved in the Kozai mechanism depends strongly on the parameters of the Mercury-Sun orbit, and weakly on the orbit of the satellite. They would have had to move the satellite considerable distance away from Mercury, used a very circular orbit, and/or put it into an orbit aligned with the Mercury-Sun orbit. Most of its propellant was used by the time it finished orbital insertion. It would not have had enough fuel to make a large orbit change at this point, and small changes would only delay the mechanism's process by a couple years. They would have had to fundamentally change the project from the start, including scrapping studying of the poles that previous probes did poorly at, and scrapping any close study that required elliptical orbits.

  5. In this case it is gravity's fault... by Anonymous Coward · · Score: 4, Informative

    Normally I would agree with you on how gravity gets represented and how in a lot of situations you can replace a body with the same mass black hole with no changes (although get close enough, and things do change, e.g. innermost stable orbit).

    However, in this case the problem is gravity. The primary cause of orbital decay for MESSENGER is the Kozai mechanism, which is a three body interaction between the Sun, Mercury, and the probe, causing the probe's orbit to increase in eccentricity until it hits the surface. They had to keep using fuel to keep the eccentricity reasonable, especially considering it is in a pretty low orbit.

  6. Re:It's succumbing to atmospheric drag, not gravit by Anonymous Coward · · Score: 2, Informative

    Mercury has virtually no atmosphere, even with stuff from the Sun there is no atmospheric drag on the relevant timescales. As others point out, there is a three body physics effect here, in particular, it is the Kozai effect that makes the orbit eventually intersect the surface using just gravity alone.

  7. +5 but unfortunately wrong by Anonymous Coward · · Score: 3, Informative

    I can't blame people for modding the comment up, because of how much movies and some journalists get wrong with gravity. But in this case the statement came from the actual scientists and people on the project, because it is actually gravity in this case causing orbital decay. It isn't just from Mercury, but from the Sun being so near that three-body instabilities are much larger. Other comment(s) above explain in a little more detail already.