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NASA's Dawn Spacecraft Becomes First To Orbit a Dwarf Planet

The Grim Reefer writes with news that at 7:39 AM EST (12:39 UTC) today, NASA's Dawn spacecraft was captured by the gravity of dwarf planet Ceres. Mission controllers at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California received a signal from the spacecraft at 5:36 a.m. PST (8:36 a.m. EST) that Dawn was healthy and thrusting with its ion engine, the indicator Dawn had entered orbit as planned. "Since its discovery in 1801, Ceres was known as a planet, then an asteroid and later a dwarf planet," said Marc Rayman, Dawn chief engineer and mission director at JPL. "Now, after a journey of 3.1 billion miles (4.9 billion kilometers) and 7.5 years, Dawn calls Ceres home." In addition to being the first spacecraft to visit a dwarf planet, Dawn also has the distinction of being the first mission to orbit two extraterrestrial targets. From 2011 to 2012, the spacecraft explored the giant asteroid Vesta, delivering new insights and thousands of images from that distant world. Ceres and Vesta are the two most massive residents of our solar system's main asteroid belt between Mars and Jupiter. Further details available from the Planetary Society.

49 comments

  1. Can't...resist...pun by Tablizer · · Score: 3, Funny

    This is the dawn of a new era in space exploration.

    1. Re:Can't...resist...pun by Anonymous Coward · · Score: 1

      You can't be cereous, are you?

    2. Re:Can't...resist...pun by xevioso · · Score: 1

      don't make me kick your as-teroid.

    3. Re:Can't...resist...pun by sconeu · · Score: 1

      Your UID is too high to remember him, but this would have been a perfect response for the "IF I EVER MEET YOU I WILL KICK YOUR ASS" guy.

      --
      General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
    4. Re:Can't...resist...pun by InterGuru · · Score: 1

      don't make me kick your as-teroid.

      Do you mean ass toroid -- a toilet seat?

  2. No pictures yet by mike2006 · · Score: 3, Funny

    The processing and removal of the larger and slightly smaller brightly lit pyramids will take time.

    1. Re: No pictures yet by hal9035 · · Score: 1

      Why the news black out for a month? All of a sudden the cameras won't work until nearly the end of April? Explanation? BUELLER? BUELLER?

  3. Now for the orbit of a gnome planet by Anonymous Coward · · Score: 0

    Because we can't be racist and favor dwarves over others.

  4. Slow boo boo versus fast boo boo by Tablizer · · Score: 1

    My understanding is that the ion engine acts quite slowly. It seems that the "news" of an orbit failure would be a matter of not being where it's expected to be, and there should be a period of uncertainty when the "error" is within expected measurement noise range such that "orbit failure" would be a slowly increasing probability value instead of a one-time confirmation. I don't get the "news point" thing of today.

  5. I believe the preferred term by xevioso · · Score: 4, Funny

    I believe the preferred term is "Little Person Planet"

    1. Re:I believe the preferred term by jtownatpunk.net · · Score: 3, Funny

      So when does the satellite toss it?

    2. Re:I believe the preferred term by spire3661 · · Score: 1

      Dont tell the Elf.

      --
      Good-bye
    3. Re:I believe the preferred term by Anonymous Coward · · Score: 0

      Elf planet*

    4. Re:I believe the preferred term by sconeu · · Score: 3, Funny

      I believe they prefer the term "Gravitationally Challenged"

      --
      General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
    5. Re:I believe the preferred term by Anonymous Coward · · Score: 0

      And I think the politically correct term for "orbiting" is "gravitationally assisted elliptical motion".
      We do not want the Little Person Planet feel "weight challenged".

  6. Pretty amazing by argStyopa · · Score: 5, Interesting

    Ceres gravity is 0.27 m/s2 (Earth's is 9.8, Luna is a hefty 1.6)

    So 'going into orbit' of something so vanishingly weak is really an amazing accomplishment, discussed in their blog at http://www.planetary.org/blogs....

    (Amusing point of reference, with 3 ion engines, Dawn's 0-60 speed is 11 days. Take that, Jeremy Clarkson!)

    Congrats all.

    --
    -Styopa
    1. Re:Pretty amazing by nadaou · · Score: 2, Informative

      > Ceres gravity is 0.27 m/s2 (Earth's is 9.8, Luna is a hefty 1.6)

      Hold your finger out in front of you. Over 1 second accelerate it to
      end up 27 cm below where it started. It's still a reasonably attractive
      force.

      --
      ~.~
      I'm a peripheral visionary.
    2. Re:Pretty amazing by tompaulco · · Score: 3, Informative

      On the other hand, on Earth, by the time you have fallen for two seconds, you are traveling almost 20 meters per second, and you are probably going to die on impact. On Ceres, you can fall for over 70 seconds and over 700 feet and not reach the same velocity.

      --
      If you are not allowed to question your government then the government has answered your question.
    3. Re:Pretty amazing by Anonymous Coward · · Score: 0

      Over 1 second

      More precisely, 1.414 seconds.

    4. Re:Pretty amazing by Anonymous Coward · · Score: 0

      Ceres gravity is 0.27 m/s2 (Earth's is 9.8, Luna is a hefty 1.6)

      0.27 m/s^2 is close to acceleration due to Earth's gravity at geosynchronous orbit. Comparing surface gravity has as much to do with a body's density as it does with its total mass. But away from the surface then depends more on the actual total mass and distance.

    5. Re:Pretty amazing by nadaou · · Score: 1

      right.

      on cerces square roots you too.

      --
      ~.~
      I'm a peripheral visionary.
    6. Re:Pretty amazing by Anonymous Coward · · Score: 0

      And Rosetta is orbiting a comet, with a gravity field several orders or magnitude weaker.
      The two important parameters are the mass of the object you want to orbit and the distance from the center of gravity, for Rosetta the distance is much lower, but the mass difference more than makes up for it.
      Besides that, Ceres (and Vesta), are objects which are reasonably spherical, so the gravity field is esay to model as depending only on the distance to the center of the object as an inverse quare law (then orbit perturbations can give information about the internal structure). Given the shape of the comet, its gravity field can only approximated with the same simple model at distances far larger than Rosetta's.

    7. Re:Pretty amazing by argStyopa · · Score: 1

      Just FYI I think it's an asshole American who responds to China's landing a rover on the moon with "so what, we were there already, nyah, nyah"

      Your response, and my reaction to you: pretty much the same in both ways.

      --
      -Styopa
  7. dwarf planet definition is bullshit by rubycodez · · Score: 2, Interesting

    "Has to have cleared orbit". Even if Earth or any other rocky planet put where Ceres or Pluto was, they couldn't clear that orbit.

    They're planets. "Dwarf planet" is an invention of morons, 95 percent of the astronomers in the IAU didn't vote on it because of when the vote was done.

    1. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 1

      "Has to have cleared orbit". Even if Earth or any other rocky planet put where Ceres or Pluto was, they couldn't clear that orbit.

      Okay? So then Earth would be a dwarf planet if it were where Pluto is. And if my aunt had balls she'd be my uncle. So what? All categories are just words we make up to group things. We either had to put Pluto in the "not a planet" group, or expand the "planet group" to cover many, many more objects.

      I think you're just angry that something you learned as a child has changed.

    2. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 0

      Even if Earth or any other rocky planet put where Ceres or Pluto was, they couldn't clear that orbit.

      And you base this statement on what? You're gut feeling that is trying to rationalize what you want?

      The Stern-Levison parameter has been found to relate to ability of a body to clear out its orbit over a time period comparable to the solar system formation, and if the number is much bigger than 1, it is able to do so, and much less than 1, it isn't. Earth's parameter is ~150000 in its current orbit, and would still be ~600 if placed in Pluto's orbit. Pluto's Stern-Levinson parameter on the other hand is ~0.003. Even if you moved Pluto to where Earth is, it wouldn't have much chance to clean things out.

      Orbits aren't hard to clean out because there is a lot of stuff there, as all orbits used to have junk in them. Causation goes the other way, there is a lot of stuff there because the body isn't doing a good job of cleaning it out. It happens the ability to do so scales with mass squared, so that makes a huge difference when comparing Pluto to other rocky planets.

    3. Re:dwarf planet definition is bullshit by rubycodez · · Score: 4, Interesting

      Nonsense, I'd have no problem with 14 planets now rather than the 9 there were defined when I was a child.

      We expand the list of discovered planets, with a sane definition of "planet". That's the proper thing to do.

    4. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 0

      "Dwarf planet" is an invention of morons, 95 percent of the astronomers in the IAU didn't vote on it because of when the vote was done.

      People make a big deal about the percentage of people who weren't there, yet disregard so many other things: the decision could have been made without a general vote and was originally going to be done by a committee and it only went to general vote because they were unsure exactly which of three definitions to use; that those general assembly meetings tend not to have a majority of IAU members in them; that when a petition was given to all 9000 members to sign to object, only ~80 of them did; that the members that did vote had good representation from planetary astronomers; or that various other efforts to survey the IAU members show overwhelming majority support it just like the actual vote did.

      Even if only 5% of the members were there, everything points to it being a representative vote on the matter and things wouldn't have been different if every member was forced to submit a vote.

    5. Re:dwarf planet definition is bullshit by itzly · · Score: 2

      If you want to call it a planet, nobody's stopping you. Myself, I think it's wrong to call one fruit an "orange" after its color, but call another fruit "banana", which has nothing to do with the color. So, therefore I always refer to it as a "yellow". The word "banana" is an invention of morons.

    6. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 0

      It's the other way around, the color came from the fruit.

    7. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 0

      This. People like to pretend that there is some inconsistency with the current definition that there wouldn't be with the one they want. But it is all just BS when you look at the actual numbers.

    8. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 0

      Calm down homie. It's a classification, that's all. It doesn't change anything other than giving it a more descriptive title. Ceres and Pluto aren't any less important now than they were before.

    9. Re:dwarf planet definition is bullshit by CaptainLard · · Score: 1

      sane definition of "planet"

      Care to elaborate?

    10. Re:dwarf planet definition is bullshit by Anonymous Coward · · Score: 0

      But what if it doesn't stop at 14? What if we discover that our old definition of planet leads to us having hundreds of planets?

      The reason you'd be happy with 14 but not with 8, by the way, is that you feel like you're losing something.

    11. Re:dwarf planet definition is bullshit by rubycodez · · Score: 1

      Yes, removing that silly rule I mentioned in this thread's first post

    12. Re:dwarf planet definition is bullshit by rubycodez · · Score: 1

      So then the solar system has lots of planets. No problem. Are you worried we'll run out of names? We will not.

  8. "reatlowing beacons"??? by SpammersAreScum · · Score: 2

    Quoting from the Planetary.org article: "While there are countless questions about Ceres, the most popular now seems to be what the bright spots are. It is impossible not to be mesmerized by what appear to be reatlowing beacons, shining out across the cosmic seas from the uncharted lands ahead." "reatlowing" doesn't appear to be a real word, and I can't figure out what was meant. Any ideas?

    1. Re:"reatlowing beacons"??? by thakalas · · Score: 2

      I think it's a perfectly cromulent word.

    2. Re:"reatlowing beacons"??? by Anonymous Coward · · Score: 1

      It's "Great Glowing", where some miscreant has purloined the G's.

    3. Re:"reatlowing beacons"??? by Anonymous Coward · · Score: 0

      great glowing beacons is my guess, and some kind of copy paste or something mucking it

    4. Re:"reatlowing beacons"??? by OolimPhon · · Score: 1

      Chance collisions with debris have eroded the camouflage covering, exposing the battle steel underneath.

  9. Re:Not the first to post by Applehu+Akbar · · Score: 1

    Didn't it previously orbit Vesta?

  10. We demand equal gravity for all planets! by mi · · Score: 1
    • What do we want?
    • Equal gravity!!
    • When do we want it?
    • Now!!!!

    The Big Astronomy does not want you to know, that big planets are getting bigger, while the small ones are getting smaller.

    --
    In Soviet Washington the swamp drains you.
  11. Approach trajectory by amightywind · · Score: 1

    The approach trajectory was particularly cunning considering that there was an outage of Dawn's ion thruster.

    --
    an ill wind that blows no good
  12. Re:"reatlowing beacons"??? - "glowing beacons" by SpammersAreScum · · Score: 1

    I posted a comment on the blog about it, and the author said he wrote "glowing" but somehow it got mangled. Fixed now.

  13. Re: Not the first to post by hal9035 · · Score: 1

    Why the news black out for a month? All of a sudden the cameras won't work until nearly the end of April? Explanation? BUELLER? BUELLER? BS?

  14. Re: Not the first to post by Applehu+Akbar · · Score: 1

    This was the time it spent transitioning from orbit at Vesta to orbit at Ceres. There was obviously not much to see during this time except for the tantalizingly increasing resolution of Ceres. People began to take notice when the two bright spots came into view.