Success! MESSENGER First Spacecraft to Orbit Mercury


After more than a dozen laps through the inner solar system, NASA’s MESSENGER spacecraft appears to have moved into orbit around Mercury tonight. Although Mariner in the 1970s and MESSENGER in the past several years have done flybys, MESSENGER is the first spacecraft to orbit the innermost planet in our solar system. NASA is stopping short of saying the spacecraft has achieved its planned orbit, but the clapping and hand-shaking in the control room looked highly optimistic.

“Preliminary results show that the burn went just as expected,” said a jubilant Ken Hibbard, an engineer at John Hopkins University’s Applied Physics Lab (APL), in a live report on NASA TV.

UPDATE, 9:50 p.m. EDT: NASA has abandoned all its cautionary language. MESSENGER is confirmed in orbit!

MESSENGER — which stands for MErcury Surface, Space ENvironment, GEochemistry and Ranging — launched Aug. 3, 2004 from Cape Canaveral. The orbit insertion places the spacecraft into a 12-hour orbit about Mercury with a 200 kilometer (124 mile) minimum altitude. The durable spacecraft is carrying seven science instruments and is fortified against the blistering environs near the sun.

The mission is an effort to study the geologic history, magnetic field, surface composition and other mysteries of the planet. The findings are expected to broaden our understanding of rocky planets, more and more of which are being discovered in other solar systems. One of the most compelling enigmas surrounds Mercury’s magnetic field. At a diameter only slightly larger than that of the moon (about 4,800 kilometers or 2,983 miles), Mercury should have solidified to the core. However, the presence of a magnetic field suggests to some researchers that the planet’s insides could be partially molten.

During its journey toward Mercury, MESSENGER passed the planet several times, filling in the imaging gaps left by Mariner 10. Now, the entire planet with the exception of about five percent has been observed. MESSENGER will focus its cameras on getting the best possible images of the remaining portions, mostly in the polar regions.

The MESSENGER mission is led by NASA, APL and the Carnegie Institution and includes a highly dedicated team of engineers, and many scientists.

“I’ve waited 36 years for this, and I’m about as excited as a person could get right now,” said Robert Strom, a MESSENGER team member from the University of Arizona’s Lunar and Planetary Lab.

Source: NASA’s MESSENGER mission website and NASA TV.

17 Replies to “Success! MESSENGER First Spacecraft to Orbit Mercury”

  1. I wonder if you could cook an EGG on the protective shield?
    Just Kidding! This is great News, and another American 1st success!
    My feeling is that ,there is a small liquid core. Now one Planet too explore and that is Pluto…

  2. Yay! “6 down, 2 more to go.” (Uranus, Neptune.)

    By the by, I’m suffering from severe memorus interruptus today, but I believe this text may be from a press release, I have seen it before? (If not, I offer my excuses to Anne.)

    [If you must know, I’m exhausted from upping my training, and not in a good way. The day before yesterday I tried a more intensive gym class, little did I know that they incorporated strength exercises. Yesterday I had my strength exercises, followed by a class with a temp. Who thought it would be a good idea to add some strength exercises…

    I feel I have hit the right regimen, when like the military I haven’t the strength left to criticize it.]

    In any case the offered motivation reads lackluster: “to broaden our understanding of rocky planets, more and more of which are being discovered”. So, now that Kepler tell us that Neptune analogs are the most numerous, we can’t use that; it would be like saying people prefer dogs, so we study cats.

    Nor can we say that rocky planets are the most interesting for Earth modeling or astrobiology, or that Mercury turned out active so another win for the Earth/astrobiology perspective. (This may be a Messenger result, lack of memory remember, but if a fact this is a good reason _now_.)

    But we can say that there are planets like this out there. Yay. 😀

    One of the most compelling enigmas surrounds Mercury’s magnetic field. At a diameter only slightly larger than that of the moon (about 4,800 kilometers or 2,983 miles), Mercury should have solidified to the core.

    Considering that NASA’s own data now predicts that the Moon has a liquid core still, this is an overly conservative analysis IMHO. It could be less of a specific enigma and more of a general phenomena.

    1. I swear I didn’t update to see Moonshine’s similar thoughts before posting. Great minds and all that…

    2. Mercury has a large magnetic field, though it is about .01 Gauss, while Earth’s is .5 Gauss. Mercury is also fairly dense, sometimes called the “iron planet,” which suggests an iron core which might be active. I would be surprised if Mercury turned out to have a completely dead core.


  3. Great stuff.

    What I’d like to know is (and maybe it’s already common knowledge so someone here can enlighten me) why Mercury appears to be ‘dead’ volcanically? I would have thought a rocky world (however small) so close to such a large gravitational force would be more active than Io.

    1. Not long dead perhaps. Precisely MESSENGER showed that Mercury had extensive and long time volcanism:

      “During its first two flybys of Mercury, the MESSENGER spacecraft acquired images confirming that pervasive volcanism occurred early in the planet’s history. MESSENGER’s third Mercury flyby revealed a 290-kilometer-diameter peak-ring impact basin, among the youngest basins yet seen, having an inner floor filled with spectrally distinct smooth plains. These plains are sparsely cratered, postdate the formation of the basin, apparently formed from material that once flowed across the surface, and are therefore interpreted to be volcanic in origin. An irregular depression surrounded by a halo of bright deposits northeast of the basin marks a candidate explosive volcanic vent larger than any previously identified on Mercury. Volcanism on the planet thus spanned a considerable duration, perhaps extending well into the second half of solar system history.”

      As you implied, it will be exciting to learn, if possible, the why, what and where on the volcanism and how it ties into geological history of rocky planets!

    2. Io’s tidal heating is not just due to Jupiter, but to it’s orbit between Jupiter and the moons Europa, Ganymede and Callisto. So it is sort of being tugged and stretched in different directions, causing the heating. Mercury has a spin/orbit resonance with the sun, but no other tidal interaction strong enough to be causing vulcanism.

  4. At risk of sounding like a dufus, could we not utilize Messenger’s instruments to give us an early warning of mass ejections etc. from the Sun or would Mercury’s magnetic field shelter the craft from making such observations?

    1. You’ve got to remember that Mercury and the Earth orbit the sun at very different speeds, and it is certainly not every day that MESSENGER will be directly in the path of an ejection from the sun headed towards Earth. I believe we’ve got an instrument at Earth’s inner Lagrange Point looking for the early warning signs of problems and helping to warn the crew of the ISS about when to seek shelter.

  5. It is SO COOL to have this mission arrive at Mercury just as Sol begins to ramp up!
    BONUS! This mission will dovetail perfectly with STEREO and SDO data!

  6. @xrayexplorer

    I don’t think that’s really a problem. We can visually see the ejections as they occur from Earth or the SOHO probes several days before the mass arrives.

  7. The Lord will punish us for all of our scientific endeavors. He wants us to use our energy and minds to praise Him, not scurry around in space. I’m not even sure this isn’t fake. Why are we searching for answers out there (and wasting money doing it) when the answer is in our hands? The Good Book provides all the knowledge we shall ever need.

    1. I know this is a troll And Should Not Be Responded To. But it is funny to me as it relates to what I just read something from someone truly wise:

      “The only difference I have seen between fundamentalist theology and “sophisticated” theology is that the former consisted of making stuff up to try to explain how the world works; and the latter consists of making stuff up to try and explain away the science that shows how the world really works.”

      HS-teacher makes a good effort to cover both versions of insanity, I’ll give him or her that.

    2. HS-teacher, if you are so angered by humankind’s scientific endeavours,then why do you make such a massive effort to find an astronomy/physics based website, trawl through it, then sign up for a weord press account just so that you can attack the fundamental properties of this amazing website? I think you should be ashamed of yourself for the wasting of everybody’s time,including yours and mine. Please don’tcomment here again.

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