The NASA spacecraft MESSENGER swept past Mercury today, and everything looks good. Some science data were returned today, but no images have been posted as yet. Tomorrow at noon EST it will point its antenna homeward and send us the rest of the data, and I’m hoping we’ll see some images then.
The image here was taken on the 13th, from a distance of 760,000 km from the planet. You can already see many features! I can’t wait for the good stuff to come in.
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Phil Plait, the creator of Bad Astronomy, is an astronomer, lecturer, and author. After ten years working on Hubble Space Telescope and six more working on astronomy education, he struck out on his own as a writer. He has written two books, dozens of magazine articles, and 12 bazillion blog articles. He is a skeptic, and fights misuses of science as well as praising the wonder of real science.
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January 14th, 2008 at 5:03 pm
This is OBVIOUSLY a fake. Just where are all the stars in the background!?
January 14th, 2008 at 5:11 pm
“This is OBVIOUSLY a fake. Just where are all the stars in the background!?”
That isn’t even the most revealing mistake. NASA didn’t even finish rendering the planet with Photoshop!
January 14th, 2008 at 5:16 pm
What will people do when an image of Hermes shows up in the pictures of the surface?
January 14th, 2008 at 6:12 pm
I heard a rumor that Messenger was actually supposed to probe Venus but ended up at Mercury because of an English to metric conversion mistake by NASA.
January 14th, 2008 at 6:24 pm
Lugosi,
That sounds pretty unlikely, it would be more likely to just fly off into space and be lost. MESSENGER (the acronym refers to Hermes/Mercury, the messenger of the gods) was designed to go to Mercury. You may be thinking of the Mars Climate Orbiter, which was lost because a Lockheed Martin engineering team used English units of measurement while NASA used metric.
http://www.cnn.com/TECH/space/9909/30/mars.metric.02/
January 14th, 2008 at 6:43 pm
Dayum… Beautiful.
You know, you could go ahead and say “That’s the moon!” and I’d believe ya.
January 14th, 2008 at 6:44 pm
What color is Mercury? I have seen images depicting it as either gray or red.
January 14th, 2008 at 6:53 pm
(Lugosi was just being funny…. see previous two posts for “conspiratorial” context!)
Two (serious?) questions:
1> Considering how deep into the Sun’s gravity well Mercury is, do we have to account for relativistic effects in plotting Messenger’s course, or is Newton able to pull off a good enough approximation?
2> I, too, would like to know what Mercury’s natural coloration is!
January 14th, 2008 at 7:26 pm
I had heard that images will not be available for 2 weeks. Why do we not get images as they are sent, like we did during the Voyager missions?
January 14th, 2008 at 9:01 pm
Duane,
Yes, general relativity is factored in to precisely navigate the spacecraft to Mercury. Think of it this way: if the probe is whizzing by Mercury, it’s approximately as deep in the Sun’s gravity well as is the planet. However strong the GR effects are for Mercury is how strong they are for the probe.
Note: Of course, it would be possible to navigate using only Newtonian principles, but the GR effects would still be there, and the trajectory would progressively deviate from Newtonian, necessitating a great deal of trajectory adjustment along the way, wasting much propellant. It’s cheaper to just do the GR math.
January 14th, 2008 at 10:12 pm
Duane,
Check out searches on “precession perihelion Mercury”. There are Newtonian effects that cause the orbit of Mercury to precess around the Sun, but they don’t account for all of it. GR calculations actually account for the rest of it to great precision.
January 15th, 2008 at 3:02 am
Mark / Bill is there an online resource that either of you know of that explains GR as it applies to navigation in missions such as Messenger’s?
I’d just like a layman’s understanding of what is going on. Don’t GPS satellites also take this into account being so far from Earth?
BTW Emily is doing a great job through the Planetary Society blog getting the inside info on Messenger. Awesome.
Bob(big)
January 15th, 2008 at 3:30 am
Gary F:
Thanks for the valuable information. A lesser man than yourself might have assumed I was making some sort of vague attempt at humor.
January 15th, 2008 at 8:03 am
Don’t worry Lugosi, I got your joke, and responded with the laughter it deserved.
January 15th, 2008 at 9:28 am
Mark Martin: “It’s cheaper to just do the GR math.”
I don’t believe they use GR in trajectory mechanics, Newtonian mechanics still serves perfectly for this purpose. Relativistic effects at Mercury’s distance are far, far smaller than other undesired perturbations such as solar light pressure or Mercury mascons (once in orbit, of course).
GR *may* be taken in account when measuring Doppler shift for precise ranging, but IIRC all trajectory design is still done via Newtonian equations. There really is no point in GR, it would simply be overkill with all the other unmodelable perturbations.
January 15th, 2008 at 9:31 am
Note, however, that relativistic effects on Mercury amount to 43 arcseconds per century. It’s pretty insignificant over a few years, especially once you’re in orbit around Mercury. I’d bet that the errors in the trajectory due to measurement errors on position/velocity and due to anomalous forces on the spacecraft overwhelm this. That said, I’m think that JPL nav. teams do actually take relativity into account (I know some scientists have to in order to get sufficiently accurate location information on spacecraft). I could ask, but I wouldn’t have an answer very quickly.
As for color of Mercury, I don’t think that there have been a lot of multi-filter images taken, so the gray you usually see is probably just because it was a black-and-white image. On the other hand, Mercury is a lot like the Moon, as far as I know, so gray is quite possibly the dominant color. Sadly, getting accurate color from spacecraft is crazy difficult. We sincerely try our best on Cassini, but it’s amazing how much uncertainty there really is.
January 15th, 2008 at 9:39 am
“We sincerely try our best on Cassini”
OT, John, but are you working for CICLOPS? (John Weiss, perhaps?). If so, I was always interested in the way you generate color images – was it using groundbased visual spectra of Saturn or did you “borrow” detailed spectra VIMS has to offer? I notice VIMS color results look pretty close to ISS color shots in most cases (apart from “blue cranium” that is).
January 15th, 2008 at 10:10 am
Yep, that’s me. I’m not directly involved in producing public images, but I work with the guys who do it. The ground-based calibrations are used, but unfortunately they’re only so reliable since things change over the course of the launch and cruise. So star calibrations are used somewhat, but especially calibrations based off of moons. (We can compare them to HST photometry at very low phase.) It’s a pain in the tail, though, because there’s ambiguity on how to weight the various data sets. The result is that each filter has an error associate with its calibration. If you take extreme errors in the various filters, the color changes are noticeable to the human eye. As a result, it isn’t entirely automated.
January 15th, 2008 at 10:25 am
I’m only asking this because even calibrated imagery (say one that gives a white Enceladus in RGB) doesn’t produce Saturn looking like all those releases (or VIMS “proper” CIE XYZ output), but rather the blue channel ends up too dim. Same for Titan. In the end some fudging/guessing/channel mixing is probably inevitable, be it with perfectly calibrated imagery or not.
But, I digress… As I write this, MESSENGER ought to be about an hour into its data playback. Tentatively, some images might appear as early as tonight (EST), though more likely tomorrow.
January 15th, 2008 at 10:43 am
Lugosi on 14 Jan 2008 at 6:12 pm:
“I heard a rumor that Messenger was actually supposed to probe Venus…”
*snicker*