Another Martian Eclipse?

MER Web site ^ | 3/8/04

[ElkGroveDan]

In browsing the latest RAW images downloaded from the Opportunity Rover, I noticed these two strange shots from their daily solar tracking images.

Could this be another eclipse of a Martian moon? The one last week was on SOL 39. These two were taken three days later on SOL 42.

[ElkGroveDan]

Your thoughts...

[ElkGroveDan]

PING (mars list ping request)

[kahoutek]

I hate those one-eyed Martians......

[Darksheare]

If it is, it's from something pretty close in to Mars.

[Cyber Liberty]

I think I saw an article posted last week about this. It's an eclipse, alright. Moon's too small to completely cover the sun's disc.

[ElkGroveDan]

Yes, there was an article, but these pictures were taken AFTER that event. I am suggesting that this is a different eclipse event from that one.

[ElkGroveDan]

Mars has two small moons, one of them is exceedingly close.

[Crazieman]

I think its Phobos off the top of my head. And if I remember right, it goes around the planet faster than the planet rotates.

[Darksheare]

Wonder how it looks when it occults the sun, and in what direction it's orbital motion is?

[Phil V.]

Dan, the pictures are posted correctly by the time code in the picture name.

The difference in time measured in seconds between the two solar shots (sol-039 to sol-042) is 258150 sec. or 2.988 days. The interval between the two snaps on sol-042 showing a "eclipse" is 10 sec.

Perhaps part of the rover eclipsed the sun?

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If you'd like to be on or off this MARS ping list please FRail me

[Darksheare]

Possible.
Unless Mars just recently had a close call.

[Darksheare]

Just had a horrible thought for no apparent reason:

What if our attempts to measure gravity waves are like trying to measure a tidal wave with a teaspoon?
What if gravity waves are both larger and more subtle than our instruments can measure?
(Or just larger.)

[ElkGroveDan]

I don't get your point.

I was pointing out that this could be an unanticipated eclipse, perhaps by Phobos. Phobos would actually appear bigger because it is so much closer to Mars, and these little bites do look bigger than the previous eclipse.

[Spruce]

Perhaps a shutter or cleaning attachment for the lens?

[Cold Heat]

Rover watches Martian moon eclipse sun
Last Updated Thu, 04 Mar 2004 20:07:39
PASADENA, CALIF. - The Mars rover Opportunity played astronomer and geologist on Thursday, photographing a rare eclipse and flexing its robotic arm in the most complex movements yet.

Opportunity turned its panoramic camera skyward to capture the Martian moon Deimos as it crossed between Mars and the sun.

Deimos is the smaller of Mars' two moons. The Opportunity gazed up, joining the European Space Agency's orbiter, Mars Express, to watch the same piece of sky.

The photos have not yet been released.

Opportunity also ran 490 commands to accomplish complex operations with its robotic arm and instruments.

The rover used its microscopic imager and M?ssbauer spectrometer on an area dubbed Last Chance.

On the other side of the planet, Opportunity's twin, Spirit, ground a two-millimetre-deep depression into a rock, and brushed off the dust to examine it.

[Phil V.]

Dan, YOU DA MAN!!! . . .

read . . . .

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NASA Rovers Watching Solar Eclipses by Mars Moons
March 8, 2004

NASA's Mars Exploration Rovers have become eclipse watchers.

Though the Viking landers in the 1970s observed the shadow of one of Mars' two moons, Phobos, moving across the landscape, and Mars Pathfinder in 1997 observed Phobos emerge at night from the shadow of Mars, no previous mission has ever directly observed a moon pass in front of the Sun from the surface of another world.

The current rovers began their eclipse-watching campaign this month. Opportunity's panoramic camera caught Mars' smaller moon, Deimos, as a speck crossing the disc of the Sun on March 4. The same camera then captured an image of the larger moon, Phobos, grazing the edge of the Sun's disc on March 7.

Rover controllers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., are planning to use the panoramic cameras on both Opportunity and Spirit for several similar events in the next six weeks. Dr. Jim Bell of Cornell University, Ithaca, N.Y., lead scientist for those cameras, expects the most dramatic images may be the one of Phobos planned for March 10.

"Scientifically, we're interested in timing these events to possibly allow refinement of the orbits and orbital evolution of these natural satellites," Bell said. "It's also exciting, historic and just plain cool to be able to observe eclipses on another planet at all."

Depending on the orientation of Phobos as it passes between the Sun and the rovers, the images might also add new information about the elongated shape of that moon.

Phobos is about 27 kilometers long by about 18 kilometers across its smallest dimension (17 miles by 11 miles). Deimos' dimensions are about half as much, but the pair's difference in size as they appear from Mars' surface is even greater, because Phobos travels in a much lower orbit.

The rovers' panoramic cameras observe the Sun nearly every martian day as a way to gain information about how Mars' atmosphere affects the sunlight. The challenge for the eclipse observations is in the timing. Deimos crosses the Sun's disc in only about 50 to 60 seconds. Phobos moves even more quickly, crossing the Sun in only 20 to 30 seconds.

Scientists use the term "transit" for an eclipse in which the intervening body covers only a fraction of the more-distant body. For example, from Earth, the planet Venus will be seen to transit the Sun on June 8, for the first time since 1882. Transits of the Sun by Mercury and transits of Jupiter by Jupiter's moons are more common observations from Earth.

From Earth, our Moon and the Sun have the appearance of almost identically sized discs in the sky, so the Moon almost exactly covers the Sun during a total solar eclipse. Because Mars is farther from the Sun than Earth is, the Sun looks only about two-thirds as wide from Mars as it does from Earth. However, Mars' moons are so small that even Phobos covers only about half of the Sun's disc during an eclipse seen from Mars.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington, D.C.

Images of the March 4 and March 7 eclipses are available online at http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20040308a.html. Other images from the rovers and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University at http://athena.cornell.edu.

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Guy Webster (818) 354-5011
JPL

Donald Savage (202) 358-1547
NASA Headquarters, Washington, D.C.

2004-81

[GeronL]

beats ny pair od dueces

[Alamo-Girl]

Thanks for the ping!

[ElkGroveDan]

...and once again the world read it first, here on FreeRepublic!

[Phil V.]

Modesty, Dan . . . MODESTY!

but the fact remains YOU DA MAN!!!


btw . . . I haven't yet tried out your hint on "flattening out" the hazcam photos, but I WILL. Thanks for the tip.