Astronomy News
Dr. Neal Sumerlin keeps us abreast of happenings in the night sky and the progress of the new Belk Astronomical Observatory.
Blogs we recommend
Other Posts:
Search (but no rescue) on Mars (05/20/2008)
We lose a friend (05/03/2008)
Quiz winner! (04/29/2008)
Seeing and Patience (04/22/2008)
The World at Night (03/31/2008)
New Stars that are Really Old (03/14/2008)
Latest From Planetary Spacecraft (03/14/2008)
Lunar Eclipse Update (02/18/2008)
Aiming a Telescope (02/18/2008)
Observatory Update (02/04/2008)
Venus and Jupiter in the Morning (02/04/2008)
Total Lunar Eclipse (02/04/2008)
Messenger Mission to Mercury (02/04/2008)
More News from Mars
Posted on 06/04/2008There has been an absolute flood of news from the Phoenix spacecraft that landed on Mars on May 25th. I’m going to try to give you some flavor of the highlights so far, and direct you to two excellent web sites if you want to explore further. The first web site is of course the home page http://phoenix.lpl.arizona.edu/ for the Phoenix lander. The second is my favorite astronomy blog, the Planetary Society Weblog http://www.planetary.org/blog hosted by Emily Lakdawalla. Her detailed and informative posts can satisfy even the nerdiest geek. I speak from personal experience.
Mission overview-- The Phoenix spacecraft is not a rover, so it is limited to observing and analyzing its immediate vicinity. It was sent to the northern polar region of Mars (Mars latitude 68° N) in the expectation that the subsurface ice scientists seek would be more widespread there. The search for water is crucial to determining if Mars was once the abode of life. All life that we understand requires water; perhaps Mars will show evidence of fossil life or even of life currently extant. The discovery of the independent emergence of life on another planet of course has profound implications. To be clear, however: the lander is looking for water, not directly for life. it is equipped with cameras, with a digging arm, and with chemical analytical instruments for determining the composition of the soil. It is summer in the northern hemisphere of Mars right now. The good news is that there are more hours of daylight (just as there are now in Earth’s more northern latitudes); the bad news is that the sun is rather low at these latitudes, and that the darkness of winter will eventually replace the light of summer. Phoenix is not expected to survive the Martian winter. The large solar panels on either side of the main lander are required because of the low sun angle and the immobility that prevents aiming them for maximum exposure. More good news is that Phoenix’s landing site is almost perfectly flat. At least we know the panels aren’t tilted away from the southern sky where the sun is to be found!
Ice already?-- The robotic arm on Phoenix is designed to dig deep into the soil (a meter or more) with repeated backhoe-like sweeps. No one knew before going how deep the ice might lie, even though they were confident it was there. Ice has a hard time surviving on the surface of Mars, simply because the very low atmospheric pressure (equivalent to the Earth’s atmospheric pressure at an altitude of 20 miles) allows the ice to turn directly to vapor even when the temperature is rather low. There IS ice on the surface, but it is usually found in areas shaded from direct sunlight such as the interiors of craters at high latitudes. Here is one such example:
The most exciting early image from the landing site was of an area directly beneath the lander. It appeared as though the landing rockets blew off the dust covering a patch of ice. If this is an accurate interpretation of the image, the robotic arm won’t have to go far to find ice after all. Here is the image, taken by the camera on the robotic arm effectively looking backward through its legs. It has been flipped so you won’t need to stand on your head! You can see the rocket nozzles at the top of the image.
Could it be ice?
The arm has been deployed and has already dug into the soil. Preliminary looks are very encouraging. The soil is cohesive, so the sides of the trench won’t cave in, the digging is easy, and there are white streaks that may or may not be ice.
A remarkable image-- I would be utterly remiss if I did not share with you one of the most amazing images I can recall from decades of following space voyages. The HiRISE camera on the Mars Reconnaissance Orbiter is effectively an orbiting telescope. (Regular readers of these newsletters may recall that it has taken images of the possible crash site of the 1999 Mars Polar Lander.) While the Phoenix lander was parachuting to its fate at a speed of several hundred miles per hour, the MRO was passing overhead at over 7,000 miles per hour. Two speeding bullets, and one of them took a picture of the other. Grainy though it is, this just takes my breath away. This is a picture of a spacecraft parachuting to the surface of Mars. What a time to be alive! I’m going to provide you with two links that have a total of three images, so you can see the detail and the larger context as well. The close-ups are here http://www.planetary.org/blog/article/00001464 ; the larger image is here http://www.planetary.org/blog/article/00001468 . Absolutely stunning.