The case for water ice hidden in permanently shadowed regions at the north pole of the planet Mercury received another boost recently. On Wednesday March 20, 2013 at the Lunar and Planetary Science Conference, Nancy Chabot presented the very first visible-light images of what is in the shadows of these polar craters.
Before yesterday, my answer to this question would be "no." Now my answer is "probably." But it's not clear if we know which of the meteorites in our collections is from the innermost planet.
Last week the GRAIL mission published their first scientific results, and what they have found will send many geophysicists back to the drawing board to explain how the Moon formed and why it looks the way it does now. To explain how, I'm going to have to back way up, and explain the basic science behind gravity data.
Water ice at Mercury's poles? That's crazy, right? The MESSENGER team has made a very good case that radar-bright material seen by the Arecibo telescope is, in fact, water ice, covered in most places by a veneer of dark organic material.
Posted by Emily Lakdawalla on 2012/04/16 07:58 CDT
The MESSENGER mission just issued a press release announcing that they have completed the first step in the two-step process of lowering the spacecraft's orbit around Mercury.
Posted by Emily Lakdawalla on 2012/03/22 10:28 CDT
Water ice at Mercury's poles? That's crazy, right? Mercury is so close to the Sun that it seems inconceivable that you could have water ice there. But Mercury's rotational axis has virtually no tilt (MESSENGER has measured its tilt to be less than 1 degree), so there are areas at Mercury's poles, most often (but not always) within polar craters, where the Sun never rises above the horizon to heat the surface.
Posted by Emily Lakdawalla on 2011/10/05 11:04 CDT
Today I largely spent in the MESSENGER sessions. They have a lot of data to talk about.
Posted by Emily Lakdawalla on 2011/09/15 02:18 CDT
I'm preparing a talk for the Pacific Astronomy and Telescope Show here in Pasadena on Sunday afternoon at 1:45. I have spent the morning putting together a slide that I have long wanted to have for presentations.
Posted by Emily Lakdawalla on 2011/06/16 03:44 CDT
There was a press briefing today giving some early science results from MESSENGER and it was surprisingly meaty. I'm going to focus on just one set of the results that they presented.
Posted by Emily Lakdawalla on 2011/04/19 11:21 CDT
When Mariner 10 flew past Mercury, it caught an immense impact basin lying half in and half out of sunlight, which they named Caloris. Even with only half the basin visible, scientists knew it was one of the largest in the solar system. Geologists had to wait more than 25 years to see the rest of Caloris, and when they did it turned out to be even bigger than they had thought. But the fact that Caloris was only half in sunlight was fortuitous in one sense, because it meant that the spot on Mercury that was exactly opposite the area of the Caloris impact was also partially in sunlight. That spot looks weird.
Posted by Emily Lakdawalla on 2011/04/07 11:16 CDT
Regular readers of this blog will find the content of today's 365 Days of Astronomy Podcast familiar, because it's an update on what the solar system exploration spacecraft are up to, based on my monthly "what's up" updates.
Posted by Emily Lakdawalla on 2011/03/30 04:31 CDT
Today the MESSENGER mission held a press briefing to show off some of the first images and other data that are streaming in from the spacecraft, now that it has entered Mercury orbit.
Posted by Emily Lakdawalla on 2011/03/29 04:03 CDT
This is MESSENGER's very first photo from Mercury orbit, a wide-angle view that reaches right to Mercury's south pole, exposing a very tiny sliver of territory not previously seen by spacecraft.