Thursday, September 25, 2008
As always, Aura is monitoring stratospheric ozone levels. Yesterday, the "hole" or thinning over Antarctica reached a new low concentration - 106 Dobson units - for 2008.
Each year, ozone levels in the stratosphere drop in the Arctic and Antarctic in their respective winters. Cold temperatures in the atmosphere result in isolation of the air masses above the Arctic and Antarctic circles. This isolation, along with cold temperatures promote chemical reactions that favor the release of a chlorine atom from chemical compounds such as chlorofluorocarbons (CFCs). This Cl atom attaches itself to an oxygen atom and removes it from the ozone molecule. The result is a reduction of ozone in the ozone layer. This process is seasonal - once spring comes around and atmospheric temperatures rise, the isolated air masses return to normal circulation and the chemical reactions that caused the release of chlorine are no longer viable. Ozone levels in the stratosphere then return to normal.
Why are we so interested in stratospheric ozone hole? The ozone in the stratosphere protects all living beings on earth from harmful ultraviolet-c radiation. This uv-c causes the DNA in cells to break down, which can result in cancer. Without the ozone layer, uv-c would be able to penetrate the atmosphere and it would wreak havoc on all living things.
The Aura spacecraft also measures the other chemical players in the reactions that lead to the break down of ozone in the stratosphere in order to better understand how these reactions happen. This understanding can lead to the prevention of the release of chemicals that cause ozone loss into the atmosphere.
Thursday, September 18, 2008
Visitors to: http://www.airspacemag.com/space-exploration/Top_NASA_Photos_of_All_Time.html can view the top 31 images.
The following is from the Air and Space Magazine website.
On the occasion of the 50th anniversary of the National Aeronautics and Space Administration, which began its operations on October 1, 1958, we offer this list of the 50 most memorable images from NASA’s history . We recognize that any such ranking is inherently subjective. The rationale for why any one image ranked two slots higher than any other combines several factors, including our attempt to balance the list between human spaceflight, satellite imaging, and planetary exploration. Many wonderful images did not make the final cut—we couldn’t convince the editors to give us 20 pages instead of 10.
The list omits significant events from space history that were not NASA achievements, such as the famous 1958 photograph of Wernher von Braun and the other architects of the Explorer 1 satellite celebrating their success by holding a model of the satellite over their heads, an event that occurred months before NASA existed. Photos from the Apollo moon program predominate, as well they should—it remains the agency’s crowning achievement. We also recognize that, even though the first “A” in NASA stands for “aeronautics,” our list is light on aeronautical breakthroughs (see Moments & Milestones, p. 84). Our only excuse is that the ranking reflects the affinity of the division of space history staff for space topics. (http://www.airspacemag.com/space-exploration/Top_NASA_Photos_of_All_Time.html)
Tuesday, September 16, 2008
We are all recovering from Launch Fest, an open house that was held at Goddard Space Flight Center (GSFC) on September 13. According to estimates from our Public Affairs Office, 13,000 people came to see what GSFC is all about! Each of our projects were represented in some way:
- LRO had exhibits and displays outside of the white room, where the spacecraft was prominently on display
- Aura had banners and activities that discussed the role of uv radiation in the processes that control the stratospheric ozone hole
- SAM opened its doors to the Mars atmosphere simulation chamber and showed animations of the Mars Science Lab doing geochemistry on Mars
- LOLA displayed the engineering model of the instrument along with the heritage instruments MOLA and MLA (aboard MESSENGER), as well as animations of what data from LRO will look like
- New Horizons had animations of the spacecraft and science results from the Jupiter flyby