Archive for December 24th, 2008
24
Dec
Earthrise!
- Image via Wikipedia
40 Years Ago today, the Astronauts of Apollo 8, the first humans to circumnavigate the moon, finally turned their eyes from the lunar surface (on their fourth orbit) to observe the “earthrise.” Writing about it in “Happy Birthday, ‘Earthrise‘ ( NY Times), Andrew C. Revkin includes a video he compiled to mark the occasion.
As Frank Borman shifted the orientation of the capsule to see the horizon Bill Anders was moved to blurt out “Oh my God, look at that picture over there. Here’s the Earth coming up!”
Series
From the Archives
NASA image of the day
Snapshot of the International Space Station
On March 13, 2008, the International Space Station passed across the field-of-view of Germany's remote sensing satellite, TerraSAR-X, at a distance of 195 kilometers, or 122 miles, and at a relative speed of 34,540 kilometers per hour, or more than 22,000 mph. In contrast to optical cameras, radar does not 'see' surfaces. Instead, it is much more aware of the edges and corners which bounce back the microwave signal it transmits. Smooth surfaces such as those on the station's solar generators or the radiator panels used to dissipate excess heat, unless directly facing the radar antenna, tend to deflect rather than reflect the radar beam, causing these features to appear on the radar image as dark areas. The radar image of the station therefore looks like a dense collection of bright spots from which the outlines of the space station can be clearly identified. The central element on the station, to which all the modules are docked, has a grid structure that presents a multiplicity of reflecting surfaces to the radar beam, making it readily identifiable. This image has a resolution of about one meter (about 39 inches). In other words, objects can be depicted as discrete units--that is, shown separately--provided that they are at least one meter apart. If they are closer together than that, they tend to merge into a single block on a radar image. Since this image was taken, the station has expanded and is more than 90 percent complete, including a full complement of solar arrays. Image Credit: DLR
Read More