Project Starshine is a voluntary group supported by the US Naval Research Laboratory, the Space Grant Program, and NASA. It's purpose is to learn about the outer layers of the Earth's atmosphere, how it changes and how those changes effect orbiting objects. The Project Director is Prof. R. Gilbert Moore

The Starshine satellites look like large disco balls initially orbiting 470 km above the Earth in a region of the atmosphere known as the thermosphere. The International Space Station, the Space Shuttle and many other satellites orbit at the same height as the Starshine satellites.

Starshine 1 was launched on June 5th 1999 and dropped out of orbit on Feb. 18th 2000 . Starshines 2 and 3 are still up there now, 3 was launched on Sept. 29th 2001, and 2 was launched on Dec. 5th, 2001 - they're numbered in the order which production started rather than the order in which they were launched. Starshines 4 and 5 are set to be launched simultaneously in January 2003.

The satellites are spheres made of aluminium and are covered in flat mirrors. These mirrors reflectspacesunlight back to Earth and allow us to see them with the naked eye. Seen from Earth, they have the same brightness as 1st magnitude stars but pulse gently as they rotate. The mirrors were polished by groups of students from around the world in a collaborative project. Starshine 2 has 845 mirrors which were polished by 30,000 students from 26 different countries. Starshine 3 took 40,000 students to finish its 1500 mirrors. Lots of flat mirrors are much easier and cheaper to make and polish than one big spherical one. This is why the Starshines look the way they do.

The price of putting things into orbit is calculated by volume and weight and is one of the two main reasons why the starshine satellites are made primarily of aluminium. The other reason is insurance. They would need a $100,000,000 insurance policy with a $50,000 premium if any part of them was likely to survive reentry and fall to the surface of the earth. Starshine 1 was completely vaporised about 80 km up.

The air in the thermosphere is very thin but still enough to cause mild resistance. This is all part of the project. Each of the satellites loses a few meters of altitude for every orbit of the Earth as does the International Space Station - ISS however has boosters which prevent it from falling back to earth. Not so Project Starshine's birds, atmospheric resistance is part of the reason they're up there

Observers on Earth first calculate their exact position on the planet then precisely record the position and times of the satellites as they pass known stars. By entering these figures into the project's website, details of the satellites' orbits can be calculated using equations originally derived by Pierre Laplace. These orbits change as the density of the thermosphere changes.

The thermosphere and indeed the entire atmosphere regularly fluctuates in size, shape and density. This is caused by solar activity. Another layer of our atmosphere called the magnetosphere is formed by the interaction of the Earth's magnetic field and the solar wind and the Sun's interplanetary magnetic field. Seen from side on, the magnetosphere looks like the ripples around a stone in flowing water. When there is a Coronal Mass Ejection or solar flare, the solar wind increases and the magnetosphere is deformed, taking the rest of the atmosphere with it.

Until now, we did not have a good understanding of how this solar activity affected atmospheric density. Now we can see CMEs coming thanks to the SOHO satellite which permanently watches the Sun and we can find out the effect they have on the atmosphere thanks to the Starshine satellites.

To find out more about the project, visit it's homepage at www.azinet.com/starshine
The starshine satellites are visible from most parts of the Earth at some time. To find out when where to look for these and other satellites from your current location, visit www.heavens-above.com

Other sources - www.spaceweather.com, www.nasa.gov

---------
Additional - 26/4/2002
Starshine 2's orbit is now in the final stages of decay. It is set to re-enter the Earth's atmosphere some time today. This is about a month or two earlier than predicted because of recent high levels of solar activity. For re-entry times on this and other starshine satellites, you can visit :
http://www.azinet.com/starshine/starshine_reentry.html

Log in or registerto write something here or to contact authors.