Mar 3 2014 2241

Deployable Telescopes Make Microsatellites Work for EO

Deployable telescope.Microsatellites.New concepts.Spaceborne cameras

The cost of imagery from space is, you’ll pardon the expression, sky high.  Microsatellites are a good way to produce more images and achieve a better re-visit rate for every point on earth. 

Current commercial earth observation (EO) satellites weigh in at up to 2,000 kg., and can cost $500 million to develop and launch.  Microsatellites using deployable telescopes in space is the right solution to decrease associated costs while improving and increasing the quantity of images available. 

The problem is straightforward.

The size and weight of space borne sensors for earth observation (EO) depend in first order on the required ground resolved distance (GSD): the distance from the area of interest and the wavelength. The current commercial earth observation (EO) satellites provide images with approximately 0.5 meter GSD and fly at altitudes of approximately 600 km above the earth’s surface. These parameters drive the size of the primary mirror and put it at about one meter. Such mirror size pushes the satellite weight to between 1000kg to 2000kg.

Such high cost of satellites push the cost of imagery from space and limits the number of satellites available for such image production. Using a deployable telescope in space allows engineers to reduce the size of the satellite and the size of the optical imager without sacrificing performance.  This is possible because the deployable telescope enableskeeping the primary mirror at a size which allows achieving the required GSD from the orbit altitude.

Deployable telescopes provide several benefits like the ability to use the telescope at a much longer wavelength.  Typically a wavelength which is 10 times longer requires a 10 time larger mirror diameter. Using a deployable telescope keeps the size and mass of the satellite the same as for a satellite with a sensor for a 10 times shorter wavelength.

Microsatellites also potentially reduce the cost of some scientific missions, especially those which require high resolution for flyby of asteroids and other spaceborne objects. We envision a satellite class on the order of 80-100 kg, flying at altitudes of 500-400 km above the earth’s surface, providing images with resolution better than 0.5 meters. These systems would costs a fraction today’s state of the art satellites. A constellation of several satellites can achieve a better revisit rate for every point on earth. Additionally, it will provide satellite redundancy in case of a malfunction in one of them.

 

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