A U.S. patent has been granted to The U.S. Naval Research Laboratory for the Optical Orbital Debris Spotter, a low power, compact, low cost, space debris detection design concept.
The U.S. Naval Research Laboratory (NRL)’s Geospace Science and Technology Branch, reports the sensor can be integrated into larger satellite designs, or flown independently on-board nano-satellite platforms.
The amount of man-made debris now orbiting the Earth keeps increasing at an alarming rate. These objects range in size from smaller than one centimeter, to objects exceeding 100 million centimeters.
Effects of a collision at orbital velocities, approaching several kilometers per second, can vary from minor to catastrophic. In Low Earth Orbit (LEO), where many space-based assets reside, small debris objects are of concern not only due to their abundance, but because they are often difficult to track or even detect on a routine basis. Thus the urgent need for an orbiting sensor.
Continuous Light Sheet
The basic concept for the orbital debris detection sensor is to create a continuous light sheet by using a collimated light source, such as a low power laser, and a conic mirror.
The important part of this concept is to create a permanently illuminated light sheet rather than scanning a beam. All particles intersecting such a beam would scatter the light from the source, regardless of the time of intersection with the plane of the light sheet.
Dr. Christoph Englert, research physicist at NRL, explains:
“When the flight path of an orbital debris object intersects the light sheet, the object will scatter the light, and a portion of that scattered light can be detected by a wide angle camera. The knowledge of the light sheet geometry and the angles of the scattering event with respect to the camera, derived from the signal location on the sensor, allow the determination of the intersection point, and possibly even size, and shape information about the debris particle.
Using a dedicated nano-satellite, or CubeSat, the system could also be used for gathering of more comprehensive debris field data. Losing the satellite at some point during the mission by a fatal collision could be considered a justifiable risk in comparison to the odds of getting unprecedented data sets for debris field characterization and modeling.”
The sensor concept, weighs approximately two kilograms and measures approximately 10cm x 10cm x 20cm, depending on specific implementation.
It could gather valuable input for modeling and prediction software that is starved for information on small debris pieces. These data sets could then be incorporated into global space tracking tools such as the Space Surveillance Network (SSN), NASA’s Orbital Debris Engineering Model (ORDEM), and the European Space Agency’s Optical Ground Station.
Top: Low Earth Orbit (LEO) is the region of space within 2,000 kilometers of the Earth’s surface. It is the most concentrated area for orbital debris. The U.S. Strategic Command (USSTRATCOM) estimates that since the launch of Sputnik in 1957, over 39,000 man-made objects have been catalogued, many of which have since re-entered the atmosphere. Currently, the Joint Space Operations Center (JSpOC), responsible for maintaining the Space Surveillance Network (SSN), tracks more than 16,000 objects orbiting Earth. About five percent of those being tracked are functioning payloads or satellites, eight percent are rocket bodies, and about 87 percent are debris and/or inactive satellites. Credit: U.S. Strategic Command, Joint Space Operations Center