Wednesday, 27 July 2016

Better Views with Smaller Satellites


Crew of Minor Satellites Soaring around Earth – Assess Reflected Energy

According to an MIT-led research published online in Acta Astronautica, a crew of minor, shoe box-sized satellites, soaring in formation around the Earth might assess the reflected energy of the planet with double the accuracy of traditional megalith satellites. If completed accurately, such satellite swarms may also be inexpensive to build, launch as well as maintain. Led by Sreeja Nag, a former graduate student in MIT’s Department of Aeronautics and Astronautics – Aero-Astro, the researchers replicated the performance of an individual large orbiting satellite with nine sensors and compared with a bunch of three to eight small, single sensor satellites hovering together around the Earth.

 The team in particular viewed how each satellite development trials albedo or the amount of light that tends to get reflected from the Earth, which is a sign of how much heat the planet seems to reflect. The team also found that the clusters of four or additional small satellites could look at individual location on Earth from multiple angles and trail the total reflectance of that location with an error which is half of single satellites in operation, currently. Nag is of the opinion that such a correction in estimation error would considerably progress the climate projections of the scientists.

Outgoing Radiation – Biggest Worries in Change in Climate

Nag states that the total outgoing radiation is in fact one of the biggest worries in the change in climate, since it tends to be a complex function of where you could be on Earth, what season it is, what time of the day it could be and it seems to be very difficult to determine how much heat tends to leave the Earth.

 He further added that if they can evaluate the reflectance of various surface types, globally, frequently and more precisely, that a cluster of satellites would enable you to do, then at least you have solved one part of the climate problem. Nag who is presently a research engineer at the Bay Area Environmental Research Institute, NASA Ames Research Centre and NASA Goddard Space Flight Centre, has co-authored the paper with Oli de Weck, an AeroAstro professor at MIT, Charles Gatebe of NASA Goddard Space Flight Centre and David Miller, NASA Chief Technologist together with Jerome C. Hunsaker Professor in AeroAstro.

Nag states that to estimate precisely the reflectance of any ground spot on Earth, it needs measurements that are taken of the spot from various angles simultaneously. He states that the Earth does not reflect equally in all the directions.

Multi-Angle Imaging SpectroRadiometer - MISR

If one does not get these various angles you could under or overestimate how much it has been reflecting, if you have to generalize from only one direction. Presently, satellites which tend to measure the albedo of the Earth normally tend to do so with various cameras, placed on an individual satellite.

For instance, Multi-angle Imaging SpectroRadiometer – MISR instrument of NASA on the Terra satellite stocks nine cameras which take pictures of the Earth from a fan-like procedure of angles.Nag informed that the disadvantage of this design is that the cameras tend to have a restricted view since they are not intended to change angles and could only perceive within a single plane.

The team instead suggested a cluster of small satellite which tends to travel around the Earth in a loose formation, adequately close enough to each other to enable an image of the same sport on the ground from their different vantage points. Each satellite could move in the formation taking images of the same spot simultaneously from various angles.

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