When NASA's latest Cygnus cargo mission to the International Space Station (ISS) lifts off on Monday, its manifest of experiments and general supplies will include three CubeSats, including the first equipped with radar. The size of three cereal boxes and weighing only 26 lb (11.8 kg) each, the miniature satellites will be used to demonstrate new technologies in orbit.

CubeSats have come a long way since they were first introduced as a platform for training future space engineers. Today, they are increasingly being used to track ships, gather low-Earth orbit data, and two are even now en route to the planet Mars. Not bad for spacecraft that consist of 4 x 4 x 4 in (10 x 10 x 10 cm) cubes stuck together and run by computers on the level of a smartphone.

RainCube

The three CubeSats that will launch from NASA's Wallops Flight Facility in Virginia on May 21, 2018 will be removed from the unmanned cargo ship and then deployed into low-Earth orbit. These include one called Radar in a Cubesat (RainCube) and is the first satellite of its size to be equipped with an active radar system. The satellite uses a deployable antenna about 20 in (50 cm) across and operates in the high-frequency Ka radio band. According to NASA, this allows for an exponential increase in data transfer over long distances.

The NASA Earth Science Technology Office (ESTO) In-Space Validation of Earth Science Technologies (InVEST) project is a demonstrator experiment designed to show that constellations of CubeSats can monitor the Earth's weather as well as much larger conventional satellites, but faster, cheaper, and with greater mission flexibility.

"A constellation of RainCube radars would be able to observe the internal structure of weather systems as they evolve according to processes that need to be better characterized in weather and climate forecasting models," says RainCube Principal Investigator Eva Peral of the Jet Propulsion Laboratory in Pasadena, California.

CubeRRT

The second CubeSat is the CubeSat Radiometer Radio Frequency Interference Technology (CubeRRT), which is designed to test new ways of improving data collection in space. NASA says that Radio Frequency Interference (RFI) is becoming a problem for space-based microwave radiometers that are used to study soil moisture, meteorology, the climate, and other terrestrial phenomena.

To overcome the interference caused by mobile phones, radios, and televisions, CubeRRT will be used to build on present techniques for dealing with RFI that involves using large sets of data to filter out RFI-corrupted data. The hope is that CubeRRT's new subsystems will be able to detect RFI and filter out RFI-corrupted data in real time while still aboard the tiny spacecraft.

TEMPEST-D

The third CubeSat is the Temporal Experiment for Storms and Tropical Systems Demonstration (TEMPEST-D) mission, which will demonstrate a new five-frequency radiometer based on new low-noise amplifier technologies that can be used to study cloud processes, storm development, and determining when rain will begin to fall. By using drag maneuvers to alter its position and altitude, TEMPEST-D may be able to reach a target and begin investigations much faster than conventional satellites that are only able to revisit a storm system once every three hours.

"With a train-like constellation of TEMPEST-like CubeSats, we'd be able to take time samples every five to 10 minutes to see how a storm develops," says Steven Reising of Colorado State University.

Source: NASA

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