Scientists From MIT Re-Calibrate CubeSats To Capture The Planet  Better
Photo by Donald Giannatti Professors Bob Twiggs and Puig-Suari dreamt of inspiring more students to take up projects in the field of deep space communication.Their aim was to make satellites from off the shelf items and of size as small as a Rubik’s cube and accessible to students so that they could use it for research and try out new ideas without facing too many financial setbacks. What started as tech for social good project, is now a prime provider of data to the private aerospace agencies and governments across the world. With rapid commercialization of space, these inexpensive, nano satellites have found their application now more than ever.Companies like SpaceX, for instance, want to use up a network of thousands of these CubeSats that provide high speed broadband to remote parts of the world to create high speed space internet. Nano Satellites For ‘Larger’ Purposes CubeSats are used for applications such as hyperspectral imagery. Where the satellite collects the data by imaging the earth and transmitting it back when it flies over the receiver. Given  the enormity of earth’s surface, the amount of data collected by these satellites is huge and to transmit this information for high quality observation is cumbersome, given the range of these satellites. Now the scientists have engineered these flying boxes to calibrate using a laser which will direct more data at a faster rate without any major loss of information. “Small satellites can’t use these bands, because it requires clearing a lot of regulatory hurdles, and allocation typically goes to big players like huge geostationary satellites,” says Cahoy, who also has an appointment in MIT’s Department of Earth, Atmospheric and Planetary Sciences. Laser communication (lasercom) is a contender to overcome this bottleneck and provide higher throughput communications while reducing the necessary volume, weight, and power requirements on the satellite platforms. The team developed a laser-pointing platform, slightly larger than a Rubik’s Cube, that incorporates a small, off-the-shelf, steerable MEMS mirror. The mirror, which is smaller than a single key on a computer keyboard, faces a small laser and is angled so that the laser can bounce off the mirror, into space, and down toward a ground receiver. Source: Nsikan Akpan Experimental Setup The primary optical components are mounted on an optical breadboard. The calibration optical path is established by connecting a 635-nm fiber coupled laser to the collimator through the WDM. The calibration and control algorithms are implemented on the selected payload microcontroller (PMC), which is based on a Raspberry Pi Compute Module. The calibration laser source is controlled through the PMC as well as via a general purpose input-output (GPIO) connection that switches the laser on and off. Courtesy: Jennifer Chu To correct for the misalignment due to vibrations during the launch, the team has incorporated an additional calibration beam into the optical system. These two beams bounce off the mirror and the additional color is diverted away with a “dichroic beam splitter.” As the rest of the laser light travels out toward a ground station, the diverted beam is directed back into an onboard camera. This camera can also receive an uplinked laser beam, or beacon, directly from the ground station; this is used to enable the satellite to point at the right ground target. If the beams land on different parts of camera detector, then an algorithm developed by Cierny, corrects beam alignment by tilting the onboard MEMS mirror accordingly. The whole experiment is monitored and controlled via an external laptop, which connects to the PMC via a universal asynchronous receiver Transmitter interface utilizing the point-to-point protocol This corresponds to almost negligible pointing loss in the current mission design and motivates for higher performance next-generation nanosatellite lasercom demonstrations. This technique allows the satellite to fine-point its downlink beam, the mission utilizes an uplink beacon signal at 976 nm captured by an on-board 5-deg field-of-view detector. With the introduction of calibration algorithms to utilize the feedback signal, higher fidelity beam pointing control is achieved and can perform quantitative analysis by overcoming space body disturbances. In Conclusion The researchers say that these techniques can be easily tweaked so that it can precisely align even narrower laser beams than originally planned, which can in turn enable CubeSats to transmit large volumes of data, such as images and videos of vegetation, wildfires, ocean phytoplankton, and atmospheric gases, at high data rates.
Professors Bob Twiggs and Puig-Suari dreamt of inspiring more students to take up projects in the field of deep space communication.Their aim was to make satellites from off the shelf items and of size as small as a Rubik’s cube and accessible to students so that they could use it for research and try out […]
CubeSats are used for hyperspectral imagery to collect the data by imaging the earth and transmitting it back when it flies over the receiver.
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I have a master's degree in Robotics and I write about machine learning advancements.