TESS spacecraft will start to look for distant worlds that might host lifeMIT via NASA

NASA's recently-launched space telescope – the Transiting Exoplanet Survey Satellite (TESS) – is yet to formally start its science missions. However, NASA started operations of the spacecraft on July 25 and in just over 2 weeks, the planet hunter has sent back a sequence of images, showing the movement of a comet.

According to a report by the space agency, the images that were stitched together to create the video were shot over the course of 17 hours. This exercise carried out by TESS demonstrates the telescope's abilities to photograph and collect a prolonged sequence of stable images covering a broad region of the sky. These are all critical skills required in looking for and finding planets orbiting nearby stars, says NASA.

TESS Comet
Images taken on July 25 by the Transiting Exoplanet Survey Satellite. The angular extent of the widest field of view is six degrees. Visible in the images are the comet C/2018 N1, asteroids, variable stars, asteroids and reflected light from Mars.MIT/NASA's Goddard Space Flight Center

Throughout these tests, TESS captured images of C/2018 N1, a comet first spotted by NASA's own Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) June 29 this year. The comet is located about 48 million kilometres from Earth and was found in the direction of the constellation Piscis Austrinus.

In the video, it is seen moving across the screen from right to left as it orbits the Sun. The comet's tail consists of gases carried away from the comet by solar winds. It extends to the top of the frame, explains NASA, and it gradually pivots as the comet moves.

Apart from the comet, the images also reveal a number of other interesting astronomical activity. Stars shift between white and black as a result of image processing, but at the same time highlights variable stars—stars that change in brightness. This is explained as either the result of pulsation, rapid rotation, or by eclipsing binary neighbours.

In the video, white dots that are moving across the screen are asteroids, notes the report. Toward the end of the video, a faint broad arc of light – stray light from Mars – is also seen moving across the frame from left to right. The light was so apparent because the images were taken when Mars was at its closest to Earth.

NASA says that all these images were taken just before TESS's commissioning phase drew to an end, just before the start of the telescope's science missions. The mission was launched in April.  The video covers only a small fraction of TESS's full field of view, notes the report. NASA will be using TESS to find distant worlds that could support life.