spaceSpace and Physics

Briefcase-Sized Satellite Is Smallest Ever To Detect An Exoplanet


NASA’s ASTERIA mission has broken the record for the smallest ever satellite to detect a planet outside of our Solar System. First discovered in 2004, 55 Cancri e is a super-Earth that orbits its host star every 0.7 days. NASA/JPL-Caltech

Proving that size doesn’t always matter, NASA’s ASTERIA (Arcsecond Space Telescope Enabling Research in Astrophysics) mission has broken the record for the smallest ever satellite to detect a planet outside of our Solar System. Although exoplanet 55 Cancri e was already known to astronomers, its identification by the so-called CubeSat spells a big win for these compact spacecraft.

“We went after a hard target with a small telescope that was not even optimized to make science detections – and we got it, even if just barely,” Mary Knapp, the ASTERIA project scientist at MIT's Haystack Observatory and lead author of the study, soon to be published in the Astronomical Journal, said in a statement. “I think this paper validates the concept that motivated the ASTERIA mission: that small spacecraft can contribute something to astrophysics and astronomy.”


Launched from the International Space Station 9ISS) in November 2017, ASTERIA was originally destined for a 90-day space demonstration of technology that could be used on future missions. However, during one of its three mission extensions before contact was lost in December 2019, the CubeSat’s technologically advanced fine pointing control (its ability to remain steady whilst focusing on an object for a long time) was put to the test on exoplanet 55 Cancri e.

ASTERIA was deployed from the ISS on November 20, 2017. NASA/JPL-Caltech

The satellite set its lens on the target and searched the host star for dips in brightness that could indicate a passing planet. A steady spacecraft is crucial for these observations, as a wobble from the instrument itself could falsely record a dip in the data. In this case, ASTERIA’s fine pointing control was good enough to allow a marginal detection of the planet that on its own could not convince scientists of its existence, but when compared to previous observations 55 Cancri e’s presence could be confirmed.

“Detecting this exoplanet is exciting, because it shows how these new technologies come together in a real application,” Vanessa Bailey, the principal investigator for ASTERIA's exoplanet science team at NASA’s Jet Propulsion Laboratory (JPL), said. “The fact that ASTERIA lasted more than 20 months beyond its prime mission, giving us valuable extra time to do science, highlights the great engineering that was done at JPL and MIT.”

Larger planet-hunting spacecraft, like NASA’s Transiting Exoplanet Survey Satellite (TESS), need not fear retirement, however, as it’s impossible to package all of their capabilities into these smaller models. Instead, these CubeSats could play an important supporting role to help monitor stars for longer periods of time, and observe subsequent planet transits.


“This mission has mostly been about learning,” Akshata Krishnamurthy, co-investigator and science data analysis co-lead for ASTERIA, said. “We've discovered so many things that future small satellites will be able to do better because we demonstrated the technology and capabilities first. I think we've opened doors.”

The roughly 10cm x 20cm x 30cm (3.9 x 7.9 x 11.8 inches) and 10 kg (22 pounds) ASTERIA satellite, pictured here ahead of its launch in 2017. NASA/JPL-Caltech

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