Small body, big power! A small satellite of more than 30 centimeters reveals the secrets of the planet

Using a 14-inch small satellite to study "hot Jupiter" exoplanets evaporating into space

Small ultraviolet telescopes on CubeSats have been observing the evaporation of hot Jupiter's atmosphere.

The picture shows a hot Jupiter with its atmosphere blown away.

(Image credit: ESA/Alfred Vidal-Madjar (Institut d'Astrophysics de Paris, CNRS)/NASA).

While watching the atmospheres of seven "hot Jupiters" being blown away, a suitcase-sized CubeSat has discovered surprising variations in the rates at which these giant, bloated planets evaporate.

CUTE, short for the Colorado Ultraviolet Transit Experiment, was launched in September 2021 and orbits the Earth at an altitude of 525 kilometers (326 miles). It is equipped with an ultraviolet CCD camera to observe transits of giant exoplanets.

Hot Jupiters are gas giants like Jupiter that have migrated much closer to their respective stars over time, ending up with orbits just a few million kilometers away. Being so close to their stars, the heat causes the gases in these planets' atmospheres to expand. The hotter the atmosphere, the bloatedier the planet -- and the bloateder the planet, the easier it is for the star's radiation winds (like the sun's solar wind) to blow the atmosphere away. Often, these evaporating worlds develop comet-like tails as their atmospheres are blown away.

To date, CUTE has studied seven hot Jupiters, observing their orbits within their stars and detecting the profiles of gases such as iron, magnesium and hydroxyl. This detection is possible because when material is blown away from the planet, it absorbs part of the starlight. Therefore, scientists are able to infer the chemical signature of these materials by observing the absorption pattern.

However, of the seven planets, some appear to be evaporating, while others remain intact under the blast of stellar radiation.

"These planets appear to be quite diverse," lead researcher Kevin France of the University of Colorado Boulder said in a statement.

CUTE mission patch (Image source: LASP)

For example, CUTE watched the hot Jupiter WASP-189b transit its star, 300 light-years away in the constellation Libra. CUTE found that WASP-189b is losing material from its atmosphere at a staggering rate of 400 million kilograms (900 million pounds) per second.

On the other hand, another hot Jupiter named MASCARA-4b (MASCARA stands for Multi-Site All-Sky Camera), which is three times more massive than Jupiter and orbits a star 557 light-years away, has not been found to have any detectable gas loss.

CUTE system engineer Rick Kohnert and graduate student Arika Egan pose with the CUTE satellite before launch (Photo credit: LASP)

While there's no definitive explanation for why some planets appear to be whisked by their star's breeze and others aren't, it's suspected that the strength of the planet's gravity holding onto its atmosphere and the amount of activity on its star combine to control the ferocity of the gusts.

CUTE will target more hot Jupiters before its mission ends in 2027, when the tiny 14-inch-long (35.6-centimeter-long) cubesat will burn up as it falls back into Earth's atmosphere.

In addition to hot Jupiters, the mission, which was initiated in part by undergraduate and graduate students at CU Boulder, could help astronomers better understand smaller worlds.

- NASA's planet-hunting satellite discovers new 'warm Jupiter' exoplanet

- Some exoplanets are shrinking. Here's why

- Stars blow away the atmosphere of giant exoplanets, leaving behind giant tails

"There is a lot of evidence that super-Earths started out as Neptune-sized planets with large, fluffy atmospheres, then dropped dramatically in mass, leaving only a rocky core and possibly a very thin atmosphere," it said.

BY: Keith Cooper

FY: 33

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