ESCAPE (Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution) is a small research mission in NASA’s SMEX (Small Explorer) program: It is designed to measure the short-wave component in the ultraviolet spectrum, the so-called extreme ultraviolet light (EUV), from nearby stars and characterize. From this one hopes to gain insights into how planetary atmospheres have developed.
Stars emit radiation across the entire frequency spectrum with very different energies, from high-energy X-rays to low-energy radio signals. “EUV radiation, whose wavelength band lies between X-rays and ultraviolet light, can only be observed from space and has therefore only been detected for the sun and the next dozen stars,” says IMF group leader Luca Fossati, member of ESCAPE Science -Team.
One of the reasons for this is that the EUV emission is weak compared to the optical emission and is strongly absorbed by the hydrogen atoms between the stars. The only satellite that has so far examined the TEU area was EUVE (1992-2001). “The technology has improved significantly in 30 years and now makes it possible to measure the extremely ultraviolet radiation from hundreds of stars,” says Ute Amerstorfer, IMF scientist and another member of the ESCAPE science team.
For the third IMF member of the team, Herbert Lichtenegger, the examination of this part of the emitted starlight is extremely important, since it is responsible for the expansion and loss of the planet’s atmosphere and thus for its long-term development. “ESCAPE will provide exactly the information that our models of planetary atmospheres need to predict their evolution, from planetary gas giants like Jupiter or Saturn to earth-like planets in the habitable zone where life is possible,” said Lichtenegger.
Together with ESCAPE, a second NASA mission was selected for further studies. Both will receive $ 2 million each to conduct in-depth technical feasibility studies over the next nine months. The two missions are then reevaluated by NASA for final selection. The winning mission will fly in 2025.
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