The Possibility of Ultraviolet Enceladus’ Observations from Stratospheric Balloons

Stratospheric balloons are very important sources for space and terrestrial observation experiments in many disciplines. Instruments developed for astrophysical measurements are usually reusable. It is also possible to observe both hemispheres including observations from the polar and equatorial regions for thirty days or even longer. On the other hand the UV atmospheric transmittance window was used for the astrophysical observations less often than visible optical bands. At the end of the 2017 there are a few scientific groups working on near-UV or UV spectrographs and cameras for balloon flights.

In this paper we are discussing the possibility of ultraviolet measurement of Enceladus, an icy Saturnian moon, surface reflectance between 200 and 400 nm from the 20-50 km altitudes. At visible and near infrared optical channels Enceladus’ reflectance is very high (near 1.0). This value is consistent with a surface composed of water ice, however at some ultraviolet wavelengths Enceladus reflectance is lower than it would be expected for this type of surface. The scientific research done in the last decade was focused on H₂O, NH₃, and tholin particles detection on the Enceladus’ surface as a reason of low UV reflectance phenomenon. Continuous observation of Enceladus’ UV reflectance variability from stratospheric balloons may be interesting and may give us the proof of the presence of biomarkers or/and tholin particles.