ULTRASAT

ULTRASAT (Ultraviolet Transient Astronomy Satellite) is a proposed astronomical satellite mission whose wide-angle UV telescope will detect and monitor transient astrophysical phenomena in the near-ultraviolet spectral region. ULTRASAT will observe a large patch of sky, more than 200 square degrees, alternating every six months between the southern and northern hemisphere. The satellite will orbit the Earth from an altitude of about 300 km above the geosynchronous orbit, getting a ‘ride’ as a secondary payload in the fairing of the rocket carrying a communications satellite. Upon detection of a transient event, ULTRASAT will provide alerts to other ground-based and space telescopes to be directed to the source for further observation of the event in other wavelength bands. A joint American-Israeli proposal for this project was submitted to NASA by a team from Caltech/JPL (Jet Propulsion Laboratory), the Weizmann Institute of Science and Israel Aerospace Industries (IAI). The Israeli contribution will be funded by the Israel Space Agency and launch is expected before 2021.

The ULTRASAT initiative was born in 2010 in discussions between Weizmann Institute (WIS) and Caltech scientists together with the Israel Space Agency (ISA) to meet the need for a wide field space telescope for studying transient astronomical events, in a small satellite such as those suitable for SMEX. In the preliminary investigation phase, various other bands were considered, including X-ray. The ultraviolet was selected due to the technology maturity, the higher chances of successful implementation and the need to continue exploring this wavelength region. The importance of this project is confirmed in which says that the discovery rate for UV variable sources and UV transients could increase by several orders of magnitude with the launch of a space-based UV mission with a wide field of view (several deg2) and which states that "The proposed ULTRASAT mission could discover hundreds of tidal disruption events per year in the UV.

The project, originally called LIMSAT, was renamed ULTRASAT - Ultraviolet TRansient Astronomy SATellite in 2011 when a proposal was submitted to NASA for the [Explorers program] 2012 Mission of Opportunity section, in collaboration with NASA's Ames Research Center. Due to the sequester and NASA budget cuts, no proposal was selected that year. Following considerable changes in the configuration of the telescope, the planned orbit and the satellite bus, a new proposal was submitted in December 2014 in collaboration with JPL. From a concept of eight small refractive UV telescopes on a satellite in low earth orbit, ULTRASAT evolved to a single wide-field Schmidt telescope in super-geosynchronous orbit.

...
Wikipedia