ULTRASAT is a scientific mini-satellite carrying a telescope with an unprecedentedly large field of view (210 squared degrees) observing in the ultraviolet (UV, 220-280nm), that is proposed by an Israeli/US collaboration to be constructed and launched to a (near) geostationary orbit by 2022.

ULTRASAT will revolutionizing our understanding of the transient UV universe by providing the first wide-field time-domain UV survey, exploring a new parameter space in wavelength and time-scale (minutes to months stares), with a discovery rate >300 times larger than ever before. It will provide continuous NUV light curves to depths comparable to contemporary ground and space-based time-domain surveys at longer wavelengths (e.g. LSST). ULTRASAT’s key project goals are:


  1. Collect early UV light curves of hundreds of core-collapse supernovae, to measure the radii and surface composition of their massive progenitors, and to determine explosion parameters. Connecting the pre-explosion stars with their diverse explosive output will chart how the population of massive stars impact their environment through mass loss and explosion, and will specify initial conditions for explosion models.
  2. Search for electro-magnetic emission from gravitational wave (GW) sources. Ejecta from mergers involving neutron stars are predicted to radiate UV light detectable by ULTRASAT in their earliest phases. ULTRASAT will be able to slew in minutes to 50% of the sky, and its wide field-of-view amply covers the error ellipses expected from GW detectors in the 2020s.
  3. Provide continuous NUV light curves of hundreds of supernovae of all types, hundreds of tidal disruptions of stars by super-massive black holes, thousands of active galactic nuclei, and >105 flaring and variable stars. Rapid transient alerts will be provided to the global astronomical community, and all data products including light curves will be made available and updated daily.


ULTRASAT will provide cutting edge science with a satellite mission which is significantly smaller (~1m3), lighter (~100kg) and cheaper (~$100M, including launch) than most space missions. The success of ULTRASAT will lead the way to future similar missions.

The science mission is jointly led by Weizmann Institute and Caltech teams, together with international colleagues. The technological aspect of the mission is led by IAI-MBT (responsible for the construction of the spacecraft, for the integration of the telescope to the spacecraft and of the spacecraft to the launch vehicle, and for mission operations), by Elop (responsible for the construction of the telescope and for the integration of the payload), and by JPL (responsible for the construction of the UV-optimized camera, for contracting the launch opportunity and for data archiving), under a joint management of ISA and NASA. ISA is committed to the mission, pending approval of NASA funding for the US part. A proposal for funding the US part of the mission was submitted to NASA-HQ in December 2016, in response to the Astrophysics Explorer program call. A decision on funding the detailed design phase, Phase A, is expected around June 2017.

NASA, ISA, Weizmann Institute of Science, IAI,JPL, SSL, Ebit Systems