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, which achieved the rating "Category II", meaning high scientific and technological merits, but was not selected for financing.

Welsh, 2005, describes the discoveries made by GALEX, which would be vastly increased by ULTRASAT[7] One field where short cadence UV observations can make a big difference is the explosion marking the death of a star, known as a supernova (SNe).

Based on the volume of space monitored and the measured SNe rate (from ground surveys) it is expected that at least 100 such events per year will be detected by ULTRASAT within less than a day of the explosion.

Analysis of the early light curve provides valuable information (stellar radius and surface chemical composition) on the progenitor star (before it exploded) that cannot be found by other means.

ULTRASAT has been designed to cover an unprecedentedly large field of view with a highly sensitive UV camera, with repeat image times as short as 5 minutes.

One of the key science goals of ULTRASAT is the discovery of electro-magnetic emission following the detection of Gravitational waves (GW) from the mergers of binaries involving neutron stars, referred to as Kilonova.

ULTRASAT will be able to slew in minutes to >50% of the sky, and its wide field-of-view amply covers the angular error regions expected to be provided by GW detectors in the 2020s.

It will provide continuous UV light curves as well as early alerts that will enable ground-based follow-up spectroscopy and monitoring of optical and infrared emission predicted to arise later.