Mission Design Overview

Here we briefly describe the satellite, its payload, performances, modes of operations, data analysis and data dissemination to the astronomical community. ULTRASAT’s key performance characteristics are given in Table 2, and the main mission parameters are given in Table 3. The ULTRASAT spacecraft will be constructed by the Israel Aerospace Industry (IAI). It will carry a single instrument - a telescope constructed by Elbit/Elop. The telescope will have a field of view (FoV) of 200 deg2 and the camera will reach a 5σ sensitivity of 22.3 AB limiting magnitude in the mission band (220-280 nm; hereafter NUV) in 3x300s integration (based on detailed S/N calculations). The large FoV is provided by a modified Schmidt design while the high sensitivity is enabled by using a UV-optimized detector. ULTRASAT operates in two modes (see II.4): “Stare” and “Target of Opportunity (ToO)”. The implementation of the two modes takes into account the proper mission impacts (thermal profile, sky background, etc.). Mission operations, science mission profile, and data plan are described here.

Key Performance Parameters 

Field of View  200 deg2
Band 220-280 nm
Candence 300 s
Limiting mag (AB) 22.3 (5σ, 900 s)
PSF, pixel # 13", 91 Mpxl
Alert distribution <20 min
ToO 50% of sky in < 10min for ≥ 3 hr

Table 2

Key Mission Parameters
Mission Spacecraft Operations
Geo orbit Volume 1.7x1.1x0.9 (m3 ToO trigger 15 min

Stare at 2 regions

for 6 months each

Launch mass 250 kg

Power 210 W

Mission Op.: IAI

Science Op.: WIS

Life time - 3 yr

Pointing accuracy 20"

Pointing jitter 3"

Downlink 5 Mbps

Slew >30 deg/min

 

Table 3