.The SORCE Satellite consists of a small, free-flying satellite carrying four instruments to measure solar radiation incident at the top of the Earth's atmosphere. It is carrying the Total Irradiance Monitor, Spectral Irradiance Monitor, Solar Stellar Irradiance Comparison Experiment, and the XUV Photometer System. The satellite will provide daily measurements of total solar irradiance and spectral solar irradiance.

Orbital Sciences Corporation supplied the spacecraft using a version of the LEOStar spacecraft bus. The spacecraft is a 3-axis stabilized satellite for pointing the instruments towards the Sun for the primary solar measurements as well as for pointing towards stars for the SOLSTICE in-flight calibrations. The SORCE mission will orbit at a 645 km altitude with a 40° inclination.

Power:
730 watts orbit average at EOL 
6 fixed GaAs solar arrays 
23 Ah NiH2 battery

Attitude Determination & Control:
    3-axis stabilized
    Solar pointed (day side)
    Stellar pointed (night side)
Pointing
    accuracy: better than 60 arc-sec (pitch and yaw)
    knowledge: better than 36 arc-sec (pitch and yaw)
    stability: better than 1.0 arc-min/min (pitch and yaw)
    jitter: better than 20 arc-sec/sec (pitch and yaw)
Slew rate: up to 12°/min

Communications:
S-Band
    uplink 2 kbps
    downlink 1.5 Mbps
    4kbps TDRSS compatible
Hawaii, Overberg, and Perth (part of the Universal Space Network) and LEO-T ground stations at Wallops
Two passes per day
Data storage: 1024 Mbits

Bus Reliability:
0.86 at 6 years, nearly full redundant

Observatory (payload) Totals:
Mass:            101.6 kg (includes electronics)
Power:          158 watts (includes >10% contingency and flight computer) 
Data Rate:     orbit average = 6.8 kbps (mode dependent)
                    Peak rate =    32 kbps
Data Volume: 570 Mbits/day maximum