Astrid - Credit: Sven Grahn. 30,749 bytes. 328 x 223 pixels.

Swedish Space Corporation's second microsatellite (based on Astrid-1) is slated to perform high resolution E-field and B-filed measurements in the Earth's auroral regions. Additional objectives include the measurement of electron density, electron and ion distribution functions, UV auroral imaging, and UV atmospheric absorption. Spacecraft: Spin stabilised, sun pointing platform with about 10kg of instrument mass. Spacecraft is 170 x 110 x 30 cm with deployed solar panels which generate about 90W. After release from launch vehicle, and spin up (using a tiny solid rocket thruster) the spacecraft employs the SSC "sunseeker" algorithm to find and remain pointed at the sun. Attitude control is accomplished with magnetic torque coils, and a nutation damper. Attitude is determined with a star sensor, sun aspect sensor, and magnetometer. Spacecraft radios downlink at 128kbps, and accept uplinked commands at 10kbps. Data reception and satellite control occurs at SSC in Stockholm. Payload: Astrid-2 is flying several distinct instrument packages: EMMA is a comprehensive scientific experiment measuring both electrical and magnetic fields. LINDA is a Langmuir probe experiment, consisting of two 10mm diameter spherical probes mounted on two light weight booms with a probe to probe separation distance of 2.9 meters. By using two probes, scientists hope to not only measure the fine structure of the plasma density irregularities down to 1 m scales but also distinguish between temporal and spatial effects. MEDUSA is a combined electron and ion spectrometer. The instrument FOV is nearly parallel to the satellite spin plane; this area is split into 16 sectors for measurement. PIA consists of two spin-scanning photometers (PIA-1/2) for auroral imaging and one sun pointing photometer (PIA-3) for atmospheric absorption measurements. Status as of 4/10/97: Astrid has passed three system acceptance tests including EMI compatibility, vibration, and spin balancing.

Total Length: 0.9 m. Maximum Diameter: 0.5 m. Total Mass: 30 kg.

Swedish Space Corporation micro-satellite Astrid-2 was ejected from the Nadezdha 5 COSPAS satellite at 15:25 GMT and was to measure the auroral electromagnetic fields and particle environment.

• 6 - JPL Mission and Spacecraft Library, Jet Propulsion Laboratory, 1997. HTML when accessed: http://msl.jpl.nasa.gov/home.html