Astrid-2

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 stabilized, 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.

Country of Origin	Sweden
Customer/User	Swedish Space Corporation (SSC)
Manufacturer(s)	Swedish Space Corporation (SSC)
Size	95 x 45 x 40 cm (with panels stowed)
Launch	Mid 1997 launch from Plesetsk, Russia aboard a Kosmos-3M rocket.
Orbit	1000km circular, 83 degree inclination
Related Sites	Astrid-2 Web page