"Mimosa" might sound like kind of drink or a flower-bearing plant, but it is also a Czech satellite that was launched on June 30, 2003.

"Mimosa" is actually an abbreviation of "Micro-Measurements of Satellite Accelerations" and was primarily used to measure non-gravitational forces, such as atmospheric drag, solar radiation pressure, as well as infrared radiation from the Earth.

Mimosa was one of eight micro-satellites launched by the Russian SL-19 rocket on that day. The remaining were the Danish "DTUSat" and "AAU CubeSat", the Canadian "MOST" and "CanX-1", the Japanese "Cute-1" and "CubeSat XI-IV" and the American "QuakeSat" satellites.

MImosa is a polyhedron shaped satellite with a diameter of 0.6m (2 feet) and a mass of 66kg (30lbs). Its orbit at launch had a perigee altitude of 320km and an apogee altitude of 845km. This means an orbit eccentricity of 0.04, which is quite large for such a LEO satellite.

The Mimosa Satellite

CASTOR first detected this small satellite on March 8, 2010 with its wide-field CCD detector. The detected streak was very faint, as expected for such a small satellite. To date, CASTOR has only detected this satellite once, when it was at a range of only 302km.

It is most likely that CASTOR detected Mimosa at or near its maximum brightness, when its phase angle, range and orientation were all favourable for detection. It is very possible that Mimosa had passed into CASTOR's field of view on several occasions, but was not bright enough to be detected.
 

The CASTOR Image of the Mimosa Satellite.
 

Mimosa is the 3,167th satellite that CASTOR has detected since January 1, 2007. It was detected shortly after the second CASTOR Satellite Survey (2009).

The satellite's orbit has been decaying since it was first placed into orbit. Its precise decay date is currently unknown, but it is likely more than 60 days away.

Mimosa is also the name of the second brightest star in the constellation Crux (The Southern Cross). Also known as Beta Crucis, it the star that forms the left hand side of the cross, as indicated in the image below.
 

Constellations Centaurus (Centaur) and Crux (Southern Cross) as seen from Central Florida
 

Mimosa might not sound particularly important when compared with other satellites that CASTOR has detected, however it does represent a brightness limit of CASTOR's wide field CCD camera, as well as the limiting size and the limiting apparent angular velocity for such a satellite.

Mimosa is one of many exciting stories in the realm of the satellite. As with every satellite detected by CASTOR, it has a story unique to the people who designed and operated it throughout its lifetime.

CASTOR will continue to detect new satellites throughout 2010. It is expected that its unique satellite catalogue will grow to over 3,500 individual satellites before the end of the year.