ThinSat

Definition#

A ThinSat is a thin satellite module designed for very short orbital experiments in education. One module has a face close to that of a 1U CubeSat, 11.1 × 11.4 cm, but is only 1.25 cm thick[1]. Modules do not fly alone: they are joined into strings and released directly from the launch vehicle.

The programme#

The ThinSat programme lets students from middle school to university put their own sensor experiments into orbit. On the first flight, 63 ThinSats built by students from about 70 schools in nine US states were released from the second stage of an Antares rocket on 17 April 2019, a few minutes after the Cygnus cargo ship separated[2]. A second flight followed on another Antares on 20 February 2021[3].

A deliberately short life#

The strings are released into orbits with perigees near 200 km. At that altitude the air is hundreds of times denser than at 400–500 km, and the modules re-enter within days to about two weeks. The short life is a design choice rather than a limitation: it leaves no debris and keeps coordination and operations simple.

Form factor	Mass (kg)	Ballistic parameter (m²/kg)	From 200 km	From 250 km	From 300 km	From 350 km
ThinSat	0.30	0.0567	< 1 days	1 days	5 days	17 days
1P	0.25	0.0330	< 1 days	2 days	9 days	28 days
1U	2.00	0.0180	< 1 days	4 days	16 days	52 days

Kennewell density model, drag coefficient 2.2, mean tumbling area A_tot/4, re-entry at 180 km, spacecraft at the mass limit of its standard. Solar activity: low F10.7 = 70 sfu, Ap = 6; moderate 140 sfu, Ap = 12; high 210 sfu, Ap = 18.