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.

Dimensions

Deployment

On the first flight the modules were released from four canisters mounted outside the second stage; on the second, from a two-canister dispenser. The strings unfold like an accordion as they leave the dispenser[3].

Compared with other formats

Size	Envelope (mm)	Volume (cm³)	Mass limit (kg)	Deployers
ThinSatThe standard does not define a module mass; 0.3 kg is assumed. Strings weigh 1–2.2 kg.	111 × 114 × 12.5	158	Not set	Antares second stage, strings of 3 or 6
TubeSatSixteen-sided prism; dimensions are given as the bounding box.	Ø 89.4 × 127	777	0.75	NEPTUNE (planned)
SpriteThickness approximate; 4 g.	35 × 35 × ≈3	4	Not set	KickSat carrier (3U)

PocketQube Standard Issue 1 (2018); CubeSat Design Specification Rev. 14.1 (2022). The 2P length is indicative.

A short mission window

A module lives only days, so the experiment must produce data immediately after release. There is no room for detumbling, attitude control or long commissioning.

Power and thermal mass

The thin shape offers a large face for solar cells but very little heat capacity. Temperature changes between sunlight and eclipse are faster and larger than in thick-bodied spacecraft, and the thermal time constant is measured in minutes rather than hours.

Communications

Because the data travel through a commercial satellite network, student teams need no ground station of their own; in exchange, data rate and packet size are set by the limits of that network.