TubeSat

Definition

The TubeSat is a satellite kit that the Californian company Interorbital Systems (IOS) designed for individuals and schools. Its structure is a sixteen-sided prism whose faces are printed circuit boards; it is 8.94 cm across and 12.7 cm long and weighs 0.75 kg, of which 0.25 kg is reserved for the customer’s payload[1].

Business model and status

The kits were to be launched on the company’s NEPTUNE rocket into an orbit of about 310 km, from which they would decay within weeks. Public sources describe the NEPTUNE family as still in development and record no TubeSat in orbit[1]. The TubeSat is therefore interesting today less as a flight standard than as an early example of low-cost satellite kits sold together with the ride.

How it relates to other formats

Unlike the CubeSat and PocketQube standards, the TubeSat defines no deployer interface: spacecraft and launcher come from the same company. The format belongs to a business model rather than to a standard, which ties every kit to the schedule of a single launcher.

Dimensions and volume

The volume follows from a regular sixteen-sided polygon with a circumscribed diameter of 8.94 cm: about six times the volume of a 1P for three times the mass.

Structure

The boards that form the skin carry solar cells and electronics and act as the structure at the same time. No separate frame is needed, but the board joints must carry the launch vibration loads.

One launcher

Without a common deployer standard, a TubeSat can only fly on the launch arrangement designed for it, whereas a CubeSat or a PocketQube can move to any compatible deployer on another rocket.

Short life

At the intended altitude of about 310 km, drag would bring the satellite down within weeks, so the mission would have to fit a short window.

Form factor	Mass (kg)	Ballistic parameter (m²/kg)	From 300 km	From 310 km	From 350 km	From 400 km
TubeSat	0.75	0.0350	8 days	11 days	27 days	3 months
1P	0.25	0.0330	9 days	11 days	28 days	3 months

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.