PocketQube

Definition#

A PocketQube is a picosatellite assembled from cubic units of 50 mm, written "P". A 1P measures 50 × 50 × 50 mm and may weigh at most 250 g; its 125 cm³ are one eighth of the volume of a 1U CubeSat. Larger spacecraft grow along a single axis: a 2P or a 3P keeps the 50 × 50 mm cross-section and adds 64 mm of length per unit[1].

What separates the format from a scaled-down CubeSat is the mechanical interface. A CubeSat slides along four corner rails; a PocketQube is held only by a sliding backplate, a thin plate fixed to one face that protrudes beyond the body and runs in the guides of the deployer. The deployer pushes on the backplate and nothing else touches the spacecraft[1].

Origins and first flights#

Robert J. Twiggs, one of the originators of the CubeSat, proposed the PocketQube at the 2009 CubeSat Developers’ Workshop, building on work by Morehead State University and Kentucky Space[2]. The aim was to cut development and launch costs once more by halving the unit edge and simplifying the interface between spacecraft and launcher.

The first four PocketQubes reached orbit on 21 November 2013. A Dnepr rocket carried GAUSS Srl’s UniSat-5 microsatellite, whose Morehead–Rome FemtoSat Orbital Deployer (MRFOD) released $50SAT, Beakersat-1, QubeScout-S1 and WREN near 600 km[3]. The 1.5P $50SAT, built by Morehead State University and three radio amateurs from parts costing less than US$250, became the emblem of the class. No PocketQube flew for the next six years; the format returned in December 2019, when Alba Orbital’s AlbaPod released six of them from a Rocket Lab Electron[4].

The standard#

Alba Orbital, Delft University of Technology and GAUSS Srl released Issue 1 of the PocketQube Standard in July 2018[1]. It fixes the mechanical interface: the envelope, the backplate, the mass per unit and the clauses on materials, such as the recommendation of 6061 or 7075 aluminium and the consultation required for magnesium or unusual alloys[5]. Electrical, testing and operational requirements were left to later issues and are, in practice, still set by deployer providers and launch brokers.

At subsystem level TU Delft proposed the PQ9 and CS14 interface standards: a lean bus with RS-485 data lines and a few unregulated power lines that replaces the PC/104 heritage of CubeSat avionics[6]. PQ9 flew on Delfi-PQ.

Why PocketQubes#

The class does not replace CubeSats; it serves the niches in which small, cheap and numerous beats capable[7]:

• Cost of access. At the 2018 PocketQube Workshop, launch cost about 20 k€ per 1P, roughly 80 k€ per kilogram, with 10 k€ considered achievable.
• Education and fast iteration. A team can design, build and test a complete spacecraft on a handful of 50 mm boards, and repeat the cycle quickly.
• Distributed systems. Spectrum monitoring and Internet-of-Things relays need many nodes more than they need one capable satellite.
• Short orbital life. The high area-to-mass ratio brings a PocketQube down within years from the altitudes where most of them fly.

The population#

The nadir lab. review counts 77 PocketQubes launched between 2013 and 2023[4]. Activity was uneven: four units in 2013, none until 2019, then a peak of 38 in 2022, 21 of them on a single Falcon 9 rideshare (Transporter-3).

• 1P
• 1.5P
• 2P
• 3P
• 2.5P and 6P

Show the data as a table

Category	1P	1.5P	2P	3P	2.5P and 6P	Total
2013	1	1	0	0	2	4
2014	0	0	0	0	0	0
2015	0	0	0	0	0	0
2016	0	0	0	0	0	0
2017	0	0	0	0	0	0
2018	0	0	0	0	0	0
2019	3	0	1	2	0	6
2020	0	0	0	0	0	0
2021	5	2	1	0	1	9
2022	11	4	17	6	0	38
2023	5	2	4	9	0	20
2024	0	0	0	0	0	0
2025	6	4	0	6	0	16

By unit count 1P (32%), 2P (30%) and 3P (22%) dominate, followed by 1.5P (12%), 2.5P (3%) and one 6P. Two commercial operators account for 39% of all units: Fossa Systems with 17, mostly the 2P FossaSat-2E series, and Alba Orbital with 13 Unicorns. Counting batches rather than designs explains why surveys disagree on the most common size: weighted by spacecraft, 2P and 3P lead; weighted by mission, 1P does[8].