CubeSats

Throwing boxes in space for fun

Posted by Yoann on June 2, 2015

Categories: notes,satellite
This article gathers a few information on cubesats. This is extracted from diverse wikis, press articles, papers, websites etc.

Launching a satellite into orbit is, as can be expected, very costly. So when a company decides to launch a satellite, they generally prefer to use well known, proven and often deprecated technologies.
This was true and accepted until the end of the 90's when California Polytechnic State university (CalPoly) developped a system specification to send normalized nanosatellites into space carrying experimental payloads: Cubesats. We'll cover here a few aspects of these cubesats, from their specification and launch modalities to their usefulness for telecom applications.

What is a CubeSat?

A framework for space experimentations

Artistic view of a cubesat (AAU CubeSat) deployed in orbit
Figure 1: Artistic view of a cubesat (AAU CubeSat) deployed in orbit [JPG]

A CubeSat is basically a simple 1.5kg 10cm cubed container normalized and validated for space conditions.
They are launched into space aboard another full satellite launch from the ISS. Once brought onto their final orbit, they are thrown using a Picosatellite Orbital Deployer (basically just a triggered spring and a guide) called P-POD in the case of CalPoly cubesats, a P-POD can carry up to 3 1U cubesats.
Other nanosatellites and their respective POD have been designed, with their own respective names. You may stumble on X-POD, J-POD in some articles, they are different mainly because of the size of nanosatellite they allow to deploy.

The 1U cubesat specification figure from the cubesat spec rev13
Figure 2: The 1U cubesat specification figure from the cubesat spec rev13 [PNG]

The 10 cm cubed version is the 1U cubesat, as shown on Fig. 2. Other versions of cubesats have been normalized: 1.5U, 2U, 3U, 3U+ which are just the linear stacking of 1U cubesats. 4U and 6U are also possible, but they use a modified version of the P-POD.

The PPOD, extracted from the cubesat spec rev13
Figure 3: The PPOD, extracted from the cubesat spec rev13 [PNG]

Launching a CubeSat

A cubesat ride, as is often called a launch aboard a standard heavy rocket along with a full-size satellite, costs around 100k$ for the 1U version which is nothing compared to the tens of million $ spent on bigger satellite launches. This allows universities and smaller companies to be able to launch their own experiments, for research or educational purposes.
Regarding deployment orbits, everything is possible. Most of the time, they are deployed on LEO orbits where remains of atmosphere will create a small drag to bring the cubesat back to earth safely (for other orbiting objects) after its lifetime (cubesats have no thrusting system so they are basically just debris in LEO which) a few months or years later. Sometimes however, they are launched on a higher orbit, or even in deep space for exploration matters.

Payloads

A cubesat can carry commercial off the shelf components as embedded electronics, which allows to demonstrate state-of-the-art technologies in real-life conditions. The limitations are the payload size, weight and power budget as well as evironmental conditions.
Power budget is a proble as there is a very small surface to cover with solar panels and very little room for a battery.

Notable missions

The LightSail Cubesat being prepared by the LightSail team.
Figure 4: The LightSail Cubesat being prepared by the LightSail team. [JPG]

The amount of cubesat missions is growing each year, with a record of more than 70 launches in 2014. Among them:

  • LightSail is a 3U cubesat funded by the Planetary Society carrying a 32 square meters solar sail demonstrator. Launched in May 2015, it experienced a software glitch but quickly recovered from it.
  • JAXA's cubesat launches from the Kibo robotic arm aboard the ISS. And in particular the PhoneSats launches, the 1U cubesats launched in 2013 that brought Samsung Galaxy S1 smartphones into space as on-board computers. (They ran on Android).
  • The Flock-1 constellation of Earth imaging cubesats, deployed from the ISS, demonstrating that large cubesats deployements are feasible and worthy for short term missions.
  • The AAU CubeSat by the Aalborg University in Denmark, which was the first student-built cubesat to demonstrate the capabilities of the cubesats.
  • And last but clearly the most exciting cubesat launch of this list, the two MarCo, or Mars Cube One that will watch and help maintain communications with Earth ground stations during descent of 2016 Nasa's InSight mission.
  • Another hypothetical cubesat constellation launch (or nanosatellite launch) could be what Elon Musk reffered to in his big Space Internet announcement in January.
The insight mission with cubesats as communication relays
Figure 5: The insight mission with cubesats as communication relays [PNG]

Who's launching them?

Cubesats are regularly accepted as secondary payloads by NASA , SpaceX (Falcon 1 and now 9), ISC Kosmotras (Dnepr rockets), ESA (Vega), as well as other Russian and Indian space agencies. NASA is currently calling for more cubesats launch services, and working on a new dedicated cubesat launch system, the VCLS.


Sources:

  1. The Cubesat Specification
  2. Light Sail website
  3. B.Klofas: Survey of CubeSats communication systems
  4. P.Muri & J.McNair: Survey of communication subsystems for ISL & Cubesats missions
  5. A.Toorian, J.Puig-Suari & R.Twiggs: Cubesats as Responsive Satellites
  6. SingularityHub.com
  7. SPACE.com: cubesats & deep space exploration
  8. ESA: Vega maiden flight cubesats
  9. Nasa InSight's CubeSats
  10. Power Budget matters for cubesats
  11. Makezine
  12. Wikipedia


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