Structures and thermal control (STR/TCS)

Also known as STR, TCS, Structure, Thermal control, Mechanisms

The frame that carries launch loads, the mechanisms that deploy antennas and arrays, and the thermal design that keeps every part within its temperature range. Small-satellite frames are mostly machined aluminium; thermal control relies on surface finishes.

Document
SQ-SS-005
Updated
20 Oct 2026
Reading time
7 min
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Definition#

The structure is the frame that carries every component, the interface surfaces that touch the deployer and the mechanisms of deployable elements such as antennas and arrays. Thermal control keeps every component within its allowed range while the heat loads change around the orbit. The two are designed together, because inside a spacecraft heat flows mostly through the structure.

Structure#

The CubeSat Design Specification recommends aluminium alloy structures; 7075, 6061, 6082, 5005 and 5052 are typical for the main frame and rails. Aluminium surfaces in contact with the deployer rails must be hard anodized to prevent inside the deployer[1].

Most commercial CubeSat frames are machined from 6061 or 7075 aluminium, and 1U, 3U and 6U frames are the most common products; some CubeSats have flown with printed polymer structures instead of metal[2]. PocketQubes use aluminium frames too, but many 1P designs let their printed circuit boards carry the loads: SMOG-1 has no separate frame at all, only boards and threaded rods[3].

Thermal environment#

A spacecraft in low Earth orbit sees three external heat sources: direct sunlight, about 1361 W/m²[4]; sunlight reflected by the Earth (albedo, about 0.3 on average); and the Earth’s infrared emission, about 237 W/m² on average[5]. Internal dissipation from electronics and battery adds to these. The only way back out is radiation to space.

flowchart LR
  SUN["Direct sunlight"] --> SAT["Spacecraft surfaces"]
  ALB["Albedo"] --> SAT
  IR["Earth infrared"] --> SAT
  INT["Internal heat: electronics, battery"] --> SAT
  SAT --> SPACE["Radiation to space"]

Passive and active control#

Small-satellite thermal design is dominated by traditional passive technology: paints, coatings, tapes, multilayer insulation () and thermal straps. Active control is mostly limited to battery heaters governed by a thermostat or a temperature sensor[6].

References

  1. [1]The CubeSat Program, Cal Poly SLO. (2022). CubeSat Design Specification, Rev. 14.1 (CP-CDS-R14.1). California Polytechnic State University.nasa.gov
  2. [2]NASA Small Spacecraft Systems Virtual Institute. (2026). Structures, Materials, and Mechanisms. State-of-the-Art of Small Spacecraft Technology (2026 edition), Chapter 6. NASA Ames Research Center.nasa.gov(accessed 20 October 2026)
  3. [3]nadir lab. (2026). Materials engineering for PocketQube picosatellites: A scaling-based review and design guide [Preprint]. nadir lab.Read on nadir lab.
  4. [4]Kopp, G., & Lean, J. L. (2011). A new, lower value of total solar irradiance: Evidence and climate significance. Geophysical Research Letters, 38, L01706.doi:10.1029/2010GL045777
  5. [5]Wertz, J. R., Everett, D. F., & Puschell, J. J. (Eds.). (2011). Space Mission Engineering: The New SMAD. Microcosm Press.
  6. [6]NASA Small Spacecraft Systems Virtual Institute. (2026). Thermal Control. State-of-the-Art of Small Spacecraft Technology (2026 edition), Chapter 7. NASA Ames Research Center.nasa.gov(accessed 20 October 2026)
  7. [7]nadir lab. (2026). PocketQube picosatellites: A review of standards, mission trends and miniaturization constraints, with lessons learned from Grizu-263A, Türkiye’s first PocketQube [Preprint]. nadir lab.Read on nadir lab.
  8. [8]Kovács, R., & Józsa, V. (2018). Thermal analysis of the SMOG-1 PocketQube satellite. Applied Thermal Engineering, 139, 506–513.doi:10.1016/j.applthermaleng.2018.05.020
  9. [9]Gilmore, D. G. (Ed.). (2002). Spacecraft Thermal Control Handbook, Vol. I: Fundamental Technologies (2nd ed.). The Aerospace Press.
  10. [10]Uludag, M. S., Yakut, E., Speretta, S., Radu, S., Chronas-Foteinakis, N., Bouwmeester, J., Menicucci, A., & Gill, E. (2019). Getting the Delfi-PQ ready for multiple launch options. In: International Symposium on Space Technology and Science (ISTS), Fukui (2019-f-08).pure.tudelft.nl

Cite this SatWiki entry

@misc{nadirlab2026structures,
  author       = {{nadir lab.}},
  title        = {{Structures and thermal control (STR/TCS)}},
  year         = {2026},
  month        = oct,
  howpublished = {nadir lab. SatWiki SQ-SS-005 (Rev. 3)},
  url          = {https://nadirlab.space/en/wiki/structures-thermal/}
}