1. The rattling capsule

Tom Wolfe’s The Right Stuff describes the early Mercury flights as a sustained assault on the human body: noise, vibration, and acceleration that no simulator fully captured. The astronauts survived because their couches absorbed the worst of it and because the vehicle was overbuilt. Small satellites do not get a couch. They get a mounting bolt and the hope that the design was right.

This entry reads about the launch vibration and shock environments that small satellites must survive.

2. The launch environment stack

A satellite sees several mechanical environments on the way to orbit:

  • Transportation and handling: lower-level vibration, bumps, and thermal transients before launch.
  • Lift-off and ascent: broadband random vibration from aerodynamic turbulence and engine noise, plus low-frequency sinusoidal loads from vehicle maneuvering.
  • Stage separation and fairing jettison: pyrotechnic shock events with high peak acceleration and short duration.
  • Deployment: snap loads from dispenser springs or separation systems.

For small satellites, the most damaging environment is often not the steady acceleration but the random vibration during ascent and the shock at separation.

3. Standard test levels

NASA’s General Environmental Verification Standard (GEVS) provides a baseline. For small parts and components, random vibration levels of 6.8 to 20 grms are common, depending on whether the test is acceptance, protoflight, or qualification. The Surrey paper argues that these levels can be unrepresentative for small satellites, because a CubeSat on a dispenser sees a different load path than a large instrument on a primary structure. The SmallSat Europe paper reinforces this: testing must be tailored to the actual load path, not just copied from a standard table.

The lesson is that standards are a starting point, not a substitute for understanding how the hardware is mounted and how the loads get in.

4. What this changes

  • Launch vibration and shock are added to the list of things the desktop’s rack and cell assembly must survive.
  • The exact levels cannot be set until the launcher and mounting arrangement are known.
  • GEVS is identified as a useful baseline, but the Surrey paper’s critique is noted.
  • The next entry will look at how the tests are actually run.