ECLSS Thermal-Vacuum Qualification Chamber (2D)

Chamber Controls

Hot shroud temperature 70 °C

Cold shroud temperature -60 °C

Orbital cycle period 90 min

Time acceleration 120×

Chamber State

Status: IDLE · Cycle 0 / 4

Shroud temperature

20.0 °C

Article temperature

20.0 °C

Net radiative flux

0 W

Elapsed test time

00:00:00

How it works

In vacuum there is no air to carry heat by convection, so a test article exchanges heat with its surroundings by thermal radiation alone. This rig integrates the real Stefan–Boltzmann radiative heat-transfer equation for the article's own temperature T as it sits inside a chamber whose shroud walls are driven to a cycling temperature T_shroud(t), the way sun/eclipse exposure cycles a spacecraft's external temperature once per orbit:

dT/dt = εσA·(T_shroud⁴ − T⁴) / (m·c)

σ = 5.670374×10⁻⁸ W/(m²K⁴)   (Stefan–Boltzmann constant)
ε = 0.85   (article surface emissivity)
A = 0.55 m²   (article radiating area)
m·c = 7200 J/K   (article thermal mass — 8 kg aluminum, c = 900 J/kg·K)

Because m·c is finite, the article's temperature always lags the shroud — its own thermal inertia damps and delays the swing, exactly like a real spacecraft component riding out an orbital thermal cycle. The chart below plots both temperatures live so you can see that lag and the settling behaviour directly.

Hot / cold shroud temperature — the two extremes the shroud walls cycle between, standing in for direct sun exposure and cold-space eclipse.
Orbital cycle period — how long one full hot→cold→hot sweep takes; a period much shorter than the article's own thermal time constant (≈ 42 min for these defaults) suppresses its temperature swing, a longer one lets it track the shroud closely.
Time acceleration — runs simulated seconds faster than real time so a multi-cycle qualification completes in view.

Pass requires the article's temperature to stay inside its qualified operating range, −20 °C to +55 °C, for the full duration of 4 consecutive cycles — the same electronics-box qualification band and cycle count used in real thermal-cycling acceptance testing.

Hot soak Cold soak Article