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The parachute for the Mars Science Laboratory (with the Curiosity rover) was tested in the NASA Ames Research Center 80 by 120 Foot Wind Tunnel.

enter image description here

The wind tunnel is currently capable of air speeds up to 100 knots (190 km/h; 120 mph). But how was the parachute tested with a speed and pressure similar to a real entry to Mars? Only by scaling speed and air viscosity or by using a smaller model parachute instead of the original size?

Picture and speed data from Wikipedia.

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The full scale wind tunnel testing did not attempt to duplicate Martian conditions.

The purpose of the full scale testing was to to

provide an end to end test of the parachute system from mortar fire to parachute inflation.

and

initial inflation strength qualification

Much more detail about subscale wind tunnel testing and other parachute tests can be found in the paper Overview of the Mars Science Laboratory Parachute Decelerator Subsystem. A sample:

a multi-phase delta qualification by analysis and subscale supersonic wind tunnel test program to address the fundamental physics of the supersonic operation of DGB parachutes as a function of Mach number , parachute size, and capsule wake interaction. The first phase is computational fluid dynamics (CFD) of a 2% scale rigid parachute canopy and capsule validated by a 2% scale wind tunnel test of the rigid configuration over the MSL Mach and Re number deployment range in the Ames 9x7 ft. unitary tunnel. Phase two is fluid structure interaction (FSI) analysis of a flexible canopy with capsule validated by 5% scale wind tunnel tests over the MSL deployment Mach and Re range in the GRC 10x 10 ft. unitary tunnel. The final phase is the application of the validated FSI tools to the prediction of the full scale para chute performance in Mars type deployment conditions providing predictions of supersonic drag performance, stability, and canopy loading.

DGB = Disk Gap Band

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  • $\begingroup$ Is it possible to achieve the same forces to the parachute at high speed and very low pressure (marsian conditions) and low speed and a pressure of about 1 bar (conditions in the wind tunnel)? $\endgroup$ – Uwe Jan 12 at 18:25
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    $\begingroup$ @Uwe: if you had unlimited budget, a lot of things are "possible". The parachute engineers did what they judged to be the most practical given their engineering and budgetary constraints. $\endgroup$ – whatsisname Jan 12 at 18:38
  • $\begingroup$ @Uwe, some of the historical NASA wind tunnels were sealed to allow operation at a range of pressures to compensate for scale effects, so supersonic and pressure adjusted tunnels exist but have not found a users guide or similar listing the current tunnels and capabilities. $\endgroup$ – GremlinWranger Jan 13 at 1:32
  • $\begingroup$ @GremlinWranger But the photo I used in the question does not like a sealed wind tunnel that may be used at a pressure much smaller or greater than ambient pressure. The wall shown would not resist the forces of a larger pressure difference. $\endgroup$ – Uwe Jan 13 at 12:34
  • $\begingroup$ @Uwe, not my field but agree, presence of humans suggest this is at earth pressures and relatively low speeds, but done because it is the best achievable test of the flight hardware with technology available to NASA per Organic Marble's answer. The inability to fully test is mentioned as a major risk for Insight in the quote here space.stackexchange.com/questions/32262/…. Possible complication with closed tunnels for this specific test is that deployment probably produces a bunch of debris that risks damage a closed tunnel fan system. $\endgroup$ – GremlinWranger Jan 14 at 9:40

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