Fuel Level Measurement On Spacecraft, discussion & ideas Options

[RoverDriver]

If you had multiple (>3) orbiters, could you use them to make precise measurements of each others' positions?


Doug M.

You would need to synchronize OD, MRO, MEX and the rovers to make such a measurement... like at an EDL event? I wonder if the telemetry gathered during MSL EDL could be used for that purpose. My knowledge on orbital mechanics is pretty limited, so I have no idea whether this is possible or not.

Paolo

[nprev]

New topic for this old problem.

[stevesliva]

Re Stardust: good reference on that in http://www.spaceops2012.org/proceedings/do...5-Paper-001.pdf

Really interesting paper. Talks about more than the depletion burn and fuel estimates, but the relevant points:

The spacecraft signaled its readiness to retire a few days before decommissioning, when the telemetry showed a small step change in the tank pressure. The propulsion subsystem engineers reviewing the data concluded that this was a sign of pressurant gas being ingested into the screen of the propellant management device, indicating an empty tank. The decommissioning burn a few days later, on March 24, 2011, showed that the first thruster indicated signs of processing both gas and fuel 30 seconds into the burn, indicating that the tank indeed was empty at the start of the burn.
The decommissioning burn showed that the PGS methodology had provided the most accurate estimate of remaining fuel for this particular situation. There had been many discussions within the operations and science teams about the conservatism of these results and the impact it was having on the mission planning. However, had
the project not adjusted its mission plan to account for this worst case prediction, the spacecraft would not have had enough fuel to complete its mission, and would not have captured the images the comet shown below.

The PGS (Propellant Gauging System) methodology [1] relies on building a detailed thermal model of the fuel tank and its interaction with the spacecraft and any other thermal boundaries. This model is then correlated to thermal transient data obtained by heating and cooling the spacecraft fuel tank, thus calculating
the contribution of the thermal mass of the fuel to the transient thermal behavior. Such heating tests were implemented on the Stardust spacecraft in 2008 and 2009 the data was incorporated in the PGS model. This yielded a prediction of 10.8±0.4 kg remaining fuel, compared to the 12.9±1.0 kg predicted by the ‘book-keeping’ system at this stage of the mission

wow.

[chris]

While Googling for information on the design of spacecraft fuel tanks (since I know little about them), I found this set of papers:

http://www.psi-pci.com/Technical_Papers.htm

Chris

[Tom Dahl]

There is an entertaining video clip on the psi-pci web site of tank burst tests. A couple of dozen exploding tanks are great fun to see.

Pressure Systems Inc. has been around for many decades and created thousands of aerospace pressure vessels. They produced most of the tanks on the Viking orbiter, aeroshell, and lander, for example.