Fuel Level Measurement On Spacecraft, discussion & ideas |
Fuel Level Measurement On Spacecraft, discussion & ideas |
Sep 7 2012, 07:44 AM
Post
#1
|
|
Member Group: Members Posts: 102 Joined: 8-August 12 Member No.: 6511 |
We got answers!
Here's what the good people at Mars Outreach have to say. QUOTE 1) As of today (having just completed an Orbit Trim Maneuver (OTM)), Odyssey has 17.3 kg, +3.0 / -5.0 propellant. 2) 1.9 kg is obligated for a follow-on OTM in January 2014. Odyssey utilizes approximately 1 kg / year and historically has budgeted 1 kg / year for unexpected safing events. So, propellant life should be between 5.2 to 9.2 years. These numbers are based on no onboard anomalies that would require propellant above the safing budget, no changes in Odyssey's basic operations (three operating reaction wheels, high gain antenna and solar array servos (motors) continue to function normally, etc.) and no further programmatic maneuvers. Consideration is being given to performing a procedure in the future that has the potential to refine the +3 / -5 uncertainty of fuel remaining. When prop is exhausted, the mission ends because the spacecraft is no longer able to desaturate the reaction wheels and / or provide thruster control; the spacecraft can no longer be pointed to maintain communications and solar panel illumination. 3) The statement is basically correct: THEMIS, which is comprised of two imagers, visible and infrared, and two instruments of the Gamma Ray Suite, High Energy Neutron Detector and the Neutron Spectrometer, all continue to operate and gather science data. The Gamma Ray Spectrometer of the Gamma Ray Suite and Marie have both been decommissioned. Thanks again for your questions and your interest in Mars exploration! Wow! Okay, so what comes to mind from this? Well, the first thing is that there's an awfully large uncertainty in the amount of fuel left. 17.3 kg +3 / -5 ? The range of uncertainty is almost half the total amount of fuel. I wonder why; and I also wonder what the "procedure" might be to narrow the range. Second is, they have a fair amount of propellant left -- enough for at least another five years of operation. So, barring mechanical failure, Odyssey should see the arrival of MAVEN (2014) and quite possibly of Mars Insight (September 2016 if they make their launch window) and ExoMars Part One (ditto). Doug M. |
|
|
Sep 10 2012, 11:44 AM
Post
#2
|
|
Member Group: Members Posts: 255 Joined: 4-January 05 Member No.: 135 |
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 |
|
|
Sep 10 2012, 04:41 PM
Post
#3
|
|
Member Group: Members Posts: 101 Joined: 3-May 12 From: Massachusetts, USA Member No.: 6392 |
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. |
|
|
Lo-Fi Version | Time is now: 31st May 2024 - 04:14 PM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |