MARS PATHFINDER UPDATE
We started flight system Assembly, Test, and Launch Operations (ATLO) at JPL on June 1, 1995, 18 months before launch on December 2, 1996. Our first ATLO phase from June through December 1995 starts with initial subsystem integration, including the rover and the science instruments, and ends with system test of the launch, cruise, Entry, Descent and Landing (EDL) and surface operations phases of the mission. We work ATLO one shift per day, 5 days per week and use extra shifts and weekends to catch up if we fall behind. In addition, we have 36 workdays of schedule reserve built into the Phase 1 schedule to ensure we complete everything we set out to do before we start ATLO Phase 2.
In Phase 1, everything is laid out in a "2-dimensional configuration". For instance, the cruise and lander stages sit side by side, electrically connected through jumper cables so that we can easily get to a piece of equipment in case of a problem. Both engineering and flight model subsystems are used in Phase 1 which is like a dress rehearsal, problem shakeout period for Phase 2, the formal space qualification phase. This begins in January 1996 with all flight model equipment now on board. Here we assemble the flight system for the first time, and it goes together sort of like "Russian nested dolls": the lander folded up around the rover which is in turn enclosed inside the aeroshell/backshell cocoon.
It is in Phase 2 that we do our system environmental tests: acoustic vibration, cruise solar/thermal vacuum, surface solar thermal/Mars atmosphere, pyro shock, electromagnetic compatibility, weight and center of gravity, and spin balance with system tests inserted before and after each major environmental test. In addition, we practice all the assembly and test steps that are conducted at the launch site.
We have 33 days of workday schedule reserve built into Phase 2, the end of which culminates ATLO activities at Pasadena with completion of a final system test, a partial disassembly of the flight system for packing and its shipping with support equipment to the Eastern Test Range (ETR) at Cape Canaveral, Florida for launch preparations and launch: ATLO phase 3.
In Phase 3, September 1996 to launch, final flight system assembly is accomplished including installation of the flight aeroshell, parachute, air bags, rockets, pyro firing devices, and propellant. Flight representative models and referee propellant were used in Phase 2.
At completion of assembly, the final system test accomplished in Pasadena is repeated to verify that all subsystems remain ready for launch. A final set of cruise and entry spin balance tests are accomplished-then launch vehicle mate, launch day practice, a final end to end data flow test with Flight Mission Operations in Pasadena, countdown and launch!
In Phase 3, we have 24 workdays of schedule reserve, commonly called "beach time" for unused portions. In Phases 2 and 3, the Flight Mission Operations team trains with the flight system during system tests, commanding the spacecraft and processing its telemetry data. Actual flight sequences of events planned for use in flight are used and checked out. Just prior to launch, a final software update is loaded.
Flight system operations is handed over to the Mission Operations Team by the ATLO Team immediately after launch.
--Tony Spear
