Engineering Science Payload Delivered to Phoenix Mission "PIT"
27 Jun 2006
(Source: University of Arizona)
The stage is built.
The lights are in.
The computer "brain" that simulates the workings of the Phoenix Mars Lander spacecraft and runs its science payload and telecommunications system is ready for action.
Now a team at the Phoenix Science Operations Center (SOC) at The University of Arizona in Tucson has begun adding engineering models of science payload instruments to a mock lander.
The mock lander is central to the Payload Interoperability Testbed, or "PIT." SOC and the PIT will be the theater of operations for the Phoenix Mission, both for pre-landing practice and post-landing science surface mission operations.
The first in NASA's "Scout" program, the Phoenix Mars Lander will launch in August 2007 for a May 2008 touchdown. The Phoenix mission is led by Principal Investigator Peter H. Smith, of the University of Arizona, with project management at NASA's Jet Propulsion Laboratory and development partnership with Lockheed Martin Space Systems. International contributions for Phoenix are provided by the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen, and the Max Planck Institute in Germany. .
The mission will explore a Mars polar landing site to uncover clues about the history of water and potential for habitat to support life. The payload includes a nearly eight-foot long robotic arm for digging down through soil into ice, a robotic arm camera, a surface stereo camera, a descent camera, a meteorological station, a high-temperature furnace and mass spectrometer, a powerful atomic force microscope and a miniature wet chemistry laboratory.
"The PIT is going to be a Martian stage set, the mission's rehearsal theater," said Smith, a senior research scienetis at UA's Lunar and Planetary Laboratory (LPL). "We'll create an interesting scene for the science team to interact with. We'll set up puzzles in the terrain we'll dig into and have the science team solve the puzzles in paydirt. You won't mistake this for Mars, but it will look Mars-like."
"The PIT is a complete test environment that will allow us to test all of the commands that will be sent to the lander," SOC Manager Chris Shinohara said. "The PIT allows us to have a dedicated testbed for testing science instruments so we can verify how we will operate them on the surface of Mars."
The 2,500-square-foot PIT doesn't look much like the Red Planet yet. But by fall, the 30-inch-high, 1,600-square-foot mock lander platform will sport terrain fashioned from painted drop cloths, a Mars crater, a dust devil and other Martian features.
The mock lander is perched next to a 16-foot by 8-foot digging slot. Technicians will slide bins of prepared soil into the slot in tests of the robotic arm.
The "Payload Test Lab" (PTL) computer occupies a 170-square-foot cubicle with walls covered by silver antistatic material. PIT workers are erecting a PTL cubicle canopy of the same silver stuff. The computer has 30-foot extension cables for controlling the PIT lander deck. The PTL can be remotely operated from the Jet Propulsion Laboratory in Pasadena or Lockheed Martin, which has an identical twin computer in Denver, if needed.
Aluminum foil on the ceiling above the raised platform helps create ambient Mars-like lighting. The wrinkled foil diffuses light from a dozen 1,000-watt floodlights pointing upwards. In addition, four very narrow 1,000-watt spotlights mounted in a line on a single, adjustable stand can be moved around the lander platform to simulate light from sun's disk on its daily journey across the Martian sky.
Swamp coolers help humidify PIT air -- not because real Mars air is humid, but to control electrical sparks that could fry sensitive electrical parts on science instruments in the mock lander payload. Electrical discharges won't be a problem with the real payload on Mars, of course, because there's no one around to touch the devices on Mars.
One corner of the 20,000-square-foot room has been painted a Mars-like reddish brown. The painted wall sets off Phoenix Mars Lander exhibits designed by the Pima Air and Space Museum. The PIT also includes an operations room, office space and a conference room.
The mission team will use the PIT to develop and test efficient "integrated payload surface operations," Shinohara said. Phoenix operations sequences have to be efficient if the team is to get the most science data possible before the arctic sun sets and the three-month-or-more mission ends in 2008.
Teams from UA's LPL, Lockheed Martin and NASA's Jet Propulsion Laboratory will be adding flight science instruments to the Phoenix spacecraft at Lockheed Martin in Denver next month.
When the mock lander instruments have been installed, engineers and scientists will begin using the PIT to test payload instruments for any hardware and software glitches, said PIT manager Rick McCloskey. "It's cheaper and easier to troubleshoot any problems here than to do it with the real instruments being installed on the real lander at Lockheed Martin," McCloskey said.
"The PIT also plays an important role in training science and engineering teams," Shinohara added.
Phoenix mission scientists from academic institutions and laboratories around the world will convene for PIT rehearsals, called "ORTs," or operations readiness tests next March. Two more ORTs are scheduled before landing, in September 2007 and January 2008.
Team members will write the sequences that will command the robotic arm to dig into frozen soil that ranges from rock-hard ice to loose sand. They'll practice delivering samples to the suite of sophisticated instruments on the lander deck, then simulate running experiments for analyzing the soils. They'll photograph the mock Mars environment in ambient lighting that simulates the harsh Martian light.
"We'll play 'What ifs'," McCloskey said. "What if there's a rock right in the middle of where we want the robotic arm to dig? Or what if there's a data drop-out and we don?t have all the data we'd like to decide what we're going to do the next day?"
Mission operations will move to the UA's SOC building after the Phoenix spacecraft has landed safely and is found to be operating normally. The SOC facility then will support about 100 people from all over the world who are on instrument, spacecraft, ground data system and science teams, Shinohara said.