NASA's latest flight test for future human space exploration is called Pad Abort 1, or PA-1. The test is set for May 6 at the Orion Abort Flight Test Launch Complex 32E at the U.S. Army's White Sands Missile Range near Las Cruces, N.M. Although Orion is a component of the agency's Constellation program, the future of which is currently under Congressional review, the test is part of NASA's ongoing mission to develop safer space vehicles for all human spaceflight applications. Information gathered through PA-1 testing will be valuable in design and development of future systems built for use in providing a safe escape for the crew in the event of an emergency. The launch abort system, or LAS, could be used on the launch pad or during the first stage of ascent to orbit.
The LAS comprises three solid propellant rocket motors: an abort motor, an attitude control motor, and a jettison motor. The primary motor is the abort motor, which is used to propel the crew module away from the pad. The attitude control motor steers the vehicle to actively maintain stability and reorient it as needed. The jettison motor will pull the whole launch abort system away from the crew module and make way for parachute deployment and landing. In addition to the motor stack, the launch abort system also includes a fairing assembly that covers the crew vehicle and a nose cone.
During the test, an abort command will be sent from the mobile operations facility that ignites the LAS abort motor. The motor will burn for approximately six seconds, with the highest impulse in the first 2.5 seconds. The crew module will reach approximately 445 miles per hour in the first three seconds in its upward trajectory away from the pad, to about one mile high.
The attitude control motor fires simultaneously with the abort motor and provides adjustable thrust vectoring to keep the crew module on a controlled flight path. As the launch abort vehicle completes the burnout of the abort motor it is reoriented in preparation for a programmed sequence of events. Explosive bolts fire and the jettison motor discards the spent abort system from the boilerplate crew module to allow the recovery parachute system to be deployed.
Alliant Techsystems, or ATK, developed the attitude control motor, which includes eight thrusters producing up to 7,000 pounds of thrust. ATK also developed the abort motor, which can produce a momentary half-million-pound thrust as it pulls the capsule away from the launch pad. Aerojet developed the jettison motor, which is the only motor of the three that would be used in all flight cases to pull the escape tower from the crew module.
Credit: NASA/Marc Havican/ Space City Films
The crew module for the PA-1 test was moved to the launch pad March 23. Technicians rolled out the launch abort system motors to the pad a week later, with stacking of the components scheduled to follow shortly. Over the next five weeks, combined systems tests will be conducted leading up to the actual flight test.
Brent Cobleigh, director of Exploration Systems at NASA's Dryden Flight Research Center in California, reports that the NASA team at White Sands has completed the integration of all systems, pyrotechnic devices, and parachutes into the crew test module.
Jay N. Estes, deputy manager in the Orion Flight Test Office at NASA's Johnson Space Center in Houston, congratulated the NASA and contractor team that has been laboring for more than two years to bring the launch abort system to actual flight test.
"It is a huge accomplishment for the Pad Abort 1 team that we have achieved this milestone," he said. "It's been a long tough effort, but we're almost done!"
After integrating the last rocket motor, the attitude control motor, with the rest of the launch abort system, the joint NASA and Lockheed Martin team electrically connected the system to the crew module for a series of integrated tests in a hangar, Cobleigh said. During these tests, special equipment simulated an abort of a launch while the vehicle is still on the launch pad - essentially "fooling" the vehicle systems into believing that the vehicle was flying an abort sequence. The abort simulation allowed the team to verify that all systems are ready to proceed to the Pad Abort 1 test flight.
The test module and launch abort system stack were built at NASA's Langley Research Center in Virginia. Systems installation and integration took place at NASA's Dryden Flight Research Center at Edwards Air Force Base in California. The module was airlifted to White Sands last August. Langley leads the development of the LAS in partnership with NASA's Marshall Space Flight Center. Dryden is conducting the launch abort flight test effort for the Orion Project Office at the Johnson Space Center, Houston.
Lockheed Martin is the prime contractor to NASA for the Orion crew exploration vehicle. Orbital Sciences Corporation is responsible for the design, development, test and integration of the LAS for Lockheed Martin.