MIZZOU NEWS

Safer Shuttle Landings

Researcher designs guidance system for next generation shuttle

Eventually, NASA will launch a new generation of space shuttles, and when the first mission is finished and the shuttle has returned to the earth’s surface, Craig Kluever will smile with a sense of humble satisfaction. Kluever, an associate professor of mechanical and aerospace engineering at the University of Missouri-Columbia and a former NASA consultant, will know that he helped the vehicle land safely.

The remaining shuttles of the current generation contain guidance and landing-control systems based on technology from the mid-1970s. The dated systems limit a shuttle’s ability to guide itself toward landing or to correct its flight pattern if there is a mechanical failure. This limitation is one reason that engineers at NASA's Marshall Space Flight Center (MSFC) in Alabama are designing a new generation of safer and technologically superior shuttle vehicles.

Kluever serves a critical role in the MSFC project. His research will allow the shuttle’s guidance system to recognize and steer toward the runway, as well as have the right amount of energy to reach the landing area. In this case, energy is determined through a combination of the shuttle’s altitude and speed.

“We've got to figure out a path to the runway,” Kluever says. “We must line it up with the right energy. Remember that the vehicle is an unpowered glider, so you get only one shot. There’s no fly around.”

During entry — the phase of space flight when an orbiter re-enters the earth’s atmosphere and gravity pulls the orbiter toward the earth’s surface — a shuttle moves from Mach 25 to Mach 2. At approximately Mach 2, the shuttle enters a transitional phase know as Terminal Area Energy Management (TAEM). It is during this stage that engineers must prepare the shuttle for landing. The challenge of the TAEM phase is to ensure that the shuttle aligns itself with the runway and has the proper amount of energy for landing.

The remaining shuttles of the current generation contain guidance and landing- control systems based on technology from the mid-1970s. These systems limit a shuttle’s ability to guide itself toward landing or to correct its flight pattern if there is a mechanical failure. Photo courtesy of NASA

After obtaining data from MSFC engineers on the size, weight and aerodynamic properties of the new vehicle, Kluever designs and tests “robust” guidance algorithms that will automatically guide the vehicle to a landing site. Guidance systems on current shuttles enable the vehicles to land themselves, although astronauts choose to operate them manually during final approach and landing. The algorithms are a mathematical profile that constitutes a flight pattern range in which the shuttle can safely navigate. Engineers use the term “robust” to describe a new guidance system that is more autonomous and adaptable, which means that the new vehicles will have the power to re-compute guidance commands and correct flight patterns if there is a mechanical failure or dramatic environmental change.

“We can design our guidance system regardless of aerodynamic properties,” Kluever says. “That’s what sets it apart from the current shuttles. It’s adaptable.”

The proper amount of energy is another challenge Kluever faces. Each shuttle enters the TAEM phase at a unique speed, and Kluever must design a guidance system that acknowledges that speed and develops an appropriate route to ensure the remaining energy is sufficiently depleted during the remaining ground track to the runway.

Kluever has a contract with NASA’s MSFC to support his research. Another contract with NASA’s MSFC is pending until the U.S. Congress passes the federal budget.

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Last Update: July 2, 2009