Nov 15, 2007

Moon Rocket Parachute Tests a Success


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Nov. 15, 2007: How do you bring a 200,000-pound rocket booster back to Earth after it catapults its payload toward the moon? Very carefully!

It's something NASA has to learn to do. The agency is laying plans to return to the moon in the next decade, and designs for the new Ares moon rocket call for reusable boosters. These massive side-rockets can't just crash back into the ocean when they're out of fuel -- they've got to be lowered gently.

Today NASA took an important step toward accomplishing this spectacular feat when engineers successfully tested the colossal parachute designed to bring the Ares I Crew Launch Vehicle's first stage booster back down.1 The 150-foot diameter ribbon parachute passed with "flying colors." Sporting broad, bright stripes of red and blue, the parachute drifted to Earth from 16,500 feet above and gently (relatively speaking) placed its huge passenger on the Yuma, Arizona ground:


Above: The Ares parachute in action. More images: #1, #2.

"Everything had to happen exactly according to plan for us to get a 42,000-pound weighted tub out the back of a C-17 airplane and time the free fall just right," says James Burnum of NASA's Marshall Space Flight Center. "We had to deploy our parachute according to the prescribed test conditions--and it worked perfectly."

The Nov. 15th test follows another successful drop on Sept. 25th. In both cases, the payload was less than the full 200,000 pounds. Nevertheless, the tests gave engineers a chance to measure the parachute's drag area2 and validate its design.



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NASA already has plenty of experience with parachutes: A parachute recovery system brings shuttle solid rocket boosters back to Earth for refurbishment and reuse, and engineers are using a similar design for the Ares booster recovery system. The Ares booster is much heavier and will plummet Earthward faster than do the shuttle solid rocket boosters, so stronger materials have to be used.

"These chutes are made of Kevlar, and shuttle chutes are made of nylon," says Ron King, also of Marshall. "Kevlar is stronger and lighter than nylon, so the chute can be bigger but fit in the same size pack and weigh less. Still, the design for this recovery system is much the same as the shuttle's."

This proven design may be one reason for the successful tests, but the full story of the parachute requires a trip into history:

Leonardo Da Vinci dreamed up the idea of a parachute almost 500 years ago. About 100 years later, Faust Vrancic built a rigid-framed parachute based on Da Vinci's tattered old sketches. Vrancic tested his rickety contraption by jumping from a tower in Venice. He somehow landed safely on the ground below. [ref]

In 1793, Jean Pierre Blanchard used silk to make the first soft, foldable parachute. Andrew Garnerin put Blanchard's design to the test for the first time in 1797 by leaping from a hot air balloon. [ref]


Right: Andrew Garnerin performs the first recorded parachute jump. Gouache and watercolor painting by Etienne Chevalier de Lorimier. [ ]


More than a century later, in 1912, Albert Berry thrilled onlookers with another first by jumping from an airplane to test a parachute. The plane took off from somewhere near St. Louis with Berry on board. He climbed down through the fuselage frame, stood on the axel, and hopped off. He executed a perfect drop, although he admitted to feeling "uneasy" since he fell nearly 500 feet before the chute opened.[ref]

Fast forward to the present and listen to Ron King, who experienced his own moment of uneasiness during NASA's first parachute test.

"We were a little apprehensive because of the size and weight of our payload," says King. "We weren't sure how something that size would behave, but we expected success and we got it."

The Ares I parachute system consists of three types of parachutes: (1) a small pilot chute, which pulls out the drogue chute; (2) a 68-foot diameter drogue chute, which maneuvers the booster into a vertical position and slows its descent, and (3) three main parachutes, which slow the booster more, carrying it to splashdown.

Testing of the parachute system is scheduled to continue through 2010.

"These events were the first real live tests of flight development hardware for the Ares vehicle – our ride back to the moon," says King. "They represent a first step."

They bring to mind other first steps of centuries past--like the first steps a few men took from great heights into thin air, supported only by their own courage and a hope that an unproven parachute strapped to their backs would work. So far so good. Now, on to the moon!


Author: Dauna Coulter | Production Editor: Dr. Tony Phillips | Credit: Science@NASA


1. United Space Alliance designed and manufactured the parachute under subcontract to Alliant Techsystems, the Ares I First Stage prime contractor. NASA’s Marshall Space Flight Center is the project management organization for the Ares I First Stage and leads the design and development of the solid rocket booster recovery system. Other parties involved in the testing were Pioneer Aerospace, which is part of Zodiac Aerosafety Systems, Fox Parachute Services of West Virginia, the Yuma Army Proving Grounds in Yuma, Arizona, and the Air Force C-17 flight crew from Washington State.

2. According to Ron King, the drag area is the amount of surface area (measured in square feet) that the parachute canopy provides for resisting airflow. The drag area is used to calculate the total load (drag area X Dynamic Pressure) of the parachute, which is the resultant force acting upward to slow the descending booster.


web links

NASA Conducts Second Test of Main Parachute for Ares Rockets -- press release

NASA's Future: The Vision for Space Exploration