Originally created 05/23/01

Spacecraft to capture solar wind particles



The Lockheed Martin-built Genesis spacecraft set to launch this summer is expected to help unlock the mysteries of our solar system's birth by snatching bits of the sun and whisking them to the Utah salt flats.

Once there, a helicopter crew will be poised to snag the incoming capsule in midair.

The NASA spacecraft is scheduled for takeoff from Cape Canaveral on July 30, and Lockheed Martin engineers in Denver are wrapping up final tests before shipping it to Florida at the end of this month.

The Denver engineers will control the spacecraft throughout its $200 million mission and are charged with bringing it down safely in September 2004.

Genesis will be NASA's first try at using a midair capture to return samples to Earth, a technique the military has used to catch unmanned planes. Project scientists don't want the spacecraft to hit the ground because they fear its precious cargo - bits of "solar wind" - could be contaminated or damaged.

Lockheed Martin hired Vertigo Inc., a California research and development firm, to handle the mid-air capture. Vertigo, in turn, hired helicopter pilots and trained them to catch mock capsules dangling from parachutes in the skies over Arizona and Utah.

"We've done 35 to 40 tests and have never missed on the first try," said Peter Doukas, Lockheed Martin's lead mechanical engineer for the Genesis project.

After Genesis launches atop a Delta 2 rocket in July, it will execute a giant figure eight in space, first flying away from the sun, then looping around and zipping back past Earth and toward the sun. When the spacecraft is nearly 1 million miles from Earth, it will hover there for 2 12 years.

The top half of the Genesis capsule will open on a hinge, like a giant clamshell. Inside is a sealed metal canister that contains the solar-particle collectors, which are made of ultra-pure silicon wafers. Once the canister is unsealed and the collectors are exposed, particles ejected from the sun will pelt the silicon and become embedded.

After gathering solar samples, Genesis will head back to Earth.

The return capsule will slam into Earth's upper atmosphere at 20,000 mph, glowing red-hot and trailing flame as its exterior heats to about 3,600 degrees.

Its heat shield and foam insulation are designed to protect the solar sample by keeping the silicon collectors below 158 degrees, said Neil Tice, head of the Genesis thermal-system team for Lockheed Martin.

When the capsule is 100,000 feet above the Utah flats, a small parachute will unfurl to slow and stabilize it. At about 20,000 feet the main parachute - a gliding, Band-Aid-shaped parafoil like those used by skydivers - will open.

Two helicopters will be hovering at 12,000 feet, waiting for the capsule, said Roy Haggard, vice president of Vertigo Inc. Radar at Utah's Hill Air Force Base will spot the 5-foot-wide capsule and relay its position to the helicopters, which will dash in for the capture.

The capsule will corkscrew down in a half-mile-wide spiral, dropping at about 700 feet per minute. The first helicopter to the scene will move in behind the chute, lowering a 12-foot-long boom with a hook.

"We'll fly formation with it, right behind it," Haggard said.

"When we get all set up and we've lowered the boom, then we simply overtake the parafoil, flying 15 to 20 knots faster than it's going," he said. "Then we set the hook basically right on center and collapse the parafoil."

Once captured, the capsule will hang from a 100-foot line as it's lowered into the shipping container that will take it to NASA's Johnson Space Center in Houston.

Scientists will analyze the solar particles, measuring the relative abundance of different forms of oxygen, nitrogen, helium and other elements.

The outer layers of the sun, which release the solar wind particles Genesis will bring home, are thought to be made of nearly the same material that condensed to form our home star and its planets 4.6 billion years ago.

Scientists hope that studying the solar particles will help them understand how a giant cloud of gas, dust and ice, known as the solar nebula, collapsed to form the solar system. Hence the name Genesis.