Spaceflight Now: Breaking News

Pegasus rocket to launch from a locale far, far away

Posted: October 2, 2000

The L-1011 touches down at Kwajalein facility on Saturday. Photo: MIT
After taking a weekend ferry to a tropical paradise in the central Pacific Ocean, an Orbital Sciences air-launched Pegasus rocket is being readied to carry a NASA satellite into space to seek out the most powerful explosions in the universe.

Latched to the belly of a modified L-1011 carrier aircraft, the $15 million Pegasus was flown 4,200 miles from its home base at Vandenberg Air Force Base in California to Kwajalein Missile Range in the Marshall Islands, a U.S. military center located on a stretch of island-like atolls just north of the equator in the middle of the Pacific. The trek began Friday afternoon and included an overnight stop in Hawaii.

The launch is scheduled for early Saturday when the Pegasus will be flown over the Pacific and dropped from the "Stargazer" jet for an 11-minute jaunt to Earth orbit. Drop time is slated for 0545 GMT (1:45 a.m. EDT), with an available launch window extending about nine hours.

Riding on the end of the three-stage rocket is the High-Energy Transient Explorer 2, a 273-pound satellite built by the Massachusetts Institute of Technology in a cooperative endeavor sponsored by NASA.

Dubbed HETE 2, the satellite is a replacement for its earlier namesake that was lost in a launch failure four years ago.

Flying nearly 400 miles above the planet in an orbit tightly restricted around the equator, HETE 2's three instruments aim to detect gamma ray bursts. Within seconds, the $8 million satellite will be able to tell astronomers that a burst has occurred and its approximate location.

"Gamma ray bursts are colossal explosions. They are the most energetic events since the Big Bang, yet one occurs about once a day in the sky," said George Ricker, the mission's lead investigator from MIT.

  HETE 2
HETE 2 undergoes pre-flight testing. Photo: MIT
Scientists believe these mysterious gamma ray bursts come from hypernovas billions of light years away when a giant star explodes with up to 1,000 times more power than a supernova. Other possibilities of their creation include an orbiting pair of neutron stars coming together or maybe a neutron star being sucked into a black hole.

"It's still a mystery what causes these things. We hope to shed some light on that," said Daniel Reichart, a California Institute of Technology astronomer. "Beyond that, this mission is probably going to discover things that we can't possibly predict."

But getting HETE 2 aloft will present a unique challenge.

The Pegasus rocket, now in its 10th year of flight, has been launched from five different sites -- four in the U.S. and the Canary Islands off Africa. This week's mission will add a sixth staging locale.

The Kwajalein Missile Range is known for its role in testing missiles for the U.S. military. However, the site has never launched a satellite cargo into orbit -- just ballistic and theater-type missile tests.

Saturday's historic first is the result of massive planning to prepare for the Pegasus mission, including work to set up a remote launch control center half-a-world away in Florida.

Only two dozen rocket and satellite specialists traveled to Kwajalein. Senior officials, meanwhile, stayed back in the U.S. and will gather in the Mission Directors Center of Cape Canaveral Air Force Station to govern the launch.

"It has been a challenge. No doubt about it," NASA Launch Manager Chuck Dovale says of establishing the control center so far away.

Never before has a launch been controlled from such a distance, historians say.

A map shows the track the L-1011 followed from Vandenberg to Kwajalein. Photo: U.S. Army
Engineers have rigged three voice and data communications lines to link the two sites so officials can oversee the operation. Only one line would be needed, giving plenty of backup margin, Dovale said.

In addition, the technicians that flew to Kwajalein had to take plenty of spare parts and backup equipment just in case.

The whole reason for going to Kwajalein is so the HETE spacecraft can be placed into its desired equatorial orbit. The Pegasus rocket isn't powerful enough to get the satellite into such an orbit if launched from Cape Canaveral, for example, nor does HETE 2 have an onboard kick engine for orbital maneuvering.

"It is a big advantage if you truly want an equatorial orbit," Dovale said of using Kwajalein.

The satellite's planned orbit will never go higher than 5 degrees north or south of the equator, preferably less than 2 degrees. A vast network of ground stations scattered along the equator will ensure HETE 2's gamma ray burst detections are received on Earth continuously.

Spaceflight Now will provide extensive live updates during Saturday's launch. Coverage will begin at 0430 GMT (12:30 a.m. EDT), which is 15 minutes before the L-1011 takes off for the drop zone.

Flight data file
Vehicle: Hybrid Pegasus
Payload: HETE 2
Launch date: Oct. 9, 2000
Launch time: 0545 GMT (1:45 a.m. EDT)
Staging site: Kwajalein Missile Range

Pre-launch briefing
Mission preview - Our story describing the launch of the HETE 2 satellite.

Launch timeline - Detailed chart of events to occur during the launch.

HETE 2 - Description of NASA satellite to search of gamma ray burst.

Video vault
The High Energy Transient Explorer 2 spacecraft as seen in NASA animation. HETE 2 will seek out gamma ray bursts.
  PLAY (206k, 14sec QuickTime file)
From the history archives watch a previous Orbital Sciences Pegasus rocket launch, which is dropped from the belly of an L-1011 carrier jet.
  PLAY (179k, 17sec QuickTime file)
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