Spaceflight Now

The Mission

Rocket: Pegasus XL
Payload: Space Tech 5
Date: TBD
Time: 1357-1519 GMT (8:57-10:19 a.m. EST)
Site: Vandenberg Air Force Base, California
Satellite feed: AMC 6, Transponder 17, C-band, Digital

Spaceflight Now +

Premium video content for our Spaceflight Now Plus subscribers.

Pegasus abort
During the final seconds prior to the planned launch of the Space Technology 5 mission on March 15, a retention pin that holds the starboard-side fin aerosurface on the Pegasus rocket first stage did not retract. That forced the launch team to call an abort. This movie shows the scrub as it happened.

 Play video

Shuttle launch delay
Space Shuttle Program Manager Wayne Hale announces his decision to replace suspect fuel-level sensors inside the liquid hydrogen portion of Discovery's external tank. The three-week job means Discovery will miss its May launch window, delaying the second post-Columbia test flight to the next daylight period opening July 1. Hale made the announcement during a news conference from Johnson Space Center on March 14.

 Dial-up video:
   Part 1 | Part 2

 Broadband video:
   Part 1 | Part 2

Stardust science
NASA's Stardust spacecraft returned to Earth in January with the first samples ever retrieved from a comet. This briefing with mission scientists held March 13 from the Johnson Space Center offers an update on the initial research into the comet bits.

 Dial-up video:
   Part 1 | Part 2

 Broadband video:
   Part 1 | Part 2

MRO's orbit insertion explained
The make-or-break engine firing by the Mars Reconnaissance Orbiter to enter orbit around Mars and the subsequent aerobraking to reach the low-altitude perch for science observations are explained by project manager Jim Graf in this narrated animation package.

 Play video

MRO overview briefing
Fuk Li, Mars program manager at JPL, Jim Graf, MRO project manager, Rich Zurek, MRO project scientist, and Dan McCleese, the principal investigator for the Mars Climate Sounder instrument, provide an overview on the Mars Reconnaissance Orbiter on March 8, about 48 hours before arrival at Mars.

 Play video:
   Dial-up | Broadband

STS-9: Spacelab opens
Spacelab was an orbiting laboratory tucked in the payload bay of the space shuttle for scientists to conduct a range of experiments. The joint European/NASA program flew multiple times aboard shuttle missions starting with STS-9 in November 1983. In this post-flight film presentation, the astronauts from that Columbia mission narrate the highlights from Spacelab-1.

 Small | Medium | Large

Become a subscriber
More video


Sign up for our NewsAlert service and have the latest news in astronomy and space e-mailed direct to your desktop.

Enter your e-mail address:

Privacy note: your e-mail address will not be used for any other purpose.


Follow the countdown and launch of the Orbital Sciences Pegasus rocket with NASA's Space Technology 5 micro-sat demonstration. Reload this page for the very latest on the mission.

FRIDAY, MARCH 17, 2006

Launch is now no sooner than Wednesday, March 22, pending resolution of the pin issue.

2120 GMT (4:20 p.m. EST)

Initial inspections of the locking system for the Pegasus aerosurfaces has not uncovered any obvious reason why the pin on the starboard fin failed to retract during this morning's launch attempt, NASA officials said a short time ago.

Workers are heading home after a long day of countdown activities and the post-scrub operations. The troubleshooting will resume in the morning.

NASA says next Tuesday, March 21, is the earliest possible date for rescheduling the Pegasus launch of Space Technology 5, given a variety of factors, including available slots on the Western Range and the weather outlook. But the 21st is highly tentative and no date has been booked on the Range yet.

1600 GMT (11:00 a.m. EST)

Delivery of three miniaturized technology demonstration satellites into orbit to prepare for future constellations of space weather probes was aborted today because of problems readying their air-launch rocket booster.

Slung beneath a modified L-1011 aircraft, the 55-foot long Pegasus rocket departed Vandenberg Air Force Base in California before dawn this morning bound for a spot over the Pacific Ocean west of Monterey for the sunrise launch.

Stacked inside the nose cone of the Orbital Sciences-made rocket rode NASA's Space Technology 5 micro-sats. The 55-pound birthday-cake-size craft will test whether such tiny satellites can be used in monitoring the impacts of solar storms on Earth.

Countdown clocks were targeting a 1427 GMT (9:27 a.m. EST; 6:27 a.m. PST) release of the Pegasus from the Orbital Science "Stargazer" jet to begin the $130 million ST5 mission.

At about T-minus 45 seconds, the rocket technician aboard the aircraft -- known as the launch panel operator, or LPO -- activated the battery that power the Pegasus' first stage aerosurface fins during flight. The fins are used to steer the rocket during its initial climb to space.

Next, retention pins that held the fins in place during the ferry to the launch zone were supposed to disengage, allowing the fins to undergo a final pre-flight "sweep" test to show they were working correctly.

But something prevented the starboard fin pin to retract.

"The pin pullers were told to pull out and unlock the fins. But we were not able to get motion on the starboard side," said Omar Baez, the assistant NASA launch manager for ST5.

"PLT, can do you do maneuvers for stuck pin," the launch panel operator (LPO) aboard the L-1011 requested to the aircraft pilot.

"LC, PLT, we're doing stuck pin maneuvers now," the pilot radioed to the launch conductor on the ground.

"Roger that," the launch conductor replied.

A chase plane flying alongside the L-1011 relayed live video of the carrier aircraft banking its wings left and right in a rolling motion in hopes of freeing the stubborn locking pin.

The additional attempts to retract the pin where unsuccessful, leading to the immediate launch scrub.

"This is LC, abort, abort. This is LC on mission freq(uency), abort, abort," the launch conductor instructed the team.

"PLT copies abort."

"LPO copies abort."

There was scant time to wrestle with the problem. The restrictive life span of the fin battery means a Pegasus rocket must be launched within about 90 seconds of activation to ensure a safe margin during flight. Otherwise, the launch has to be aborted and the battery replaced. That is what happened today.

The launch team safed the rocket, and the L-1011 returned to Vandenberg within a half-hour of the abort to begin troubleshooting the locking pin problem.

"It could be something mechanical, it could be ice, a number of things," Baez said of the possible culprit.

Meanwhile, ground crews will replace the expired fin battery, a job that will take 48 hours and push the next launch attempt to Friday at the earliest.

But a new launch date hinges on the time required to fix the pin issue and booking a new reservation on the Western Range schedule at Vandenberg. The Air Force-operated range provides tracking, safety and communications services for all launches from the base, plus ground tests and other military operations. Whether Friday could be made available for Pegasus was not immediately clear this morning.

1500 GMT (10:00 a.m. EST)

The L-1011 has landed at Vandenberg.

1446 GMT (9:46 a.m. EST)

Omar Baez, the assistant NASA launch manager for ST5, says it will take 48 hours to change out the expired fin batteries. So that puts launch no earlier than Friday. However, a firm new launch date can't be determined until engineers figure out why the lock pin did not retract and officials find an open slot on the Western Range schedule at Vandenberg.

1441 GMT (9:41 a.m. EST)

Pegasus has been verified safe for landing back at Vandenberg a short time from now.

1433 GMT (9:33 a.m. EST)

During the final seconds prior to launch, the retention pin that holds the starboard-side fin aerosurface on the Pegasus rocket first stage did not retract. The rocket's fin battery, which has a short life span, had been activated by that point in the countdown. That left little time to resolve the problem. The launch conductor then called an abort, ending today's attempt to send the Space Technology 5 micro-sats into orbit.

The L-1011 is now returning to Vandenberg Air Force Base for troubleshooting of the pin retraction problem.

There is no estimate on when the next launch attempt could be made. At a minimum, the expired fin battery has to be replaced and the pin issue fixed.

1430 GMT (9:30 a.m. EST)

The drop mechanism has been safed.

1428 GMT (9:28 a.m. EST)

Pegasus has switched back to external power. The rocket has been safed.

1428 GMT (9:28 a.m. EST)

This will be a scrub for today because the fin batteries will expire shortly.

1427 GMT (9:27 a.m. EST)

ABORT. The countdown has been stopped because one of the pins did not retract prior to drop.

1426 GMT (9:26 a.m. EST)

The batteries for the first stage flight control fins have been activated, allowing the fins to undergo a sweep test prior to launch. The fins are used to steer the rocket during its initial climb to space.

With the batteries activated there is just 90 seconds to launch today or else an abort will be called. That is due to the limited life of the batteries.

In the final moments prior to release of Pegasus, the L-1011 carrier aircraft crew will oversee the last seconds of the countdown and flip the switch that will drop the vehicle, with the ST5 spacecraft aboard, from the belly of the jet.

1425 GMT (9:25 a.m. EST)

T-minus 2 minutes.

1424 GMT (9:24 a.m. EST)

The rocket's SIGI guidance computer is being configured for flight.

1423 GMT (9:23 a.m. EST)

The launch team has been given a "go" to enter the final phase of the countdown.

1423 GMT (9:23 a.m. EST)

T-minus 4 minutes. The launch time has been adjusted a few minutes.

1421 GMT (9:21 a.m. EST)

The Pegasus rocket's avionics have switched from power provided by the L-1011 to internal battery power.

1419 GMT (9:19 a.m. EST)

The launch control team on the ground and the aircraft crew are experiencing some communications problems.

1417 GMT (9:17 a.m. EST)

NASA Launch Manager Chuck Dovale has polled his team for the "go" to enter terminal count. "NASA and ST5 are ready," Dovale said.

1413 GMT (9:13 a.m. EST)

The flight termination system is now running on internal power. The safety system would be used to destroy the Pegasus rocket in the event a problem during launch.

1411 GMT (9:11 a.m. EST)

The launch team members report they are ready to switch the rocket's flight termination system to internal power.

1410 GMT (9:10 a.m. EST)

T-minus 15 minutes. The drop mechanism that releases Pegasus from the belly of the L-1011 aircraft has been armed.

1409 GMT (9:09 a.m. EST)

A chase plane is flying beside the L-1011/Pegasus duo over the Pacific Ocean to relay video back to the launch control team.

1407 GMT (9:07 a.m. EST)

T-minus 18 minutes and counting. Stargazer is flying at the launch altitude of 39,000 feet.

1359 GMT (8:59 a.m. EST)

The carrier jet is passing through the launch point, verifying good weather conditions. The aircraft is heading northward right now but will soon make a wide, sweeping U-turn for return to the rocket drop zone on a southerly heading.

1357 GMT (8:57 a.m. EST)

The L-1011 is now 33,000 feet in altitude.

1355 GMT (8:55 a.m. EST)

Now 30 minutes till launch. Today marks the 37th flight of the air-launched Pegasus rocket and the 27th using the XL version.

1345 GMT (8:45 a.m. EST)

The jet is flying a pre-determined "race track" pattern over the Pacific to reach the proper launch point west of Monterey where Pegasus will be released to roar into orbit.

1335 GMT (8:35 a.m. EST)

Now 50 minutes from the scheduled launch of Pegasus. The modified L-1011 is climbing to the launch altitude of nearly 40,000 feet.

1327 GMT (8:27 a.m. EST)

WHEELS UP. The "Stargazer" carrier aircraft with the Orbital Sciences Pegasus XL rocket has departed Vandenberg Air Force Base in California for today's launch for NASA's Space Tech 5.

1326 GMT (8:26 a.m. EST)

The L-1011 is rolling down the runway.

1324 GMT (8:24 a.m. EST)

A poll of the ground launch team has been completed by the Orbital Sciences launch conductor. Takeoff is just a few minutes away now.

1323 GMT (8:23 a.m. EST)

NASA Launch Manager Chuck Dovale has polled the space agency team to verify all is in readiness for takeoff of the L-1011 aircraft. Everything is "go." There are no issues with the Pegasus rocket, ST5 spacecraft, weather or downrange tracking assets.

1322 GMT (8:22 a.m. EST)

The pre-takeoff checklist has been opened.

1317 GMT (8:17 a.m. EST)

NEW LAUNCH TIME. Takeoff of the L-1011 is now scheduled for 1327 GMT for launch of the Pegasus rocket at 1425 GMT. A waiver has been approved for the pressure measurement that had been under discussion this morning.

1311 GMT (8:11 a.m. EST)

Today's available launch window extends to 1519 GMT (10:19 a.m. EST; 7:19 a.m. local time). So the L-1011 needs to be off the ground within the next 70 minutes.

1306 GMT (8:06 a.m. EST)

A NASA spokesman says the issues under discussion involve pressure readings and positioning of the nose fairing. Once these reviews are completed, approval would be given for the L-1011 to depart Vandenberg Air Force Base. Launch of Pegasus will occur roughly 58 minutes after the aircraft takes off.

1302 GMT (8:02 a.m. EST)

Delay. The takeoff time has been pushed back this morning. A new time has not been set yet. Once the L-1011 is airborne, it will fly a 58-minute course to the launch point over the Pacific Ocean.

1257 GMT (7:57 a.m. EST)

The aircraft has completed the taxi to the runway. However, NASA now says the takeoff time depends on some engineering discussions about a couple of potential issues that have arisen. The takeoff is supposed to happen at 1304 GMT.

1251 GMT (7:51 a.m. EST)

The taxi was delayed a little bit this morning due to some engineering reviews that are on-going.

1250 GMT (7:50 a.m. EST)

The Stargazer carrier jet has started the roll from its staging area to the 10,000-foot long runway at Vandenberg Air Force Base in preparation for takeoff.

1248 GMT (7:48 a.m. EST)

The "go" has been given to begin the L-1011 taxi to the runway.

1231 GMT (7:31 a.m. EST)

Everything is proceeding well in this morning's countdown to the Space Technology 5 launch. No significant technical issues are being worked, NASA says, the weather is fine along California's Central Coast and activities remain on schedule for the planned launch time of 1402 GMT (9:02 a.m. EST; 6:02 a.m. local).

1148 GMT (6:48 a.m. EST)

The L-1011 carrier aircraft flight crew is aboard, the doors have been closed and final preparations are now underway for today's launch of the Pegasus rocket with NASA's Space Technology 5 mission.

The jet's engines are scheduled to be started momentarily. And in a little while the aircraft will taxi over to the runway from the "hot pad" staging area at Vandenberg Air Force Base where the Pegasus rocket was mated to the L-1011's underside.

Takeoff time is scheduled for 1304 GMT (8:04 a.m. EST; 5:04 a.m. local) to begin the 58-minute flight out to the launch point off the California coast.


A technology demonstration mission to blaze the trail for swarms of tiny spacecraft that could one day offer advance warning of solar storms impacting Earth is scheduled for launch Wednesday.

NASA will put three micro-sats into orbit to test miniaturized technologies and techniques for operating constellations of science probes. The Space Technology 5 mission will last three months.

The ST5 craft will be blasted into space by the air-launched Pegasus XL rocket made by Orbital Sciences. A modified L-1011 carrier aircraft, called the Stargazer, hauls the three-stage booster off the California coast from Vandenberg Air Force Base where the winged rocket will drop at approximately 1402 GMT (9:02 a.m. EST; 6:02 a.m. local).

With the push of a button in the Stargazer's cockpit, the Pegasus rocket is cast free to fall for five seconds, dropping 300 feet below the aircraft. During the plunge, the onboard flight computer will sense the rocket's separation from the carrier jet and issue a command to release the safety inhibits in preparation for ignition.

The first stage solid-fueled motor of Pegasus is lit at T+5 seconds to begin the powered journey to orbit for the $130 million ST5 mission.

At T+1 minute, 17 seconds, the Orion 50S XL first stage motor consumes all of its solid-fuel propellant and burns out at an altitude of 34 miles. A short ballistic coast period begins before the spent first stage is separated to fall into the Pacific Ocean.

The Pegasus rocket's Orion 50 XL second stage begins firing at T+1 minute, 31 seconds to continue the trip to orbit. During the firing, at T+2 minutes, 11 seconds, the payload fairing that protected the micro-sats during atmospheric ascent is jettisoned 71 miles above Earth.

Having consumed its supply of solid-fuel propellant, the second stage motor burns out at T+2 minutes, 44 seconds. The rocket will coast for a couple of minutes before releasing the spent stage.

The solid-fueled Orion 38 third stage ignites at T+plus 5 minutes, 3 seconds about 176 miles high to deliver the ST5 spacecraft into the desired elliptical orbit around Earth. That orbit of 186 by 2,796 miles, inclined 105.6 degrees to the equator, is achieved with cutoff of the third stage at T+6 minutes, 11 seconds.

Release of the 55-pound micro-sats from the launcher occurs one by one from a special rack that supported them during the ride to space. The forward-most craft jettisons at T+plus 9 minutes, 31 seconds; the middle at T+plus 12 minutes, 41 seconds; and the aft-most at T+plus 15 minutes, 51 seconds to complete the Pegasus rocket's 37th launch since debuting in 1990.

1748 GMT (12:48 p.m. EST)

Mission managers met up a short while ago to receive a briefing on the latest weather forecast for tomorrow's launch of the Pegasus rocket. Air Force meteorologists now say there is a 100 percent chance of acceptable weather conditions for the air-launch rocket to be ferried off the California coast and released from the belly of an L-1011 aircraft.

NASA spokesman George Diller says there are no technical issues being addressed. The rocket and the Space Technology 5 micro-sats are ready to fly.

MONDAY, MARCH 13, 2006
1620 GMT (11:20 a.m. EST)

A dismal weather forecast for Tuesday's opportunity to launch three miniaturized technology demonstration satellites off the coast of California has forced NASA to postpone the $130 million mission by 24 hours.

The Space Technology 5 launch has been rescheduled for Wednesday during a window extending from 1357-1519 GMT (8:57 to 10:19 a.m. EST; 5:57 to 7:19 a.m. local time).

An air-launched Pegasus rocket made by Orbital Sciences will haul the three birthday-cake-size spacecraft into a highly elliptical orbit and then deploy them for a 90-day mission. The 55-pound micro-sats will probe Earth's magnetic field using highly sensitive magnetometers to demonstrate whether such tiny craft can do the job.

"The future of space science is dependent upon the continual development of new and ever more powerful space-borne technologies," said Jim Slavin, ST5 project scientist. "The lessons learned from the development and flight of ST5's three full-service micro-spacecraft constitute a major step toward the use of 'constellations' or 'swarms' of small spacecraft to accomplish science that cannot be done with a single spacecraft, no matter how capable."

The Pegasus rocket is mounted to the belly of Orbital's L-1011 carrier aircraft at Vandenberg Air Force Base, California. The jet will carry the rocket over the Pacific Ocean and release it for the launch into space. Wednesday's targeted "drop time" to launch the rocket is 1402 GMT (9:02 a.m. EST; 6:02 a.m. local).

The bleak weather outlook for Tuesday -- an 80 percent chance of violating the launch rules due to clouds, rain and lightning -- prompted mission managers to forego a countdown, which would have commenced at 1:30 a.m. local time.

And the forecast for Wednesday is the complete opposite. Air Force meteorologists predict an 80 percent chance of favorable weather.

Officials didn't want the ground crews working overnight if there was little hope of launching Tuesday. That, coupled with the good weather on Wednesday, led to the decision to postpone the mission 24 hours, NASA spokesman George Diller said.

Watch this page for a complete launch preview later today.