Space and astronomy news and information for the American Southwest. Coverage includes Vandenberg AFB rocket and missile launches.

Pegasus XL Rocket / WIRE Launch

2006 May 21

The webmaster took the following images during the 1999 March launch of a Pegasus XL rocket carrying NASA's WIRE (Widefield Infrared Explorer) satellite. An L-1011 jumbo jet carried the rocket from Vandenberg Air Force Base to the drop point above the ocean southwest of Monterey. Although WIRE achieved orbit, a spacecraft malfunction prevented it from accomplishing its intended mission. These photos were taken from the north slope of a high hill in Ventura County, California while covering the launch for public radio.

The launch was scheduled to occur long after sunset and expected to resemble a moving point of light. After launch, the Pegasus unexpectedly climbed into sunlight and provided an impressive display as the second stage exhaust plume was backlit by the Sun.

A few minutes later, the third stage fired and its plume was also illuminated by sunlight. Because of the his obstructed horizon towards the south, the webmaster was not aware of this until it was too late to attempt a photograph.

Pegasus XL rocket launch photo

This cropped version of the original time exposure shows the second stage rocket motor burn. The camera was aimed at a point in the sky that the rocket was expected to pass through during the burn. The plan was to open the camera's shutter just before second stage ignition and hold it open to record the trace from the second stage.

At first, the second stage resembled a semi-bright star or distant aircraft light. However, as the vehicle climbed during the second stage burn, it began to receive illumination from the Sun and the stage's appearance changed from a point of light to a point of light at the tip of a wedge-shaped. The color of the second stage's trail and exhaust plume changed from deep orange to yellow as the rocket gained altitude.

Visible in the background are the planets Venus, Jupiter, and Mercury which resemble short dashes due to trailing caused by the Earth's rotation. The bottom portion of the sky has a brown color due to light pollution. The short line on the right margin is a trail from the lights on an aircraft.

BBC news later used this image on its website.

Pegasus XL rocket launch photo

This is black and white version of the top photo with labels added to identify the planets in the background.

Pegasus XL rocket launch photo

This brief exposure was an attempt to record the large, wedge-shaped exhaust plume during the later portion of the second stage burn. Unfortunately, it fails to capture the surprising amount intricate, feathery plume detail that was visible to the naked eye. The white speck to the right is Venus.

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