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Big Dog Flies
Big Dog Flies
23 Jan 2004
(Source: Southwest Research Institute)

SwRI suborbital science payload gets the goods on Mercury, searches for Vulcanoids
Southwest Research Institute
January 23, 2004

A new major scientific payload flew in space last week after launching aboard a NASA suborbital Black Brant rocket. The payload, consisting of a telescope/spectrometer combination and an image-intensified imaging system, successfully explored the ultraviolet spectrum of the planet Mercury and also searched for the long-sought belt of small bodies called Vulcanoids that may lie even closer to the Sun than Mercury. Southwest Research Institute (SwRI) provided the payload and is responsible for data analysis.

"The rocket flew a textbook flight and got the goods on our calibration star (Zeta Ophiuchus), Mercury and the Moon -- everything in the flight plan," says Dr. Alan Stern, mission principal investigator and director of the SwRI Space Studies Department. "The secondary payload, the so-called VULCAM (Vulcanoid camera) imager, also worked like a champ, searching for Vulcanoids while the spectrograph studied Mercury itself."

The payload's main instrument is a large (almost 500 pound), highly sensitive, ultraviolet spectrograph designed to observe objects too close to the Sun for the Hubble Space Telescope and other orbital instruments to view. The new SwRI instrument has been dubbed "Big Dog" by its inventors, owing to the large size of the payload.

"We built Big Dog specifically to fill a niche -- exploring objects in the deep inner solar system," explains SwRI's Dr. David Slater, project scientist for the instrument and leader of the field team that took the payload to White Sands for the launch preparations and flight. "This flight proves we can now examine objects -- like Venus, Mercury and bright comets close to the Sun -- that are normally lost in the Sun's glare to orbiting telescopes, on a routine basis. This is a real asset for planetary astronomy and for certain kinds of astrophysics as well."

VULCAM scientist Dr. Dan Durda, also of SwRI, added, "VULCAM is a derivative of an imaging instrument we have flown many times on F-18 aircraft, but which has the potential to become an even more powerful tool for searching for Vulcanoids from 260+ kilometer (165+ mile) altitudes that NASA suborbital missions can reach. VULCAM also performed flawlessly."

"Never before in history has it been possible to obtain an ultraviolet spectrum of Mercury," says Stern. "With the data gathered last week, we expect to reveal new details about this mysterious inner planet's surface composition and, hopefully, to help the upcoming NASA MESSENGER mission to Mercury plan its ultraviolet observations."

Primary funding for this mission came from NASA, with supplemental support from The Planetary Society. The NASA Wallops Island Flight Facility managed the mission and provided both the launch vehicle and the pointing, telemetry and recovery systems required to support the flight. The Center for Astrophysics and Space Astronomy at the University of Colorado at Boulder also collaborated on the mission.

Vulcanoids are a hypothesized population of small asteroids that is exceedingly difficult to observe from the ground because of its proximity to the Sun. Researchers have made previous ground-based searches for Vulcanoids during total solar eclipses, during the brief twilight period after sunset before the Vulcanoids themselves set or just before sunrise after the Vulcanoids have peaked above the horizon.

Editors: An image of the rocket is available at

More information on the Wallops Island Flight Facility is available at, the Center for Astrophysics and Space Astronomy is at, the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) mission is at and The Planetary Society is at

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Last Updated: 24 Jan 2004