NASA - National Aeronautics and Space Administration

NASA's Ames Vertical Gun Range (AVGR) was designed to conduct scientific studies of lunar impact processes in support of the Apollo missions. In 1979, it was established as a National Facility, funded through the Planetary Geology and Geophysics Program. In 1995, increased science needs across various discipline boundaries resulted in joint core funding by three different science programs at NASA Headquarters (Planetary Geology and Geophysics, Exobiology, and Solar System Origins).

Ballistic technologies, utilizing a light-gas gun or a powder gun enable launching projectiles to velocities ranging from 1 to nearly 7 km/sec. The light-gas gun uses conventional smokeless powder to drive a polyethylene piston down a pump tube. This serves as a long, single-stroke compression of the hydrogen gas into a heavy-wall (conical converging) section called the "high pressure coupling." Here the gas is raised to extreme pressure and temperature. A rupture disk in the high-pressure coupling, which initially seals the launch tube from the pump tube, ruptures allowing the high pressure propellant gas (hydrogen) to drive the projectile down the launch tube. A powder gun, which uses the smokeless powder as the propellant to drive the projectile down the launch tube, is a simpler and less expensive means for attaining velocities up to 3 km/sec.

The types of projectiles that can be launched include spheres, cylinders, irregular shapes, and clusters of many small particles. The projectiles can be metallic (i.e. aluminum, copper, iron), mineral (i.e. quartz, basalt), or glass (i.e. pyrex, soda-lime).

	Photo No. A-33996 - 30 calibabor Vertical Gun Range in horizontal loading position. Dr. William Quaide and Donald Gault of Ames planetology branch used this gun range to study the formation of impact craters on the Moon. + View Larger Image
	Photo No. A74-1318 - Professor Lobos Kohoutek, Czech-born astronomer who discovered the comet named after him briefs the news media on what they might expect to see when the comet makes its closest approach to Earth on January 5, 1974. + View Larger Image
	Photo No. A74-1321 – University of Arizona - Three images of Comet Kohoutek taken at the Catalina Observatory with the 42 cm Schmidt telescope. These images of the (top) 28th and (middle) 29th of November show the "kink" in the tail that moved away from the head of the comet. This may have been a result of interaction with the solar wind. Image 1 was taken November 28, 1973. Image 2 was taken November 29, 1973, and Image 3 was taken December 6, 1973. + View Larger Image
	Photo No. A74-1323 – 'Rays' of Comet Kohoutek. University of Arizona – This photograph of the Comet Kohoutek was taken on January 19, 1974, by E. Roemer assisted by L.M. Vaughn, with a 90-inch reflecting telescope of the Steward Observatory. Details of the ray structure of the inner part of the Type I tail are well shown. + View Larger Image

Comet Halley: Next two images taken at NASA Ames 'Vertical Gun,' particle-impact study. (Polek and Brooks thermal physics study.) Peter Tsou of the Jet Propulsion Laboratory (JPL), Pasadena, Calif. was also involved in this study, related to Comet Halley.

	Photo No. AC85-0321-21 – Vertical impact image. + View Larger Image
	Photo No. AC85-0321-6 – Horizontal impact image + View Larger Image

Halley's Comet studied by Pioneer-Venus spacecraft: The next two images show Comet Halley in Lyman Alpha light from hydrogen ions. These images were created from data collected by the Ultra-Violet Spectrometer on the Pioneer Venus Orbiter spacecraft during the days of February 2-6, 1986. During the six days, the spacecraft was maintained in a fixed attitude while the comet moved past, and the instrument scanned across the coma.

During the six days, telemetry data was collected from Deep Space Network (DSN) stations in Spain, Australia and California. The data was processed to assemble the scans into false color images where the lightest colors indicate the strongest signal.

These images show the cloud of hydrogen ions, which surrounded the comet during February 2-6. These images are actually a composite because different parts of the cloud were scanned each day, and also because individual ions moved from the nucleus to the edge in about four days. At the time that these images were acquired, the hydrogen coma was the largest object in the Solar System with a radius of about 0.1 Astronomical Unit. In ultra-violet light, the comet was the second brightest object in the Solar System (exceeded only by the Sun).

These images show asymmetry caused by radiation pressure from the Sun. Hydrogen ions initially leave the nucleus in all directions but eventually are deflected by radiation pressure and move away from the Sun. The size of the Hydrogen coma indicates that water was being evaporated from the nucleus at a rate of about 40 tons per second.

	Photo No. AC86-0107-1 -- Feb. 11, 1986, Purple data, taken directly from imaging system of spacecraft. + View Larger Image
	Photo No. AC86-0107-5 – Halley's Comet, Ultra Violet Hydrogen emission (reddish circular band). + View Larger Image

Kuiper Airborne Observatory, images take from C141 aircraft:

	Photo No. AC86-0720-2 – Taken from Kuiper Airborne Observatory, C141 aircraft April 8/9, 1986, New Zealand Expedition, Halley's Comet crossing Milky Way. Disconnection of ion tail. Both photos taken with equipment designed, mounted on the headring and operated by the Charleston (South Carolina) County School District CAN DO Project. + View Larger Image
	Photo No. AC86-0720-4 – Taken from Kuiper Airborne Observatory, C141 aircraft October 1, 1986, 1986, New Zealand Expedition, Halley's comet (with darker background).

Comet Wilson images, 1987, Pioneer 12 to Venus spacecraft:

AC87-0264-1 – Comet Wilson, red indicates hydrogen. This ultraviolet image shows the cloud of hydrogen surrounding Comet Wilson. The Pioneer 12 spacecraft--as it orbited Venus--obtained this image. The hydrogen is produced when sunlight breaks down the water, which is sublimating from the nucleus at a rate of 5.9 tons per second. Researchers at NASA Ames Research Center, Moffett Field, Calif.; the University of Colorado at Boulder; and the University of California at Davis produced the image. + View Larger Image