God Bless America

July 22 2000

News from NASA

Time-Sensitive Space Event!

Comet LINEAR will reach maximum brightness around July 23, 2000, as it glides past the bowl of the Big Dipper. Sky watchers have been hoping that LINEAR would become visible to the unaided eye. However, monitoring data from a global network of astronomers suggest that the comet's brightness will peak at a visual magnitude of +6.5, just below the threshold for naked-eye visibility. LINEAR should still be a visual treat when viewed through binoculars or a small telescope.

ALSO: The Boulder sunspot number soared this week to a value of 401. Experts say that's rare, even near the peak of the solar maximum.

For more information please visit http://www.spaceweather.com 

News Stories from Spaceviews

Astronomers Discover New Moon Orbiting Jupiter

Astronomers said Friday they have discovered with a groundbased telescope what appears to be a tiny moon orbiting far from the giant planet Jupiter.

The discovery of the natural satellite, provisionally known as S/1999 J 1, came from observations made in October and November of last year by the 0.9-meter (36-inch) Spacewatch telescope atop Kitt Peak, Arizona.

When first discovered, the object was thought to be an asteroid, and given an asteroid designation, 1999 UX18. The somewhat unusual motion of the object -- more like a comet in an elliptical orbit than an asteroid -- initially eluded astronomers.

The object's true nature remained hidden until Tuesday, when Tim Spahr at the Minor Planet Center (MPC) in Cambridge, Massachusetts, ran a computer program on some of the data of the "asteroid" and found that the orbit the program generated fit the observed positions poorly. Spahr wondered if Jupiter, near the position of the object, might be influencing its orbit -- or of the object itself was a distant satellite of the planet.

Additional analysis confirmed that the best fit to the observed positions of 1999 UX18 was if the asteroid was in fact a moon of Jupiter. Astronomers at the MPC eventually fit an orbit to the moon using five nights of data between October 6 and November 4 of last year.

The current orbit for S/1999 J 1 shows it to be in a somewhat elliptical orbit, averaging about 24 million kilometers (15 million miles) from Jupiter and with an orbital period of 774 days -- just over two years -- moving in the opposite, or retrograde, direction of moons closer to the planet.

The irregular, retrograde orbits of this and four other similar satellites -- Ananke, Carme, Pasiphae, and Sinope -- suggest that all five were asteroids captured by Jupiter after the formation of the solar system. The new moon's small size -- as little as five kilometers (three miles) in diameter -- would make it the smallest moon orbiting a planet in our solar system. It's also the first moon discovered orbiting Jupiter since the Voyager spacecraft discovered three small inner moons over 20 years ago.

The challenge for astronomers now is to make new observations of the object to pin down its orbit and confirm that it is really a moon of Jupiter. Bob McMillan, director of the Spacewatch program at the University of Arizona, said that such observations have not been possible for several months because Jupiter is in conjunction -- on the opposite side of the Sun from the Earth -- and thus lost in the Sun's glare.

New observations will not be possible from Spacewatch for several months, when Jupiter moves farther away from the Sun in the sky. However, McMillan said that larger telescopes might be able to resume observations sooner.

Larger telescopes may be needed in any case since the initial observations were made when Jupiter came about as close to the Earth as it does during its 12-year orbit around the Sun. New observations will be made when Jupiter is farther away from Earth, making the newly-discovered satellite dimmer and thus harder to observe.

Mars Mission Indecision

It's clear that NASA is agonizing over whether to send an orbiter or a lander to Mars in 2003. The space agency announced Thursday that it would hold a news conference Monday afternoon, July 24, to reveal what spacecraft, if any, it would send to Mars during that launch window. The next day, though, the agency abruptly postponed the press conference. No new date has been set, but NASA associate administrator Ed Weiler said an additional one to two weeks may be required as the decision was "much more complex and difficult than anticipated." The two finalists for the mission are an orbiter with a very high resolution camera and a large scientific rover, landed on the surface using Pathfinder-like airbags.

KSC Train Derailment

A set of solid-fuel booster segments escaped damage when the train carrying them derailed at the Kennedy Space Center Tuesday. The train was carrying six of the booster segments to a processing facility at the center when two of the cars inexplicably jumped the tracks. The booster segments were not damaged, in part because the train was traveling at just 5 kmph (3 mph) at the time of the derailment, although a short segment of track did sustain damage. The train accident, believed to be the first to take place at KSC, should not disrupt the schedule of upcoming shuttle launches.

Rocket Engine Merger

Aerojet and Pratt & Whitney (P&W) announced plans Monday to merge their rocket engine businesses into a new company controlled by P&W. The new company will bring together P&W's RL-10 engine used on the Centaur and the Delta 3 upper stage and RL- 180 engine used on the first stage of the new Atlas 3 with Aerojet's diverse line of engines, ranging from the shuttle's orbital maneuvering system to the engines for Kistler Aerospace's K-1 reusable launch vehicle. The deal is seen as evidence of the continued struggles in the aerospace industry, particularly as demand for launch vehicles and propulsion systems has not ramped up as fast as once thought. "We have maintained that the propulsion industry needs to consolidate in order to reduce costs and become more efficient," said Bob Wolfe, chairman and CEO of GenCorp, Aerojet's parent company. In addition, P&W announced Friday it had acquired Space Power Incorporated, a company that makes electric thrusters used by spacecraft to maintain their orbits.

Levitating Lunar Dust

Ultraviolet photons bombarding the lunar surface helps create a levitating layer of dust seen by Apollo astronauts, scientists concluded last week. Scientists at the University of Colorado conducted experiments that confirmed theories for the dust, first noticed by the Surveyor lunar landers in the mid- 1960s. The ultraviolet photons ionize dust grains as well as rocks on the lunar surface, giving each a positive charge. The dust grains then levitate about a meter above the surface as the grains balance the attractive force of gravity and the repulsive electrostatic force. Scientists believe that other moons, asteroids, and even spacecraft could generate similar layers of dust, which in some instances could be a contamination hazard. "By understanding how and why these dust particles charge, scientists can find ways to better protect telescope lenses, spacecraft instruments and astronauts from the negative effects of charged space dust," said Colorado graduate student Amanda Sickafoose.

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Submitted by
CMDR Constance Sanders
USS Yorktown
Chief, Space Activities Committee, SFC
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