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Archive for October, 2004

23-Oct-04 | Deep Impact arrives in Florida

NASA’s Deep Impact probe arrived at the Florida Spacecoast on 16 October. It was transported by specialized semi truck from Ball Aerospace in Boulder, Colorado, and is now in a cleanroom environment at the Astrotech Space Operations facility near the Kennedy Space Center. There it will undergo pre-launch processing and then be mated to the Star 48 third stage of its Delta vehicle.

Deep Impact is scheduled to launch in late December, and on 4 July 2005 it will fire an 820-pound copper projectile into comet Temple 1 to watch the ejecta and analyze the comet’s composition.

23-Oct-04 | Spitzer: planet building “a big mess”

The latest observations from the Spitzer Space Telescope (launched as SIRTF on Delta 300) have shown that “planet building is a big mess,” the product of massive collisions between chunks the size of mountain ranges that generate copious clouds of dust.  The real mystery is why astronomers would have expected less chaotic circumstances — nearly every event in the universe exhibits cataclysmic behaviour, so why not planet formation? (18-Oct-04 NASA Press Release)

23-Oct-04 | Frame-dragging

The researchers who in 1998 announced the first empirical evidence of frame dragging have reported vastly improved findings.

The original results, reported in this 27-Mar-98 NASA Press Release, had no more than 20 percent accuracy due to the uneven shape of the Earth’s gravitational field; the variations in gravity have much greater effect on the orbits of LAGEOS 1 & 2 than frame dragging might. Using a new model of Earth’s gravity field based on data from NASA’s GRACE satellite, the team was able to factor out those fluctuations and reach results of 99 percent of the predicted dragging, with a 10% margin of error.

Frame-dragging is an effect, first predicted by Einstein’s general theory of relativity in 1920, wherein a large spinning mass can drag the surrounding fabric of spacetime around with it as it spins. The effect is so slight as to be almost imperceptible, and as yet it could still be considered merely theoretical. However, these improved results make it that much more likely that, once again, Einstein had it right.

The research is truly international in origin: the principal investigators hail from Lecce, Italy, and Baltimore, Maryland, while the EIGEN-GRACE02S gravity model came out of Potsdam, Germany, and Austin, Texas. Another noteworthy fact is that the latest frame-dragging report had virtually no hardware cost: both GRACE and LAGEOS were built and flown for other research projects, and in particular the latter are older, passive satellites that are expected to sail along in their medium-altitude orbits for decades to come. (LAGEOS 1 dates back to Delta 123 in 1976.)

This latter fact, and the way the press has characterized the report as a “scoop” of Gravity Probe B (currently in its science phase and gathering data), has NASA on the public-relations defensive. Mission managers for the $700 million project are offering assurances that recent troubles with one of the craft’s gyroscopes are inconsequential, and that the results will continue to be a substantial advance beyond those of Ciufolini and Pavlis. Gravity Probe B launched aboard Delta 304 on 20 April 2004. (21-Oct-04 NASA Press Release, Nature, 20-Oct-04)

23-Oct-04 | Genesis update

Preliminary reports from the Genesis Mishap Investigation Board suggest that a direct cause of its disastrous September return to Earth may have been reentry accelerometers that were installed upside-down — hence leaving the spacecraft unaware that it had entered the atmosphere. Beyond that, as usual the Board is likely to indict certain aspects of management at NASA, JPL, and Lockheed-Martin, not to mention the use of accelerometers whose design inherently allows them to be installed incorrectly. Meanwhile, despite the tragic appearance of the spacecraft following impact, scientists continue to express confidence that substantial portions of the samples may yet be salvageable.

23-Oct-04 | Next launch

The next Delta II launch will be NAVSTAR IIR-13 for the U.S. Air Force’s Global Positioning System. The flight is now scheduled for Saturday, 30 October. Hurricanes Frances and Jeanne caused only minor damage at SLC-17, but managed to delay operations by a couple of weeks, from 8 to 25 October. Now an explosive line igniter for the third stage spin stabilization motors (a leak was found on a similar component at the factory) and the need to ensure the well-being of the flight control system (after a test anomaly on another Delta II booster) have pushed the flight back by another 5 days.

Delay at Pad B has had a ripple effect at Pad A, where the Delta Med-Lite 7320 for NASA’s Swift has been stacked since 8 October. Swift was mated to its payload attach fitting on 21 October but might not be moved to the pad until after the NAVSTAR launch. Spaceflight Now states that officials are concerned about a possible “launch accident that could damage Swift,” an event accurately called “highly unlikely.” (Spaceflight Now, 22-Oct-04)

     

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