Contour Set to Launch

June 28, 2002 | On July 3rd, NASA’s Comet Nucleus Tour (Contour) is scheduled to launch from Cape Canaveral, Florida. The original launch date of July 1st was scrubbed due to the discovery of particulate matter on a solar panel. The mission will encounter at least two comets during its planned four-year lifespan. Included on the agenda are flybys of Comets Encke (November 12, 2003) and Schwassmann-Wachmann 3 (June 19, 2006). Contour will also have the flexibility to examine any serendipitous comets that may be discovered during its lifetime. The craft will analyze the chemical composition of the comets and will take high-resolution images of the icy wanderers. The mission is NASA's sixth Discovery mission, coming in with a budget of $159 million.

For more information, visit Contour's Web site:

Does Gravity Brighten the Farthest Quasars?

June 26, 2002 | Among the many fruits of the Sloan Digital Sky Survey is a bumper crop of newfound quasars, some of which have redshifts around 6, implying that they — and the billion-solar-mass black holes that apparently power them — were born within a billion years of the Big Bang. In some minds, these quasars’ stupendous luminosities challenge the Cold Dark Matter theory of cosmology, which predicts that massive structures grow slowly. (A quasar’s luminosity is proportional to the mass of its central black hole.) But the challenge is lessened, writes Princeton University expert Edwin L. Turner in tomorrow’s Nature, if gravitational lensing has boosted the apparent brightness of many high-redshift quasars, as many astronomers have conjectured. That may well be happening, write Harvard University astronomers J. Stuart B. Wyithe and Abraham Loeb in the same issue of Nature: after crunching the numbers they conclude that up to one-third of the highest-redshift quasars “will have had their observed [brightness] magnified by a factor of ten or more, as a consequence of gravitational lensing by galaxies along the line of sight.” But fellow Harvard astronomer Joshua N. Winn cautions that the effect is sensitive to the still-unknown distribution of early quasar luminosities and may well be considerably weaker. Astronomers should know the answer once a Hubble Space Telescope snapshot survey of Sloan quasars, just starting now, is completed.

Chandra Spots Pulsar Bull's-eye

June 26, 2002 | Astronomers using the Chandra X-ray Observatory have uncovered a bright ring of high-energy particles surrounding the supernova remnant SNR G54.1+0.3. The image shows the bright central pulsar, the encompassing ring (presumably a shock front), and an extended nebula. Taken as a whole, the scene is a snapshot from a star's afterlife — revealing the radiation and particles that spew out from a supernova's corpse.

A press release and image are at:


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