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The Measure Of Eros

SKY & TELESCOPE'S NEWS BULLETIN
APRIL 2, 1999

[snip]

THE MEASURE OF EROS

Had things gone according to plan, NASA's Near Earth Asteroid Rendezvous
spacecraft would now be snugly in orbit around minor planet 433 Eros. But
last December 20th a botched rocket firing caused the spacecraft to sail
past its target. The unintended flyby wasn't devoid of scientific results,
however. According to investigator Joseph Veverka, NEAR acquired images of
Eros good enough to resolve features roughly 400 meters across. Overall,
the asteroid measures a very elongated 33 by 13 by 13 kilometers. Veverka
adds that the flyby was close enough (3,827 km) and slow enough (965 meters
per second) to alter NEAR's trajectory very slightly. These deviations were
barely measurable by tracking stations, but they allowed orbital specialist
Donald Yeomans to determine that Eros has a mass of about 7 trillion tons
and a bulk density near 2.5 grams per cubic centimeter. This density is
similar to that of asteroid 243 Ida and much higher than that of 253
Mathilde, whose interior is apparently very porous. A careful search by
NEAR turned up no satellites circling Eros any larger than 50 meters
across. NEAR will close in for another attempt to orbit Eros on February
14, 2000.

[snip]
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Copyright 1999 Sky Publishing Corporation. S&T's Weekly News Bulletin and
Sky at a Glance stargazing calendar are provided as a service to the
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