Posted on 08/15/2002 12:26:09 PM PDT by crypt2k
Mission operators are looking for a signal from CONTOUR, several hours after a scheduled maneuver to send the spacecraft from Earth's orbit onto a path to encounter multiple comets.
CONTOUR's STAR 30 solid-propellant rocket motor was programmed to ignite at 4:49 a.m. EDT and deliver 1,920 meter-per-second boost which CONTOUR needed to escape Earth's orbit. At about 140 miles (225 kilometers) above the Indian Ocean, the spacecraft was too low for NASA's Deep Space Network (DSN) antennas to track it at the scheduled time of the burn.
The CONTOUR mission operations team at the Johns Hopkins University Applied Physics Laboratory expected to regain contact at approximately 5:35 a.m. EDT to confirm the burn, but the DSN has not acquired a signal.
The mission operations team is working through several backup plans to establish contact with the spacecraft, searching along the predicted trajectories for a successful burn.
CONTOUR, a Discovery-class mission to explore the nucleus of comets, was built and managed by the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., for NASA.
However, it is now way overdue.
CONTOUR 1 27457U 02034A 02218.70833333 .00000000 00000-0 00000-0 0 145 2 27457 30.5521 190.6101 8915936 340.4630 356.7346 0.57921679 02Fifth field in line #2 is eccentricity, decimal point assumed. If it's 0.8916, spacecraft is still in Earth orbit.
The initial parameters of the geocentric phase are period 2,482 min, apogee 108,498 km, perigee 183 km, and inclination 30.2 deg.
NORAD should be able to track pieces along the intended path, and verify Contour is not where it should be.
For sure we'll know in a few hours.
August 15, 2002 -- 7:30 p.m. (EDT)
CONTOUR Contact Attempts Continue
Mission operators continue to scan the skies for the CONTOUR spacecraft, working through a list of strategies for re-establishing contact with the solar-powered probe through NASA's Deep Space Network (DSN).
"We're still trying to get a telemetry link," says CONTOUR Mission Director Dr. Robert Farquhar, of the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. "We're trying to send commands to spacecraft to switch between its two transmitters and use different on-board antennas, in case they turned off for some reason. But we really won't know what happened until we contact it."
CONTOUR's STAR 30 solid-propellant rocket motor was programmed to ignite at 4:49 a.m. EDT and deliver a 1,920 meter-per-second boost that would send CONTOUR out of Earth's orbit and onto a path that would eventually take it past two comets. At about 140 miles (225 kilometers) above the Indian Ocean, the spacecraft was too low for DSN antennas to track it at the scheduled time of the burn. NASA's Jet Propulsion Laboratory, Pasadena, Calif, operates the DSN.
The CONTOUR mission operations team at the Johns Hopkins University Applied Physics Laboratory expected to regain contact at approximately 5:35 a.m. EDT to confirm the burn. When no signal was received, the team immediately began working through backup plans to re-establish contact, searching along the predicted trajectories for a successful burn.
"We're looking at the nominal path, as if the burn occurred," Farquhar says. "We're working on the assumption that the motor fired, and the team is putting its priority there."
CONTOUR's on-board computer is also carrying a command that, about 24 hours after the scheduled burn time, would turn the craft about 40 degrees and perhaps improve its antennas' fix on Earth. Farquhar adds that without knowing CONTOUR's status, it is difficult to know what commands it can, or did, execute. Still, he says, "we're cautiously optimistic that we will find the spacecraft."
CONTOUR, a Discovery-class mission to explore the nucleus of comets, was built and managed by the John Hopkins Laboratory Applied Physics Laboratory, Laurel, Md., for NASA. Additional information about CONTOUR is available on the Internet at: http://www.contour2002.org.
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