August 19, 2002 -- 4 p.m. (EDT) CONTOUR Team Listens for a Signal With electronic eyes and ears pointed to the sky and a fix on CONTOUR's location more than 1.3 million miles (2.1 million kilometers) from Earth, the mission team continues checking for a signal from the spacecraft. "The plan is to watch and monitor," says Mission Director Dr. Robert Farquhar of the Johns Hopkins University Applied Physics Laboratory, which built CONTOUR and manages the mission for NASA. "We realize the possibilities are small, but we can't discount the idea that the spacecraft is still operable. We have to determine that before we give up." Since Friday the team has received telescope images from several observatories showing two objects traveling along CONTOUR's predicted path Ð which engineers believe is CONTOUR and part of the spacecraft that may have separated from it when CONTOUR's solid rocket motor fired on Aug. 15. Mission operators at APL and navigators at NASA's Jet Propulsion Laboratory are using these images to pinpoint the spacecraft's orbit and are aiming the Deep Space Network's powerful 70-meter and 34-meter antennas along that trajectory. "Without knowing how big the objects in the telescope images are, we're going to work on the assumption that the spacecraft may still be largely intact," Farquhar says. "You need at least three separate observations to determine an orbit, and we have that. We know we're looking in the right place." This week, mission operators are listening to determine if CONTOUR is alive and can carry out a timed command to cycle and attempt to transmit through three of its four antennas. The sequence is timed to start 96 hours after CONTOUR receives its last command. Because the team can't determine which commands the spacecraft may have received late last week, the cycling between transmitters and antennas could have started as early as 4:09 (EDT) this morning or could start as late as 10:09 (EDT) tonight. The 60-hour sequence begins with the first of CONTOUR's two transmitters cycling 10 hours each through the low-gain and multidirectional (pancake) beam antennas on CONTOUR's aft side Ð opposite the dust shield Ð and the forward-side low-gain antenna. (Because of its narrow beamwidth and the unlikely prospect of its facing Earth, CONTOUR's high-gain dish antenna is not part of the sequence.) The second transmitter then repeats the pattern. "It may be difficult to hear anything because, depending on the spacecraft's position and condition, the antennas might not have a direct line of sight toward Earth," says CONTOUR Mission Operations Manager Mark Holdridge. "But we'll be listening." If the team doesn't hear from the spacecraft this week, Farquhar says, a final concentrated effort will be implemented in December when the antennas are in a more favorable orientation. "We're obligated to give it this last try," he says. "And who knows, we might get lucky." August 18, 2002 -- 2 p.m. (EDT) Current Operations: Radar and Radio Checks The effort to locate and contact the CONTOUR spacecraft Ð through telescope, radar and radio checks Ð continues. Aided by an Aug. 16 telescope image from the Spacewatch Project showing two objects along a path close to CONTOUR's predicted trajectory, mission operators "know where to look now," says Dr. Robert Farquhar, CONTOUR mission director from the Johns Hopkins University Applied Physics Laboratory. Beginning Monday, Aug. 19, the team plans to check if CONTOUR carries out a timed command to cycle and attempt to transmit through different antennas. The sequence is timed to start 96 hours after CONTOUR receives its last command Ð meaning it could start as early as 4:09 a.m. (EDT) or as late as 10:09 p.m. Monday Ð and would last several hours. "We aren't sure that the spacecraft is completely gone, and that's what we're going to be working on over the next several days," Farquhar says. August 16, 2002 -- 1 p.m. (EDT) Search for CONTOUR Continues Mission operators continue to listen for a signal from CONTOUR. Using its 34-meter antennas, NASA's Deep Space Network stations are scanning the spacecraft's expected path beyond Earth's orbit, attempting to pick up radio signals from CONTOUR's transmitters. The CONTOUR team is also awaiting feedback from several NASA-sponsored and other optical and radar sites that have been searching the skies for signs of the spacecraft. CONTOUR's STAR 30 solid-propellant rocket motor was programmed to ignite at 4:49 a.m. EDT on Aug 15, boosting the spacecraft out of an Earth parking orbit and onto a trajectory to encounter two comets over the next four years. The spacecraft was too low for DSN antennas to track it during the burn - about 140 miles (225 kilometers) above the Indian Ocean - and the CONTOUR mission operations team at the Johns Hopkins University Applied Physics Laboratory expected to regain contact about 45 minutes later to confirm the burn. No signal was received, and the team has been working through plans to find the craft along the predicted trajectories for a successful burn. CONTOUR's onboard computer was carrying a command that, starting at 6 a.m. EDT today, would have turned the spacecraft and pointed another of its four antennas toward Earth. So far, however, no signal has been received. 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." August 15, 2002 -- 1 p.m. (EDT) Mission Operations Awaiting Contact from CONTOUR Spacecraft 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.