The CONTOUR mission team clings to the hope they'll hear from the still-silent comet probe. The spacecraft is now more than 1.3 million miles (2.1 million kilometers) from Earth.
"The plan is to watch and monitor," said CONTOUR Mission Director Robert Farquhar of the Johns Hopkins University Applied Physics Laboratory (APL), the organization that built the probe and manages the mission for NASA.
"We realize the possibilities are small, but we cant discount the idea that the spacecraft is still operable. We have to determine that before we give up," Farquhar said in an APL-released statement today.
The $159 million mission for NASA was rocketed into Earth orbit July 3.
Following more than a month of circling the Earth, CONTOUR fired up its STAR 30BP solid-propellant rocket motor on August 15. That firing nudged the probe out of its parking orbit, with the intent that the probe would encounter two comets over the next four years.
However, ground controllers lost contact with the craft after the rocket motor firing.
Solid rocket motor
Since Friday, the team has received telescope images from several observatories showing two objects traveling along CONTOURs predicted path. Engineers believe these are CONTOUR and part of the spacecraft that may have separated from it when CONTOURs solid rocket motor fired on August 15.
The STAR 30BP is a solid propellant rocket motor, provided by ATK Tactical Systems - Elkton Operations in Elkton, Maryland. The firm is part of the larger ATK Thiokol Propulsion, headquartered in Edina, Minn., a $2 billion aerospace and defense company specializing in propulsion, composite structures, munitions, and precision capabilities.
ATK headquarters referred all questions regarding STAR 30BP to APL's Edward Reynolds, CONTOUR Project Manager, who told SPACE.com that "APL and ATK are working together to evaluate scenarios in an ongoing effort to support a spacecraft recovery."
Timed command
Mission operators at APL and navigators at NASAs Jet Propulsion Laboratory are using these images to pinpoint the spacecrafts orbit and are aiming the Deep Space Networks powerful 70-meter and 34-meter antennas along that trajectory.
"Without knowing how big the objects in the telescope images are, were going to work on the assumption that the spacecraft may still be largely intact," Farquhar said. "You need at least three separate observations to determine an orbit, and we have that. We know were looking in the right place," he added.
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 cant 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.
Listening post
The 60-hour sequence begins with the first of CONTOURs two transmitters cycling 10 hours each through the low-gain and multidirectional (pancake) beam antennas on CONTOURs aft side opposite the dust shield and the forward-side low-gain antenna.
Because of its narrow beamwidth and the unlikely prospect of its facing Earth, CONTOURs 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 spacecrafts position and condition, the antennas might not have a direct line of sight toward Earth," said Mark Holdridge, CONTOUR Mission Operations Manager. "But well be listening."
If the team doesn't hear from the spacecraft this week, Farquhar said, 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," Farquhar said. "And who knows, we might get lucky."
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