Mars craft's engine fires, but no signal
Artist's conception of the Mars climate orbiter
September 23, 1999
Web posted at: 6:12 a.m. EDT (1012 GMT)
By Robin Lloyd
CNN Interactive Senior Writer
(CNN) -- NASA's next Mars orbiter fired its engine to push itself into orbit around the red planet early Thursday but engineers failed to receive a signal that all went well.
The Mars Climate Orbiter engine fired as expected at 5:01 EDT, with a chorus of "Yes!" coming from the control room at Jet Propulsion Laboratory.
However, engineers waiting for a digital signal at 5:26 a.m. heard nothing. They had expected to receive digital data from the spacecraft as it emerged from behind Mars, which blocked signals for 10 minutes after the 16 minute engine burn.
"The spacecraft should have appeared from behind Mars just a little bit less than 6 minutes ago," said NASA spokesman David Seidel.
The morning's events are critical to NASA's first effort to look directly for water on Mars and study its weather closely, with the spacecraft set to enter the red planet's orbit to ready itself for contact with two upcoming lander missions.
Following a 286-day journey, Mars Climate Orbiter fired its engine for 16 minutes to position itself so the gravity of Mars captured it and pulled it into its orbit.
It is possible that the spacecraft was fine but antennae on Earth were unable to detect its signal, Seidel said.
Digital data to confirm the spacecraft's health and location were not expected until about 5:35 a.m. when Climate Orbiter cruised out from behind Mars where most of its communications were temporarily blocked.
The worse case scenario was that the engine, tested repeatedly on Earth, would fail to fire at the key moment. In that case, the spacecraft would sail by Mars and miss its window of opportunity.
Should there be any trouble with Mars Climate Orbiter, the first lander mission to follow -- Mars Polar Lander -- will have to communicate with Earth, albeit less efficiently, on its own.
It has its own radio communication system for "talking" with Earth, although it is less sophisticated than the relay system with the orbiter.
Mars Polar Lander
Orbiter designed for science too
The plan is to have Climate Orbiter ready to relay signals from the martian surface on December 3 when its partner spacecraft -- Polar Lander -- lands on the red planet. Climate Orbiter's communications role for that mission will last up to 90 days.
Polar Lander is designed to extend a robotic arm to dig for water ice in the martian soil and conduct other science experiments focusing on martian weather.
Together, the missions cost $327.6 million and are aimed at understanding Mars' history and the potential for life in its past and elsewhere in the universe.
Climate Orbiter also is expected to relay signals for a follow-on Mars lander mission set for launch in 2001.
But between its communications duties, Climate Orbiter will study Mars' weather on its own from a distance.
The orbiter carries a camera to track Mars' atmosphere and an infrared radiometer to measure the atmosphere's temperature, pressure and contents -- water vapor, dust, carbon dioxide.
Overall, the orbiter will study Mars' weather patterns for a martian year -- about two Earth years.
Four days to aerobraking
Within four days of its arrival at Mars, the spacecraft will start to trim its orbit to make it more circular by successively grazing the planet's atmosphere -- a process called aerobraking.
Aerobraking was first was tested at Mars by Mars Global Surveyor, an orbiter currently mapping the planet.
Climate Orbiter initially will take 13 hours to circle Mars, but after 44 days of aerobraking that figure will drop down to two hours. The orbiter's final path will be about 400 km (about 270 miles) above the surface.
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Mars Climate Orbiter
Mars Global Surveyor
Mars Meteorite Home Page (JPL)
Fossil Record of the Cyanobacteria
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