After more than a week of unsuccessful attempts to communicate with Russia’s Phobos-Grunt spacecraft, the European Space Agency (ESA) has ceased relaying orbit-raising commands to the unmanned Mars probe stranded in low Earth orbit since its Nov. 8 launch from the Baikonur Cosmodrome in Kazakhstan, according to ESA officials.
“After two days’ attempt at Maspalomas [in the Canary Islands], we did not succeed to get commands into the spacecraft and to get response by telemetry,” said Manfred Warhaut, mission operations chief at ESA, referring to the agency’s ground station in Spain’s Canary Islands. “We have agreed that by the end of today in the absence of any success we would terminate all of our support to the Phobos-Grunt mission.”
Warhaut said ESA would stand by to assist Russia “in case there is any sign or glimpse of hope from their side,” he said.
Russian ground controllers first reached the stranded Mars’ moon probe Nov. 22 via ESA’s tracking facility in Perth, Australia, after the agency augmented a 15-meter-dia. antenna at the station. A second attempt Nov. 23 resulted in one-way communication with the spacecraft, and shortly afterward Russia was able to make contact from its Baikonur ground station, Warhaut said, though subsequent efforts failed.
Phobos-Grunt controllers sent a new set of real-time commands at midday Dec. 1 and Dec. 2 from Maspalomas after a similar modification to the 15-meter array there was made, but contact was not established.
Since ESA’s first contact, ground controllers have encountered several factors complicating efforts to send and receive telemetry. Specifically, because the spacecraft has a limited onboard power supply, its transponder assembly functions only when illuminated by the Sun, a situation that occurs in relatively short passes over Perth in the evening and early morning hours GMT, and midday over Maspalomas.
“Some indications we are receiving tell us that the spacecraft has power but it is in an eclipse,” Warhaut said. “We have other indications which tell us the contrary, so it’s inconclusive at this point.”
Warhaut said Russian ground controllers have tried to raise the spacecraft’s orbit in an effort to minimize the eclipse and widen the window of time during which ground controllers could attempt two-way communications with the probe. To do this, the team used a combination of time-delayed commands set to execute at specific points in the spacecraft’s orbital trajectory, and real-time telemetry sent to the onboard transponder.
“But the interleaving was not successful,” Warhaut said. “Yesterday and today it was direct commanding only.”
As of today, Warhaut said, Russia will continue to attempt to contact Phobos-Grunt on its own.
“They will try to send some thruster commands in direct mode … in order to raise the orbit whenever they send the commands, but they will do this in such a way that they try this procedure out on a simulator and once it is confirmed to run on a simulator then it would expose this to their Baikonur ground station to the spacecraft over the weekend,”
Warhaut said the window for reaching the spacecraft from Baikonur and commanding its thrusters to boost it into an escape orbit on a trajectory toward Mars’ moon Phobos has all but closed.
“It’s not really very realistic,” said Wolfgang Hell, ESA’s Phobos-Grunt service manager.
In addition to help from ESA, Russia has received assistance fromin attempting to communicate with Phobos-Grunt.
“has been providing assistance in attempting to establish contact with Phobos-Grunt, including use of our Deep Space Network,” said NASA spokesman Bob Jacobs, adding that the U.S. space agency had to divert some resources last week due to the Nov. 25 launch of its Mars Science Lab. “But we are continuing to work with Russia, as are a number of international space agencies.”
Warhaut said before the mission launched that ESA had already agreed to provide tracking support for the Phobos-Grunt mission’s cruise and deep-space phases at Russia’s request.
“We had anyhow conducted a lot of preparation activities in close cooperation with them, including compatibility testing for the range of frequencies,” he said. “This is why we had also a good understanding of their transponder characteristics, we knew what commands were accepted.”
What ESA was not prepared for, he said, was any kind of emergency immediately following launch.
“But let me say this: It is standard practice in our business, if some agency declares a spacecraft emergency we try our utmost to help out, because it may happen to us on another day,” he said.
Warhaut said the goal now “is to get to a higher orbit to park it there and then to have more time to think, to diagnose and then to redefine the mission, and that is what the Russians are trying to do now.”
In the meantime, telemetry received from ESA’s initial contact with Phobos-Grunt Nov. 22 indicates the unmanned probe is currently in a stable orbit at 200 km x 340 km, where it is likely to remain until January or February, when the spacecraft is expected to re-enter Earth’s atmosphere.
Although the Russian space agencyhas had little to say regarding the botched Mars mission, agency chief Vladimir Popovkin said in a Nov. 14 statement that if the Phobos-Grunt mission cannot be salvaged, the spacecraft is expected to burn up on re-entry and pose no danger to Earth.
“There is no doubt that the device will explode when entering the atmosphere,” Popovkin said in a Nov. 14 statement posted on the agency’s website.