Unspecified forces in the Western hemisphere may be shooting down Russian spacecraft, including the Fobos-Grunt probe, which is expected to hit the atmosphere this week, Russia's top space official said.

"I don't want to blame anyone, but there are powerful technologies that are capable of impacting spacecraft, and we cannot rule out their usage," Vladimir Popovkin, head of the Federal Space Agency, told the Izvestia daily in an interview published Monday.

He pointed out that Russian spacecraft often malfunction "when flying above the part of Earth that's in a shadow zone for Russia — where we don't see them and receive no signals from them."

Since December 2010, Russia has lost five satellites and one space truck. That includes Fobos-Grunt, a unique unmanned probe that was to bring back soil samples from Phobos, a moon of Mars.

The probe was to execute its mission to Phobos in 2 1/2 years. Instead, it is now expected to fracture and fall to Earth between Wednesday and Sunday, with debris possibly raining on parts of South and North America, Australia, Africa, Europe, Asia and southern Russia.

Popovkin, a former deputy defense minister, did not elaborate on the suspects, but said Russia plans to deploy in 2013 a new system of three transmission satellites, Luch-5, to constantly monitor all its spacecraft in real time regardless of their place in orbit.

This is the first time a senior Russian official has blamed the problems of the country's space program on outside interference.

When Fobos-Grunt became stranded in orbit after its Nov. 9 launch, Popovkin put it down to time constraints for the launch and insufficient funding for the project, valued at 5 billion rubles ($158 million).

The failures of the space programs have already cost Popovkin's predecessor, Anatoly Perminov, his job. He was sacked last April.

Meanwhile, NASA moved to correct the course for the Atlas-5 vehicle carrying its Curiosity rover to Mars, Itar-Tass reported Tuesday.

The probe was successfully launched on Nov. 26 and is expected to land on Mars on Aug. 5.