The Russian Mars curse has struck again.

Since 1960, the Soviet Union and, later, Russia have launched 18 unmanned missions to Mars. Sixteen failed completely, and two returned data from the planet only briefly.

Now engineers are scrambling to save the country’s latest attempt.

Known as Phobos-Grunt, the spacecraft, loaded with scientific instruments, lifted off early Wednesday Moscow time from the Baikonur Cosmodrome in Kazakhstan. The ambitious mission marked Russia’s first attempt to send a spacecraft beyond Earth’s orbit since a 1996 Mars probe crashed shortly after launch.

Phobos-Grunt was to land on one of the Red Planet’s two small moons, scoop up half a pound of dirt (“grunt” is Russian for “soil”), and return this scientific prize to Earth.

But after reaching orbit around the Earth, the 15-ton spacecraft failed to fire its upper-stage rocket as scheduled. The craft is circling the Earth as mission engineers try to diagnose the problem and light the rocket.

“I’d bet even money these guys will pull it off,” said James Oberg, a retired space shuttle engineer who closely watches the Russian space program. “Nothing irreversible has happened, they haven’t burned up any fuel or jettisoned any tanks. They are in a safe parking orbit, so they’re good for a few weeks.”

Oberg said Russian mission controllers will attempt to start the rocket late Wednesday.

The Russian news service RIA quoted Vladi­mir Popovkin, head of the Russian space agency Roscosmos, as saying the rocket failure could be a software problem, which might be fixable. “This error can be corrected, and the flight can be continued,” RIA quoted Popovkin as saying.

But if there is a hardware problem, the “flight may no longer be continued,” Popovkin said.

“If there is a problem with the engine itself, and the command was in fact sent to the engine and the engine did not fire, very little can be done,” said Anatoly Zak, a Russian space historian, journalist and publisher of Russian­

A dearth of mission-tracking resources makes recovery work more difficult.Just one communications station in the world — at Baikonur — can send commands to the craft as it passes overhead.

“They need to download data, analyze data, upload data,” Zak said. “So they have a very narrow window of opportunity to save the mission.”

Early Wednesday, Roscosmos called on amateur satellite trackers to follow the troubled craft. The first of two crucial rocket burns was scheduled while Phobos-Grunt sped over South America, but observers in Brazil dd not see the engine fire, Oberg said.

Likewise, astronauts on the international space station, including American Mike Fossum, awoke early to watch one of the rocket burns, said NASA spokesman Kelly Humphries. The astronauts also could not spot a telltale flare.

Planning for the $170 million mission began in the 1970s but was interrupted by the collapse of the Soviet Union. It later became an international mission after China added a small, detachable craft, Yinghuo-1, that was to orbit Mars. The French contributed several scientific instruments, and the U.S.-based Planetary Society provided a small disk carrying hardy microbes to see whether life could survive the 34-month round trip to Mars.

Thirty tiny tubes of bacteria, yeast, and near-microscopic animals known as tardigrades, or water bears, are now trapped in space, going in circles.

“It’s not a failure yet,” said Bruce Betts, the Planetary Society scientist leading the $500,000 Living Interplanetary Flight Experiment, or LIFE. “It’s in limbo. It’s a little stressful. It’s a feeling of helplessness.”

The Russian romance with Mars extends back more than a century, said Cathleen Lewis, a Russian space specialist and curator at the Smithsonian’s National Air and Space Museum.

“Some of the earliest Soviet and pre-Soviet era science fiction stories of space exploration were about going to Mars,” Lewis said. She pointed to a 1908 novel, “Red Star,” by Alexander Bogdanov, as especially influential. In the book, a Russian engineer solves the social problems of a Martian race by introducing the aliens to socialism.

If engineers can’t light the Phobos-Grunt rocket, the huge spacecraft will eventually crash to the ground.

“If it comes in, it’s going to be a nightmare,” Oberg said. “It will probably be the most toxic satellite ever. It’s got at least five tons of toxic fuel aboard.” The craft carries tanks of hydrazine and dinitrogen tetroxide fuel. Both are “nasty substances,” Oberg said.