Red Planet rover sent Earth photo over

NASA's Mars Curiosity rover has sent its first photo of Earth, from 99 million miles away, after a month of exciting milestones.

After 18 months of crumbling across the surface of Mars, the Curiosity rover has beamed home an image of an inky Martian sunset, with Earth and its moon visible as distant points of light above a black, dune-swept horizon.

"Look Back in Wonder," boasted the vehicle's Twitter feed. "My 1st picture of Earth from the surface of Mars."

Just two days before the photo's release, the mobile laboratory had achieved another milestone by ascending its first Martian sand dune.

"I'm over the moon that I'm over the dune!" tweeted the spindly wonder, whose safe ascent hadn't been certain.

The three-foot-tall dune, which leads to a site dubbed "Dingo Gap," had stood between Curiosity and a southwestward route across Mars' Gale Crater, toward areas believed to contain a rich diversity of rocks. The rover's long-term science destination is on the lower slopes of Mount Sharp, in the middle of the crater.

Curiosity is a project of NASA's Mars Science Laboratory mission, whose objective is to find evidence of a past environment that could have supported microbial life. The rover, which landed in the Gale Crater by parachute in August 2012, now spends its days drilling, scooping, and analyzing samples of Martian rocks.

This week's triumphs capped off a busy fortnight for both Curiosity and its seemingly indestructible older sibling, Opportunity. On Jan. 24, as Opportunity celebrated its 10th anniversary of Martian roving from the edge of the immense crater Endeavour, NASA announced that the vehicle had detected traces of ancient water in the crater. Mineral analysis indicated that around 4 billion years ago, fresh water flowed under the planet's surface – fresh enough to support Martian life.

The two rovers, both managed by NASA's Jet Propulsion Laboratory, are the only earthly vehicles active on Mars. Two earlier pioneers, Sojourner and Spirit, remain on the Red Planet in a state of long-term retirement.