Comet Siding Spring Buzzes C2013 A1 Mars in Once-in-a-Lifetime Flyby

Credit: SLOOH

Comet Siding Spring C2013 A1 zoomed by Mars today (Oct. 19) in an extremely rare close encounter that scientists billed as a "once-in-a-lifetime" event that may help researchers better understand the earliest days of our solar system.

Comet Siding Spring C2013 A1 came within just 87,000 miles (139,500 kilometers) of the Martian surface at 2:27 p.m. EDT (1827 GMT) today, about one-third of the distance between Earth and the moon.

At the time of closest approach, the comet barreled by at 126,000 mph (203,000 km/h) relative to the Red Planet, NASA officials said.

All seven spacecraft currently operating on or around Mars were scheduled to observe the close shave, with the aim of learning more about comet composition and behaviour.

The US Deep Space Network monitored the NASA Mars satellites currently orbiting Mars.

Credit: SLOOH

NASA Curiosity Mars Rover Prepares for Fourth Rock Drilling

In this image from NASA's Curiosity Mars rover looking up the ramp at the northeastern end of "Hidden Valley," a pale outcrop including drilling target "Bonanza King" is at the center of the scene. 

The rover's Navcam captured this northward view on Aug. 4, 2014, from the valley's sandy floor.

Image Credit: NASA/JPL-Caltech

The team operating NASA's Curiosity Mars rover has chosen a rock that looks like a pale paving stone as the mission's fourth drilling target, if it passes engineers' evaluation.

They call it "Bonanza King."

It is not at the "Pahrump Hills" site the team anticipated the rover might reach by mid-August.

Unexpected challenges while driving in sand prompted the mission to reverse course last week after entering a valley where ripples of sand fill the floor and extend onto sloping margins.

However, the new target outcrop's brightness and its position within the area's geological layers resemble the Pahrump Hills outcrop.

This Aug. 14, 2012, image from the Mastcam on NASA's Curiosity Mars rover shows an outcrop that includes the "Bonanza King" rock under consideration as a drilling target. 

Raised ridges on the flat rocks are visible at right. 

Tread marks from a rover wheel are in the lower half.

Image Credit: NASA/JPL-Caltech/MSSS

"Geologically speaking, we can tie the Bonanza King rocks to those at Pahrump Hills. Studying them here will give us a head start in understanding how they fit into the bigger picture of Gale Crater and Mount Sharp," said Curiosity Deputy Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory in Pasadena, California.

Mount Sharp is the mission's long-term science destination, offering a stack of layers holding evidence about environmental changes on ancient Mars.

The mountain rises from inside Gale Crater, where Curiosity landed in August 2012.

All three rocks the rover has drilled so far have been geologically associated with the crater floor, rather than the mountain.

Sample material pulled from the first two and delivered to Curiosity's onboard analytical laboratories in 2013 provided evidence for ancient environmental conditions favorable for microbial life.

A drilled sample from Bonanza King may add understanding about how environments varied and evolved.

This image from NASA's Curiosity Mars rover looks down the ramp at the northeastern end of "Hidden Valley" and across the sandy-floored valley to lower slopes of Mount Sharp on the horizon. 

The rover's Navigation Camera captured this southward view on Aug. 12, 2014, after exiting the valley. 

Image Credit: NASA/JPL-Caltech