Washington, Sep 3 (IANS): US space agency NASA Perseverance rover has likely retrieved a rock sample on Mars at its second attempt.

"The data received on September 1, from NASA's Perseverance rover, indicates that the team has achieved its goal of successfully coring a Mars rock. The initial images downlinked after the historic event show an intact sample present in the tube after coring," the US space agency said in a statement.

The rover failed to gather samples of rock in its first attempt in early August. While Perseverance, using its 2-metre-long robotic arm, drilled a hole on Mars, it could not collect and store samples, as intended.

After completing its second coring, Perseverance manoeuvred the corer, bit, and open end of the sample tube in order to be imaged by the rover's Mastcam-Z instrument.

The target for the sample collection attempt was a briefcase-size rock belonging to a ridgeline that is more than half-a-mile (900 metres) long and contains rock outcrops and boulders.

The initial set of images from Mastcam-Z showed the end of a cored rock within the sample tube, NASA said.

After taking these images, the rover began a procedure called "percuss to ingest", which vibrates the drill bit and tube for one second five separate times. The movement is designed to clear the lip of the sample tube of any residual material. The action can also cause a sample to slide down farther into the tube. After the rover finished the procedure, it took a second set of Mastcam-Z images.

In these images, the lighting is poor, and internal portions of the sample tube are not visible.

"The project got its first cored rock under its belt, and that's a phenomenal accomplishment," said Jennifer Trosper, project manager at NASA's Jet Propulsion Laboratory in southern California.

"The team determined a location, and selected and cored a viable and scientifically valuable rock. We did what we came to do. We will work through this small hiccup with the lighting conditions in the images and remain encouraged that there is sample in this tube," Trosper added.

Perseverance rover was launched on July 30 last year and arrived at the red planet on February 18 after a 203-day journey traversing 472 million kilometres. It will be the first mission to collect and cache Martian rock and regolith -- broken rock and dust.

It is currently exploring two geologic units containing Jezero Crater's deepest and most ancient layers of exposed bedrock and other intriguing geologic features. The first unit, called the "Crater Floor Fractured Rough," is the floor of Jezero. The adjacent unit, named "Setah", has Mars bedrock as well, and is also home to ridges, layered rocks, and sand dunes.