Curiosity completes its longest drive yet as Nasa scientists explain the morse code hidden in its tyre tracks

Curiosity completes its longest drive yet as Nasa scientists explain the morse code hidden in its tyre tracks

Researchers say drive went flawlessly, and plan to take more images of the rover's landing site

Rover moved 400 metres on its way to a large rock formation where engineers will use its drill for the first time

Morse code used to orient the rover on the barren martian surface

Nasa's Mars rover Curiosity has taken its longest drive on the red planet.

Engineers sent the rover commands to set it on a quarter-mile (400 metres) drive to a nearby rock formation.

The drive, the rover's first 'science' drive, as previous moves were to test its systems, takes it to a spot where engineers now plan to drill into the martian rocks to analyse them.

The rover drove eastward about 52 feet (16 metres) on Tuesday, its 22nd Martian day after landing. 

This image released by NASA on shows Curiosity's wheels after it made its third drive on Mars. The six-wheel rover landed on Aug. 5, 2012 on a mission to study the red planet's environment.

This third drive was longer than Curiosity's first two drives combined. 

The previous drives tested the mobility system and positioned the rover to examine an area scoured by exhaust from one of the Mars Science Laboratory spacecraft engines that placed the rover on the ground. 

'This drive really begins our journey toward the first major driving destination, Glenelg, and it's nice to see some Martian soil on our wheels,' said mission manager Arthur Amador of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

 

'The drive went beautifully, just as our rover planners designed it.'

Glenelg is a location where three types of terrain intersect. Curiosity's science team chose it as a likely place to find a first rock target for drilling and analysis. 

'We are on our way, though Glenelg is still many weeks away,' said Curiosity Project Scientist John Grotzinger of the California Institute of Technology (Caltech) in Pasadena. 

Nasa also revealed images showing the morse code messages hidden in Curiosity's tyre tracks, spelling out the letters JPL, the lab where the rover was made.

'We plan to stop for just a day at the location we just reached, but in the next week or so we will make a longer stop.' 

During the longer stop at a site still to be determined, Curiosity will test its robotic arm and the contact instruments at the end of the arm. 

At the location reached Tuesday, Curiosity's Mast Camera (Mastcam) will collect a set of images toward the mission's ultimate driving destination, the lower slope of nearby Mount Sharp. 

A mosaic of images from the current location will be used along with the Mastcam images of the mountain taken at the spot where Curiosity touched down, Bradbury Landing. 

This stereo pair taken about 33 feet (10 meters) apart will provide three-dimensional information about distant features and possible driving routes.

Nasa has also revealed why it put morse code onto the rover's tyre tracks.

'The purpose of the pattern is to create features in the terrain that can be used to visually measure the precise distance between drives,' said Matt Heverly, the lead rover driver for Curiosity at JPL.

This driving tool, called visual odometry, allows the rover to use images of landscape features to determine if it has traveled as far as predicted, or if its wheels have slipped. 

For example, when the rover drives on high slopes or across loose soil, it will routinely stop to check its progress. 

By measuring its distance relative to dozens of prominent features like pebbles or shadows on rocks -- or patterns in its tracks -- the rover can check how much its wheels may have slipped. 

If Curiosity has not slipped too much, it can then re-plan the next leg of its drive, taking its actual position into account.

'Visual odometry will enable Curiosity to drive more accurately even in high-slip terrains, aiding its science mission by reaching interesting targets in fewer sols, running slip checks to stop before getting too stuck, and enabling precise driving,' said rover driver Mark Maimone, who led the development of the rover's autonomous driving software.

The Morse code imprinted on all six wheels will be particularly handy when the terrain is barren. Curiosity won't be able to read the Morse code symbols in the track marks directly, but it will note that the pattern is a high-contrast feature. 

This will give the rover the anchor it needs in an otherwise featureless terrain.

'Imagine standing in front of a picket fence, and then closing your eyes and shifting to the side. 

'When you open your eyes, you wouldn't be able to tell how many pickets you passed. 

'If you had one picket that was a different shape though, you could always use that picket as your reference,' said Heverly. 

'With Curiosity, it's a similar problem in featureless terrain like sand dunes. 

'The hole pattern in the wheels gives us one 'big picket' to look at.'

A view the one of Curiosity's rear cameras, showing the path of its longest drive yet.