ESA’s Rosalind Franklin twin rover on Earth has drilled down and extracted samples 1.7 metres into the ground – much deeper than any other martian rover has ever attempted.
The successful collection of soil from a hard stone and its delivery to the laboratory inside the rover marks a promising milestone for the ExoMars 2022 mission.
“The long-awaited success of the ExoMars drill on Earth would be a first in Mars exploration,” says David Parker, ESA’s director of human and robotic exploration. 7 cm is the deepest ever drill dug on Mars.
The Rosalind Franklin rover is designed to drill deep enough, up to two metres, to get access to well-preserved organic material from four billion years ago, when conditions on the surface of Mars were more like those on infant Earth. The Ground Test Model is a replica of the Mars rover. As part of a series test at the Mars Terrain Simulator in Turin, Italy, the first samples were collected. The drill was developed by Leonardo, while Thales Alenia Space is the prime contractor for ExoMars 2022.
Rosalind Franklin’s twin has been drilling into a well filled with a variety of rocks and soil layers. A block of medium-hardened cemented clay was used as the first sample.
Drilling took place on a dedicated platform tilted at seven degrees to simulate the collection of a sample in a non-vertical position. The drill collected the sample as a small pellet about 1 cm in diameter by 2 cm in length.
Rosalind Franklin’s drill retains the sample with a shutter that prevents it from dropping out during retrieval. Once the sample is captured, the drill transports it to the surface. Then, the sample is delivered to the laboratory within the rover.
With the drill completely retracted, the rock is dropped into a drawer at the front of the rover, which then withdraws and deposits the sample into a crushing station. The powder is then distributed to the ovens and containers that will be used for scientific analysis of Mars.
“The reliable acquisition of deep samples is key for ExoMars’ main science objective: to investigate the chemical composition –and possible signs of life– of soil that has not been subjected to damaging ionising radiation,” says ExoMars project scientist Jorge Vago.
A unique drill for Mars
The ExoMars drill is an assembly of mechanisms that rely on an automated choreography of tools and mounting rods. Pietro Baglioni (ExoMars rover team lead) says that the drill’s design and construction was so complicated that the team achieved deep drilling for the first time.
Rosalind Franklin’s drill works on rotation. The drill string is made up of a series of tools and extensions rods that can be connected together to reach a maximum length 2m.
The drill can penetrate the ground at 60 rotations per minute, depending on the consistency of the soil. Digging into sandy or clay solid materials could take between 0.3 and 30 mm per minute. The drill also has a two-degree freedom positioner, which allows it to place the sample at the correct angle in the laboratory.
No easy feat
“Drilling hard stones to a depth of two metres on a mobile wheeled platform with less than 100 watts of power is a complex task,” explains Andrea Merlo, ExoMars Rover functional engineer from Thales Alenia Space.
Doing it on Earth is even more difficult because the Ground Test Model must be offloaded to recreate the weaker martian gravity level – Mars gravity is about one-third of Earth’s. The model is suspended from the ceiling using a gravity compensator.
Since the twin rover consists of models that are beyond their nominal lifetime, the team had to tune some parameters during the deep drilling test. Andrea says that this already gives engineers an indication of how Mars could be degraded.
Tests to roving on Mars
The Ground Test Model has successfully completed a number of tests to move to and to identify targets while acquiring images and data. These dry runs to rehearse the rover operations on Mars started in June 2021.
The rover has demonstrated that it can follow precise trajectories and survey the environment on and below the surface with its instruments, including cameras, spectrometers and a sub-surface sounding radar and neutron detector.
In parallel, the real Rosalind Franklin rover is being prepared for its flight to Mars in nearly a year’s time – the launch window for ExoMars opens on 20 September 2022.
Notes to editors
The ExoMars programme is a joint endeavour between ESA and Roscosmos. In Europe, The rover is a joint venture between Thales Alenia Space – Italia (67%) and Leonardo (33%). Thales is the industrial prime. Leonardo provides the drill and complex laboratory mechanisms, while Thales supplies the drill and Leonardo the payload. NASA/JPL, IKI/Roscosmos and Thales are the NASA/JPL members. Astrium Ltd. (ASU), is responsible for the rover.