In 2004, a year after Europes very first mission to Mars was released, the flight dynamics group at ESAs operations centre came across a severe problem. New computer designs revealed a worrying fate for the Mars Express spacecraft if mission controllers continued with their strategies to deploy its giant MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) radar.
Artists impression of Mars Express. Credit: Spacecraft image credit: ESA/ATG medialab; Mars: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO
MARSIS main antenna. Credit: Universität der Bundeswehr– München
This extremely sensitive radar instrument covers 40 metres across when completely extended, making it longer than a Space Shuttle orbiter and was constructed with the direct intention of finding water below Mars surface. By sending a series of chips in between 1.8 and 5.0 Mhz in subsurface mode would scour the red planet for any signs of water anywhere down to a depth of a few kilometres. A secondary ionosphere mode at 0.1 to 5.4 Mhz surveyed the electrical conductivity of the Martian upper atmosphere.
2 radar booms, 20-metre long hollow cylinders, 2.5 centimetres in diameter, and one 7-metre boom, were folded in a box like a concertina. As soon as the box was opened, all of the saved flexible energy from the glass fiber booms would be released, a little like a jack-in-the-box, and they would lock into a straight line.
New and updated computer models, nevertheless, showed that these long rods would swing back and forth upon release with an even higher amplitude than previously thought, possibly entering into close contact with the fragile parts of the Mars Express body.
Implementation was held off
Artists impression of MARSIS Boom 1 deployed. Credit: ESA
Strategies were made to get the spacecraft in a robust mode before the deployment of each boom and while the glass fiber cylinders were extended. After each deployment the control team would conduct a full assessment of the spacecraft, using up to a few days, before moving onto the next phase.
The first implementation started on 4 May 2005 with one of the 2 20-metre dipole booms, and flight controllers at ESAs operations centre quickly realised something wasnt rather. 12 out of 13 of the boom sections had actually snapped into place, however one, potentially number 10, was not in position.
Implementation of the third and second booms was postponed
Additional analysis showed that extended storage in the cold conditions of deep space had impacted the fibreglass and Kevlar material of the boom. What could be done to warm it up?
MARSIS boom 2 implementation begins. Credit: ESA, CC BY-SA 3.0 IGO
Get in: the Sun. Mission teams decided to swing the 680 kg spacecraft to a position that would enable the Sun to warm the cold side of the boom. It was hoped that as the cold side broadened in the heat, the opened segment would be pushed into place.
One hour later on, as contact was restored at 04:50 CET on 11 May, comprehensive analysis showed all sectors had effectively secured place and Boom 1 was successfully released!
Following the rollercoaster rollout of the very first antenna, flight controllers spent a long time mulling over the events. A complete examination occurred, lessons were found out, and plans were put in place to prevent the same abnormality from taking location in the next 2 deployments.
By 14 June 2005, operators felt positive that they, and Mars Express, were all set to release the 2nd boom. At 13:30 CEST the commands were sent out.
This time, Mars Express was set into a slow rotation to last 30 minutes throughout and after the release of the 2nd 20-metre boom. The rotation was prepared so that all of the booms hinges would be appropriately heated up by the Sun previously, throughout, and after deployment.
MARSIS totally released. Credit: ESA, CC BY-SA 3.0 IGO.
Simply 3 hours later on and the very first signs of success reached ground control, revealing that Mars Express had appropriately re-oriented itself and was pointing towards Earth, transferring data.
The data validated that the spacecraft was working with 2 totally and properly released booms, and their release had actually not caused any damage to the spacecraft.
Not long after, the 3rd boom was deployed, and the full MARSIS setup was total on Mars Express.
Let the science start
Simply four months later on, and ESA was reporting on the radars activities. MARSIS radar researchers were collecting data about an extremely electrically carrying out layer– surveyed in sunlight. They were likewise continuing the laborious analysis of information in the search for any possible signs of underground water, in a frozen or liquid state.
MARSIS prospecting for water. Credit: ESA
Radar science is based on the detection of radio waves, showed at the borders between different products. Each material engages with light in a different method, so as the radio wave crosses the boundary between different layers of material, an echo is created that carries a sort of finger print, providing details about the kind of material causing the reflection, including ideas to its composition and physical state.
The Red Planet
Like Earth, Mars has two ice caps covering its poles, and early attempts to determine the composition of these regions suggested the northern cap might be composed of water ice, while the southern cap is made up of carbon dioxide ice.
Map southern pole at Mars, stemmed from OMEGA infrared spectral images. Credit: ESA/OMEGA.
Later observations by the OMEGA instrument on board Mars Express suggested the southern cap remained in reality composed of a mix of co2 and water. Nevertheless, it was just with the arrival of Mars Express that scientists had the ability to get direct confirmation for the very first time that water ice exists at the south pole.
MARSIS, the first radar sounder ever sent to orbit another planet, revealed that both polar ice caps are up to 3.5 km thick, each with a core of water ice that is covered by a layer of carbon dioxide ice, centimetres to decimetres thick.
An impressive discovery
Mars Express discovers water buried under the south pole of Mars. Credit: Context map: NASA/Viking; THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/JPL/ ASI/Univ. Rome; R. Orosei et al 2018
On 25 July 2018, fifteen years after its launch, it was verified that data from years of Mars Express observations were telling us something impressive. Hidden below Mars south pole is a pond of liquid water, buried under layers of ice and dust.
The existence of liquid water at the base of the polar ice caps had actually long been suspected, however previously proof from MARSIS had actually remained inconclusive. It has taken the perseverance of scientists dealing with this subsurface-probing instrument over years, developing new strategies in order to collect as much high-resolution data as possible to validate such an amazing conclusion.
Kasei Valles mosaic. Credit: ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO
Liquid water can not endure on the surface of Mars, as the low atmospheric pressure triggers it to evaporate in a matter of hours. Orbiters, together with rovers and landers exploring the martian surface area, also found minerals that can only form in the existence of liquid water.
Over the course of the Red Planets 4.6 billion year history, its environment has greatly altered, indicating scientists today need to try to find water underground. We now understand for particular that under its surface Mars harbours ancient masses of liquid water.
Mars northern polar ice cap. Credit: NASA/JPL-Caltech/MSSS
Kept in a liquid state by the vast pressures from glaciers above, it is thought that this water is also a briny option. The presence of salts on Mars might even more lower the melting point of water, keeping it liquid even at below-freezing temperature levels.
Dmitri Titov, ESAs Mars Express job scientist: “This thrilling discovery is an emphasize for planetary science and will add to our understanding of the evolution of Mars, the history of water on our neighbour world and its habitability.”
Congratulations to everyone involved in this unbelievable discovery, and thank you to the flight controllers at ESAs operations centre in Darmstadt whose devotion and resourcefulness 14 years ago made possible what we know today.
This exceptionally delicate radar instrument spans 40 metres across when fully extended, making it longer than a Space Shuttle orbiter and was constructed with the direct intention of finding water underneath Mars surface area. They were likewise continuing the tiresome analysis of information in the search for any possible signs of underground water, in a frozen or liquid state.
Mars Express discovers water buried under the south pole of Mars. Liquid water can not make it through on the surface of Mars, as the low atmospheric pressure triggers it to vaporize in a matter of hours. Orbiters, together with landers and rovers checking out the martian surface area, also discovered minerals that can just form in the presence of liquid water.
