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Comet-67P

Astrophotographer finds Comet 67P has its own tiny Churymoon

The Rosetta mission of the European Space Agency spent two years at comet 67P/Churyumov-Gerasimenko. The mission ended in 2016 when the spacecraft collided with the comet. In the time spent at 67P, a huge number of images were captured. These images are now freely available at Rosetta website. An astrophotographer from Spain, Jacint Roger noticed something interesting in the images, an ice chunk traveling with 67P. He created a gif from the images which focused on the icy companion.

The images obtained were from two months after perihelion in the month of August 2015. 67P was basking in full sunlight at that time. The comet was inside dust as the heat of the Sun released comet gases in space which also carried dust with it. Along with dust, the ice chunk was also released from the comet in this time. The ice chunk is visible as the images focus on the nucleus of the comet. Less than 4 meters in diameter it is called Churymoon, a term coined by Julia Marín-Yaseli de la Parra, Ph.D. and ESA Researcher on Rosetta mission.

The images used by Jacint Roger are from OSIRIS instrument of Rosetta. It had a wide-angle camera for mapping the gas and dust near the comet and a Narrow-Angle Camera for mapping the nucleus of the comet in a high-resolution scale. Rosetta was at a distance of 400 kilometers from the center of the comet when the images were captured by the NAC. After leaving the comet, Churymoon spent the first 12 hours at a distance between 2.4km and 3.9km from the center of the comet in an orbital path. Then it went through the coma whose brightness made it hard to view it. It was again visible after emerging from the coma and its path was confirmed until 23rd October 2015.

Rosetta’s mission also included a study of the debris which was ejected from the planet. Churymoon is possibly the largest debris detected which will be further studied by researchers. It also had to watch the comet moving through perihelion. It took ten years for traveling to 67P/G-C. Earlier comets were only considered as dirty ice chunks moving through space. But Rosetta revealed the complexity of the comet in a detailed way. 67P is all possibility might be the result of a comet collision.

Eberhard Grün, a scientist working on Rosetta said that comets such as 67P/G-C are geographically complex worlds where several processes are involved in creating the comet’s surface and activity.

ExoMars prototype rover

Radio science instrument for ExoMars 2020 mission ready for the Red Planet

ESA’s Lander Radioscience experiment (LaRa) for ExoMars Mission 2020 has completed its testing in conditions similar to Mars and will be carried to Russia for its acceptance review, followed by integration onto the Kazachok Surface Platform.

At about 8 x 8 x 20 cm and a trio of antennas, LaRa is a high-operating transponder maintaining an extremely stable direct radio-frequency link between Earth and Mars for a full Martian year. LaRa has been planned by the Royal Observatory of Belgium, developed through ESA’s PRODEX programme and funded by the Belgian Space Policy Office.

The latest testing of LaRa was done in ESA’s Mechanical Systems Laboratory (MSL) at the Agency’s ESTEC technical heart in Noordwijk, the Netherlands. It is able to perform space simulation test, serving spacecrafts, mini-satellites, subsystems.

After vibration testing on an MSL shaker for simulating harsh launch conditions, atmosphere re-entry, landing on Mars, LaRa was placed inside a thermal vacuum chamber for functional testing in hot and cold conditions. At first, it was kept in high vacuum to outgas fumes which could pose problems in space. Then it faced simulated Martian conditions, with 6 millibars of carbon dioxide and varying temperature to test its performance. The electronic box of LaRa will be kept warm by the heater of ExoMars lander.

Developed in collaboration between ESA and Université Catholique de Louvain, the unique antenna will be installed outside the thermally controlled conditions to withstand extreme temperature as cold as -90°C and as hot as 10°C. Engineers advanced to remove sensors and cables fitted for testing after opening the thermal chamber before placing the instrument along with the antennas into sterile bags to avoid microbial infection.

Lieven Thomassen of LaRa prime contractor Antwerp Space said that the interior is made of four layers of circuit board which has been cleaned fully. It is completely sealed, with only 2mm diameter hole to avoid excess pressure in space.

LaRa is one of the two ESA instruments on the ExoMars Surface Platform. The first role of the platform is to make sure that itself and the Rosalind Franklin ExoMars rover, also made by ESA safely lands on the Oxia Planum lowlands in Mars. Then Kazachok will be running 13 experiment packages aboard. LaRa will be receiving X-band radio signal from Earth which will be relayed back again. By measuring the small Doppler shifts in this two-way signal, scientists will identify small periodic shifts in the position of Surface Platform as time passes.

Véronique Dehant of the Royal Observatory Belgium, the instrument’s principal investigator said that this will disclose information of planet’s internal structure, accurate calculation of its rotation and orientation and variation in angular momentum due to mass redistribution such as seasonal transfer of mass in carbon dioxide when a portion of the atmosphere freezes. The main challenge is to maintain the highly stable direct radio link in the planned operating schedule of LaRa, that is two sessions of an hour each per week, especially when Mars is at a maximum distance of 401 million km from Earth.

ESA microwave engineer Václav Valenta, manager of the LaRa project said that they will be using huge 70m antennas of Deep Space Network of NASA for transmitting X-band radio signal towards Mars and to pick up a delayed replica with as low as 5W of radio power generated by LaRa.

On Mars, LaRa will need enough sensitivity to detect very low radio signals. When Earth and Mars approach closer, the Estrack ground stations of Europe will close the link with LaRa. This was successfully tested in the radio frequency compatibility tests in ESOC mission control center in Darmstadt, Germany.

The atmosphere of Mars is a complicating factor. It enables convection for carrying away the waste heat. Though thinner than the atmosphere of Earth, radiofrequency operation leaves a risk of corona effects. Václav said that LaRa was formerly subjected to ESA’s High Power Radio Frequency Laboratory to remove corona risk which is ionization of local gases leading to adverse lightning-like discharge.

It also was tested inside the Maxwell chamber of ESTEC for electromagnetic compatibility to check that all the elements work properly. For verifying the robustness of LaRa against mechanical shocks due to the carrier module separation, a shock model was developed and tested at ESTEC Test Centre. After testing was completed, it was moved to ESA’s Metrology Laboratory for accurate measurements of its surface flatness for perfect fit and thermal contact with its lander interface to maintain a proper operational temperature.

After that, it will be moved to the Space Research Institute of the Russian Academy of Sciences, IKI for final approval testing followed by full assembly-level testing at Cannes in France. Václav said that the LaRa team worked very hard as actual developments for the flight model started a year late. ExoMars 2020 will be launched by the Russian Proton launcher from Baikonur, Kazakhstan on July 2020.

NASA Curiosity Rover at Gale Crater Mars Illustration

Traces of groundwater system found on Mars

Scientists in Geneva have declared, lately, that they have perceived the first ever evidence of an ancient groundwater system consisting of interconnected lakes on Mars. These interconnected lakes lay deep beneath the planet’s surface, five of which may have minerals vital for survival.

Although Mars appears to be a sterile land, its surface shows potent signs that once there were large quantities of water existing on the planet.

Researches and researchers have said that the history of water on Mars has been a complicated topic, and is intricately associated with understanding whether or not life ever arose there – and, if so, where, when, and how it did so.

The recent study, which was earlier predicted by models, says that: “Early Mars was a watery world, but as the planet’s climate changed, this water retreated below the surface to form pools and groundwater“.

The lead author Francesco Salese of Utrecht University, further added – “We traced this water in our study, as its scale and role is a matter of debate, and we found the first geological evidence of a planet-wide groundwater system on Mars”.

Salese and his colleagues explored 24 deep, enclosed craters in the northern hemisphere of Mars, with floors lying roughly 4000 meters below Martian ‘sea level’ (a level that, given the planet’s lack of seas, is arbitrarily defined on Mars based on elevation and atmospheric pressure).

Global Groundwater

How Mars Express gathered evidence for groundwater on Mars. (Source: NASA/JPL-CALTECH/MSSS; DIAGRAM ADAPTED FROM F. SALESE ET AL. (2019))

They found features on the floors of these craters that could only have formed in the presence of water. Many craters contain multiple features, all at depths of 4000 to 4500 meters – indicating that these craters once contained pools and flows of water that transformed and diminished over time.

These features include channels etched into crater walls, valleys carved out by sapping groundwater, dark, curved deltas thought to have formed as water levels rose and fell ridged terraces within crater walls formed by standing water, and fan-shaped deposits of sediment associated with flowing water. The water level aligns with the proposed shorelines of a putative Martian ocean thought to have existed on Mars between three and four billion years ago.

“We think that this ocean may have connected to a system of underground lakes that spread across the entire planet,” adds co-author Gian Gabriele Ori, director of the Università D’Annunzio’s International Research School of Planetary Sciences, Italy.

“These lakes would have existed around 3.5 billion years ago, so may have been contemporaries of a Martian ocean.”

Exploring these sites reveal the conditions suitable for finding past life, and are therefore highly relevant to astrobiological missions such as ExoMars – a joint ESA and Roscosmos endeavor. While the ExoMars Trace Gas Orbiter is already studying Mars from above, the next mission will launch next year.

ExoMars Trace Gas Orbiter Model at ESOC

ExoMars Trace Gas Orbiter, seen at ESOC in Darmstadt, Germany (Source: wikimedia.org)

Mars Express was launched on 2 June 2003 and reached 15 years in space in 2018. The studies and researches conducted lately, have been proved to be fruitful as we have got some really good results from them.