Mars loses water to space during warm, stormy seasons

All kinds of geological formations on Mars, alluvial fans, dry lake beds and eroded river valleys, suggest the Red Planet once hosted an abundance of water. Today, the water is mostly gone. What's left is largely locked up in the planet's polar ice caps. Scientists have been trying to figure out where all the water went and how fast it disappeared. New research, published this week in the journal Science, suggests Mars' seasonality may have dictated the rate at which water vapor was able to escape from the atmosphere and into space. In addition to the water trapped in the Red Planet's ice caps, trace amounts of water vapor persist in the Martian atmosphere. If these tiny water crystals rise high enough into the atmosphere, they can dissipate into space. To better understand this mechanism of water loss, scientists used data collected by the NASA spacecraft ExoMars Trace Gas Orbiter to produce vertical distribution of water in the Martian atmosphere. "TGO uses solar occultation method," researcher Anna Fedorova, an astrophysicist at the Space Research Institute in Moscow, told UPI in an email. "The presence of water vapor and their amount are determined using the spectroscopic signatures near 1.38 micrometer [infrared bands] by the NIR/ACS spectrometer." In other words, TGO studies how sunlight is absorbed as it passes through the Martian atmosphere in order to detect the presence of H2O. "The results were obtained using the analysis of absorption features of H2O and CO2 gases," Fedorova said. "For each occultation we have the vertical profiles of H2O density and temperature from CO2."

Scientists surveyed the data for links between temperature and water distribution and found the Martian atmosphere became supersaturated during the warmest portions of its orbit. Their findings suggest water is more likely to rise into the upper atmosphere and escape to space when Mars is warmer and wetter.

Authors of the new study suspect their findings will improve a variety of Martian climate models.

"Saturation is one of the key points in the water transport on Mars," Fedorova told UPI. "The climate models have to be updated to predict such levels of supersaturation and perform the necessary adjustments."

So far, TGO has only collected water vapor distribution data during Mars warm season, so there isn't enough data to understand the full picture of seasonal water distribution on Mars.

"We don't have information that the cold aphelion season is less supersaturated," Fedorova said.

That data will be available soon, and when it is, scientists will have more analysis to do.

Bernese Mars camera CaSSIS sends first colour images from Mars

The Mars camera CaSSIS on the ExoMars Trace Gas Orbiter has returned its first colour images of the red planet. The camera system, which was developed at the University of Bern, is now ready for the start of its prime mission on April 28, 2018. The Colour and Stereo Surface Imaging System (CaSSIS) has been designed by an international team under guidance of the University of Bern. The Mars camera is on board of the ExoMars Trace Gas Orbiter, a European Space Agency/Roscosmos mission. It has now returned its first colour images from the orbit at Mars. The camera system was switched on 20 March and has been undergoing tests in preparation for the start of its prime mission on April 28, 2018. "We have had a couple of minor software issues in the initial test phase", says Principal Investigator, Nicolas Thomas from the Center of Space and Habitability (CSH), University of Bern in Switzerland, "but the instrument is actually in good health and ready to work." The UniBern team transmitted a completely new software version to the instrument at the start of test phase. "It is amazing that you can totally change the software in an instrument flying around Mars more than 100 million kilometres away and that it works", says Thomas.

Korolev crater (Mars)

Some of the first images have been spectacular. The example image is from the rim of an ice-filled crater called Korolev at high latitude in the northern hemisphere. The bright material is ice that can be seen on the rim of the crater (which is much larger than the image).

The picture has a resolution of just over 5 metres and outperforms the resolution of images from Hubble and other telescopes by far. In the future, CaSSIS should operate from slightly lower altitudes to give resolutions of less than 5 metres.

"We were really pleased to see how good this picture was given the lighting conditions", says Antoine Pommerol, a member of the CaSSIS science team at the CSH working on the calibration of the data. "It shows that CaSSIS can make a major contribution to studies of Mars's carbon dioxide and water cycles."

The image is a composite of three images in different colours that were taken almost simultaneously by CaSSIS on April 15, 2018. They were then assembled to produce this colour view.

"Our aim is to fully automate the image production process", says Thomas. "Once we achieve this, we can distribute the data to the community quickly for analysis."

Observing dynamics on Mars

CaSSIS is designed to complement the data acquired by the other payload on TGO and other Mars orbiters while also enhancing our knowledge of the surface of Mars. It is now known that Mars is more dynamic than previously thought.

Of particular interest to the 25-strong science team from 9 countries (incl. US and Russia) is the chance CaSSIS offers to study changes that occur over the day and over the Martian seasons. Further studies of recently discovered liquid water on the surface will be one of the main aims.