Mars Surprise! --Atmosphere is Supersaturated with Water Vapor

 

Startling new analysis of data sent back by the SPICAM spectrometer on board ESA's Mars Express spacecraft has revealed for the first time that the planet's atmosphere is supersaturated with water vapor. This surprising discovery has major implications for understanding the Martian water cycle and the historical evolution of the atmosphere.

In the image above colorful water clouds are visible just after sunrise in and around a maze of canyons known as Noctis Labyrinthus (the labyrinth of the night). Scientists don't yet know, however, why these clouds formed, and why some stick to the canyons. One exciting possibility is that water sometimes condenses in shaded regions of the canyons, only to evaporate into clouds when exposed to the morning Sun. Water in any form on the Martian surface might be important to sustaining life and possible future human exploration. Viking Orbiter 1, which visited Mars in 1976, took the above picture. The region shown is about 100 kilometers across.

Although numerous spacecraft have visited Mars over the past half a century, very few direct measurements of the vertical structure of the planet's atmosphere have been made. Since most of the spacecraft instruments have looked down at the surface, it has only been possible to infer the horizontal distribution of gases in the atmosphere, leaving the question of how water vapor is being mixed into the atmosphere almost unexplored.

This lack of direct measurements has meant that descriptions of the vertical distribution of water vapor – a key factor in the study of Mars' hydrological cycle – has generally been based upon global climate models.
This gap in the data has now been addressed by the SPICAM (Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars) imaging spectrometer on Mars Express.

The instrument can be used in occultation mode, when it studies light from the Sun that has passed through the planet's atmosphere just after sunrise or before sunset. The measurements can then be analysed to generate vertical concentration profiles for several atmospheric constituents, including water vapor.

The new results, based on SPICAM data obtained during the northern spring and summer, indicate that the vertical distribution of water vapor in the Martian atmosphere is very different from previous assumptions.

An international team led by Luca Maltagliati of the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) in Guyancourt, France, describe SPICAM observations at infrared wavelengths that for the first time provide evidence for the existence of supersaturated water vapor on Mars.

The atmosphere of Mars holds 10,000 times less water vapor than that of Earth. However, water vapor is a very dynamic trace gas, and one of the most seasonally variable atmospheric constituents on Mars.
Under normal conditions on Earth, water vapor condenses around tiny dust or aerosol particles or salts when the atmospheric temperature drops below a certain "dew point". The atmosphere is then said to be "saturated", since it cannot hold any more moisture at that temperature and pressure. Any water vapor in excess of the "dew point" will normally condense to form droplets or icy crystals.

However, supersaturation may occur when some of the water vapor remains in the atmosphere, instead of condensing or freezing. When condensation nuclei (assumed to be dust aerosols on Mars) are too rare, condensation is impeded, leaving substantial amounts of excess vapor.

Until now, it was generally assumed that such supersaturation cannot exist in the cold Martian atmosphere: any water vapour in excess of saturation was expected to be converted immediately into ice. However, the SPICAM data have revealed that supersaturation occurs frequently in the middle atmosphere – at altitudes of up to 50 km above the surface – during the aphelion season, the period when Mars is near its farthest point from the Sun.

Extremely high levels of supersaturation were found on Mars, up to 10 times greater than those found on Earth. Clearly, there is much more water vapor in the upper Martian atmosphere than anyone ever imagined. It seems that previous models have greatly underestimated the quantities of water vapour at heights of 20–50 km, with as much as 10 to 100 times more water than expected at this altitude.

"The vertical distribution of water vapor is a key factor in the study of Mars' hydrological cycle, and the old paradigm that it is mainly controlled by saturation physics now needs to be revised," said Luca Maltagliati. "Our finding has major implications for understanding the planet's global climate and the transport of water from one hemisphere to the other."

"The data suggest that much more water vapor is being carried high enough in the atmosphere to be affected by photodissociation," added Franck Montmessin, also from LATMOS, who is the Principal Investigator for SPICAM and a co-author of the paper.

"Solar radiation can split the water molecules into oxygen and hydrogen atoms, which can then escape into space. This has implications for the rate at which water has been lost from the planet and for the long-term evolution of the Martian surface and atmosphere."

The new paper analyzes SPICAM data obtained when the Martian atmosphere is relatively dust-free. The absence of dust enables the instrument to measure the vertical profile to within 10 km of the planet's surface. The supersaturation levels are likely to plummet in the southern summer, when dust storms inject large amounts of aerosols into the atmosphere, increasing the supply of condensation nuclei.

The Daily Galaxy via European Space Agency and science.com

Image credit: Credit: Viking Project, USGS, JPL, NASA

Comments

[Lewis Michael Rhinehart]

As a Photo Analyst for MARS (Mars Anomaly Research Society)I have known for nearly 3 years that Mars is a fully inhabited Planet, harboring abundant life. This "new discovery" is simply a trickle down of an established truth. LMR

[Denny]

Drip, drip, drip. People laughed when we said there is standing, liquid water on Mars, now NASA and ESA readily accept it. People still laugh when you tell them there is compelling evidence for vegetation on Mars. More complex life? Who knows but I guess we'll be waiting another 10 years for NASA or ESA to spill on these so called "new" discoveries.

I'm all for a robust scientific process but academia tends to hold things back for bragging rights. I think it has less to do with some dark government agenda and more to do with an arrogant and elitist base of aristocratic info hoarders. They ABSOLUTELY know things the general public does not and they are absolutely selfish for holding back. This planet desperately needs a profound, outside influence to change our course.

Maybe my kids will get the answers we've all had to wait so long to hear.

[Artor]

@Lewis Michael Rhinehart #1
Oh please, do tell! If you have credible evidence to support your statement, you could have a Nobel prize if you come forward with it. Why do you not have the prize? Because you have no credible evidence. Prove it, please.

[insomnia]

Please tell us more about this life on Mars. How do you explain the pictures showing barren wastelands?

[insomnia]

Please tell us more about this life on Mars. How do you explain the pictures showing barren wastelands?

[valentin rusu]

well if this pictures it was made in 1976 why do we see it now :| i dont get it ...are we gonna see pictures taken now in 34 years ??? and why ?if is life in space who cares i dont .if tomorrow someboby its gonna tell me oh they found life outside this planet how its that info gonna change my life ?its not at all maybe ill be a little happy but thats all .and even if its gonna be life on mars dosent have to be like here on earth but its ok .for those who dont beleive let me tell u something 400 years ago people knew that the earth its flat now we know its not but there NO LIFE ELSEWHERE right .

[tibor legyel]

i agree whit Mr.Rhinehart there is vegetation on Mars i saw a doc. about one of those rover missions in that film i could see the true colors of that planet briefly it appeared that the sky was blue not red there was green grass-like vegetation not red white rocks not red matter fact nothing was red now call me crazy but Mars the red planet is just some folk-story rather than the truth

[SB]

We all know that Mars is made of Cool Ranch Doritos and the cover up is to protect Doritos monopoly on the product. Where do you think NASA gets it's funding from.

[New era hats]

"The vertical distribution of water vapor is a key factor in the study of Mars' hydrological cycle,