At the beginning of the 21st century, the Mars Exploration Program Analysis Group (MEPAG) under the National Aeronautics and Space Administration (NASA) once proposed that the scientific direction of NASA’s Mars exploration is Martian life, Martian geology, Martian climate, and preparations for manned landing on Mars. . Among these scientific research goals, water is the most basic requirement for sustaining life, and plays an important role in understanding the evolution of the Martian climate and the formation process of Martian geology. In the future, manned landings on Mars will also require the use of water on Mars. Resources. It can be said that “water” is the focus of these scientific research goals, and “tracking the traces of water” became one of the important strategic goals of NASA’s Mars exploration at that time.
At the end of September 2015, NASA announced the heavy news that “The mystery of Mars has been solved.” Although it is not a “Martian” discovery, it does have enough weight-there is spectral evidence that there is now liquid water on Mars. If this is the case, maybe the Mark in “The Martian” does not need to use rocket fuel to make water, and he does not need to worry about “the coffee I drink today is derived from the coffee I drank yesterday.”
The guitarist’s transformation has an “adventure”
So, what kind of evidence is it that makes scientists in the field of Mars exploration so inspiring? Let us first talk about its discoverer—Lujendra Ojha, an unknown doctoral student at Georgia Tech University in the United States. This landmark discovery in the history of human exploration of Mars originated from this Nepalese man-as a former rock band guitarist, his style of painting has changed and he has become a university hegemon who influences human space journey. It is also amazing .
So how did Oga make this major discovery? In 2011, Ou Jia started to study Mars when he was still undergraduate. At the right time, the data he used came from the high-resolution camera HiRISE mounted on the Mars Reconnaissance Orbiter MRO: This camera can see objects up to 1 meter in size on Mars and can perform fine imaging on the surface of Mars. When the MRO spacecraft orbits Mars, it can also pass through the same location multiple times, which allows Oga to compare the changes in the same location after a year, a month, or even a day. With the help of the HiRISE camera, Ou Jia saw a “living” Mars.
When Olga looked at a large number of remote sensing photos of Mars, he unexpectedly discovered that on the steep slopes of certain craters in the mid-latitudes of the southern hemisphere of Mars, there were some “strange things”-some dark lines, about a few meters in width and length It can reach several hundred meters; what’s even stranger is that these lines appear and spread whenever Mars arrives in summer, and then gradually disappear in winter. It’s as if something flows down after it melts! This is an extremely exciting idea! Because, the most likely to appear in those dark lines is the source of life—water.
Of course, as a well-trained student master, Ou Jia would not make such a hasty assertion that this is water. He gave these lines a name, “temporary slope strip” (TSL, later renamed “seasonal slope pattern” by academic circles, abbreviated RSL). Next, what Ou Jia has to do is to find evidence and prove convincingly that this is the liquid water on the surface of Mars that people have always been looking for.
Seasonal patterns Daqi Di slope
if it really is water – is the primary problem faced by Olga: explain how water flows on Mars, there could be? It turns out that the distance between Mars and the sun is about 50% farther than the distance between the sun and the earth, and it receives less sunlight from the sun. Because of its low mass and thin atmosphere, the surface temperature of Mars is much lower than that of the earth. Most of the time, the temperature in most areas on Mars is equivalent to that of the South Pole of the Earth, and only during a short period of time during the summer of Mars, the temperature near its equator can reach above 0°C. However, the seasonal slope pattern that Oujia sees will continue to exist for a while when the surface temperature of Mars has dropped below 0°C. If it is really water, how can it remain liquid below the freezing point?
There is a possibility: the water is brine, that is, water with high salinity. We know that the freezing point of water with salt will decrease. Laboratory studies have shown that the freezing point can be reduced to minus 40°C by adding an aqueous solution of ammonium salt. If so, it can explain the existence of liquid water on Mars.
Therefore, Oujia used the spectral equipment CRISM carried by MRO to study the areas where seasonal slope patterns were found on the surface of Mars. The results show that according to the spectral data of these regions detected by CRISM, the spectral lines are drawn, in which the downwardly concave “absorption peaks” are basically consistent with the spectra of hydrated salt substances (perchlorate solutions). It can be inferred from this that there is liquid water with high salinity in these seasonally sloped areas on Mars. On this basis, according to the changes in the hydrated salt content monitored by the spectrum in the seasonal slope, it can be determined that these seasonal slopes are formed by the action of water current.
This also explains the source of water to a certain extent—perchlorate solids are often used as desiccants on the earth. It can absorb trace water vapor in the Martian atmosphere, fix and enrich it; and when the temperature rises , The water can be melted and released. Of course, because the Martian atmosphere contains very little water vapor, some people believe that the source of water is groundwater buried in the crust when Mars was in the ice age.
Looking for water in order to continue to “search for life signals”
In fact, this is not the first time humans have detected evidence of the existence of water on Mars. In places like Mars Mariner Valley, people have already found traces of ancient flowing water. The Phoenix probe, which landed on the north pole of Mars, also shoveled down to dig out a piece of water ice. However, as evidence of the existence of liquid water on Mars “now” for the first time, Ou Jia has done a great job. Because liquid water is the cradle of life. Seasonal liquid water still exists on Mars. This fact greatly inspired our human beings to explore the dream of possible “Martian life”.
Liquid water is a hotbed of life, and it has always been an asset that people on earth are proud of. However, over the years, the information sent back to the solar system probes has made us believe more and more that liquid water is not exclusive to the earth. The discovery of liquid water on terrestrial planets has also greatly inspired people to search for life signals in space. “Enthusiasm.
In Europa Europa, scientists believe that under the ice surface of 10-30 kilometers thick, due to the heating of geological activities, there is a subglacial ocean as deep as 100 kilometers; and its icy surface appears as The red-brown lines that resemble modern art and wantonly vertical and horizontal are also believed to be caused by the heating of these geological activities. If it is true, Europa contains twice as much liquid water as the Earth’s oceans. In this dark and vast ocean, it is possible to produce organisms that use geothermal heat instead of solar energy to sustain life. In 2013, the movie “Europa Report” starring Daniel Wu told the sci-fi story of an astronaut who went to Europa and encountered large marine creatures and wiped out the entire army.
In Enceladus, Saturn’s huge tidal force heats the ice and produces a global subglacial ocean that may not be inferior to Europa; Europa, the largest satellite of the solar system, is also suspected of being warm and salty due to its auroral activity. Ocean under ice.
If the attributive “liquid” is removed, the existence of water in the solar system is even more common: in the polar regions of the moon, in the crater of Ceres, in the vast glacial mountains of Pluto, and even on the hot Mercury near the sun, we all Traces of solid water have been found. The same is true in the solar system, and the abundance of water in the universe may far exceed our imagination. How many warm, humid and vibrant worlds will there be in that trillion exoplanet system?
From the earth to Mars, from Mars to the endless deep space, I wonder how many miracles of the universe and life are waiting for us to explore!