There is an abundance of evidence, provided to us by NASA’s many missions, that there is water on Mars. Most of this is ice water, but there are tiny amounts in the Martian atmosphere and recently there has even been evidence that liquid water is found on the surface. But how did we come to know this, and what is the significance?
Before NASA and before the age of space technology, there have been many cultures and civilisations that had observed the night sky. With the development of the telescope in the 17th century, many people observed and recorded their observations of the red planet.
In 1877 an Italian astronomer, Giovanni Schiaparelli, studied Mars through his telescope and wrote about “canali”, which means channels in Italian. The word was translated as “canals” in English, and here started the Canal Craze. Popularised by Percival Lowell, many people began to believe that there were intelligent beings on Mars that had created this network of canals. Other astronomers such as William Herschel saw darker regions of the planet to be oceans and William Whewell concluded Mars had “oceans of green and lands of red”. By the start of the 20th century, it was widely accepted that Mars was colder and drier than Earth and out went the theory of oceans.
Mariner 9 – First spacecraft to orbit Mars, 1971
The 20th century saw the rise in technology we could use to categorically analyse the Martian atmosphere and its surface instead of using the mere eye. Mariner 9, an orbiter, was the first to collect images that suggested water in the form of ancient relics of riverbeds and canyons, giving us evidence of flowing water once in Mars’ ancient history. The image on the left is of a meander in Scamander Vallis, the shape suggests that water once flowed on this red planet. The image on the right shows Valles Marineris in the centre, considered the Grand Canyon of Mars. It was taken by a Viking orbiter and named after Mariner 9 for its discovery and it is thought that water also once filled this gigantic structure.
Viking – first project to successfully land spacecraft on the surface of Mars, 1975
After the Mariner series came the Viking Program. The Viking Program had two orbiters and two landers. It became famous in 1976 as the first mission to land two spacecrafts safely on another planet.
The Viking project solidified what NASA found with the previous Mariner series, with over 16,000 high-resolution pictures. We found in summer, water vapour is relatively abundant in the far north, and that in the northern polar cap, ice water is visible on the surface. One of the main goals of Viking was to undertake biological experiments for the presence of life. These tests unfortunately came back negative but the data Viking landers collected on the composition of Martian soil, some of which suggest low levels of chemically bound water, left astronomers in awe with a wealth of further questions.
Mars Odyssey, 2001
Mars Odyssey is an orbiter still in orbit around Mars. Using Gamma Ray Spectroscopy, we could map out the chemical distribution of the Martian surface. The large quantities of hydrogen distribution lead scientists to believe that there is large amounts of water ice locked under the surface of Mars.
Mars Reconaissance Orbiter, 2015
Using Imaging Spectroscopy, researchers found evidence of hydrated minerals and salts that advance down slopes in streaks, called recurring slope lineae, found near the equator. Scientists monitored two sites at the Grand Canyon of Mars, with the dark streaks appearing on both northern and southern sides. The north facing slopes are active during the time the sun is reaching them more, and vice versa for the southern slopes. An explanation for this is they are active when the temperature is rises. As hydrated salts lower the freezing point of water, it is possible that liquid water (albeit not pure) is present in the cold temperatures of Mars.
When considering NASA’s Journey to Mars and their plan to send humans to the planet in the 2030’s, finding water near the equator is monumental. Ice water found at high latitudes would require astronauts to deal with the incredibly low temperatures and even if they could, whether or not this water is easily accessible is another question. By learning more about this water found at the equator, it opens up the possibility of it being used as a resource for future missions.
Chemical analysis needs to be done of these slope recurring lineae and that would require the use of landers and rovers. This is unlikely however since current rovers won’t be able to climb up steep slopes safely in order to carry out the necessary tests. Also since these areas are now considered special regions, extra precautions must be taken to avoid contamination.
The question of whether or not life may currently exist is still not closer to being answered. There is evidence that liquid water was present on Mars in its ancient history, but we’re still to find where all this water went. Did Mars lose its water to space? How did so much water end up subsurface?
*All information was received from NASA’s official website(s)