Water on Mars has been an on-going topic throughout planetary research and only recently has new evidence shown that it could be true in present day conditions. As technology advances, our knowledge on space exploration does also and technologies such as HiRISE, Curiosity and MRO have allowed us to gain an understanding of Mars that wouldn’t have been possible years ago. This report aims to bring together a small range of information about water on Mars from scientific research in an attempt to help the reader understand the progress. RSL, Curiosity, and mud cracks are few of the covered topics that have led scientists to believe liquid water is available on Mars and ultimately the potential for extra-terrestrial life.
It was in 1659, when Dutch scientist Christian Huygens (1629-95), first identified a large dark blemish on the planet Mars, which has now been identified as Syrtis Major – a low-relief shield volcano (Hiesinger and Head, 2004). By recording series of data and photographic evidence over numerous weeks of changes in the spot, he was able to come to the conclusion that: a day on Mars was similar to that on Earth and Cassini (1625-1712) confirmed it was 37 minutes longer in 1666. A century later, William Herschel was able to prove that Mars rotated at an angle of approximately 25°, much similar to Earth (Crawford, 2013), indicating that like Earth, Mars had seasons as it orbited the Sun leading scientists to believe that they shared similar characteristics; one being Mars’ ability to retain liquid water and possibly sustain life.
Consequently, this report will gather the past and present data regarding water on Mars and highlight the geological and geochemical evidence that suggests this idea.
In order to write this report, secondary sources of information that were used were websites (NASA, Space.com) for up-to-date material, scientific journals written by specialists in the subject and news articles e.g. The New York. To ensure an accurate representation of known information, reliable sources were chosen such as those from public sector organisations as the data and material provided is regularly updated and government controlled ensuring reliability.
Previous research led scientists to believe that liquid water was once abundant on the Martian planet as they discovered physical and chemical evidence through images taken by the Mars Reconnaissance Orbiter (Redd, 2015). This new evidence also allowed verification of geological formations such as RSL, mud cracks and ancient waterbeds and chemical indications of hydrated salt deposits.
Recurring Slope Lineae
On September 28, 2015, it was announced that an imaging spectrometer on MRO had detected images of downhill streaks (Runyon and Ojha, 2014) on the surface named Recurring Slope Lineae. (NASA, 2015). RSL are narrow surface markings, up to 5m wide, that are typically darker than the surrounding ground and were previously reported in southern middle latitudes (McEwen et al. 2013) but now known to be plentiful in equatorial areas such as Valles Marineris. These linear patterns seemed to appear during the warmer spring and summer seasons (Choi, 2011) and are believed to be the remnants of flowing liquid water. This suggests that water is present, as the rock remains the same colour, with a change in brightness as when water is in contact with sand on Earth.
Mud cracks and hydrated minerals
With new technologies such as HiRISE, scientists are able to obtain more information than ever before on the surface of Mars. Images of polygonal mud cracks were detected on the surface similar to those found on riverbeds here on Earth: this suggests large expanses of water such as oceans. The cracks were initially thought to be the result of thermal contractions in permafrost; however, the size was far too large to have been caused by this at 70-140 meters in diameter (Space.com, 2009), whereas thermal contractions are usually approximately 65 meters. Furthermore, remains of hydrated salts were found which, is a clear indication of the previous existence of water on Mars.
Perchlorates are hydrated minerals left behind after expanses of briny water dry up (Chang, 2015). It was found that the minerals on Mars were made up of mostly magnesium perchlorate, magnesium chlorate and sodium chlorate (CRISM, 2015). Curiosity rover picked up traces of perchlorates in Gale Crater in 2012 (Jet Propulsion Laboratory, NASA, n.d.) previously and these perchlorates have been identified to resist the freezing of liquids at temperatures as low as -70°C. The presence of perchlorates has positive and negative impacts: it is a good thing as it suggests evidence of water and has been discovered to be a source of oxygen but it also has consequences as the percentage on Mars is between 0.5-1% which is toxic for astronauts (Carrier and Kounaves, 2015).
From the research carried out, it is gathered that evidence of pre-existing liquid water is unmistakable and using newly found evidence (RSL); it could suggest that the water runs on Mars even today. The recurring slope lineae have no other explanation as to what caused them and without knowing the topography of the planet, as even HiRISE isn’t able to detect it, it is a good hypothesis to suggest liquid water as the creator. The mud cracks are clear evidence of former lakes and oceans and mimic those on Earth with similar characteristics and features. The perchlorates can be interpreted in different ways but in a broader context, they could only have formed by liquid transportation of salts i.e. briny liquid flowing water. These factors all point to remnants of water on Mars.
This information gives us an insight on the planet and helps us determine whether or not there is life on mars. It is a fact that water is needed to sustain life on a planet and if found on Mars, scientists believe it could link to life on the planet.
However, the RSL have yet to prove that it is actual flowing water as it would either boil rapidly or absorb into the soil and freeze, so one would have to witness it happening to undoubtedly say that it was liquid. Currently, only the evidence of water being present has been suggested and no actual water found – be this because of technology not being advanced enough to apprehend this data or simply because it no longer exists. It is almost certain that a billion years ago water on Mars was plentiful as seen from ancient lakes and waterbeds but whether there remains liquid water today is the true question.
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