Mars. Image: Yaroslav Vakulenko/Shutterstock
Many missions will play a role in sending humans to Mars in a couple of decades, with MAVEN, in particular, a project of huge significance.
A lot can happen in a few years. In 2013, for example, Pope Benedict XVI became the first pope to resign in more than seven centuries.
Edward Snowden released a tranche of NSA documents into the media.
Croatia made the EU a 28-member club and, in space travel, China and India sent missions to the moon and Mars, respectively.
Since then, we’ve seen major political upheaval, immense scientific discovery through the likes of CRISPR, and satellites landing on comets.
Also since 2013, when NASA’s Mars Atmosphere and Volatile Evolution Mission (MAVEN) took off from Cape Canaveral, we’ve learned more and more about the Red Planet, through a growing number of projects.
For example, to find out what it’s like to live on Mars, several scientists have taken part in programmes looking at the living conditions of harsh desert environments.
The exact location of water on Mars may have been found, while the planning for a Martian outpost is well underway. Elsewhere, two men have successfully spent 365 consecutive days in space.
Now, more than 1,000 days in orbit around Mars, NASA has revealed MAVEN’s 10 most important discoveries, each playing a role in, one day, sending humans to one of our nearest neighbours.
- Imaging of the distribution of gaseous nitric oxide and ozone in the atmosphere showed that, surprisingly, there are dynamical processes of exchange of gas between the lower and upper atmosphere that are not understood at present.
- Some particles from the solar wind are able to penetrate unexpectedly deep into the upper atmosphere, rather than being diverted around the planet by the Martian ionosphere.
- MAVEN made the first direct observations of a layer of metal ions in the Martian ionosphere, resulting from incoming interplanetary dust hitting the atmosphere. This layer is always present, but was enhanced dramatically by the close passage to Mars of the Siding Spring comet in October 2014.
- MAVEN identified two new types of aurora. Unlike what we believe about most aurorae on Earth, these aurorae are unrelated to either a global or local magnetic field.
- These aurorae are caused by an influx of particles from the sun ejected by different types of solar storms. When particles from these storms hit the Martian atmosphere, they also can increase the rate of loss of gas to space by a factor of 10 or more.
- The interactions between the solar wind and the planet are unexpectedly complex. This happens due to the lack of an intrinsic Martian magnetic field and the occurrence of small regions of magnetised crust that can affect the incoming solar wind on local and regional scales. The magnetosphere that results from the interactions varies on short timescales and is remarkably ‘lumpy’ as a result.
- MAVEN observed the full seasonal variation of hydrogen in the upper atmosphere, confirming that it varies by a factor of 10 throughout the year. The source of the hydrogen, ultimately, is water in the lower atmosphere, broken apart into hydrogen and oxygen by sunlight.
- The mission also used measurements of the isotopes in the upper atmosphere to determine how much gas has been lost through time. These measurements suggest that two-thirds or more of the gas has been lost to space.
- MAVEN measured the rate at which the sun and the solar wind are stripping gas from the top of the atmosphere to space today, along with the details of the removal processes. Large amounts of gas have been lost to space through time.
- The Mars atmosphere has been stripped away by the sun and the solar wind over time, changing the climate from a warmer and wetter environment early in history to the cold, dry climate that we see today.
