In Sight

Originally published in the Informanté newspaper on Thursday, 22 November, 2018.

In about 4 days, a mission that was started on 5 May 2018 will reach its critical phase. On 26 November 2018, NASA’s newest Mars probe is set to enter the Martian atmosphere, and begin its ‘seven minutes of terror’, as it enters the atmospheric entry, descent and landing phase of the mission. For it to successfully land on Mars, it needs to hit the atmosphere at the exact right angle.

During these seven minutes, the InSight probe will be travelling at almost 21 000 km/h as it enters the atmosphere. Its heat shield will increase in temperature to about 1 370 degrees Celsius, as the friction with the atmosphere brakes the spacecraft. After about 3 to 5 minutes, when it has slowed enough for the parachute to deploy. Thirty seconds after deployment, the heat shield will be jettisoned, and the onboard radar will be activated. This allows the craft to measure its speed and height above Mars. 

Then, 40 seconds before touchdown, it will jettison the parachute as well, and start freefalling, spinning away from the parachute and heat shield. Finally, just before it hits the ground, it will fire its rocket thrusters in preparation for contact and slow its speed. In those seven minutes, it would have reduced its speed from 21 000 km/h to just 8km/h as it lands on the planet, and thus successfully increasing the active robot population on Mars to two.

Landing on Mars is hard, as only 40% of all missions sent to the red planet have been successful. All of these have been by NASA, and their recent missions have been quite successful. After the first Sojourner rover lasted just under three months on Mars’ surface, the next few far exceeded their operational lifetimes. In particular, the Spirit rover was planned to be operational for only 90 Martian solar days but lasted 2 269 days until contact was lost on 22 March 2010, while the Opportunity rover mission was also planned for 90 Martian solar days, and lasted 5 613 days before entering hibernation after a dust storm on 10 June 2018. 

As such, the Curiosity rover was designed for an operational lifetime of 668 Martian solar days and is currently on day 2237 of its mission – currently the only robot active on Mars. InSight, however, is something different, as its mission is not to explore the surface of Mars, but rather the interior of Mars. Its name is a backronym for INterior exploration using Seismic Investigations, Geodesy and Heat Transport (INSIGHT) which describes the instruments this Mars lander carries. 

Insight will take measurements of the inside of Mars, via seismology, heat flow and radio science. Why? Well, to tell us more about how planets were formed. While we’ve had ample opportunity to study our own planet, we’ve had no readings of the interior of other planets to compare it to. Mars and Earth seem like they were close to identical at one point in the past – about 3 to 4 billion years ago. Both were warm, humid, and covered in thick atmospheres. But in the time since then, these two took different paths. 

Essentially, this mission is trying to examine why Mars essentially stopped changing, while the Earth never stopped. The Earth developed tectonic plates that converge across the surface of the planet and allow new crust to emerge from the inside of the planet. This new crust brings along more than rock – it releases some gases which are vital to life, such as water, carbon dioxide and methane. Mars, however, does not seem to have tectonic plates, and InSight seeks to try and measure marsquakes for the first time to try and study its interior. Each marsquake will set off seismic waves that can be studied to illuminate the structure of Mars for the first time.

Rocky planets also trap heat in their interior, either at formation, or via radioactive decay of elements over time. This heat could have been responsible for Mars’ early conditions, and its evolution into the red planet we know now. For this reason, InSight also contains a heat probe that will be drilled 5 meters into the planet, to try and discover how this heat shaped the planet. 

Heat also keeps a planet’s core molten, and as its metallic elements flow, they generate electric currents. On Earth, this results in a magnetic field around the planet, which not only aided us in navigating the planet by allowing equipment such as compasses to work, but also shields the planet from certain types of radiation. Mars, however, had a strong magnetic field once, but it seems to have dissipated. InSight therefore contains a radio experiment to detect the wobble of Mars’ axis, and via that, to learn more about the planet’s core, which in turn provide clues as to why its magnetic field disappeared. 

So with the dreaded ‘seven minutes of terror’ in sight, hopes are high that this mission will succeed. InSight could provide much insight not only into the early formation of our own planet, but also into what features to look for in extrasolar planets that makes them much more compatible to supporting life. The insights gained from this mission could dwarf those from prior missions, and we might finally have the first clues to point us towards extra-terrestrial life in sight.

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