Category: Science

I’m not just talking about you and I, or the family or whatever. I mean us. The human race.

Look at what happened at 05:21GMT this morning. We deposited a new robot on the surface of Mars.

OK, so far so “heard it before”. But this is the largest machine we’ve placed there yet, weighing over a ton. And then you get into how we even got the thing there. It wasn’t “dropped” – it was lowered gently.

It takes about 14 minutes for radio signals sent from Mars to reach Earth, so there was no real way this could be done by some guy piloting it with a joystick. The entire thing was automatic.

In the 7 minutes it takes from the craft hitting the Martian atmosphere, it had to be slowed right down to near-stationary and its payload deposited on the surface. All without someone directly controlling it, or being able to override anything if anything happened and in an environment we can’t fully test on Earth.

This video on NASA’s website covers the details in 5 minutes, but briefly:

First off, the craft has to be guided as it ploughs through the upper atmosphere to ensure it lands where it’s supposed to. The calculations involved in this are incredible, ensuring that it starts to enter the atmosphere at the right time based on forecasting the position of the planet in relation to ours at the time we launched the original rocket from Earth so that we knew what the craft would be aiming at. The module will be jostled during its travel as it heats up to incredible temperatures while the on-board computers keep it on target using directional rockets.

The atmosphere on Mars is 100 times “thinner” than that of Earth. That mean there’s enough that the craft has to take it into account while it descends, but not enough to help with slowing the thing down to as large an extent as it would here. As a result, the largest parachute NASA have ever fabricated is put into use, slowing the craft from 1000mph to something more manageable. This parachute needs to withstand 65000lbs (29500kg) or force, yet only weighs 100lbs (45kg) itself.

Once the parachute is deployed, the heatshield on the base of the unit “pops” off exposing RADAR equipment which takes speed and distance readings for the next stage of the landing.

The parachute does a great job, but only slows the unit down to 200mph. Still far too fast for a safe landing. Instead, rockets will be used to slow its descent over the final stages. The parachute is detached and the rockets first of all push the main unit sideways, away from it to ensure that the two don’t become entangled.

While still ensuring the lander is travelling towards the designated site, the rockets further slow the descent to something more manageable.

However, we have one final problem. Mars is covered in very fine dust. If the rockets were used to take the actual exploratory unit right down to the surface, so much dust would be kicked up that visibility would be nill and there would be a significant risk of the mechanics and electronics being damages.

This is where it gets really cool.

At 20m above the surface, safe from kicking up that cloud, the rocket unit hovers. Then lowers the actual wheeled exploratory unit on a “skycrane”, winching it down to the surface at a slow speed. It allows it to touch down and settle, then disconnects and flies off to crash elsewhere so that it won’t get in the way of the planned examination of the planet’s surface.

All of this automated control is the result of 500,000 lines of computer code.

We did this. Human beings did this.

We foresaw every possible problem. We built rockets and units and mechanics and a host of other devices and bundled them into a package the size of a small truck. We then shoved a means of generating power, sensors, RADAR, propulsion and more into a unit the size of a small hatchback car. And then we flung the whole lot into space, managing to land it on a pre-determined spot the size of our back garden a distance of 140 million miles (250 million km) away.

We worked all of those final stage problems out to the extent that we could give instructions to a computer to handle everything. 500,000 lines of code sounds like a lot, but when you consider all the calculations and instructions necessary to hit the levels of precision necessary it’s paltry.

In a week that also sees the Olympics going on, the geek in me is overjoyed to see science grabbing the headlines for a few hours. I’m convinced the landing was scheduled for the early hours so it wouldn’t have to compete with any of the events at the Games!

Between both events, they demonstrate the pinnacles of human achievement both physical and intellectual.

I say again. We – Are – Awesome.

As a race, we are capable of so much. We waste a lot of our potential or expend it on stupid things like wars, but when we actually put the effort in these are the things of which we are capable. To be able to point at the staff of NASA, or the athletes breaking record after record, it gives our children something to go “wow” at – and hopefully the desire to emulate and exceed these achievements.

[Please excuse any glaring inaccuracies in the numbers in this post – I’ve used very rough figures and averages for some of them, and any cockups will be mine]

Related articles

• NASA rover successfully lowered to surface of Mars – CNET (news.cnet.com)
• Curiosity Lands on Mars: A Primer for 7 Minutes of Terror (theatlantic.com)
• Touchdown! Nasa’s Curiosity rover survives 13000mph plunge onto Martian surface – Daily Mail (dailymail.co.uk)
• Seven Minutes of Terror: Engineering the Mars Rover’s Impossible Landing (bigthink.com)
• NASA Rover Lands After “Seven Minutes of Terror” (voanews.com)