Why Curiosity is a big deal

7 08 2012

With all the great press coverage of Curiosity, Cosmoboy’s family asked one unexpected question: “Why is there so much fuss about Curiosity when there have been a bunch of other Mars rovers?”

Although the “Countdown to Curiosity” articles detailed all of Curiosity’s amazing scientific apparatus, the articles didn’t really put into perspective how much better Curiosity is than the other Mars rovers (Sojourner, Spirit and Opportunity). So let’s right that wrong!

Sojourner landed way back in December 1996! I was actually studying for my PhD at the time, but there was a lot of great press coverage. It was perhaps the first space mission to really use the internet effectively. But for all the communication successes, Sojourner didn’t really have a great suite of scientific instruments. Given it’s small size, just a little over 10 kg and only 60 cm long, there wasn’t all that much space for scientific payloads. The key scientific instrument (other than cameras) was an Alpha Particle X-ray Spectrometer for determining the elements in rocks (Curiosity has a much more advanced one). But what many people remember about Sojourner was how slow it moved: it had a top speed of a little over 0.5 cm a second! But there again, this mission was put together on one tenth the budget of Curiosity.

The twin Spirit and Opportunity rovers came next, landing in January 2004. Like Sojourner, they both carried an APXS, but this time they came with more sophisticated spectrometers to make even better assessments of the precise elemental components of the Martian rocks and minerals. Much larger in size, at 185 kg and around 1.6 metres long, they were much more capable of carrying a heavy payload. They also had the advantage of a robotic arm so they could get in close and even abraid the surface of rocks to see what was lying underneath (the RAT tool!) But perhaps what everyone remembers about Spirit and Opportunity was their “Energizer Bunny” impressions – they just kept going and going! With it’s solar cells still operational, Opportunity is still working today after having covered almost 22 miles! Spirit got stuck in a dusty soil area in 2009 and unfortunately sent its last communication on 2010.

Fast forward to today’s super-rover: Curiosity! Now we’re talking about a 900 kg vehicle roaming about, which is capable of carrying half the total mass of Spirit in scientific experiments alone! NASA likes to use the analogy that Curiosity is about the same size as a Mini-Cooper. In terms of the scientific experiments, the list is pretty amazing (Curiosity is the first rover with a laser): ChemCam (remote sensing, including the laser, for chemistry) APXS, ChemMin (for mineraology and chemistry), SAM (detailed sample analysis), RAD (radiation assessment),  DAN (for detecting ice near the surface), REMS (for monitoring Martian weather) and not to mention a whole bunch of cameras! All in all, Curiosity is leaps ahead of went before it! It should truly help us understand the Martian geology and mineralogy in unprecedented detail.

Hopefully, that makes it clear why Curiosity is so important for studying Mars. It’s scientific designation, “Mars Science Laboratory” puts into perspective what this mission represents – a true suite of lab experiments on the surface of Mars!

And one last image to leave you with – a shot of all three rovers compared (but not on Mars!)

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Countdown to Curiosity: Landed!

6 08 2012

Congratulations to the Curiosity team! I’ve put a capture of the very first image downloaded from the surface to the left. Hard to believe after the months of flying through interplanetary space that Curiosity is on Mars!

The NASA website has already gone down with everybody trying to download the initial images, but keep trying! News coming in by the second – they’ve just managed to get things going again.

A press conference is schedule for 11:15 Pacific, but just to keep the info flowing, here’s what we said about the landing in the blog:

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Imagine hurtling toward a planet at tens of thousands of kilometers an hour. Your millions of miles away from the Earth and there’s no human pilot to plot a course once you’re inside the atmosphere to avoid any unexpected events. Sounds pretty risky, yeah? And it is… Beagle 2 was the last surface mission to fail (and we think we found the wreckage), but just four years earlier two missions, Mars Climate Orbiter and Mars Polar Lander, both failed as well. If you want statistics, NASA has landed on Mars successfully five (yes only five) times! And when it comes to Curiosity, the landing procedure that’s been chosen is more complex than any other mission before it…

While the Apollo missions entered into orbit around the Moon, Curiosity is going to slow down from interplanetary speeds without this step. In this sense its landing will be somewhat similar to the Apollo “splashdowns” on Earth. Thus Curiosity is going to hit the Martian atmosphere travelling at over 20,000 km per hour, and again, just like the Apollo missions, the spacecraft carrying Curiosity has a heat shield underneath to protect the rover from the extreme heat (a peak of 2100 C) produced in re-entry. All the steps that follow are given on this great graphic provided by NASA:

Once into the atmosphere Curiosity will begin a series of maneuvers at several times the speed of sound, before deploying its parachute while still at supersonic speeds. This part of the descent is anticipated to go pretty well. Supersonic breaking parachutes have been used since the Mercury missions in late 1950s early 1960s so the technology is nothing new.

But once Curiosity has descended to about 1.8 km above the surface, and is travelling at aroud 400 km per hour, it will separate from the parachute and begin a powered descent. In about 40 seconds it will be down to just 20m above the Mars surface, and then perhaps the most risky part of the whole mission begins: lowering to the surface on the end of a “sky crane”. Curiosity can’t just be “dropped” – it’s too heavy at almost 1 ton in mass. Once the sky crane is fully deployed the spacecraft will slowly descend down at about 0.75m per second. Once it detects that Curiosity is on the ground it will cut the lines on the crane and fly away at least 150 m away from the rover.

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Update: 10:45 am (ADT) still waiting for those images from MARDI showing the descent! 🙂