Saturday, 11 August 2012

Mars Curiosity Lander special

'First pics from Mars Curiosity's successful landing!'

ABC World News Now: NASA Mars Rover Landing (ignore the wittering - watch the pics)

On Sunday, the 5th of August, at 22:31, GMT, NASA's specially-built sky-crane gently touched the Mars Curiosity Lander down onto Mars' surface, having been decelerated from 21000 kph, as it entered the Martian atmosphere. 
The first stage of braking utilised a heat shield, and nothing less than Mars' own atmosphere - thin compared to the Earth's, but useful nonetheless - and slowed the whole apparatus from 21000 to 1600 kph. The friction involved will have heated the shield to 2100°C - easily enough to make it glow in visible light (incandescence).
The next stage involved a 20-metre parachute, beneath which which hanged the rest of the apparatus, on 55m cables strong enough to retain integrity when 30 tonnes of force snapped them taught. The heat shield dropped away, and the Lander got its first views of the Martian surface.
Then, at 300 kph, the cables released, the retro-rockets fired, and at 20 metres from the surface, the Lander was lowered, via sky-crane, from the rest of the apparatus, holding steady above the ground. When fully extended, the whole crane lowered the remaining 15 metres to the ground, where the Lander settled at a dainty 2.5 kph, and the sky-crane flew away to land at a safe distance.
This whole process took 7 minutes and 12 seconds!

It might sound pointlessly complicated, but with such a large payload (899 kg), the downforce of the rockets could excavate the dusty surface, and maybe leave the Lander trapped and/or partially submerged. By the use of a sky-crane, the Lander could be put down gently, but distant from the rockets' thrust.

And now consider that there is a several-minute-long delay in communications between NASA and the Lander (simply because of the distance), causing scientists involved to title the wait 'seven minutes of terror'!

[video] (addition) 'Curiosity Before Mars: Seven Minutes of Terror'

Despite these efforts, dust was still gouged out of the Martian surface.
"The thrust from the rockets actually dug 0.5 meter (1.6 feet) trench in the surface," [said John Grotzinger], "it appears we can see Martian bedrock on the bottom."
But it hasn't harmed the mission, as far as i know, and has thrown up some unexpected evidence of Martian geology. As well as the dust, of course.

"When the landing was announced after a tense, seven-minute entry, descent and landing, NASA's Jet Propulsion Laboratory filled with jubilation as the mission team cheered and exchanged Mars chocolate bars."

"And Charles Bolden, the NASA administrator, applauded all the other nations -- including France, Canada, Finland, Spain, Russia and Germany -- whose scientists contributed to experiments on board the rover's Mars Science Lab."

Images from the lander:

[video] The Lander's first shots, taken by the MarDI (Mars Descent Imager) before it had even touched the surface.
This video sequence comes from a sample of 297 of the 1504 colour images taken, on its way down. You can see the heat shield fall away, beneath it, and the plumes of dust thrown up by the retro-rockets.
[picture] Also, there is a picture, from the Lander's hazard-avoidance cameras, of the nearby peak in Gale Crater.

Soon after landing, in the morning of 6th August (GMT)

Another early image, which might or might not have managed to catch the dust cloud thrown up by the sky crane, landing 2000ft away (the blob in the middle)
See a plan view of the site, further down the article....

This is a view of the Martian landscape, and also a self-portrait, edited together using images from the Lander's navigation cameras.

Mars in colour: This picture was taken on the afternoon after landing
"When the robotic arm, turret, and MAHLI are stowed, the MAHLI (Mars Hand Lens Imager) is in a position that is rotated 30 degrees relative to the rover deck. The MAHLI image shown here has been rotated to correct for that tilt, so that the sky is "up" and the ground is "down"."
"The main purpose of Curiosity's MAHLI camera is to acquire close-up, high-resolution views of rocks and soil at the rover's Gale Crater field site. The camera is capable of focusing on any target at distances of about 0.8 inch (2.1 centimeters) to infinity. This means it can, as shown here, also obtain pictures of the Martian landscape."

And here's the big one: 'Mars rover sends back 1st 360-degree color view'
Awesome picture :)

"The first impression that you get is how Earth-like this seems, looking at that landscape," said chief scientist John Grotzinger of the California Institute of Technology.

And this is where it landed:

Gale Crater is 154 kilometers wide and it contains a 5-km-high mound of layered sediments, which is a primary target for Curiosity. The mound is dubbed Mt. Sharp by scientists, who estimate the crater formed by a massive impact 3.5 to 4 billion years ago.
The image is woven together from 205 individual images, the vast majority of them taken by THEMIS (Thermal Emission Imaging System) on the Mars Odyssey Orbiter, which has since taken pictures of the Curiosity Lander.
"In all, [Jonathon Hill, Mars researcher at ASU] says, it took about two and a half weeks to put [the picture] together. "The thing that made it take so long was that when you blow the image up that big, or when you zoom in that much, any misalignment of the images becomes very obvious." In the end, he had to align and custom fit most of the frames manually."
You can go on a tour of the crater, if you like - but be prepared to wait - the whole file is 325 MB - and because of the scale, it can only resolve objects as big as 20m across!
Even thought he Lander is the bigggest ever sent to Mars, at 3m, it's too small to be seen by THEMIS.

As has already been mentioned, the sky crane landed about 650 metres from the Lander, so that gives you an idea of scale, in this picture.
Notice how the rockets of the sky-crane point directly away from the Lander's site, forming a kind of arrow-shape, pointing at the Lander!

As NASA's Mars Reconnaissance Orbiter, or MRO, flew by, it pointed its HiRISE camera at the descending Curiosity Lander, and snapped it on its way down to the ground, underneath its 20-metre parachute:

There have been four prior mission successes to Mars: Viking 1 and 2 (1976), Pathfinder (1997), rovers Spirit and Opportunity (2004) and Phoenix (2008).
Curiosity's the heaviest mission to Mars, and also the most expensive, costing $2.5 billion - $1 billion over budget! Now how many people can do that, and get away with it? I've heard famed physicists bemoan the practice of leaving budgeting to scientists, before, but $2.5 billion for a frontier-pushing project like this is peanuts. Stock traders lose that much every time they go for a toilet break! Curiosity's worth every cent.

[audio] (Addition) : David Blake and John Zarnecki (the guy who did the Huygens probe that's currently on Saturn's moon - Titan) certainly think it's worth it.

Even so, the Lander's only been designed to function for 98 Earth weeks, or about one Martian year. Having said that, Spirit and opportunity were only built for 90 days, and Opportunity's still going strong after 8 years!

After sailing 352 million miles (566 million kilometers) and eight months, Curiosity parked its six wheels near the Martian equator, where it will spend the next two years poking into rocks and soil in search of the chemical ingredients of life.
Its ultimate destination is a mountain towering from the center of the crater floor, which has been named 'Mount Sharp'. Preliminary estimates indicate Curiosity landed four miles away from its base, which is thought to contain signs of past water — a starting point to learning whether microbial life could exist there. Also, the Lander might be able to find ground-based evidence of the tectonic activity that the already-mentioned THEMIS scope has recently found evidence for.

Before the 899-kilogramme, nuclear-powered Curiosity can start roving, however, it will have to undergo several weeks of tedious but essential health checks.

The Curiosity Toolkit

Ten instrument-based science investigations on board:

1) Mast camera (MASTCAM) contains two megapixel color cameras that act as the left and right eye of the rover, and are capable of returning stills, video and 3D images.

2) Chemistry and Camera (CHEMCAM) is a rock-vaporizing laser and telescope combination that can target a rock 23 feet (seven meters) away, burn it and analyze the light that emerges to identify the chemical elements inside.

3) Alpha Particle X-Ray Spectrometer (APXS) is on the robotic arm and can identify chemical elements in rocks and soil.

4) Mars Hand Lens Imager (MAHLI) is a color camera on the end of the robotic arm for use in getting closeups of the ground or wider scenes of the landscape.

5) Chemistry and Mineralogy (CheMin) analyzes powdered rock and soils with X-ray diffraction.

6) Sample Analysis at Mars (SAM) has three tools to check for carbon-based compounds that are the building blocks for life, examine the chemical state of other elements important for life and search for clues about planetary changes.

7) Rover Environmental Monitoring Station (REMS) records daily and seasonal changes in the weather on Mars.

8) Radiation Assessment Detector (RAD) monitors high energy atomic and subatomic particles from the sun that could pose a danger to astronauts if a human mission to Mars ever occurs.

9) Dynamic Albedo of Neutrons (DAN) can detect underground water beneath the rover at a distance of 20 inches (50 centimeters).

10) Mars Descent Imager (MARDI) records full-color video of the final few minutes of the rover's descent onto the Martian surface. A few images are expected back within days of the landing, but the full video may take longer.

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