RATs and Monuments on Mars

In a previous post, I made the comment that I don’t necessarily think humans ought to colonize other planets; at least, not until we know a lot more about the environment upon which we intend to force ourselves. Manned exploration is another story. Sending men to another planet to survey the environment is much simpler than trying to replicate a man’s honed skills and keen mind in a machine – aside, of course, from the challenges associated with getting him there in the first place. Such tools exist on the recently silent Mars Exploration Rovers (MER) Spirit and Opportunity. But the rover’s tools serve an unlikely second purpose. They stand as a tribute to those lost during the terrorist attacks on the World Trade Centre on September 11, 2001. (Left, MER rover Spirit captures its own shadow. Mars, 2004.)

Rocks are fantastic time keepers – their composition, shape, and age can make an otherwise barren and featureless environment reveal its secrets. This is particularly true in the case of Mars; the planet’s surface is a veritable garden of exposed rocks. But finding the story locked in the rocks takes a certain knowledge base, namely, a strong background in geology.

Geology has already proved a necessary tool in manned space exploration. Geologists knew that moon rocks held the secret to the moon’s formation and ultimately prove a vital piece of the puzzle surrounding the Earth-moon system. But not just any rocks would do. A complete picture of the moon and its genesis required that the Apollo astronaut collect and return a variety of samples.

To this end, all Apollo astronauts were trained in geology – both in classrooms and in the field. They were taught how to recognize different types of rock, differentiate between a rock worth bringing home and one of relative uninterested, and also how to describe everything they saw to the geologists in mission control. Most importantly, however, they learned how to survey their environment – scanning the scene before them to zero in on good candidate rocks to collect during their limited surface EVAs. (Apollo 17 lunar module pilot Jack Schmitt was the only trained geologist to walk on the moon. Here, he collects a rock with a custom tool – leaning down to pick up a rock is not an easy task on the moon. 1972.)

The same goes for Mars. A complete picture of the planet means collecting and returning a variety of rocks. But this is considerably easier said than done. We’re not quite at the point where we can send a team of geologists – or any team – to the red planet. Engineers have therefore had to provide rovers and landers with some analogue to the geologist’s skill. Twin rovers Spirit and Opportunity were sent on a one-way mission to Mars. As such, their investigation was done in situ, requiring each to have sufficient hardware to serve as virtual geologists for the scientists watching from Earth.

A geologist’s most important tools are his eyes, his hands, and his hammer – he can scan the scene, pick up a rock, and break it open to see what’s inside. This was the basic practice of the Apollo astronauts on the moon.

For Spirit and Opportunity, their cameras acted as eyes for the scientists on Earth; pictures allowed them to identify and direct the rover to an interesting rock. Hand and hammer presented more of a challenge. The rovers couldn’t pick up a rock and break it open. A hammer or any pointed object swinging around could be hazardous – what if it fell and broke a vital piece of hardware, ending the scientific portion of the mission before it started? (Right, Opportunity reaches out to touch a rock. 2004.)

The team behind the rovers came up with a simpler way to reach the inside of interesting rocks. The rover would approach its target rock and bore into it, exposing its inside. Then it would be up to the individual instruments to do their job – spectrometers determined the composition of the rock, magnets were used to collect any magnetic dust particles, and a microscopic imager took high resolution photos.

Boring into the rock was the job of the rock abrasion tool or RAT, a small tube-shaped instrument about the size of a soda can designed to continuously grind and brush away dirt to expose the rock’s inside. Weathered surfaces and layers of dust from the constant storms on the surface gave way to the rock’s history and vital information on the hunt for traces of water or primitive life on the planet.  (Left, RAT holes.)

The RAT was built by Honeybee robotics, a small company in lower Manhattan that builds custom instruments. The morning of September 11, 2001, Honeybee founder and chairman Steve Gorevan’s morning bike ride to work was interrupted by the sound of an airplane hitting the North tower of the World Trade Centre.

Only a mile northeast from the site of the WTC, Honeybee employees were able to watch the morning’s events unfold from the building’s rooftop. They saw the towers fall and watched as masses migrated away from the site, most of whom were ghostlike from being covered in soot. Within two weeks, work at Honeybee had resumed but the mood remained morose. Missions to Mars can’t be rescheduled.

As the company in New York regained its momentum, JPL engineer in charge of the Honeybee RAT contract Steve Kondos devised a way for the company to honour the victims. A simple memorial made with material from the WTC site sent to Mars on the rovers would be a fitting tribute from the whole MER team. The proposal went through formal paths, eventually reaching Now York’s mayor Rudy Giuliani who approved the idea; within three months a box containing debris from both towers arrived on Gorevan’s desk. (Right, enhanced colour image of RAT holes demonstrates what the instrument could reveal in a rock – the red and blue hues are indicative of different composition of the rock’s surface and its interior.  Endurance Crater, 2004.)

Part of the debris was a piece of aluminum, the same lightweight metal that made up most of the RAT’s construction. Gorevan and lead RAT engineer Tom Myrick immediately saw that the aluminum could be reworked into cable shields – a casing designed to cover the electrical wires and protect the whole instrument in the event it bangs into a rock. Each piece of molded aluminum was adorned with an American flag. Like the rovers, the RATs have stopped working but remain a silent tribute to those lost.

The American flag on the RAT's cable shield as seen by Spirit's own camera.

Suggested Reading

Roving Mars, Steve Squyers. Hyperion. 2005.

Comments

  1. JupiterIsBig says

    Minor correction needed
    >”Like the rovers, the RATs have stopped working but remain a silent tribute to those lost.”
    Opportunity is still working, isn’t it ?

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