Star Talk: Curiosity rover will have size and power to accomplish more on Mars than predecessors

NASA is set to launch its next planetary rover to Mars in just a few weeks. Curiosity is larger, mor
This artist rendition shows NASA’s Mars Science Laboratory Curiosity rover, which is due to land in Gale Crater in August.
This artist rendition shows NASA’s Mars Science Laboratory Curiosity rover, which is due to land in Gale Crater in August.

NASA is set to launch its next planetary rover to Mars in just a few weeks. As part of the Mars Science Laboratory mission, this latest rover is a mobile test platform that will analyze rocks and test the Martian soil to investigate whether conditions on the Red Planet have ever been favorable for microscopic life.

The new rover, named Curiosity after a survey on the NASA website, is larger, more complex and more versatile than any rover that has been sent to Mars. Curiosity is about the size of a MINI Cooper car and is able to move more than 650 feet a day. Unlike the previous Mars rovers, which used solar panels to provide power, this robotic behemoth will use electricity produced from the heat generated by a radioactive power supply.

This kind of energy source is similar to those that have powered missions to the planets Jupiter and Saturn and beyond. At the distances to objects in the outer solar system, sunlight is so dim that a spacecraft cannot generate enough power using a reasonably sized solar array. By designing Curiosity with an alternate energy source, the rover has the power to operate a suite of 10 scientific instruments — day or night — for a full Martian year (about two Earth years).

Further, the radioactive source will make it possible for this rover to explore over a greater range than was doable with the previous rovers. Finally, excess heat from the power supply will be piped around the rover to keep its electronics and instruments at operating temperatures.

Novel landing

The launch window for the Mars Science Laboratory opens at 10:21 a.m. on Nov. 25. If liftoff does not take place at that time, NASA can still launch the mission through Dec. 18 for a landing on Mars between Aug. 6 and 20.

During the approximate eight-month cruise to Mars, the spacecraft and its systems will be monitored and any course corrections made so the rover can make an accurate landing. When the spacecraft reaches the Martian atmosphere, the entry, descent and landing phase begins.

Since this new rover weighs just under 2,000 pounds, the familiar air bags that were used to bounce the last three rovers to a landing on Mars cannot be used — Curiosity is simply too large and heavy; the air bags would burst. Engineers have devised an innovative way to deliver this rover safely to the surface.

The new method will get under way as the capsule containing the rover enters the atmosphere of Mars. First, the capsule will slow itself by steering a series of S-curve maneuvers through the thin Martian air — similar to the flight plan that was used to slow a space shuttle for landing once it entered Earth’s atmosphere.

Then, three minutes before the mobile Science Laboratory reaches the surface, a parachute will be deployed to slow the space capsule further. At an altitude of one mile, the capsule will separate and the parachute will carry the shell away. A retrorocket frame will then ignite to provide a powered descent for the rover. At a height of only 65 feet, the frame will deploy the rover upright on a tether, as if being lowered by a sky crane. The rover will extend its wheels as it is lowered and, after contact with the surface, the cable will be severed as the rocket frame flies away.

This new technique increases the precision of an accurate landing, making it possible to deliver a spacecraft to places that were formerly rejected because of local terrain. For example, now a mission could land on a crater floor while avoiding the crater’s steep walls; previously, such a scenario would not have been possible because a less precise landing would be too risky.

Curiosity is aimed for Gale Crater. It is a site on Mars where minerals have formed in a wet (presumably water) environment. Once the rover is on the surface and declared operational, it will use its set of instruments to assess whether this region ever had, or still has, the conditions favorable for some kind of microbial life.

Curiosity is also equipped with a robotic arm that can extend out to 6 feet. Much like a human arm, the rover’s arm has three joints that act as a wrist, elbow and shoulder. Mounted at the end of the arm is a handlike structure capable of holding five tools that can acquire, image or prepare rock and soil samples for testing.

The Mars Science Laboratory will go beyond NASA’s basic “follow the water” strategy. Its science payload can identify the organic compounds that make possible the building blocks of life. By landing in a region of Gale Crater that resembles an area shaped from sediments carried by water, Curiosity may find clay-rich layers that, according to research performed on Earth, can attract and protect organics over long periods of time.

November sky

The planets are starting to line up across the sky from dusk to dawn. Although some are difficult to see at the opening of November, by the end of the month the overhead “bowl of the night” will be rich with planets.

Mercury and Venus begin November pretty much hidden in the glow of sunset. But after two weeks, it will be easy to tease Venus out of the twilight by searching with binoculars. At the end of November though, finding Venus above the southwestern horizon a half hour after sunset without observing aids will much easier, particularly on the early evening of Nov. 26, when a thin crescent moon is just to the right of Venus.

Mercury is more difficult to find because it is even lower in the sky than Venus. It appears under Venus through Nov. 15, then comes into view closer to the horizon each day; it disappears into the sunset sky by the last week of November.

Who hasn’t seen Jupiter? Its brightness beams from the east after sunset, from the south by midnight and from the west by dawn. On Nov. 9, the moon will be a day before full when it is positioned next to Jupiter.

Mars is in the southeast by dawn and the third quarter moon will be to its right on Nov. 18. Saturn spends the month racing out of the morning twilight. Watch for the crescent moon near the ringed planet before sunrise on Nov. 22.

Richard Monda is an astronomer living in the Capital Region.

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