NASA's Curiosity all set to land on Mars

Curiosity, NASA’s one-ton roving vehicle, is scheduled to land on Mars early Monday. If all goes as planned, Curiosity and the Mars Science Laboratory will come to rest in Mars’ Gale crater. All Mars landers since 1997 have employed a system of airbags during landing. The airbags, inflating moments before landing, cushion the payload as it bounces across the Martian landscape before rolling to a stop. Not so with MSL — it’s too heavy for airbags.

An artist's conception of the sky crane gently lowering the Curiosity rover onto the surface of Mars.

Mars Science Laboratory will employ a heat shield, parachute and a rocket-powered disposable descent stage. Once it’s through protecting Mars Science Laboratory during its entry into Mars’ thin atmosphere, the heat shield separates shortly after the parachute deploys. Powered descent begins after releasing the parachute as eight rockets ignite on the descent stage, or “sky crane.” Shortly before touchdown the lander is lowered to the surface with lanyards. After touchdown the lanyards are cut and the sky crane flies off to a crash landing.

A similar plan was once considered in the early 1960s for the Apollo Moon-landing mission. A descent stage would have slowed the lunar module to a low hover then would separate, go off and crash. The “lunar crasher” concept was described as “dicey” by NASA engineer Caldwell Johnson and the idea was discarded. Seems the notion of intentionally crashing a piece of equipment near a soft landing site rubbed some engineers the wrong way. That is apparently no longer the case.

During August, two planets and a bright star form an ever-changing triangle low in the western sky. On Monday evening, they form an equilateral triangle. The triangle’s top point is the planet Saturn. The corners of the base are, from left to right, the star Spica and the planet Mars. Spica is the brightest star in the constellation Virgo and is 260 light-years away.

During the next few days, Mars continues eastward and passes between Saturn and Spica from Aug. 13-14. The trio is joined by the crescent moon on Aug. 21, posing for a unique group photo opportunity.