NASA's Curiosity rover completes crucial course correction en route to Mars

NASA's car sized Curiosity Mars Science Lab fired its thrusters to set in on course for its scheduled touchdown in the Red Planet'sGale Crater, where, if the landing goes well, it will begin searching for signs of habitability.

Now just 1 week out from landing beside a 3 mile high (5 km) layered Martian mountain in search of lifes ingredients, aiming thrusters aboard the cruise stage of NASAs car sized Curiosity Mars Science Lab successfully fired to set the rover precisely on course for a touchdown on Mars at about 1:31 a.m. EDT (531 GMT) early on Aug. 6 (10:31 p.m. PDT on Aug. 5).

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Two precise and brief thruster bursts lasting about 7 seconds were successfully carried out just hours ago earlier today at 1 a.m. on July 29, EDT (10 p.m. PDT on July 28). The effect was to change the spacecrafts velocity by about 1/40 MPH or 1 cm/sec as it smashes into Mars at about 13,200 mph (5,900 meters per second).

This was the fourth and possibly last of 6 interplanetary Trajectory Correction Manuevers (TCMs) planned by mission engineers to steer Curiosity since departing Earth for the Red Planet.

If necessary, 2 additional TCMs could be implemented in the final 48 hours next Saturday and Sunday before Curiosity begins plunging into the Martian atmosphere late Sunday night on a do or die mission to land inside the 100 mile wide Gale Crater with a huge mountain in the middle. All 6 TCM maneuvers were preplanned long before the Nov 26, 2011 liftoff from Cape Canaveral, Florida.

Without this course correction firing, MSL would have hit a point at the top of the Martian atmosphere about 13 miles (21 kilometers) east of the target entry point. During the preprogrammed Entry, Descent and Landing (EDL) sequence the vehicle can steer itself in the upper atmosphere to correct for an error amounting to a few miles.

On landing day, MSL can steer enough during its flight through the upper atmosphere to correct for missing the target entry aim point by a few miles and still land on the intended patch of Mars real estate. The missions engineers and managers rated the projected 13-mile miss big enough to warrant a correction maneuver.

The purpose of this maneuver is to move the point at which Curiosity enters the atmosphere by about 13 miles, said Tomas Martin-Mur of NASAs Jet Propulsion Laboratory, Pasadena, Calif., chief of the missions navigation team. The first look at telemetry and tracking data afterwards indicates the maneuver succeeded as planned.