Tuesday marks a milestone anniversary for NASA’s Curiosity rover – one full Martian year on the surface of the red planet. In the span of just 687 short Earth-days, Curiosity has marked several firsts and important scientific discoveries on Mars as she heads toward her primary scientific target of Mount Sharp in the Gale Crater.
Curiosity mission background:
Part of NASA’s Mars Exploration Program, the Mars Science Laboratory is part of the long-term effort by NASA to conduct robotic exploration of the red planet as part of a precursor series of missions to the first human missions in the coming decades.
The mission itself is managed by the Jet Propulsion Laboratory of the California Institute of Technology and follows and builds upon the previous successful NASA Mars rovers Spirit and Opportunity, which arrived on Mars in 2004 (of which Opportunity is still functioning).
For this particular mission, the Mars Science Laboratory rover Curiosity was given four distinct scientific goals: to determine its landing site’s past habitability, the role of water at the landing site, study of the Martian climate, and study of the local Martian geology.
Originally, Curiosity was slated to launch in 2009. However, its launch was pushed back to 2011 to allow engineering teams more time to adequately finish construction of the rover and properly test its systems in a non-rushed timeline.
On 26 November 2011 at 10:02 EST, Curiosity lifted off from the Cape Canaveral Air Force Station in Florida aboard an Atlas V rocket and began its 8.5-month interplanetary cruise to Mars.
6 August 2012: 7 minutes of terror
Curiosity’s entry into the Martian atmosphere was one of engineering brilliance.
Executing a precision landing via a series of preprogrammed computer commands encoded by scientists and engineers months earlier, Curiosity steered herself to the most precise, pinpoint landing of any robot on the surface of any non-Earth planet in history.
Following atmospheric entry and aero-braking, Curiosity’s super-sonic parachute deployed and the heat shield detached from the bottom of the vehicle.
The parachute phase of Curiosity’s landing ended at an altitude of 1.1 miles and a velocity of 200 mph when the rover literally dropped from the bottom of its aeroshell and began a momentary free-fall toward the surface of Mars.
Shortly after free-fall began, Curiosity’s descent stage platform fired its rocket thrusters to veer the vehicle away from still-descending aeroshell and parachute and to slow Curiosity’s decent from 220 mph to a near-hover over the Martian surface.
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Finally, at an altitude of just 27.3 meters, pyrotechnic devices fired and began lowering the rover, attached to three bridles, toward the surface of Mars.
Once Curiosity’s lowering began, the rover immediately reconfigured itself from its stowed, interplanetary cruise configuration into its landing configuration.
Shortly thereafter, the extension bridles came to a full 25-foot extension below the descent stage, and at a relative velocity to the ground of just 0.75 m/s Curiosity made the first-ever wheels-first, sky crane landing on the surface of Mars.
Once landing was confirmed, it was discovered that Curiosity had touched down just 1.5 miles from the center of the targeted landing location – a record-setting (near-perfect) landing precision following a 350 million mile journey from Earth to Mars.
Curiosity’s landing brought NASA’s success rate at Mars to 14 in 20 (a 70 percent success rate) and 4 for 4 in the U.S. space agency’s attempts to land a rover on Mars (a stunning 100 percent success rate).
Once Curiosity was safely on the Martian surface, her landing site was named in honor of the recently passed pillar of science, or in this case, science-fiction, Ray Bradbury (Bradbury Landing).
The dedication continued the tradition of colloquially naming the landing sites of successfully-landed NASA Mars rovers, following Carl Sagan Memorial Station for Sojourner, Columbia Memorial Station for Spirit, and Challenger Memorial Station for Opportunity.
Just days after landing in Gale Crater, Curiosity shockingly (from the sheer short amount of time it took) accomplished its primary mission objective by determining that Gale Crater’s previous conditions were habitable for simple life forms.
The historic confirmation of this long-held scientific supposition highlighted in short order the benefits of robotic spacecraft exploration.
Curiosity’s examination of the Gale Crater riverbed revealed that the site was once a lakebed with mild water, the essential elemental ingredients for life, and a type of chemical energy source used by some microbes on Earth.
In addition to this momentous discovery, Curiosity has successfully assessed the natural radiation levels both during the flight to Mars and on the Martian surface, providing guidance for designing the protection needed for future human missions to Mars.
The rover has also measured the level of heavy-v-light variants of elements in the Martian atmosphere – information showing that much of Mars’ early atmosphere disappeared by processes favoring loss of lighter atoms, such as those from the top of the atmosphere.
Other measurements from Curiosity have found that Mars’ atmosphere holds very little, if any, methane, a gas that can be produced biologically.
Another landmark finding from Curiosity came in the form of geological analysis. For the first time, the age of a rock on another planet was determined, as well as how long the rock has been exposed to harmful radiation.
This information will provide avenues for learning when water flowed across Gale Crater and for assessing degradation rates of organic compounds in rocks and soil samples.
Up next for Curiosity:
All of these discoveries have come during a slow-going but steady drive to Aeolis Mons, otherwise known at Mount Sharp.
Once Curiosity arrives at Mount Sharp, the mission team will seek evidence not only of habitability, but also of how environments evolved and what conditions favored preservation of clues to whether life existed there.
Form Curiosity’s current location, the entry path to the mountain is a gap in a band of dunes edging the mountain’s northern flank approximately 2.4 miles (3.9 kilometers) ahead of the rover’s current location.
At that distance, based on Curiosity’s current driving distance rate, the rover could arrive in one Earth-year’s time (roughly half a Martian year).
However, it is likely to take slightly longer than one Earth-year to reach the base of Mount Sharp based on the need to avoid hazards in the Martian terrain that could prove damaging to the rover’s wheels.
The current path outlined for Curiosity will take the rover across sandy patches as well as rockier ground. Terrain mapping and driving path calculations are and will be derived from imaging from NASA’s Mars Reconnaissance Orbiter.
Regardless of how long it takes Curiosity to reach Mount Sharp, the fact that the rover has come through its first Martian year in excellent condition is a true testament to the teams of engineers who spent years designing, building, testing, and programing the rover.
While Martian day 687 will be an important moment for the rover and her teams, day 688 will be even more important: The day Curiosity officially surpasses its original mission duration of one Martian year.
Interestingly, that is the only mission duration mark that Curiosity has had.
In early 2013, the mission and its teams were given the highly unusual, but very beneficial, honor of receiving an indefinite mission extension.
With no fixed end date to the mission, Curiosity’s teams will be able to stop the rover when needed to performed science operations at various locations along the way to and at Mount Sharp – science stops that might have been prioritized out of the rover’s schedule had there been a pressing end of mission date.
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