By Mary O’KEEFE
The Mars Science Laboratory rover is continuing its journey to the red planet. It is on day 82 of its 254-day journey traversing 126 million miles.
“The MSL is in really good shape,” reported Arthur Amador, MSL cruise mission manager at the Jet Propulsion Laboratory. “The spacecraft is healthy and operating as expected.”
MSL was launched on Nov. 26, 2011 from Cape Canaveral. The spacecraft carries Curiosity, a large rover that includes many scientific instruments as part of its rolling laboratory. The spacecraft is scheduled to land on Mars on Aug. 6 UTC (Coordinated Universal Time), which equates to Aug. 5 at 10 p.m. Pacific Standard Time.
“We are on an orbit transfer trajectory between Earth and Mars,” Amador said. “[What that means] is we give the spacecraft enough energy to climb to Mars’ orbit through the Earth’s orbit. … [This] August we will intersect Mars’ orbit, that will catch us in Mars’ gravity field.”
The spacecraft will land in a specific, pre-chosen area of the planet inside Gale Crater. Like the spacecrafts that carried Spirit and Opportunity, a parachute will be used to decelerate the lander as it approaches the surface of Mars. However, with the twin rovers, the landing was more like a bouncing ball. Airbags inflated around the rovers to cushion the impact as they were dropped onto the surface and then bounced into position. This time with such a large rover, engineers designed the Sky Crane method to get MSL onto the surface.
The spacecraft will descend on a parachute and then, during the final seconds prior to landing, lower the upright rover on a tether to the surface, much like a sky crane, according to the JPL website. But before there is a landing the spacecraft has to reach Mars safely.
“During the cruise we have a lot to do,” Amador said. “Number one is to get to Mars at the right point in time and the right point in space.”
To do this they track the MSL movements by bouncing radio waves off the spacecraft and measuring the range using Doppler radar.
The engineers know where the spacecraft is and have scheduled trajectory correction maneuvers to adjust the course when required. That first adjustment was in January. There will be another toward the end of March and then a couple more planned in July.
“With those adjustments we are kept on course to arrive in the right place,” Amador said.
The second important item on the checklist engineers are monitoring throughout MSL’s journey deals with the power source and communications.
“There are other things we have to do that keep us oriented in space,” he said. “We have to point the spacecraft toward the sun to illuminate the solar panels [a power source].”
The spacecraft is also maneuvered to keep its antenna pointing to Earth.
“The third major thing is to check out and calibrate our instruments,” Amador added.
Scientists and engineers will check the instruments on board by turning them on periodically. MSL is a laboratory with a science payload that includes 10 instruments that will be able to study Mars like no other rover has done. It even has a drill that will take samples and analyze the surface. It will study whether Gale Crater has evidence of past and present habitable environments. It will also be able to study the Martian atmosphere.
“The entire scientific payload will [be] checked out in March when we turn them on and calibrate,” Amador added. “It is a pretty busy cruise.”
Amador has been with JPL for 25 years. His first mission in the 1980s was Galileo and then Mars Exploration Rovers, Spirit and Opportunity.
“It feels good to be back on Mars. It is a familiar journey,” he said.
Amador added the trip to Mars has been made several times by those at JPL.
With each trip to Mars, engineers learn how to do it better the next time. The Mars team on Earth is partnered with the team of spacecraft on, and orbiting, the planet. Spirit, which landed in January 2004, was originally scheduled for a 90-day mission. It went well beyond that estimate and officially ended its mission on May 25, 2011. Opportunity landed shortly after its twin rover and, although its power levels are decreasing, it continues to explore.
Then there are the ever-watchful spacecraft that orbit the planet, Mars Reconnaissance Orbiter (MRO) and Mars Odyssey.
“NASA and JPL have these orbiters around Mars. We have this great infrastructure around (the planet) that sometimes we take for granted,” Amador said. “With MRO we can see the rovers on the surface [of the planet].”
Through the orbiters’ cameras, the footprints, or trails, of the rovers are seen.
“It is amazing,” Amador said. “We can see the first roads on Mars.”