Hundreds of Jet Propulsion Laboratory staffers are working on NASA’s mission to Mars, but when the one-ton rover Curiosity lands Aug. 5 on the Red Planet, they will not know it.
Seven minutes are expected to pass between the time the spacecraft carrying Curiosity enters Mars’ atmosphere and the time it settles on the Gale Crater. JPL scientists and engineers won’t know if the operation was a success for at least 14 minutes, the time it takes for the Mars Odyssey orbiter to communicate with Earth. They won’t receive the first photographs for hours.
“It’s pretty nerve-racking,” said Ravi Prakash, a JPL entry, descent and landing engineer working on the Mars Science Laboratory project. “We can’t control anything, so it’s all on its own.”
If all goes well, the rover will rest its six wheels on a spot picked specifically to determine if Mars once sustained life. But the team managing the mission at JPL will be holding its breath until receiving word back from the orbiter that Curiosity is alive.
The spacecraft will enter an atmosphere 100 times thinner than Earth’s at 13,000 mph, slowing down with the help of a parachute. A carbon-based heat shield, JPL technology that will be used on Mars for the first time, will protect the rover from the elements.
The rover is designed to fall out of the spacecraft with a rocket-powered “backpack,” which gently lowers Curiosity on a three-cable sky crane. Once on the ground, the rover will fire explosive devices to cut off the cables and a data cord. The remaining part of the spacecraft then flies away to crash and evaporate on another part of the planet.
Curiosity will then stay in place for several weeks before it begins to explore the area, gathering rock samples and looking for elements that signal the past presence of water.
Curiosity can handle a 30-degree slope, but if it lands on its side or its back, it won’t be able to pull itself upright, Prakash said.
“The way we designed it, it will land on its wheels,” he said. “But there are things that could go wrong. We don’t underestimate that things could go very, very badly that day.”
JPL has been collecting data about Mars’ weather, gravity and atmosphere each month, with an eye toward landing the craft safely. Engineers will use that information, along with data collected from orbiters and the Deep Space Network, to tell the spacecraft where to go.
“We do all the navigation from the antennas on Earth, so it’s like going to some place and looking back in your rearview mirror to look back to know where you are,” said Mars Science Laboratory Navigation Team Chief Tomas Martin-Mur. “You are not looking ahead, you’re looking back.”
The team’s main job is to deliver the spacecraft to the right position to enter Mars’ atmosphere and then tell the spacecraft where it is as it lands. They will do this by predicting the path of the spacecraft, said Martin-Mur.
“In order to land on the Gale Crater, you have to know where you are when you enter the atmosphere,” he said. “There is no GPS on Mars.”