Our SpaceFlight Heritage: A voyage driven by Curiosity
KENNEDY SPACE CENTER, Fla — Curiosity, NASA’s Mars Science Laboratory rover, touched down three years ago on this date, August 6, 2012. Just getting the one-ton rover onto the surface of the Red Planet required a new way of landing the robotic geologist on the flash-frozen world. NASA found a way through this and other hurdles and has spent the last three years exploring Gale Crater on Mars.
The rover launched atop a United Launch Alliance Atlas V 541 (AV-028) rocket from Cape Canaveral Air Force Station’s Space Launch Complex 41 in Florida on Nov. 26, 2011, at 10:02 a.m. EST (15:02 GMT). The Atlas V is a two-stage rocket that utilizes a Russian-made RD-180 rocket engine in its first stage and has a Centaur engine in its upper stage. Attached to the first stage were four Aerojet (now Aerojet Rocketdyne) produced solid rocket boosters.
After it had lifted off, the spacecraft entered into the cruise stage of the mission where it would spend the next 253 waiting for its “big day”. However, this part of the flight was not just about waiting until arrival.
It required its own set of thrusters, each fueled by the highly toxic propellant hydrazine, which was stored in two titanium tanks. These thrusters were arranged in two groups consisting of eight thrusters total.
Two X-band antennas provided communications of the vehicle’s status back to mission managers on Earth.
When Curiosity had reached Mars, the cruise stage was detached via a cable cutter. The aeroshell and its precious cargo were then ready for the next step of the mission.
After transiting the void between our world and the next, Curiosity was now set to conduct the most perilous portion of its flight – Entry, Descent, and Landing, or “EDL”. This phase of the mission is more commonly known as the “seven minutes of terror”.
Given that those who had spent countless hours grooming the robot and its systems for this moment had exactly no control over what was taking place, it is not surprising that this phase of the mission is referred to as such.
Owing to the advances made in technology since the last time a rover had landed on Mars some eight years earlier, Curiosity’s landing was completely automated – and very complex.
The system used an aeroshell as well as propulsion systems based on those used on the Viking missions that landed on Mars in 1976.
When all was said and done, Curiosity carried out one of the most precise landings on the Martian surface to date. Mission planners aimed for and hit an area on the Aeolis Palus section of Gale Crater. The target area measured some 4.3 by 12.4 miles (approximately 7 by 20 kilometers).
Once the rover had passed this part of its journey, the rover’s aeroshell split, with the front half plummeted toward the surface.
The rovers that preceded Curiosity – Sojourner, Spirit, and Opportunity – all employed airbags to touch down on the Red Planet. As noted, Curiosity’s weight, at about a ton, along with the fact that it is the size of a mini-Cooper, was too big for that. So, instead, the robot utilized the novel “Sky Crane” system.
Sky Crane has frequently been referred to as a “James Bond jetpack”. This both is and is not an accurate description as – while the device did allow the rover to “fly” – its primary job was to hold the rover in the Martian sky as Curiosity was lowered to the ground via a tether to the dusty terrain below.
Once it detected that it had touched down, the tether was cut and Sky Crane flew a short distance away where it impacted the Martian surface.
“The biggest surprise about EDL was there were no surprises,” said Adam Steltzner, one member of the team who worked on the rover’s EDL systems. “But soon after we were confirmed down, what I saw on the screen absolutely floored me.”
Despite safely touching down on Mars, mission managers did not want to convey that the nuclear-powered rover was ready to begin exploration. It is here that NASA-ese, the complicated, acronym-laden speak that the agency is known for, actually came in handy. The word “touchdown” would have led those not initiated in what all had to take place before EDL officially could be called to a close, was done. So, “touchdown” became “Tango Delta Nominal“.
“If we said ‘touchdown’, then people not intimately familiar with EDL might infer that Curiosity was good to go,” said Steve Sell, an engineer with the MSL team. “But two more major calls had to be made before I could begin to breathe again.”
Perhaps the most amazing thing of all is the fact that NASA’s Mars Reconnaissance Orbiter High-Resolution Imaging Science Experiment camera (HiRISE) snapped a picture of the spacecraft, with its parachute deployed, descending down to the surface. Those working on the mission doubted they would be able to capture the moment.
“We thought the odds were pretty small that we would see it,” Steltzner said.
This was not the first time that the space agency had achieved this feat – a similar image was captured in 2007 when the Phoenix Mars Lander conducted its landing.
Gale Crater, and the 3.1-mile tall (5-kilometer) Mount Sharp which extends out of its center, was selected as the rover’s destination in 2011 – Gale rose to the top out of some 60 different potential targets.
Curiosity has a series of objectives. Most follow the gradual approach of planetary exploration that NASA has set for the Red Planet, such as studying the planet’s climate and geology. Another of the robot’s directives is meant to help the agency with its human spaceflight ambitions. The MSL rover is collecting data to help a possible crewed mission to Mars, which is currently slated to take place sometime in the 2030s.
All of the discoveries regarding the world, which resides some 140 million miles (225,308,160 km) away from our own, began with a risky landing that took place on this date in space flight history. To help the public become better acquainted with the planet, it has unveiled Mars Trek. This project was made possible in large part thanks to the spacecraft and rovers that have been sent to the world.
“At three years old, Curiosity already has had a rich and fascinating life. This new program lets the public experience some of the rover’s adventures first-hand,” said Jim Erickson, the project manager for the mission at JPL.
Video courtesy of NASA Jet Propulsion Laboratory
Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology, Space.com, The Mars Society and Universe Today.