Helping Phoenix Land
The Phoenix Mars Lander launched on Saturday, August 4, beginning a journey to never-explored regions of the Red Planet to search for frozen water beneath the Martian surface. What it discovers will help scientists determine if Mars could support life.
NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. and Langley Research Center in Hampton, Va. are working together with the University of Arizona and Lockheed Martin Space Systems on Phoenix, the first project in NASA’s Mars Scout Missions program.
The University of Arizona is leading the mission, JPL is managing the project and Lockheed Martin built the spacecraft. Langley is serving a supportive, although equally important, role.
"Langley’s contributions are in a number of areas," said Prasun Desai, senior engineer and Entry, Descent and Landing (EDL) lead engineer. "Our role is to help with the development of the EDL system. We’re supporting JPL and Lockheed Martin by defining the requirements for Phoenix’s design so that it can meet what it needs to do when it gets to Mars to land safely."
To fulfill its role, Langley performs analyses in a range of disciplines — from flight dynamics and mission design to aerodynamics to EDL systems engineering.
Phoenix will land on the northern polar regions of Mars, comparable in latitude to central Greenland or northern Alaska, and claw into the Martian soil using its 7.7-foot-long robotic arm. The lander will then retrieve samples of soil and water ice and analyze those samples by using an "oven" and a "portable laboratory" to heat the soil and water ice and examine their characteristics.
According to Desai, NASA wants Phoenix to gather clues and answer critical questions — Can the Martian arctic support life? What is the history of water at the landing site? How is the Martian climate affected by polar dynamics?
NASA hopes that what Phoenix finds will answer some of these questions.
"There is a lot of work being performed to determine the best possible landing location so that we can get answers to the questions that are being asked," said Desai. "We use simulations and software tools to wring out the system as best as possible to try to improve it."
This process often involves estimating what the atmosphere of Mars will be like and running thousands of simulations according to those estimations.
"We understand the system better and we believe the system will do what it’s supposed to do because we’ve simulated it in so many different ways," said Eric Queen, research engineer at Langley.
As Phoenix makes the nine-month journey to Mars, the workload of the Langley engineers will intensify as they prepare for a successful entry, descent and landing — the period lasting three hours before the spacecraft enters the Mars’ atmosphere until it safely reaches the ground.
"Three months before landing is when things will really get busy for us," said Desai.
During the "cruise phase," or Phoenix’s flight, Langley will explore different scenarios of possible extreme conditions on Mars to get an idea of how the system will respond. According to Desai, exploring such scenarios enables engineers to fine-tune the system and make it as "robust as possible."
"We can fix anything software-related that needs to be tweaked while it’s in flight," said Jill Prince, aerospace engineer at Langley Research Center.
Prince, Desai and Queen plan to relocate to JPL for those demanding months prior to landing.
"It’s so much easier to work with everybody when you’re in the same room rather than when you’re across the country," said Prince.
One major challenge the team faces is Phoenix’s "soft" landing. Unlike the previous Mars missions Spirit and Opportunity, which used airbags for landing, Phoenix will use propulsive engines to slow its descent and then land on three legs.
"It’s going to come in and fire engines all the way down once it comes off the parachute," said Desai. "It’s a more sophisticated lander than the landing systems that we’ve previously flown."
Several factors could adversely affect the landing. High winds could make landing much more difficult. High landing speeds or too much tilt at landing will also risk damage to the spacecraft.
Upon a successful mission, the Phoenix team will be able to determine if there is water ice in the subsurface of Mars, how much exists and how it will be able to be used in the future.
"By having ice there, it helps future missions significantly because you can live off the land," said Desai. "You can melt the ice and have water so that, whenever we send humans, they have something to drink. So, you don’t have to bring water with you."
According to Desai, humans could also obtain oxygen on Mars from the water ice by conducting a typical, high school chemistry experiment that involves an electrical current in water separating the water into hydrogen and oxygen and using the oxygen to breathe.
"Knowing how much water is on Mars helps us get an idea of what resources are there so we can try to anticipate how we do future missions from that perspective," said Desai.