MAVEN: In Search of the Missing Atmosphere
Wayne Sidney and his team of engineers have had a pretty interesting job the last 10 months. And it’s about to turn more dramatic.
Last Nov. 18, NASA launched the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft aboard a United Launch Alliance Atlas V, propelling it on a 442 million mile journey to Mars to study the red planet’s upper atmosphere.
On Sunday, Sept. 21, MAVEN will arrive at its destination, where it will fire its thrusters to slow the spacecraft, allowing the planet’s gravity to capture and insert MAVEN into orbit.
Sidney, MAVEN flight team lead at Lockheed Martin, and those he leads have been operating the spacecraft since its launch and monitoring its progress en route to Mars.
As MAVEN has progressed on its course, flight controllers have been updating mission parameters and injecting scenarios into the timeline to identify potential problematic events and head anomalies off at the pass.
“We’ve been looking at what-if scenarios, what if this failed or this happened at this time, and playing through all those scenarios to see if there are changes we can make to be able to recover and still do the thruster burn,” said Sidney. “Since March, we’ve been focusing to make sure all these are unlikely scenarios.”
Six days before orbital insertion, the team will load the final parameter files, sequences and contingency products to the spacecraft to execute the insertion. Three days out, the team will follow up by sending a command to activate the insertion sequence.
“At that point, all spacecraft activities are executed on time sequences,” said Sidney. “There is a precise orchestration of activities to get the spacecraft configured and oriented to the right attitude, all at the right time.”
The spacecraft does this autonomously, 138 million miles away.
Beyond those activities, the team expects the actual day MAVEN enters orbit to be relatively quiet. The team will monitor the spacecraft from Lockheed Martin’s Mission Support Area near Denver, checking telemetry and ensuring no anomalies are present.
The team will be ”on console” when MAVEN closes in on Mars, and MAVEN program management from NASA Goddard and the University of Colorado will be there with the team. It is at that point Sidney and his crew will ensure the spacecraft is approaching at the right angle.
“One major challenge of getting to Mars is to make sure we’re coming in where we think we are relative to the planet,” said Sidney. “Currently, the navigation solutions are showing very consistently that we’re definitely right where we want to be in terms of our approach box. Once the orbiter starts feeling Martian gravity, solutions solidify.”
NASA’s Jet Propulsion Laboratory manages navigation for the mission.
Two opportunities exist for us to perform trajectory corrections from the ground – one about 24 hours out and another around six hours before. As team members start measuring the effects of Mars on MAVEN’s trajectory, they can respond with predetermined sequences.
“You don’t want to come in so low, you hit the planet,” said Sidney. “So, if we’re out of the box, it’s better if we come in a little high. We have those contingency maneuvers pre-built to make adjustments quickly, if needed, to keep us on path.”
Sidney admits that putting a spacecraft into orbit around Mars isn’t as dramatic as landing one on the surface, but it’s also not an everyday event.
“I’ve been fortunate to have been on six Mars orbiter missions over my career, and even though there are many similarities, each has its own personality. Mars is a challenge, and we’re fully aware of what’s at stake,” said Sidney. “Most of the folks on our MAVEN flight team are very experienced on spacecraft operations and have worked on Mars Reconnaissance Orbiter, Mars Odyssey, Juno or a number of other missions. We definitely have an experienced team working to get MAVEN into orbit and ready for science.”
Critical Transition Phase
Once MAVEN is in orbit, the really hard work begins, as it marks the start of a critical transition phase to prepare the spacecraft to perform its one-year science mission. It is during this phase the team will steer the spacecraft into its final science orbit, prepare science instruments and position the spacecraft to avoid the remnants of a comet.
“This is the beginning of a very intense period for us,” said Sidney. “During these five weeks, we will perform eight propulsion maneuvers to get us in final orbit to conduct the science mission. We will conduct several deployments of science booms to extend instruments for operation, then calibrate those instruments. And we will ensure everything is pointed and aligned right.”
Earlier, researchers spotted a comet on approach toward Mars and calculated it would be in the vicinity of the planet around the time MAVEN entered orbit around the planet. NASA trajectory estimates determined the comet wouldn’t strike Mars, but concern about the hazards posed by the comet’s debris field persists.
“We’re taking proactive steps to protect MAVEN from the comet,” said Sidney. “We will turn the vehicle sideways to minimize exposure, and we will perform a maneuver so MAVEN will be shielded by the planet. It will take about an hour and a half to get beyond the debris field and resume normal operations.”
The Science of the Mission
The efforts of the flight team will position MAVEN for its mission, to study Mars’ upper atmosphere, how it interacts with the sun and solar winds and how that interaction may have led to the loss of atmosphere and water over time.