 "NASA beefs up traffic monitoring to keep Mars missions safe")
USA’s National Aeronautics and Space Administration (Nasa) has beefed up a process of traffic monitoring, communication and manoeuvres planning to ensure Mars orbiters stay away from each other.
In early January, two spacecraft orbiting around the planet came within two km of each other. Last year two new spacecraft started orbiting Mars, bringing the number of orbiters to five — the highest ever. Nasa’s Mars Atmosphere and Volatile Evolution (MAVEN) and India’s Mars Orbiter Mission joined the 2003 Mars Express from the European Space Agency and two from Nasa — the 2001 Mars Odyssey and the 2006 Mars Reconnaissance Orbiter
The newly enhanced collision-avoidance process, according to Jet Propulsion Laboratory (JPL), also tracks the approximate location of Nasa’s Mars Global Surveyor, a 1997 orbiter no longer working. JPL is a federally funded research and development centre for robotic exploration of the solar system, managed for Nasa by the California Institute of Technology.
In early January, two spacecraft orbiting around the planet came within two km of each other. Last year two new spacecraft started orbiting Mars, bringing the number of orbiters to five — the highest ever. Nasa’s Mars Atmosphere and Volatile Evolution (MAVEN) and India’s Mars Orbiter Mission joined the 2003 Mars Express from the European Space Agency and two from Nasa — the 2001 Mars Odyssey and the 2006 Mars Reconnaissance Orbiter
The newly enhanced collision-avoidance process, according to Jet Propulsion Laboratory (JPL), also tracks the approximate location of Nasa’s Mars Global Surveyor, a 1997 orbiter no longer working. JPL is a federally funded research and development centre for robotic exploration of the solar system, managed for Nasa by the California Institute of Technology.
Traffic management at Mars is much less complex than in Earth orbit, where over 1,000 active orbiters plus additional pieces of inactive hardware add to hazards. As Mars exploration intensifies, though, and will continue to do so with future missions, space agencies are intensifying the monitoring. The new process was established to manage this growth as new members are added to the Mars orbital community in years to come.
All five active Mars orbiters use the communication and tracking services of NASA's Deep Space Network, which is managed at the Jet Propulsion Laboratory (JPL). This brings trajectory information together, and engineers can run computer projections of the future trajectories out to a few weeks ahead for comparisons, said JPL on their site.
It's not just the total number that matters, but also the types of orbits missions use for achieving their science goals. MAVEN, which reached Mars on September 21, 2014, studies the upper atmosphere. It flies an elongated orbit, sometimes farther from Mars than NASA's other orbiters and sometimes closer to Mars, and thus it crosses altitudes occupied by those orbiters. For safety, NASA also monitors positions of ESA's and India's orbiters, which both fly elongated orbits.
According to JPL, mission teams for the relevant orbiters, like ISRO's mission team, are notified in advance when projections indicate a collision is possible, even if the possibility will likely disappear in subsequent projections. This situation occurred on New Year's weekend, 2015. Previously, only the Odyssey and MRO teams chatted about such matters. Now, NASA monitors data non-stop.
"Previously, collision avoidance was coordinated between the Odyssey and MRO navigation teams," said Robert Shotwell, Mars Program chief engineer at NASA's Jet Propulsion Laboratory, Pasadena, California, was quoted on the JPL website as saying. "There was less of a possibility of an issue. MAVEN's highly elliptical orbit, crossing the altitudes of other orbits, changes the probability that someone will need to do a collision-avoidance manoeuver. We track all the orbiters much more closely now. There's still a low probability of needing a manoeuver, but it's something we need to manage."