It was a close call indeed earlier this week, as NASA's MAVEN orbiter had maneuvered out of the path of the Martian moon Phobos. This small correction helped the spacecraft avoid a collision that would have been due to take place today.
According to an official press release from NASA, the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft is closing in on its third year orbiting Mars, as it studies the planet's atmosphere, ionosphere, and how it interacts with the sun and its solar winds. This week's collision avoidance maneuver marked the first time in that near-three-year span that NASA had to make adjustments to ensure MAVEN misses the crater-filled Martian moon.
Phobos, according to a 2016 report from Space.com, orbits just about 4,200 miles above Mars, making it extremely close to its host planet. (Other reports estimate the moon as being about 3,700 miles above.) The Space.com report described the satellite as a "doomed" moon, as it has been drawing closer to Mars over the past several centuries, and is destined to break up or get sucked into the Red Planet's surface.
The moon was first believed to exist early in the 17th century by famed astronomer Johannes Kepler, who theorized that Mars might have two moons due the fact it is located between Earth and Jupiter, which have one and four satellites respectively. But it was only in 1877 when American astronomer Asaph Hall confirmed Phobos' existence, doing so just six days after he discovered Deimos.On February 28, the MAVEN spacecraft performed a "minor rocket burn," which, according to Spaceflight Now, lowered its speed by less than one mile per hour. That tiny decrease in speed allowed MAVEN to avoid colliding with Phobos, with the craft now expected to miss the moon by about two and a half minutes.
MAVEN, India's Mars Orbiter Mission, and the European Space Agency's Mars Express all make elliptical paths and frequently cross paths with other probes, as well as Phobos itself. Considering this, as well as the peculiar size and shape of the Martian moon Phobos, NASA said that there was a good chance that MAVEN would collide with Phobos on Monday, March 6. Both the spacecraft and the moon were expected to be about seven seconds within each other, had they reached their orbit crossing point.
In a prepared statement, MAVEN principal investigator Bruce Jakosky expressed his pleasure in how NASA and its Jet Propulsion Lab, in particular, had acted quickly and accurately when conducting the collision avoidance maneuver.
"Kudos to the JPL navigation and tracking teams for watching out for possible collisions every day of the year, and to the MAVEN spacecraft team for carrying out the maneuver flawlessly."
NASA's collision avoidance framework was first announced in 2015 and is known as the Multi-Mission Automated Deep Space Conjunction Assessment Process. This formal framework is facilitated by JPL scientists, who notify spacecraft operators about potential collisions and close encounters. The agency also has its Deep Space Network, which is a group of antennas located in various parts of the world – California, Spain, and Australia – that provides tracking services to orbiters from multiple space agencies, including NASA itself and ESA.
In a meeting held on February 22, JPL Mars exploration director Fuk Li underscored the need for proper tracking and communications systems, as there are seven more spacecraft on track to arrive at Mars by 2021, joining the active fleet of eight spacecraft as of the present.
"All these missions, potentially, will also require very detailed tracking in order to do the precision navigation to make sure they are entering orbit the right way. The month of February (2021), and a few weeks before that, will be extremely hectic, but we look forward to such things because of the science that will come after that."
With the growing importance of the above systems and the fact that MAVEN had had such a close call with the Martian moon, it's safe to say that this week's maneuver may be followed by more in the future.
[Featured Image by NASA]