14 DAY TRIAL // Officials with the European Space Agency (ESA) announce that their Mars Express orbiter, currently flying low above the surface of the Red Planet, will carry out the closest-ever flyby of the Martian moon Phobos this Sunday, December 29.
During the event, the probe will be just 45 kilometers (28 miles) away from the moon, which will enable it to study the intricate nature of its weak gravitational field. The debate currently still rages on about the nature and origins of this diminutive moon.
Some experts argue that it formed out of ejecta material cast out into space when an ancient impactor hit Mars. Other scientists argue for the capture hypothesis, which holds that the object was an asteroid captured by our neighboring world's gravitational pull.
Mars Express will be traveling way too fast on Sunday to be able to capture any images of Phobos' surface. Additionally, the spacecraft will be entirely too close to its target for its powerful cameras to be able to zoom in and focus properly, Space reports.
However, ESA investigators say that the flyby will enable them to study the gravitational field around the small Martian moon, which measures no more than 18 kilometers (11.1 miles) in diameter. An average human, weighing around 68 kilograms (150 pounds), would weigh 56 grams (2 ounces) on Phobos.
No matter how small its gravitational field, the moon will still nudge Mars Express off its planned trajectory by a little bit. By analyzing this effect via tracking stations on Earth, researchers will be able to measure Phobos' pull in more detail than ever before. Additional data about its mass and density will also be derived from this flyby.
“By making close flybys of Phobos with Mars Express in this way, we can help to put constraints on the origin of these mysterious moons,” ESA Mars Express project scientist Olivier Witasse explains.
“We've been carrying out maneuvers every few months to put the spacecraft on track and, together with the ground stations that will be monitoring it on its close approach, we are ready to make some extremely accurate measurements at Phobos,” says Mars Express operations manager Michael Denis.
The spacecraft has been orbiting Mars for a decade. Its anniversary was on Christmas Day, when Mars Express officially reached its 10th year of operations in orbit. The vehicle achieved orbital insertion around Mars on December 25, 2003.