Ten years ago, NASA's MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) satellite launched and flew to Mercury to orbit its surface, collect photos, and study its atmosphere.
Rob Gold, an astrophysicist at the Johns Hopkins Advanced Physics Laboratory outside Baltimore, helped persuade NASA on sending a satellite 58 million km away from Earth to orbit Mercury.
It has eluded even the most powerful telescopes because of Mercury’s proximity to the blinding sun.
|MESSENGER take a picture of the sun-lit side of Mercury [NASA]
But on the 10-year anniversary of its launch on August 3, the spacecraft MESSENGER has proven its worth by sending back more than 200,000 images - 10 times the number that had been hoped for.
It has tackled all the mission's core objectives: identifying the planet's surface properties, its exosphere, and the intriguing composition of its core elements and the impact of the solar wind.
But its biggest discovery suggests that craters on its North Pole contain water ice.
That conclusion has lit up the eyes of those who envision eventual human settlement in deep space.
"This is saying to us that one of the processes that takes place in our solar system can trap water and have it there if we ever get there," Gold told Al Jazeera.
Many of the craters, according to Brown University geologists Jennifer Whitten and James Head, were formed by volcanoes. Some of them are still active.
That offers one clue to the formation of Mercury, according to the scientists, which together with the other planets of the solar system, are believed to be four and a half billion years old.
Rich deposits of sulphur
The geochemical measurements taken have shown small amounts of iron but rich deposits of sulphur and sodium.
Those findings, said Lawrence Nittler of the Carnegie Institution of Washington, "show that the interior is highly chemically heterogeneous, providing important clues to the early geological history of the planet".
Over the next few months, MESSENGER will send back even higher-resolution images as it circles the planet to an even lower orbit.
The orbiter is currently less than 100km above the planet's surface.
Its fuel has lasted a bit longer than projected but as it loses altitude, the satellite is expected to crash sometime in April 2015.
The researchers will then take another year to sift through and analyse all of the data collected, but Mercury still harbours plenty of mysteries and very little of the planet remains known.
As a result, in 2016, the European and Japanese space agencies plan to launch two separate orbiters, each bound on a five-year journey to reach Mercury’s skies once again and understand its composition.