A Look Back at NASA History: A Tribute to the Mercury MESSENGER

Mercury in order to provide us with more insight than ever before about the planet.  It also happened to be the first spacecraft to successfully orbit Mercury, providing us with key information about the planet that we never knew before.  To this day, it’s recognized as one of the most historically significant spacecrafts thanks to its incredible findings, and its stunning innovations that allowed the historic mission to take place.

The Mercury MESSENGER

The Mercury MESSENGER served the purpose of investigating the planet Mercury, by orbiting it for a total of 4 years.  More specifically, its aim was to observe the planet’s chemical composition, geology, and magnetic field.  Its name stands for Mercury Surface, Space Environment, Geochemistry, and Ranging, and references the Roman god Mercury.

Its first launch was in August of 2004, aboard the Delta II rocket.  It did several flybys, flying by Earth once, Venus two times, and Mercury three times, first flying by Mercury in 2008.  It was only the second spacecraft to ever reach Mercury, following the Mariner 10 in 1975.  The MESSENGER’s first successful mission was completed in 2012, before impacting the planet’s surface for the first time in 2015.

Data was collected starting in April of 2011, and within just under a year, acquired almost 100,000 unique images.  At the same time, the spacecraft produced a 100% map of Mercury in 2013, along with detailed information about the planet’s magnetic field.  The mission also uncovered water ice on the planet’s north pole, confirming suspicions that NASA scientists had maintained for years.

The Beginning Stages

The mission was first proposed all the way back in 1998, with the intention of sending an orbiting spacecraft to Mercury, in order to learn more about the planet that had been explored the least.  Between 1975 and 1998, numerous proposals to return to Mercury were scrapped due to the high cost of actually orbiting the planet, and due to less efficient technology at the time that would have held back the mission from reaching its full objectives of discovery.

The spacecraft’s design was conceived at John Hopkins University Applied Physics University, where it was also built.  Costing $450 million to build, it weighed 2,400 pounds.  It also employed innovative communications technology, with two small deep transponders that allowed the spacecraft to remain in contact with the Deep Space Network, along with three advanced antennas. 

Two cameras were outfitted for the MESSENGER as well: a narrow-angle camera and a wide-angle camera, mounted to the spacecraft’s pivoting platform, to allow for full range of motion and the ability to capture detailed images on command.  This allowed the spacecraft to create a complete map of Mercury in color image.  Additionally, a gamma-ray spectrometer measured the planet’s emissions to determine its chemical composition, to a depth of 10 centimeters.  Meanwhile, a neutron spectrometer allowed for the recording of the planet’s hydrogen mineral composition, while a magnetometer measured the planet’s magnetic field.

The Launch

In August of 2004, the spacecraft saw its first launch at Cape Canaveral, in Florida.  The burn sequence lasted for 57 minutes, and was successful. It took another 9 years before it would arrive, due to the complications of bringing a spacecraft into Mercury’s orbit.  A dramatic velocity change is required while in transit, due to the heavy influence of the sun’s gravity well.  The thinness of Mercury’s atmosphere, meaning that spacecraft needs to constantly accelerate in order to accommodate for the sun’s pull.  This requires an enormous amount of fuel, which just isn’t realistic.  Instead, the spacecraft did a series of flybys, using gravity assist maneuvers to enter an elliptical orbit.  This unique trajectory came with some benefits, like allowing the spacecraft to record the impact of solar wind on Mercury, and accumulate more extensive imaging of the planet’s surface and exosphere.

In Conclusion

The Mercury MESSENGER was a groundbreaking spacecraft for its ability to bring back enormous amounts of information about Mercury, having discovered critical findings about its chemical makeup, its presence of ice water, its exosphere, its impact from solar wind, and its magnetic field.  Before its initial launch, it was long believed that making such intensive findings were impossible, due to the precarious nature of traveling to Mercury.  Its career ended in 2015, when it crashed into the planet’s surface, and because of its location, the crash was undetected as it occurred.  NASA finally confirmed the incident on April 30, 2015, saying goodbye to 4 years of incredible revelations and discoveries.

Its impact is still widely felt today, as insight into Mercury has allowed us to relate better to what was once the least-explored planet in our solar system.  Because of this, the legacy of the MESSENGER lives on.