KinetX Aerospace, the first commercial company to navigate any spacecraft to distant planetary bodies, announced that it has successfully guided the MESSENGER spacecraft through its final and perhaps most challenging mission phase. MESSENGER, a NASA spacecraft built and operated by the Johns Hopkins University Applied Physics Laboratory (APL), was launched in August 2004 and has been in orbit around the planet Mercury collecting data since March 2011.

During all that time, KinetX has been responsible for navigating the spacecraft to arrive at the planet, and then for maintaining precise knowledge of the spacecraft's position while in orbit. Having now exhausted all of its onboard fuel, MESSENGER is expected to impact the planet on Thursday, April 30 in a spectacular conclusion to a highly successful mission.

There have been numerous navigation challenges faced by the MESSENGER team from the start. In one of the most complex interplanetary trajectories ever attempted, the spacecraft flew by Earth once, Venus twice, and Mercury three times before becoming the first spacecraft to orbit Mercury.

For most of the orbital phase of the mission, the highly eccentric orbit was designed to allow science instruments to acquire high-resolution images and other measurements of the planet from distances as close as 200 kilometers from the surface. But the orbit has evolved over time as a result of the unrelenting gravitational pull of the Sun, and for the past two years the spacecraft's closest approach altitude has been progressively decreasing with each orbit.

Starting in March 2015, the mission began its final phase, dubbed the "hover campaign" and so named because a series of orbit-correction maneuvers caused the spacecraft's closest approach to "hover" within a very-low-altitude band for more than two months. This series of maneuvers has delayed the probe's inevitable impact onto Mercury's surface.

Onboard fuel used to raise the closest approach distance was exhausted on April 6, and even the helium gas originally used as pressurant in the propulsion system was depleted during the final maneuver on April 28.

During the final mission phase the spacecraft skimmed over the surface, approaching as low as 5 km above the planet, providing unprecedented opportunities to collect extraordinarily high-resolution images and science data. Navigating a spacecraft so close to a planet's surface had never been attempted before and was fraught with risk. An onboard laser altimeter provided excellent confirmation of the KinetX navigation team's altitude predictions, and the hover campaign has been a huge success, capping off one of the most successful missions in the history of space exploration.

"The MESSENGER mission presented new technical challenges for mission design and navigation that were successfully met through close cooperation and innovation by the APL and KinetX flight operations teams," said Dr. Bobby Williams, who leads the KinetX Space Navigation and Flight Dynamics group in Simi Valley, California.

The Principal Investigator for the MESSENGER mission, Prof. Sean Solomon of Columbia University's Lamont-Doherty Earth Observatory, praised the work of the KinetX team by saying, "With five major propulsive maneuvers and 16 trajectory-correction maneuvers prior to orbit insertion, as well as 18 orbit-correction maneuvers once in orbit, the MESSENGER mission has kept our navigation team on their toes for more than a decade.

The KinetX team has been fully up to the task. They have been an integral part of the engineering and mission operations teams that have enabled an outstanding scientific return from the MESSENGER project."

Although the MESSENGER mission is nearly over, there are still numerous challenges ahead for the KinetX team. KinetX is the lead organization responsible for navigating the New Horizons spacecraft (also built and operated by APL), which is on course to fly by Pluto on July 14, 2015.

And when the OSIRIS-REx spacecraft launches in September 2016, KinetX, working with NASA's Goddard Space Flight Center, will be responsible for navigating the spacecraft to rendezvous with the asteroid Bennu and return a sample to Earth. The success of KinetX on MESSENGER and its other deep space missions proves that this is a company at the forefront of the commercialization of space, and one to be watched.