Mercury orbits quickly around the Sun and scientists seeking to understand its mysteries have quickly identified a spacecraft capable of reaching it within sufficient timeframe.
Slowing a spacecraft with flybys may be straightforward, but getting it to Mercury’s speed requires more complicated methods. Here’s how scientists plan to achieve their goal.
Mariner 10
Chen-Wan Yen had conducted extensive calculations at JPL orbital dynamics specialist Chen-Wan Yen had demonstrated in the late 1980s that multiple flybys of Mercury combined with modest propulsive maneuvers could put a spacecraft into orbit around it and provide comprehensive analyses of its surface, atmospheric components, and physical characteristics from orbit.
Mariner 10 was launched on time and returned over 2,800 television photographs of Mercury. These revealed its lunar-like surface pockmarked with craters and scars as well as chains of steep cliffs possibly formed by volcanic activity in Mercury’s past. Furthermore, Mariner 10 photographed a giant impact basin called Caloris Basin; data indicated it had both an exosphere composed of hydrogen and helium captured from solar wind as well as a massive core rich with iron.
However, despite its considerable accomplishments, the Mercury orbiter mission never received full approval by NASA; as a result, American planetary science fell into what many refer to as an extended hiatus known as “the lost decade.”
MESSENGER
The National Aeronautics and Space Administration’s MESSENGER spacecraft revolutionized our understanding of Mercury during its four-year orbital mission that ended in April 2015. Photos and other data revealed, for example, that Mercury’s northern pole contains water ice and organic compounds and that crater formation occurred over different timescales.
Launched August 3, 2004, MESSENGER used multiple gravity assists from flybys of Earth, Venus, and Mercury to reduce its speed relative to the Sun so its main rocket engine could finish slowing it enough for planetary orbit insertion. This reduced onboard propellant requirements but increased travel distance over time.
MESSENGER returned photos and formatted data totalling more than 10 terabytes to NASA’s Planetary Data System archive during its mission, inspiring further modern exploration efforts like bepiColombo launched by European Space Agency and Japanese Aerospace Exploration Agency that’s expected to arrive at Mercury by 2025.
BepiColombo
BepiColombo was launched from Kourou in French Guiana on 20 October 2018 to take scientific lead in exploring Mercury. Comprising an MTM and MPO developed jointly by ESA and JAXA, bepiColombo will begin exploring Mercury scientifically for years.
Both orbiters will study Mercury from various perspectives. Furthermore, their instrument payloads differ significantly from those included on MESSENGER by carrying additional instruments not found there – including thermal infrared spectrometer and plasma physics instruments that will enhance our knowledge of Mercury exosphere dust environment such as altitude distribution and temporal variation as well as role played by micrometeoroids and comets as source processes.
The MTM and MPO were built for a seven year journey to Mercury that includes flybys, electric propulsion arcs, coast arcs and high temperatures up to 400degC on one side and -190degC on the other. A special solar array is tilted in order to avoid excessive temperatures while providing enough power to run their thrusters at full strength.
Future Spacecraft
Technology necessary to explore outer space is ever evolving, from sending robot rovers across to Jupiter’s moons in hopes of discovering signs of life from an earlier era.
Future spacecraft might include self-repairing capabilities. A prototype has recently completed a test mission.
Other futuristic projects seek to advance current technologies for improved space travel. One such futuristic endeavor is Project Icarus, which involves reconceptualizing Daedalus spacecraft using fusion rockets powered by explosive annihilation of matter and antimatter to make space travel more effective.
Private companies also play an essential part in human spaceflight. NASA’s Commercial Crew Program relies heavily on SpaceX and Boeing for building spacecraft to carry astronauts into orbit at a fraction of the cost associated with riding aboard Russia’s Soyuz capsule. Such vehicles will allow humans to return to the Moon and eventually visit Mars via Artemis program’s crewed launch in 2024.