lpetrich
Contributor
Earlier this evening, US Pacific Time, the BepiColombo spacecraft was successfully launched to Mercury atop an Ariane 5 rocket from ESA"s spaceport in Kourou, French Guiana, South America (BepiColombo Spacecraft on 7-Year Trek to Mercury for Europe and Japan, 
BepiColombo).
BepiColombo will be the third spacecraft to visit that planet, after Mariner 10 (3 flybys in 1974-75) and MESSENGER (orbited 2011-15).
It will take seven years to make the trip, flying by the Earth once, Venus twice, and Mercury six times, and also using its ion engines for much of the trip. These flybys and the ion-engine thrust are all necessary to slow down the spacecraft so that it will be able to go into orbit around Mercury without needing much velocity change or delta-V.
The next scheduled event is flying by the Earth about 1 1/2 years from now in early 2020. Late that year, the spacecraft will fly by Venus, and 1 1/3 years later, in mid 2021, it will fly by Venus again. Two months later, it will fly by Mercury, after five more flybys, it will go into orbit around that planet late in 2025. It will then observe the planet and its environs for the next 2 or 3 years.
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As the spacecraft travels, its operators will use tracking data to help improve two tests of general relativity, "post-Newtonian" parameters gamma and beta. The first one is (amount of space curvature) / (amount of time curvature), and the second one is the amount of nonlinearity in the time curvature. The Newtonian limit is the lowest order of that curvature. The first one is involved in the delay and deflection of light and radio waves near massive objects, and both of them are involved in extra orbit precession over what one would predict from the planets pulling on each other.
That extra precession is most easily observable for Mercury, and it was discovered in the mid nineteenth century by Urbain Leverrier. He attributed it to an intra-Mercurian planet or planets, but despite several claimed observations, it was not possible to assemble a coherent orbit from them, and astronomers grew skeptical of the existence of such planets. Over the last century, upper limits on the sizes of such putative planets have been forced far down, recently to some 20 kilometers, the size of a small asteroid.
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The spacecraft itself has three parts: the Mercury Transfer Module, the Mercury Planetary Orbiter, and Mio (Mercury Magnetospheric Orbiter). The MTM will propel and support the MPO and Mio for the trip, and it will detach shortly before MPO goes into orbit with Mio. After entering orbit, MPO will release Mio and then propel itself into its final orbit closer to the planet.
Mio (MMO) is Japan's contribution to this mission. It will have some instruments for measuring the magnetic field and the interplanetary medium at the spacecraft.
MPO contains instruments for exploring the planet's surface and atmosphere -- a very thin atmosphere. It will have cameras, spectrometers for visible light, IR, UV, X-rays, gamma rays, neutrons, and charged particles, and also a laser altimeter -- all contributed by several nations.
Omitted for budgetary reasons was a proposed lander and rover.
But if this mission is a success, it will return a lot of nice data on Mercury.
BepiColombo).BepiColombo will be the third spacecraft to visit that planet, after Mariner 10 (3 flybys in 1974-75) and MESSENGER (orbited 2011-15).
It will take seven years to make the trip, flying by the Earth once, Venus twice, and Mercury six times, and also using its ion engines for much of the trip. These flybys and the ion-engine thrust are all necessary to slow down the spacecraft so that it will be able to go into orbit around Mercury without needing much velocity change or delta-V.
The next scheduled event is flying by the Earth about 1 1/2 years from now in early 2020. Late that year, the spacecraft will fly by Venus, and 1 1/3 years later, in mid 2021, it will fly by Venus again. Two months later, it will fly by Mercury, after five more flybys, it will go into orbit around that planet late in 2025. It will then observe the planet and its environs for the next 2 or 3 years.
-
As the spacecraft travels, its operators will use tracking data to help improve two tests of general relativity, "post-Newtonian" parameters gamma and beta. The first one is (amount of space curvature) / (amount of time curvature), and the second one is the amount of nonlinearity in the time curvature. The Newtonian limit is the lowest order of that curvature. The first one is involved in the delay and deflection of light and radio waves near massive objects, and both of them are involved in extra orbit precession over what one would predict from the planets pulling on each other.
That extra precession is most easily observable for Mercury, and it was discovered in the mid nineteenth century by Urbain Leverrier. He attributed it to an intra-Mercurian planet or planets, but despite several claimed observations, it was not possible to assemble a coherent orbit from them, and astronomers grew skeptical of the existence of such planets. Over the last century, upper limits on the sizes of such putative planets have been forced far down, recently to some 20 kilometers, the size of a small asteroid.
-
The spacecraft itself has three parts: the Mercury Transfer Module, the Mercury Planetary Orbiter, and Mio (Mercury Magnetospheric Orbiter). The MTM will propel and support the MPO and Mio for the trip, and it will detach shortly before MPO goes into orbit with Mio. After entering orbit, MPO will release Mio and then propel itself into its final orbit closer to the planet.
Mio (MMO) is Japan's contribution to this mission. It will have some instruments for measuring the magnetic field and the interplanetary medium at the spacecraft.
MPO contains instruments for exploring the planet's surface and atmosphere -- a very thin atmosphere. It will have cameras, spectrometers for visible light, IR, UV, X-rays, gamma rays, neutrons, and charged particles, and also a laser altimeter -- all contributed by several nations.
Omitted for budgetary reasons was a proposed lander and rover.
But if this mission is a success, it will return a lot of nice data on Mercury.
