Jupiter Magnetospheric Orbiter the orbiter was proposed for a lift-off in 2020 together with ESA's Jupiter Ganymede Orbiter (JGO) from which it would undock upon its arrival at Jupiter in 2025/2026. However, the EJSM collaboration was disbanded and NASA renamed its initiative with Europa Multiple-Flyby Mission, ESA's Jupiter Icy Moon Explorer, and Roscosmos's Laplace-P. The JMO objective was to undertake detailed "in situ" studies of the magnetosphere of Jupiter as a template for an astrophysical magnetised disk for "3-point" investigations of the Jupiter system via synergistic observations with other orbiters. The size and weight of the JMO would have been limited to carry
Geological history of Mars of Paleozoic, Mesozoic, and Cenozoic. The same methodology was later applied to the Moon and then to Mars. Another stratigraphic principle used on planets where impact craters are well preserved is that of crater number density. The number of craters greater than a given size per unit surface area (usually million km) provides a relative age for that surface. Heavily cratered surfaces are old, and sparsely cratered surfaces are young. Old surfaces have a lot of big craters, and young surfaces have mostly small craters or none at all. These stratigraphic concepts form the basis for the Martian geologic timescale.