Gravity on Mercury: With a mean radius of about 2,440 km and a mass of 3.30 × 10 23 kg, Mercury is approximately 0.383 times the size of Earth and only 0.055 as massive. Mercury Inside and Out. Mercury has just 38% the gravity of Earth, this is too little to hold on to what atmosphere it has which is blown away by solar winds. ρ substance = density of the fluid or substance [kg/m 3] Like its fellow terrestrial planets, Mercury has a central core, a rocky mantle and a solid crust. The acceleration of gravity on the surface of Mercury, and therefore the weight of any mass located there, is roughly 37.7% of what it is on Earth's surface. The MESSENGER spacecraft orbiting Mercury has been in a ∼12-hour eccentric, near-polar orbit since 18 March 2011 (see the Perspective by McKinnon). Gravity on Mercury is 38% of the gravity here on Earth. (Special Relativity fails catastrophically at predicting the orbit of Mercury because it omits gravity entirely.) how much room is there to live on the surface of mercury?? (p.214, published online 21 March) present the most recent determination of Mercury's gravity field, based on radio tracking of the MESSENGER spacecraft between 18 March and 23 August 2011. This means that Mercury is very dense. Mercury has less mass than earth,the surface gravity on mercury is less than the surface gravity on Earth.The surface gravity on Mercury is about 38% of the surface gravity on Earth,so that means if you weighed 100kg then you would only be 38kg on Mercury. Smith et al. SG = ρ substance / ρ H2O  SG = Specific Gravity of the substance. A man weighing 980 Newtons on Earth (about 220 pounds), would only weigh about 372 Newtons (83.6 pounds) landing on the planet’s surface. Mercury formed about 4.5 billion years ago when gravity pulled swirling gas and dust together to form this small planet nearest the Sun. However while gases escape into space they are constantly being replenished at the same time by the same solar winds, radioactive decay and … Gravity on Mercury is nearly the same as it is on Mars, about one-third the gravity on Earth, despite the fact that Mars is much larger. Newtonian gravitation fails slightly with Mercury because it doesn’t take into account General Relativity. Specific Gravity (Relative Density) - SG - is a dimensionless unit defined as the ratio of the density of a substance to the density of water - at a specified temperature and can be expressed as.