A Message from Mercury
This is a picture taken by the MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) spacecraft, currently just inside the orbit of Mercury at less than 1/3 the distance of Earth from the Sun. It shows the Earth and Moon from 114 million miles away. The Earth and Moon are overexposed to get the star background, but here we are -- from far, far away.
Pictures like this one always make me think again about our place in the grand scheme of things. The goal of the MESSENGER spacecraft is to learn more about the planet Mercury, but one of the neatest things about this kind of mission is that we always end up learning something more about our own home planet. Exploration is a wonderful thing – whether it’s in low Earth orbit on the ISS or many millions of miles away, we are learning amazing things to help us improve life here on Earth.
Mercury is the first rock from the Sun and we know less about it than any of the other planets in our solar system. Like Earth, Mercury is a rocky, terrestrial planet (there are 2 others: Venus and Mars). Closest to our Sun, Mercury has the shortest year and endures more solar radiation than any planet, and its battered surface is perhaps one of the oldest in the solar system. It experiences the largest daily range in temperatures (from daytime hottest at 840 degrees F – hot enough to melt lead, to nights dipping to -350 degrees F – cold enough to turn oxygen from a gas to liquid). Also, discovering how Mercury has sustained a magnetic field while larger bodies either lost theirs (as Mars did) or show no sign of ever having one (like Venus) will help us understand how our own planet generates its protective magnetic field.
The picture taken of Earth from the MESSENGER spacecraft is beautiful, but it doesn’t really even hint at how beautifully and perfectly placed our planet Earth is in the solar system to take care of us. When MESSENGER looks at Mercury and discovers new and exciting things about that planet, it will be especially interesting to discover more new and exciting things about our own.