NASA’s MESSENGER mission is a space probe launched in August, 2004. Its planned itinerary includes no fewer than six planetary flybys (one of Earth, two of Venus, and three of Mercury) before it enters orbit around Mercury in March, 2011.
In the past I’ve sometimes griped about Earth flybys of space probes powered by plutonium RTGs; not so much to argue that the risks of a high-altitude vaporization and subsequent release of plutonium aren’t worth it, but to call for a more-honest discussion of the risks than has sometimes been offerred by mission supporters.
But MESSENGER doesn’t represent a problem in that area; its destination in the inner solar system means that it will have plenty of Sun power from its solar panels, and so it apparently is plutonium-free.
And the Earth flyby already happened, anyway, on August 2, 2005. I talked in PhotosFromTheSpaceShuttleColumbia about the importance of having human eyes in space to deliver perspective-changing images, but even if a robot can’t be as good at catching opportunistic snapshots as a human being, it can still deliver some amazing views.
Like the one on display here: Earth departure movie. The official site’s description:
The Mercury-bound MESSENGER spacecraft captured several stunning images of Earth during a gravity assist swingby of its home planet on Aug. 2, 2005. Several hundred images, taken with the wide-angle camera in MESSENGER’s Mercury Dual Imaging System (MDIS), were sequenced into a movie documenting the view from MESSENGER as it departed Earth.
Comprising 358 frames taken over 24 hours, the movie follows Earth through one complete rotation. The spacecraft was 40,761 miles (65,598 kilometers) above South America when the camera started rolling on Aug. 2. It was 270,847 miles (435,885 kilometers) away from Earth – farther than the Moon’s orbit – when it snapped the last image on Aug. 3.