Prepare yourself for some goosebumps. The Mercury spacecraft MESSENGER took this series of images of Earth eight years ago today as it swung by the planet (again) en route to its final destination.
Few humans have seen the Earth as an entire orb. Only a handful of missions, all in the Apollo era, have ventured beyond low Earth orbit. The people who traveled furthest were Jim Lovell, Fred Haise and Jack Swigert during Apollo 13, when their spacecraft (which had been crippled by an explosion) looped around the moon on the way home.
MESSENGER is happily traveling around Mercury these days and recently recorded a cool series of images showing the planet as a colorful, spinning sphere. The spacecraft — the first to do an extended stay around that planet — has shown scientists a lot of things, including the discovery of water ice and organics.
Thanks to Astronomy Picture of the Day for reminding us of this video.
While watching the video, I wondered how fast the MESSENGER spacecraft was moving away from Earth when those images were taken. I can’t seem to find anywhere online with that information. Does anyone here know?
how long in time is it? around 5 days isn it?
The big blue marble…
The above movie is comprised of 358 frames taken over a period of 24 hours; it follows the Earth through one complete rotation. The spacecraft was 40,761 miles (65,598 kilometres) above South America at the start of the first frame on Aug. 2, 2005; it was 270,847 miles (435,885 kilometres) away from the Earth when the last frame was taken on Aug. 3, 2005.
Running the simulation from JPL “Eyes on the Solar System” gives the following information for the flyby day of August 2,2005.
At 00:00 U.T. Messenger was 202,643.4 miles from Earth travelling at a relative speed of 9,718 m.p.h.
Closest approach of 1,464.8 miles was at 19:13:10 U.T. travelling at 22,963 m.p.h.
Highest relative speed of 23,167 m.p.h. was at 19:15:23 U.T. and 1505.7 miles relative distance.
Finally at end of day 00:00:00 U.T August 3, Messenger was 57118.5 miles from Earth travelling at 11,098 m.p.h.
So Messenger travelled approximately 260,000 miles in 24 hours at an average speed of 10,800 m.p.h.
According to the MESSENGER website, the average velocity of the spacecraft during the course of its journey to Mercury was approximately 84,500 m.p.h (about 38 km/s) relative to the Sun.
It would be interesting is someone (with time) did a science experiment and calculate it just using these captured frames. Earth’s diameter is known. The time between the first and last image is also know.