Posted by DrJeff on October 6th, 2009
Copyright 2009 | About this blog
Photo caption: Part of Mercury’s never before seen surface, from MESSENGER spacecraft data obtained during the first flyby on January 14, 2008.
You want to see spectacular? Click on the photo.
Credit: NASA/JHUAPL/Arizona State University, 2008.
This post is a Teachable Moment in the News.
The picture above was the central image for my recent Special Post on the MESSENGER spacecraft’s September 29, 2009 flyby of Mercury. It is an incredibly compelling image, and there is a great back-story for how it was produced. In the image caption at the Special Post I had invited you to read the story, but I suspect many missed the link. So I decided it was worthy of its own post!
Digital images taken of a planet by a spacecraft obviously provide views as seen from the spacecraft’s position—which changes over time. The set of images, with views of the planet from different angles, allows a 3-dimensional digital model of the planet’s surface to be created. You can then ask a remarkable question, “If I could place a camera at a location in space over there, and at this particular time, what would I see”? It’s a remarkable question because the spacecraft’s camera was never at that location in space and time, yet the data can be reassembled into an image as seen by a ‘virtual camera’ placed there. The resulting image is very real. It is the original data reassembled.
Why would you do this? Maybe because your hypothetical location offers some unique viewing angle not seen in the original images.
Just in time for this post, HERE is the surface of Mercury pieced together from multiple images by Mariner 10 in 1974-75 and during MESSENGER’s 3 flybys, including the latest on September 29, 2009. This global map of Mercury was just released on October 2, 2009.
The image above was created by the MESSENGER Team for the Voyage National Program overseen by my Center. It is an initiative dedicated to the public understanding of Earth’s place in space—and celebrates that we can even know it. Voyage is a scale model Solar System permanently installed on the National Mall in Washington, DC, in front of the Smithsonian Museums, and the Voyage national and international programs are permanently installing replicas in communities world-wide. The goal—100 Voyage model Solar Systems installed across the planet, for the story of our existence on Earth knows no national boundaries, and is a thread that binds all humanity.
Each of the Voyage exhibition’s 13 stanchions include a central image that captures the subject of the stanchion. We wanted a new central image for the Mercury stanchion that captured MESSENGER’s monumental achievement during its first flyby on January 14, 2008. The location of the virtual camera was chosen to provide a very dramatic view of the side of Mercury never before seen by the human race until MESSENGER’s encounter. The image was also created at a point in time when the image would include—Earth. We wanted a view of home from an alien world.
Earth was not in the camera’s field-of-view when MESSENGER was taking images of the unseen side in January 2008. So we moved a virtual camera to a place in space and time where Earth would be visible among the stars, and the newly revealed surface would be seen in dramatic fashion. The virtual camera for this image is placed in low Mercury orbit, on February 3, 2008, when the Earth would have been seen as a blue star-like object above the horizon (seen on the left side of the image). It is a real image of Mercury obtained from the MESSENGER data, and Earth and the star fields are superimposed at their proper locations. By the time this ‘virtual’ image was taken, MESSENGER was long gone, departing Mercury three weeks earlier. But the images she left behind allowed us to ‘see’ what would have been a truly remarkable site.
The image above is now part of the permanent Voyage exhibitions in three communities.
You’re probably a little curious about Voyage, and I’m very proud of it, so I thought I’d show you some photoalbums at Facebook. Here is Voyage in Kansas City, Missouri, along downtown Baltimore Avenue from the Power and Light Building to Union Station; in Houston, Texas, at Space Center Houston, the visitor center for NASA Johnson Space Center; and along the historic waterfront in Corpus Christi, Texas (the captions for the Corpus Christi photalbum are pretty funny—read them in order.) Voyage is also approved for installation on the State Capitol grounds in Des Moines, Iowa; in Inner Harbor in Baltimore, Maryland; and on the campus of the University of Central Florida in Orlando.
I will soon be doing a post on a one to 10-billion scale model Solar System—Voyage’s scale—to give you a true sense of the nature of our existence on a tiny world in a vast space. I’ll also provide you with links to lessons at grades K-2, 3-4, 5-8, and 9-12, and to an activity for families at home, so you can set up paper versions of Voyage in a local park. Students (off all ages) will be blown away.
And hey, you might think about a Voyage in YOUR community. If you want to explore the possiblity, contact me.
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