Follow this link to skip to                                      the main content

Web Broadcasts

Text Size

MESSENGER Webcast: Science and Technology
Dr. Ralph McNutt's Presentation

Cheryle Mako: Hello and welcome to NASA Direct! I'm Cheryle Mako and I'm your host for this exciting pre-launch coverage of NASA's MESSENGER mission to Mercury. We are live in the NASA Direct! Studio at the Kennedy Space Center in sunny Florida.

Over the next two days, some of NASA's finest scientists and engineers will share fascinating information about the least explored planet in our Solar System and the spacecraft that will be going there. Some of our experts will even answer your questions live! And, we'll be announcing the names of our NASA Direct question board prize winners at the end of each broadcast.

There are few who know the science behind the MESSENGER mission better than our guest today. And we are lucky to have MESSENGER's project scientist, Dr. Ralph McNutt, live in our studios.

He'll be answering questions you submitted a little later. First, Dr. McNutt dives into the science of the Messenger Mission.

Dr. Ralph McNutt: I'm Ralph McNutt, the project scientist for NASA's MESSENGER mission to Mercury. The question that a lot of people ask is, why are we going to Mercury in the first place? We've actually been there once before with the Mariner 10 mission back in 1974 and 1975. It was a flyby mission and we only saw half of the planet.

Right now, we've got a planet that's in our own neighborhood that we really don’t know what it looks like, if I were trying to characterize the whole place. We do know a lot of interesting things from the Mariner mission, however. We know that there's a magnetic field which nobody thought that there should be one of. We know that Mercury is very dense, a lot denser than we thought it would be. As a matter of fact, if you take into account the compression of the Earth due to the Earth's gravity, Mercury is actually denser than the Earth is.

What we think that means is that the metal to silicate ratio is a lot higher on Mercury than it is on Earth, and that means something about exactly how this inner member of the terrestrial planets evolved in the first place.

There's four terrestrial planets in the Solar System -- Mercury, Venus, Earth and Mars -- and of course, there's similarities and differences between the four. With Mercury being this close to the Sun and having this high and compressed density, we think that it may be the key to really understanding a lot of the mysteries of how the Earth evolved, and why Earth and Mars and Venus all ended up being so different from each other.

In terms of actually getting usable data in terms of the overall MESSENGER mission involves a variety of flybys in order to slow the spacecraft down enough so that we can finally brake into orbit around Mercury. So there will be two Venus flybys where they will be calibrating the instruments, taking a look at the planet and perhaps being able to actually do some new science at Venus with some instruments that have never been there before. But the real first scientific payload will, of course, be with the first Mercury flyby in January 2008 where, with that flyby, we'll actually be able to see part of the unseen hemisphere and get a handle on what the rest of Mercury really looks like.

As we go with the mission, coming up towards the launch and going through the mission, people will be able to follow us on our Web site, where we'll be posting images and data. That's at

So this gives a summary of what the MESSENGER mission is going to be doing, a little bit of an idea of the kind of measurements we're going to be taking during our one-year tour of this very strange world that's hard to see from the Earth, and that will finally be able to reach out into space using spacecraft to get a handle on.