A NASA spacecraft's third and final flyby of the planet Mercury gives scientists, for the first time, an almost complete view of the planet's surface and provides new scientific findings about this relatively unknown planet.
The Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft, known as MESSENGER, flew by Mercury on Sept. 29. The probe completed a critical gravity assist to remain on course to enter into orbit around Mercury in 2011. Despite shutting down temporarily because of a power system switchover during a solar eclipse, the spacecraft's cameras and instruments collected high-resolution and color images unveiling another 6 percent of the planet's surface never before seen at close range.
Approximately 98 percent of Mercury's surface now has been imaged by NASA spacecraft. After MESSENGER goes into orbit around Mercury, it will see the polar regions, which are the only unobserved areas of the planet.
"Although the area viewed for the first time by spacecraft was less than 350 miles across at the equator, the new images reminded us that Mercury continues to hold surprises," said Sean Solomon, principal investigator for the mission and director of the Department of Terrestrial Magnetism at the Carnegie Institution of Washington.
Many new features were revealed during the third flyby, including a region with a bright area surrounding an irregular depression, suspected to be volcanic in origin. Other images revealed a double-ring impact basin approximately 180 miles across. The basin is similar to a feature scientists call the Raditladi basin, which was viewed during the probe's first flyby of Mercury in January 2008.
"This double-ring basin, seen in detail for the first time, is remarkably well preserved," said Brett Denevi, a member of the probe's imaging team and a postdoctoral researcher at Arizona State University in Tempe. "One similarity to Raditladi is its age, which has been estimated to be approximately one billion years old. Such an age is quite young for an impact basin, because most basins are about four times older. The inner floor of this basin is even younger than the basin itself and differs in color from its surroundings. We may have found the youngest volcanic material on Mercury."
One of the spacecraft's instruments conducted its most extensive observations to date of Mercury's exosphere, or thin atmosphere, during this encounter. The flyby allowed for the first detailed scans over Mercury's north and south poles. The probe also has begun to reveal how Mercury's atmosphere varies with its distance from the sun.
"A striking illustration of what we call 'seasonal' effects in Mercury's exosphere is that the neutral sodium tail, so prominent in the first two flybys, is 10 to 20 times less intense in emission and significantly reduced in extent," says participating scientist Ron Vervack, of the Johns Hopkins University Applied Physics Laboratory, or APL, in Laurel, Md. "This difference is related to expected variations in solar radiation pressure as Mercury moves in its orbit and demonstrates why Mercury's exosphere is one of the most dynamic in the solar system."
The observations also show that calcium and magnesium exhibit different seasonal changes than sodium. Studying the seasonal changes in all exospheric constituents during the mission orbital phase will provide key information on the relative importance of the processes that generate, sustain, and modify Mercury's atmosphere.
The third flyby also revealed new information on the abundances of iron and titanium in Mercury's surface materials. Earlier Earth and spacecraft-based observations showed that Mercury's surface has a very low concentration of iron in silicate minerals, a result that led to the view that the planet's crust is generally low in iron.
"Now we know Mercury's surface has an average iron and titanium abundance that is higher than most of us expected, similar to some lunar mare basalts," says David Lawrence, an APL participating mission scientist.
The spacecraft has completed nearly three-quarters of its 4.9-billion-mile journey to enter orbit around Mercury. The full trip will include more than 15 trips around the sun. In addition to flying by Mercury, the spacecraft flew past Earth in August 2005 and Venus in October 2006 and June 2007.
The spacecraft was designed and built by APL. The mission is managed and operated by APL for NASA's Science Mission Directorate in Washington.
- Fermi Telescope Caps First Year With Glimpse of Space-Time - November 8th, 2009 [November 8th, 2009]
- Antarctic Airborne Science Mission Nears Mid-Point - November 8th, 2009 [November 8th, 2009]
- NASA Awards Education Research Grants to Minority Universities - November 8th, 2009 [November 8th, 2009]
- New Celestial Map Gives Directions for GPS - November 8th, 2009 [November 8th, 2009]
- NASA Invites Reporters to Tranquility Node Ceremony at Kennedy - November 8th, 2009 [November 8th, 2009]
- Happy Halloween - November 8th, 2009 [November 8th, 2009]
- NASA's Fermi Telescope Detects Gamma-Ray From "Star Factories" in Other Galaxies - November 8th, 2009 [November 8th, 2009]
- NASA Announces Advisory Council Chairs and Committee Structure - November 8th, 2009 [November 8th, 2009]
- NASA and X Prize Announce Winners of Lunar Lander Challenge - November 8th, 2009 [November 8th, 2009]
- Successful Flight Through Enceladus Plume - November 8th, 2009 [November 8th, 2009]
- Education Secretary Hosts DC Students for Talk with Space Station - November 8th, 2009 [November 8th, 2009]
- Operation Ice Bridge Studies Antarctic Sea Ice - November 8th, 2009 [November 8th, 2009]
- NASA West Point Welcomes Home One of Their Heroes - November 8th, 2009 [November 8th, 2009]
- NASA Spitzer Observes a Chaotic Planetary System - November 8th, 2009 [November 8th, 2009]
- X-38 Crew Return Vehicle Finds New Home - November 8th, 2009 [November 8th, 2009]
- Frost-Covered Phoenix Lander Seen in Winter Images - November 8th, 2009 [November 8th, 2009]
- Have some faith He is doing his best - November 8th, 2009 [November 8th, 2009]
- The Cross - November 8th, 2009 [November 8th, 2009]
- Spring Bloom in New Zealand Waters - November 8th, 2009 [November 8th, 2009]
- NASA Hubble image showcases star birth in M83, the Southern Pinwheel - November 8th, 2009 [November 8th, 2009]
- Take Me Out to the Ballpark - On Mars! - November 8th, 2009 [November 8th, 2009]
- Poisk Poised for Live NASA TV Space Station Docking - November 8th, 2009 [November 8th, 2009]
- Ceremony Reset for ESA Handover of Tranquility to NASA - November 8th, 2009 [November 8th, 2009]
- NASA Reproduces a Building Block of Life in Laboratory - November 8th, 2009 [November 8th, 2009]
- Now Online: Aeronautics Goes E-Book - December 12th, 2009 [December 12th, 2009]
- Water on the Moon, Drought on Earth: NASA Experts Available for Radio And Podcast Interviews During Major Science Meeting - December 12th, 2009 [December 12th, 2009]
- Launch of NASA's Wise Spacecraft Delayed Until Dec. 14 - December 12th, 2009 [December 12th, 2009]
- Connecticut Students Set for Cosmic Conversation with Space Station Commander - December 12th, 2009 [December 12th, 2009]
- Magnetic Dance of Titan and Saturn To Be Main Attraction during Flyby - December 12th, 2009 [December 12th, 2009]
- Hubble's Deepest View of Universe Unveils Never-Before-Seen Galaxies - December 13th, 2009 [December 13th, 2009]
- Earth's Moon - December 13th, 2009 [December 13th, 2009]
- How do you Make a Helicopter Safer to Fly? You Crash One. - December 13th, 2009 [December 13th, 2009]
- Physicist Earns Title as Kennedy's Best - December 13th, 2009 [December 13th, 2009]
- Hubble Unveils Never-Before-Seen Galaxies - December 13th, 2009 [December 13th, 2009]
- Saturn's Mysterious Hexagon Emerges from Winter Darkness - December 13th, 2009 [December 13th, 2009]
- Fermi Sees Brightest-Ever Blazar Flare - December 13th, 2009 [December 13th, 2009]
- Magnetic Power Revealed in Gamma-Ray Burst Jet - December 13th, 2009 [December 13th, 2009]
- Just 5 Questions: Aerosols - December 13th, 2009 [December 13th, 2009]
- Hometown Heroes 2009: Astronaut & Terrible Towel Return to Pittsburgh - December 13th, 2009 [December 13th, 2009]
- Garver Honors Four for Saving the Life of a Fifth at NASA Langley - December 13th, 2009 [December 13th, 2009]
- Administrator Bolden Speaks at AAIA-WIA Luncheon - December 13th, 2009 [December 13th, 2009]
- Best (Meteor) Shower of 2009 - No Towel Required - December 13th, 2009 [December 13th, 2009]
- NASA Making Government More Accessible With Cutting-Edge Use Of New Media - December 13th, 2009 [December 13th, 2009]
- Scarce Water, Our Quiet Sun and Space Rocks Among NASA News Highlights at American Geophysical Union Meeting - December 13th, 2009 [December 13th, 2009]
- Press Credentials Deadlines Set for Next Space Shuttle Flight - December 13th, 2009 [December 13th, 2009]
- Reddish Dust and Ice Migration Darken Saturn's Moon Iapetus - December 13th, 2009 [December 13th, 2009]
- Galaxy Collision Switches on Black Hole - December 13th, 2009 [December 13th, 2009]
- I’m watching the launch of NASA’s WISE spacecraft - December 13th, 2009 [December 13th, 2009]
- SOFIA Aloft - December 13th, 2009 [December 13th, 2009]
- Guide to the International Space Station Laboratory Racks Interactive - December 14th, 2009 [December 14th, 2009]
- Freezing WISE's Hydrogen - December 14th, 2009 [December 14th, 2009]
- Local High School Wins Invention Challenge - December 14th, 2009 [December 14th, 2009]
- WISE Ready to Soar Into Space - December 14th, 2009 [December 14th, 2009]
- NASA Data Reveal Major Groundwater Loss in California's Heartland - December 15th, 2009 [December 15th, 2009]
- NASA Looks for Safer Icing Forecast For Pilots - December 15th, 2009 [December 15th, 2009]
- Challenges of Living and Working Aboard the Space Station: NASA Astronaut Nicole Stott Available for TV Interviews - December 15th, 2009 [December 15th, 2009]
- NASA Astronaut, Food Scientist Available for Interviews about Holiday Feasts in Space - December 15th, 2009 [December 15th, 2009]
- NASA Launches Web Site for Teenagers That Want More Class - December 15th, 2009 [December 15th, 2009]
- A Unique Geography -- and Soot and Dust -- Conspire Against Himalayan Glaciers - December 15th, 2009 [December 15th, 2009]
- New Study Turns Up the Heat on Soot's Role in Himalayan Warming - December 15th, 2009 [December 15th, 2009]
- NASA's WISE Eye on the Universe Begins All-Sky Survey Mission - December 15th, 2009 [December 15th, 2009]
- NASA Offers Sound Clips for Radio, Online Newscasters - December 17th, 2009 [December 17th, 2009]
- NASA Gets Up-Close Look at Far Corner of the Globe - December 17th, 2009 [December 17th, 2009]
- Orion Launch Abort System Attitude Control Motor Test-fired - December 17th, 2009 [December 17th, 2009]
- Hubble Finds Smallest Kuiper Belt Object Ever Seen - December 17th, 2009 [December 17th, 2009]
- The Dark Side of Carbon - December 17th, 2009 [December 17th, 2009]
- R97UYEA6HD8W - December 17th, 2009 [December 17th, 2009]
- NASA's AIM Satellite and Models are Unlocking the Secrets of Mysterious "Night-Shining" Clouds - December 17th, 2009 [December 17th, 2009]
- Classroom Learning Takes Off with NASA-Funded Education Projects - December 17th, 2009 [December 17th, 2009]
- NASA Buys Additional Space Shuttle Reusable Solid Rocket Motors - December 17th, 2009 [December 17th, 2009]
- Searching for New Vaccines and Studying Butterflies in Space; NASA Offers TV Interviews about Latest Space Station Science Research - December 17th, 2009 [December 17th, 2009]
- NASA Partners with Saudi Arabia on Moon and Asteroid Research - December 17th, 2009 [December 17th, 2009]
- New Results from a Terra-ific Decade in Orbit - December 17th, 2009 [December 17th, 2009]
- Deposits in Martian Trough Point to Complex Hydrological Past - December 17th, 2009 [December 17th, 2009]
- NASA Outlines Recent Greenhouse Gas Research - December 17th, 2009 [December 17th, 2009]
- Unexpected Wheel-Test Results - December 17th, 2009 [December 17th, 2009]
- Solar Storms and Radiation Exposure on Commercial Flights - December 17th, 2009 [December 17th, 2009]
- Global Digital Elevation Model - December 17th, 2009 [December 17th, 2009]
- Hubble's Festive View of a Grand Star-Forming Region - December 17th, 2009 [December 17th, 2009]
- NASA Calculates a Carbon Budget for the State of California - December 18th, 2009 [December 18th, 2009]