MESSENGER: Mapping Mercury

Animation of MESSENGER at Mercury. Credit: Solar Walk 2/Orchard

• Launch Date: August 3, 2004
• Launch Site: Space Launch Complex 17B, Cape Canaveral Florida, United States
• Launch Vehicle: Delta 7925H (no. D307)
• Mission Type: Orbiter
• Targets: Mercury
• Dimensions: 1.42 Meters Wide, 1.27 Meters Long, and 1.85 Meters tall (Main Bus)
• Mass: 1107.9 Kilograms

You can build your own MESSENGER spacecraft out of LEGO here.

Over 30 years after Mariner 10 visited Mercury, MESSENGER was launched to map it's surface in high resolution.

The Mission

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Spacecraft was launched aboard a Delta II rocket on August 4, 2004. MESSENGER's goal was to be the first spacecraft to orbit Mercury, and to map its surface.

After being put into orbit around Earth, MESSENGER's PAM-D solid rocket motor fired, and put the spacecraft onto a heliocentric orbital trajectory. MESSENGER would need many gravity assists in order to slow it down enough to be captured by Mercury's small gravitational field.

MESSENGER's first approach to Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie

The spacecraft flew by Earth on August 2, 2005, and made two Venus flybys on October 24, 2006, and June 5, 2007 respectively. Then, MESSENGER made three Mercury flybys; on January 14, 2008, October 6, 2008, and September 29, 2009.

After these gravity assists, MESSENGER finally shaved off enough orbital velocity to be captured by Mercury's gravitational field. The spacecraft entered orbit around the planet on March 18, 2011, in an elliptical 9300 x 200 kilometre orbit, with a period of 12 hours.

Marcury's magnetic field. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Carnegie Institute of Washington

Atlas of Mercury's surface from MESSENGER data. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Carnegie Institute of Washington

On February 14, 2011, MESSENGER was able to obtain a remarkible picture, including every planet in the solar system other than Neptune and Uranus, mirroring our solar system's "portrait" that was taken by Voyager 1.

After completing it's primary mapping mission on March 17, 2012, MESSENGER was then given two mission extentions, lasting until it ran out of fuel in 2015. The spacecraft's last orbital maneuvers were taken on January 21, 2015. On April 30, 2015, MESSENGER impacted Mercury's surface at  14,080 Kilometres per hour, near Janácek crater. While the precise impact location is not currently known, ESA's BepiColombo mission will probably spot it when it arrives at Mercury.

MESSENGER's predicted impact location. Credit: NASA/Johns Hopkins Applied Physics Laboratory/Carnegie Institute of Washington

The Target

Image of Mercury from NASA's MESSENGER spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie

• Date Discovered: Known To The Ancients
• Radius: 2439.7 Kilometres
• Mass: 3.301x10^23 Kilograms
• Density: 5.43 g/cm^3
• Rotational Period: 58.65 Days
• Orbital Period: 87.97 Days