About 6 months after Venus Express has settled into studies of the cloud-shrouded world, it will be joined briefly by another spacecraft.
NASA’s MESSENGER spacecraft (the name’s short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is designed to investigate Mercury, not Venus. But to catch its swiftly moving target, MESSENGER will use multiple flybys of Venus and Earth to boost its speed. On December 12, 2005, mission controllers fired the craft’s thrusters for more than 8 minutes, changing MESSENGER’s speed by 706 mph (1,136 km/h). This put the probe on track to fly past Venus at an altitude of 1,951 miles (3,140 kilometers) October 24, 2006.
This will be the first of two Venus flybys. MESSENGER will sweep more than 10 times closer to the planet June 5, 2007. After that comes a series of Mercury flybys (January and October 2008, and September 2009) that will help MESSENGER match its target’s speed. In March 2011, after 15 trips around the Sun and a 4.9-billion-mile (7.9 billion km) trek, MESSENGER’s engine will fire to insert the craft into Mercury orbit.
Planned for launch in 2008, Japan’s Venus Climate Orbiter (VCO) will complement the work of Venus Express. Four cameras will image the planet in wavelengths from infrared to ultraviolet, and a fifth camera will search for lightning. The spacecraft will capture global images of the planet every 2 hours. Moreover, for about 20 hours at the farthest end of VCO’s orbit, the spacecraft’s angular speed matches the atmosphere’s super-rotation at the 31-mile (50 km) level. Mission planners say the spacecraft’s ability to take successive global images will reveal the driving force of Venus’ strange atmosphere.