NASA's Juno spacecraft is halfway to Jupiter. The jovian-system-bound spacecraft reached the milestone Monday, August 12, 2013, at 8:25 a.m. EDT.
"Juno's odometer just clicked over to 9.464 astronomical units," said Scott Bolton of the Southwest Research Institute in San Antonio. "The team is looking forward, preparing for the day we enter orbit around the most massive planet in our solar system."
An astronomical unit (AU) is a unit of measurement used by space engineers and scientists when discussing the massive distances involved in the exploration of our solar system — and beyond. An AU is based on the distance between Earth and the Sun and is 92,955,807.273 miles (149,597,870.7 kilometers) long. The 9.464 astronomical units Juno has already traveled (or still has left to go) is equivalent to 879,733,760 miles (1,415,794,248 km). Juno was 34.46 million miles (55.46 million km) from Earth when the milestone was reached. The next milestone in the nearly five-year journey to Jupiter will occur this October, when the spacecraft flies past Earth in search of a little extra speed.
"On October 9, Juno will come within 347 miles (559km) of Earth," said Rick Nybakken of NASA's Jet Propulsion Laboratory in Pasadena, California. "The Earth flyby will give Juno a kick in the pants, boosting its velocity by 16,330 mph (about 7.3 km/s). From there, it's next stop Jupiter."
Juno will arrive at Jupiter July 4, 2016, at 10:29 p.m. EDT.
Juno was launched August 5, 2011. Once in orbit around Jupiter, the spacecraft will circle the planet 33 times, from pole to pole, and use its collection of eight science instruments to probe beneath the gas giant's obscuring cloud cover. Juno's science team will learn about Jupiter's origins, structure, atmosphere, and magnetosphere and look for a potential solid planetary core.
Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife, the goddess Juno, was able to peer through the clouds and reveal Jupiter's true nature.