NASA’s Juno spacecraft to Jupiter broke the solar-powered spacecraft distance record this past Wednesday which was previously held by ESA’s Rosetta mission (493 million miles from the sun). It is closing in fast on the solar system’s largest planet, Jupiter, with a scheduled arrival of July 4, 2016. NASA reports spacecraft remains in excellent health and is operating nominally.
Once at Jupiter (517 million miles from the sun), Juno’s solar panels will provide 500 watts of power, receiving only 1/25th of the sunlight available in Earth’s orbit. Those same panels on Earth (93 million miles from the Sun) would provide 14,000 watts of power. The distance is far enough that any craft beyond must reasonably rely on nuclear propulsion, barring a breakthrough in solar engineering technology, such as larger rockets and more lightweight panels with greater efficiency.
According to NASA, “at its closest approach, Juno will pass only 3,100 miles (5,000 kilometers) above Jupiter’s cloud tops. If Jupiter were the size of a basketball, the equivalent distance would be only about one-third of an inch (0.8 centimeter).”
Juno’s science suite of instruments will measure the water content of the clouds, and determine if Jupiter has a rocky core. The instruments will also give a much more precise measurement of the gas giant’s mass.
Jupiter’s gravitational and magnetic fields will be precisely mapped, as will its atmospheric composition, temperature, structure, and cloud opacity. Since the spacecraft will be in a polar orbit the polar regions and auroras will be studied in detail.
“Juno” was Jupiter’s wife in Greco-Roman mythology. It was said “Jupiter drew a veil of clouds around himself to hide his mischief, but his wife, the goddess Juno, was able to peer through the clouds and see Jupiter’s true nature.”