NASA has reported that its Juno mission has provided its first science results concerning the amount of water in the atmosphere of Jupiter. Juno results estimate that at the equator of the planet water makes up about 0.25 percent of the molecules in Jupiter’s atmosphere. These findings represent the first on the gas giant’s abundance of water since the 1995 Galileo mission suggested Jupiter might be extremely dry compared to the Sun.
NASA notes that the 0.25 percent water content of the Jovian atmosphere is almost 3 times that found on the Sun. NASA also notes that the comparison between Jupiter and the sun is not based on liquid water but on the presence of water components like oxygen and hydrogen. Information about the amount of water in Jupiter’s atmosphere is important for determining how winds flow on the planet and its internal structure.
Spacecraft have detected lightning on Jupiter that implied the presence of water, but an accurate estimate of the amount of water deep within the atmosphere was unknown until now. NASA scientists knew thanks to the Galileo probe plummeting into the Jovian atmosphere in 1995 that there was roughly 10 times less water in the atmosphere of the planet than expected, but Galileo was only able to transmit data for about 57 minutes during its mission.
Juno launched in 2011 and one of its mission goals is to obtain water abundance readings across large regions of the gas giant. Juno observes Jupiter from above using its Microwave Radiometer that uses six antennas to measure the atmospheric temperature at multiple depths at the same time. The instrument takes advantage of the fact that water absorbs certain wavelengths of microwave radiation.
The team says that they found water in the equator to be greater than what the Galileo probe measured. Scientists now think that perhaps the Galileo probe was unlucky and measured an unusually dry portion of the planet during its descent. Juno science team is eager to determine how atmospheric water content varies by latitude and region. The 24th science flyby of Jupiter happened on February 17 with the next flyby taking place on April 10. The team says each flyby is “an event of discovery.”