Findings From NASA’s Juno Update Jupiter Water Mystery

From NASA.

The JunoCam imager aboard NASA's Juno spacecraft captured this image of Jupiter's southern equatorial region on Sept. 1, 2017. The image is oriented so Jupiter's poles (not visible) run left-to-right of frame. Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

The JunoCam imager aboard NASA’s Juno spacecraft captured this image of Jupiter’s southern equatorial region on Sept. 1, 2017. The image is oriented so Jupiter’s poles (not visible) run left-to-right of frame. Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

Thick white clouds are present in this JunoCam image of Jupiter's equatorial zone. At microwave frequencies, these clouds are transparent, allowing Juno's Microwave Radiometer to measure water deep into Jupiter's atmosphere. The image was acquired during Juno's flyby on Dec. 16, 2017. Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

Thick white clouds are present in this JunoCam image of Jupiter’s equatorial zone. At microwave frequencies, these clouds are transparent, allowing Juno’s Microwave Radiometer to measure water deep into Jupiter’s atmosphere. The image was acquired during Juno’s flyby on Dec. 16, 2017. Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

NASA’s Juno mission has provided its first science results on the amount of water in Jupiter’s atmosphere. Published recently in the journal Nature Astronomy, the Juno results estimate that at the equator, water makes up about 0.25% of the molecules in Jupiter’s atmosphere — almost three times that of the Sun. These are also the first findings on the gas giant’s abundance of water since the agency’s 1995 Galileo mission suggested Jupiter might be extremely dry compared to the Sun (the comparison is based not on liquid water but on the presence of its components, oxygen and hydrogen, present in the Sun).

An accurate estimate of the total amount of water in Jupiter’s atmosphere has been on the wish lists of planetary scientists for decades: The figure in the gas giant represents a critical missing piece to the puzzle of our solar system’s formation. Jupiter was likely the first planet to form, and it contains most of the gas and dust that wasn’t incorporated into the Sun.

The leading theories about its formation rest on the amount of water the planet soaked up. Water abundance also has important implications for the gas giant’s meteorology (how wind currents flow on Jupiter) and internal structure. While lightning — a phenomenon typically fueled by moisture — detected on Jupiter by Voyager and other spacecraft implied the presence of water, an accurate estimate of the amount of water deep within Jupiter’s atmosphere remained elusive.

Before the Galileo probe stopped transmitting 57 minutes into its Jovian descent in December 1995, it radioed out spectrometer measurements of the amount of water in the gas giant’s atmosphere down to a depth of about 75 miles (120 kilometers), where the atmospheric pressure reached about 320 pounds per square inch (22 bar). The scientists working on the data were dismayed to find ten times less water than expected.

Even more surprising: The amount of water the Galileo probe measured appeared to be still increasing at the greatest depth measured, far below where theories suggest the atmosphere should be well mixed. In a well-mixed atmosphere, the water content is constant across the region and more likely to represent a global average; in other words, it’s more likely to be representative of water planetwide. When combined with an infrared map obtained at the same time by a ground-based telescope, the results suggested the probe mission may have just been unlucky, sampling an unusually dry and warm meteorological spot on Jupiter.

“Just when we think we have things figured out, Jupiter reminds us how much we still have to learn,” said Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio. “Juno’s surprise discovery that the atmosphere was not well mixed even well below the cloud tops is a puzzle that we are still trying to figure out. No one would have guessed that water might be so variable across the planet.”

Measuring Water From Above

A rotating, solar-powered spacecraft, Juno launched in 2011. Because of the Galileo probe experience, the mission seeks to obtain water abundance readings across large regions of the immense planet. A new kind of instrument for deep space planetary exploration, Juno’s Microwave Radiometer (MWR) observes Jupiter from above using six antennas that measure atmospheric temperature at multiple depths simultaneously. The Microwave Radiometer takes advantage of the fact that water absorbs certain wavelengths of microwave radiation, the same trick used by microwave ovens to quickly heat food. The measured temperatures are used to constrain the amount of water and ammonia in the deep atmosphere, as both molecules absorb microwave radiation.

The Juno science team used data collected during Juno’s first eight science flybys of Jupiter to generate the findings. They initially concentrated on the equatorial region because the atmosphere there appears more well-mixed, even at depth, than in other regions. From its orbital perch, the radiometer was able to collect data from a far greater depth into Jupiter’s atmosphere than the Galileo probe — 93 miles (150 kilometers), where the pressure reaches about 480 psi (33 bar).

“We found the water in the equator to be greater than what the Galileo probe measured,” said Cheng Li, a Juno scientist at the University of California, Berkeley. “Because the equatorial region is very unique at Jupiter, we need to compare these results with how much water is in other regions.”

Northward Bound

Juno’s 53-day orbit is slowly moving northward, as intended, bringing more of Jupiter’s northern hemisphere into sharper focus with each flyby. The science team is eager to see how atmospheric water content varies by latitude and region, as well as what the cyclone-rich poles can tell them about the gas giant’s global water abundance.

Juno’s 24th science flyby of Jupiter occurred on Feb 17. The next science flyby takes place on April 10, 2020.

“Every science flyby is an event of discovery,” said Bolton. “With Jupiter there is always something new. Juno has taught us an important lesson: We need to get up close and personal to a planet to test our theories.”

NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. The Italian Space Agency contributed the Jovian Infrared Auroral Mapper and the Ka-Band translator system. Lockheed Martin Space in Denver built and operates the spacecraft.

More information about Juno is available at:

https://www.nasa.gov/juno

https://www.missionjuno.swri.edu

More information on Jupiter is at:

https://www.nasa.gov/jupiter

The public can follow the mission on Facebook and Twitter at:

https://www.facebook.com/NASAJuno

https://www.twitter.com/NASAJuno

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40 thoughts on “Findings From NASA’s Juno Update Jupiter Water Mystery

  1. Wow, at last some scientific reporting instead of worthless dashcam photos.

    “Just when we think we have things figured out, Jupiter reminds us how much we still have to learn,” said Scott Bolton, Juno principal investigator

    If only Earth scientists had an equally open and honest attitude to the study of our own planet.

  2. Most of us are aware of the Earth’s – sun’s magnetic link (aurora, GCRs etc). Similar link exists between sun and Jupiter, but that one is orders of magnitude stronger (Jupiter’s magnetic field is about 20,000 times stronger than Earth’s).
    From our point of view it is important that the Earth transverses through that link every 400 days and has some influence on the shape and form of our own magnetosphere, but since most of our climate date are assembled in 365 days blocks, any useful information ripples through undetected.
    https://youtu.be/ITPizr7Pqgg

  3. … water makes up about 0.25% of the molecules in Jupiter’s atmosphere — almost three times that of the Sun.

    The sun is something like 99.85 % plasma. How can water even exist?

    • “(the comparison is based not on liquid water but on the presence of its components, oxygen and hydrogen, present in the Sun).”…

      Seems like a silly idea.

      • But the sun is mostly hydrogen so when “ the comparison is based not on liquid water but on the presence of its components, oxygen and hydrogen, present in the Sun” I assume it is based on the oxygen.

    • I’m not chemist, the important question is if the H & O nuclei can combine without presence of electrons, sun’s atmosphere does contain small amount of oxygen nuclei.

    • The article above points out: ” . . . water makes up about 0.25% of the molecules in Jupiter’s atmosphere — almost three times that of the Sun . . . (the comparison is based not on liquid water but on the presence of its components, oxygen and hydrogen, present in the Sun).” This implies to me that they assume all ionized oxygen in the Sun can be combined with an excess of ionized hydrogen to calculate the POTENTIAL amount of water vapor.

      BUT, to me, here is the real shocker:
      Because the water molecule has such strong bonds it has a characteristically high temperature of peak dissociation . . . at 3300 K a bit more than half of a large quantity of water molecules would be dissociated. Achieving 99.9% probability of dissociation requires much higher temperatures. So, in fact some water molecules can exist on the Sun in the relatively cool areas in the central portions of sunspots! — ref: http://solar-center.stanford.edu/FAQ/Qwateronsun.html and https://science.sciencemag.org/content/277/5324/328

  4. I came to a full stop when I hit the phrase “ten times less water than expected” I assume that means 1/10 but I’m 10 times less sure than I could be.

    • Thank you! Thank you so much! That drives me absolutely KNUTS (especially in purported science articles) when a fraction is expressed as an exponent. It’s just — wrong.

    • TomB February 19, 2020 at 9:50 am

      Thank you! Thank you so much! That drives me absolutely KNUTS (especially in purported science articles) when a fraction is expressed as an exponent. It’s just — wrong.

      ____________________________________

      TomB, sometimes quantities have to be taken tenfold.

      In this case it’s the ten-unfold quantity.

  5. Earth’s atmosphere is well mixed below 85 kilometers. That part of Earth’s atmosphere is called the homosphere because it is well mixed. With a couple exceptions. One is that CO2 content can vary greatly from the overall atmospheric average in a shallow temperature inversion over an area with active biomass, and it varies slightly and sometimes a little more than slightly, even without a temperature inversion, over major natural sources and sinks. The other exception is water vapor, because it condenses and precipitates.

  6. I’m just glad the article doesn’t some mandatory CO2 drivel about how rising CO2 made receipt of data more difficult

  7. Should NASA drop a probe from an orbiting spacecraft into our atmosphere .. how much water would they find above 32 km? (I assume that this is about the equivalent of a 22 bar level on Jupiter).

    Did these scientists measure real water on Jupiter, and simulated water on Sun? What is a “scientific” value of such a comparison?

  8. Would have been nice to see a table summarizing the mole fractions of all of the gases in the Jovian atmosphere.

  9. From the article: “A new kind of instrument for deep space planetary exploration, Juno’s Microwave Radiometer (MWR) observes Jupiter from above using six antennas that measure atmospheric temperature at multiple depths simultaneously.”

    I wonder if Roy Specer could use one of those? 🙂

    • Which brings up another point. Unlike in Earth’s nitrogen atmosphere, water vapor is heavier than Jupiter’s/Saturn’s hydrogen/helium atmospheres, so it tends to do the opposite and sink.

  10. Just curious – why do they keep saying, “science flybys”? What ELSE might Juno be doing that is NOT science?

    It’s weird to keep using that term when as far as we know, ALL the flybys are for science.

  11. Jupiter’s atmosphere is incredibly cold. Wouldn’t water vapor freeze out ? Just like over central Antarctica – there is almost no water vapor in the air – it exists as a solid on the ground. So wouldn’t all the water on Jupiter have frozen and settled down onto the surface/core ?

  12. I’m not clear on why they compared the water content of Jupiter’s atmosphere to that of the sun, which is a star where nuclear fusion occurs, and a chemical reaction to form a water molecule would be impossible.

    If there is 0.25 mole percent water vapor in Jupiter’s lower atmosphere, it’s very possible that the temperature there is above the freezing point of water, otherwise it would freeze out as ice and fall to the surface, especially at high pressure. At a pressure of 480 psi and 0.25 mole% water, that’s a partial pressure of 1.2 psi, which is the vapor pressure of water at 108 F, or about 42 C.

    Jupiter receives much less solar radiation than Earth, yet its surface temperatures below the thick atmosphere may be higher than those on earth. Is this evidence of heat-trapping gases in Jupiter’s atmosphere, similar to that of Venus?

    • Steve Z, there are no heat trapping gases on Venus or on Jupiter. Have a look at 5th postulate of thermodynamics that relates P, V & T. The temperature is higher at the surface due to pressure. At a pressure of about 10Pa the temperature is related to the distance from the sun for all bodies with an atmosphere. Further, think about te 4th postulate that basically says that heat can not flow from a cold body to a warmer body. CO2 and H2O(g) in the atmosphere radiate to cold space and not to a warm surface. Finally, the radiation window from the surface to space is 66 w/m2 (admitted by Dr Tremberth) so there is no imbalance of the global heat balance. AGW is based on bad (and incorrect) assumptions made to baffle non-technical persons (ie people without knowledge of thermodynamics and heat transfer)

  13. In

    https://solarsystem.nasa.gov/missions/galileo/overview/

    “Galileo orbited Jupiter for almost eight years, and made close passes by all its major moons. Its camera and nine other instruments sent back reports that allowed scientists to determine, among other things, that Jupiter’s icy moon Europa probably has a subsurface ocean with more water than the total amount found on Earth.

    They discovered that the volcanoes of the moon Io repeatedly and rapidly resurface the little world.

    They found that the giant moon Ganymede possesses its own magnetic field.”

    Change: / if appropriate

    They discovered that the volcanoes of the moon Io repeatedly and rapidly resurface the little world. –> They discovered that the volcanoes of the moon Io repeatedly and rapidly resurface on the little world.

  14. In the paragraph

    “A new kind of instrument for deep space planetary exploration, Juno’s Microwave Radiometer (MWR) observes Jupiter from above using six antennas that measure atmospheric temperature at multiple depths simultaneously. The Microwave Radiometer takes advantage of the fact that water absorbs certain wavelengths of microwave radiation, the same trick used by microwave ovens to quickly heat food. The measured temperatures are used to constrain the amount of water and ammonia in the deep atmosphere, as both molecules absorb microwave radiation.”

    The measured temperatures are used to constrain the amount of water and ammonia in the deep atmosphere, as both molecules absorb microwave radiation. –> The measured temperatures are used to determine the amount of water and ammonia in the deep atmosphere, as both molecules absorb microwave radiation.

    / if it fits

  15. “We found the water in the equator to be greater than what the Galileo probe measured,” said Cheng Li, a Juno scientist at the University of California, Berkeley. “Because the equatorial region is very unique at Jupiter, we need to compare these results with how much water is in other regions.”

    “We found the water in the equator to be greater than what the Galileo probe measured,” said Cheng Li, a Juno scientist at the University of California, Berkeley.

    ____________________________________

    “We found the water in the equator to be greater than what the Galileo probe measured,” said Cheng Li, a Juno scientist at the University of California, Berkeley. –> “We found the atmospheric water content / moisture content in the equatorial region to be greater than what the Galileo probe measured,” said Cheng Li, a Juno scientist at the University of California, Berkeley.

    “Because the equatorial region is very unique at Jupiter, we need to compare these results with how much water is in other regions.”

  16. “Every science flyby is an event of discovery,” said Bolton. “With Jupiter there is always something new. Juno has taught us an important lesson: We need to get up close and personal to a planet to test our theories.” –> “Every science flyby is an event of discovery,” said Bolton. “With Jupiter there is always something new. Juno has taught us an important lesson: We need to get up-close to a planet to test our theories.”

    / would do it. As you like it.

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