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(5 August 2020 – JPL) New results from NASA’s Juno mission at Jupiter suggest our solar system’s largest planet is home to what’s called “shallow lightning.”

An unexpected form of electrical discharge, shallow lightning originates from clouds containing an ammonia-water solution, whereas lightning on Earth originates from water clouds.

Other new findings suggest the violent thunderstorms for which the gas giant is known may form slushy ammonia-rich hailstones Juno’s science team calls “mushballs”; they theorize that mushballs essentially kidnap ammonia and water in the upper atmosphere and carry them into the depths of Jupiter’s atmosphere.

The shallow-lightning findings will be published Thursday, Aug. 6, in the journal Nature, while the mushballs research is currently available online in the Journal of Geophysical Research: Planets.

This illustration uses data obtained by NASA’s Juno mission to depict high-altitude electrical storms on Jupiter. Juno’s sensitive Stellar Reference Unit camera detected unusual lightning flashes on Jupiter’s dark side during the spacecraft’s close flybys of the planet. (courtesy: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt)

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In the center of this JunoCam image, small, bright “pop-up” clouds seen rise above the surrounding features. Clouds like these are thought to be the tops of violent thunderstorms responsible for “shallow lighting.” (courtesy: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill)

Since NASA’s Voyager mission first saw Jovian lightning flashes in 1979, it has been thought that the planet’s lightning is similar to Earth’s, occurring only in thunderstorms where water exists in all its phases – ice, liquid, and gas. At Jupiter this would place the storms around 28 to 40 miles (45 to 65 kilometers) below the visible clouds, with temperatures that hover around 32 degrees Fahrenheit (0 degrees Celsius, the temperature at which water freezes). Voyager, and all other missions to the gas giant prior to Juno, saw lightning as bright spots on Jupiter’s cloud tops, suggesting that the flashes originated in deep water clouds. But lightning flashes observed on Jupiter’s dark side by Juno’s Stellar Reference Unit tell a different story.

“Juno’s close flybys of the cloud tops allowed us to see something surprising – smaller, shallower flashes – originating at much higher altitudes in Jupiter’s atmosphere than previously assumed possible,” said Heidi Becker, Juno’s Radiation Monitoring Investigation lead at NASA’s Jet Propulsion Laboratory in Southern California and the lead author of the Nature paper.

Becker and her team suggest that Jupiter’s powerful thunderstorms fling water-ice crystals high up into the planet’s atmosphere, over 16 miles (25 kilometers) above Jupiter’s water clouds, where they encounter atmospheric ammonia vapor that melts the ice, forming a new ammonia-water solution. At such lofty altitude, temperatures are below minus 126 degrees Fahrenheit (minus 88 degrees Celsius) – too cold for pure liquid water to exist.

This animation takes the viewer on a simulated journey into Jupiter’s exotic high-altitude electrical storms. Get an up-close view of Mission Juno’s newly discovered “shallow lighting” flashes and dive into the violent atmospheric jet of the Nautilus cloud. (courtesy: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill)

“At these altitudes, the ammonia acts like an antifreeze, lowering the melting point of water ice and allowing the formation of a cloud with ammonia-water liquid,” said Becker. “In this new state, falling droplets of ammonia-water liquid can collide with the upgoing water-ice crystals and electrify the clouds. This was a big surprise, as ammonia-water clouds do not exist on Earth.”

The shallow lightning factors into another puzzle about the inner workings of Jupiter’s atmosphere: Juno’s Microwave Radiometer instrument discovered that ammonia was depleted – which is to say, missing – from most of Jupiter’s atmosphere. Even more puzzling was that the amount of ammonia changes as one moves within Jupiter’s atmosphere.

“Previously, scientists realized there were small pockets of missing ammonia, but no one realized how deep these pockets went or that they covered most of Jupiter,”said Scott Bolton, Juno’s principal investigator at the Southwest Research Institute in San Antonio. “We were struggling to explain the ammonia depletion with ammonia-water rain alone, but the rain couldn’t go deep enough to match the observations. I realized a solid, like a hailstone, might go deeper and take up more ammonia. When Heidi discovered shallow lightning, we realized we had evidence that ammonia mixes with water high in the atmosphere, and thus the lightning was a key piece of the puzzle.”

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This graphic depicts the evolutionary process of “shallow lightning” and “mushballs” on Jupiter. (courtesy: NASA/JPL-Caltech/SwRI/CNRS)

Jovian Mushballs

A second paper, released yesterday in the Journal of Geophysical Research: Planets,envisions the strange brew of 2/3 water and 1/3 ammonia gas that becomes the seed for Jovian hailstones, known as mushballs. Consisting of layers of water-ammonia slush and ice covered by a thicker water-ice crust, mushballs are generated in a similar manner as hail is on Earth – by growing larger as they move up and down through the atmosphere.

“Eventually, the mushballs get so big, even the updrafts can’t hold them, and they fall deeper into the atmosphere, encountering even warmer temperatures, where they eventually evaporate completely,” said Tristan Guillot, a Juno co-investigator from the Université Côte d’Azur in Nice, France, and lead author of the second paper. “Their action drags ammonia and water down to deep levels in the planet’s atmosphere. That explains why we don’t see much of it in these places with Juno’s Microwave Radiometer.”

“Combining these two results was critical to solving the mystery of Jupiter’s missing ammonia,” said Bolton. “As it turned out, the ammonia isn’t actually missing; it is just transported down while in disguise, having cloaked itself by mixing with water. The solution is very simple and elegant with this theory: When the water and ammonia are in a liquid state, they are invisible to us until they reach a depth where they evaporate – and that is quite deep.”

Understanding the meteorology of Jupiter enables us to develop theories of atmospheric dynamics for all the planets in our solar system as well as for the exoplanets being discovered outside our solar system. Comparing how violent storms and atmospheric physics work across the solar system allows planetary scientists to test theories under different conditions.

More About the Mission

The solar-powered Jupiter explorer launched nine years ago today, on Aug. 5, 2011. And last month marked the fourth anniversary of its arrival at Jupiter. Since entering the gas giant’s orbit, Juno has performed 27 science flybys and logged over 300 million miles (483 million kilometers).

JPL, a division of Caltech 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 the agency’s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built and operates the spacecraft.

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MSSS To provide science cameras for Janus asteroid mission

MSSS To provide science cameras for Janus asteroid mission

(14 September 2020 – Malin Space Scence Systems) Malin Space Science Systems (MSSS) has been selected to provide the science payloads for the two Janus spacecraft.

Last week, Janus was approved by NASA to proceed with final design of the mission hardware, including the MSSS cameras (called “JCam”).

The Janus principal investigator is Dr. Daniel Scheeres of the University of Colorado Boulder. The spacecraft will be built and operated by Lockheed Martin. The two Janus spacecraft will be launched in August 2022 on the same Falcon Heavy rocket as NASA’s Psyche spacecraft. They will fly by two small binary asteroids, 1991 VH and 1996 FG3, in March-April 2026.

An ECAM-M50 (Monochrome) with NFOV (Narrow Field of View) lens (left), ECAM-IR3 (right), and ECAM-DVR4 (center). JCam will appear similar to this flight camera system from another program, as JCam will use the same electronics with different lenses. Pocket knife for scale. (courtesy: Malin Space Science Systems)

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A rendering of the two Janus spacecraft showing the position of JCam. The apertures of the JCam visible and thermal IR cameras project from the inside of the spacecraft along its upper right edge. For scale, the deployed solar array span is a little less than 9 feet. (courtesy: Lockheed Martin)

Each spacecraft will carry a JCam system built by MSSS. JCam consists of an ECAM M50 visible camera and an ECAM IR3 thermal infrared camera, with a DVR4 processing/storage unit with 16 GB of flash memory. It will obtain images of the asteroid targets and also be used for spacecraft navigation and pointing during the flybys. Each complete JCam system weighs less than 3.2 kg and has a maximum power draw of less than 14 watts. These combined visible and thermal infrared imaging capabilities will enable JCam to characterize the current morphology of 1991 VH and 1996 FG3 and to constrain their evolution.

ECAM systems are flight-proven and currently operating on several missions, including NASA’s OSIRIS-REx asteroid sample-return spacecraft and Northrop-Grumman’s MEV-1 and MEV-2 satellite servicing missions. The development and production of the two JCam systems for Janus is being done under contract to Lockheed Martin for $5.8 million.

MSSS is also building the visible multispectral imaging science cameras for the Psyche mission, which will launch with Janus. Psyche is a NASA Discovery mission, led by Dr. Lindy Elkins-Tanton of Arizona State University and managed by NASA’s Jet Propulsion Laboratory. It will arrive at the main belt asteroid Psyche in 2026.

Dr. Michael Ravine, JCam project manager at MSSS, said, “We are pleased that CU and Lockheed Martin selected MSSS to provide the payload for the two Janus spacecraft. JCam will return high resolution images of these asteroids and map the temperatures of their surfaces. It also means that a single launch will be carrying three spacecraft, going to three different targets, each with two MSSS cameras. That’s a first for us, maybe a first for anybody.”

MSSS has a long history of building and operating science instruments for NASA spacecraft, most recently five cameras on the Perseverance Mars rover, launched in August 2020 and scheduled to land on Mars in February 2021. We are also currently operating three cameras orbiting Mars on Mars Odyssey and Mars Reconnaissance Orbiter, four on the surface of Mars on the Curiosity rover, and one orbiting Jupiter on Juno.

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Industry gets working on Europe’s Hera planetary defence mission

Industry gets working on Europes Hera planetary defence mission

(15 September 2020 – ESA) Today ESA awarded a €129.4 million contract covering the detailed design, manufacturing and testing of Hera, the Agency’s first mission for planetary defence.

This ambitious mission will be Europe’s contribution to an international asteroid deflection effort, set to perform sustained exploration of a double asteroid system.

Hera – named after the Greek goddess of marriage – will be, along with NASA’s Double Asteroid Redirect Test (DART) spacecraft, humankind’s first probe to rendezvous with a binary asteroid system, a little understood class making up around 15% of all known asteroids.

Hera scans DART’s impact crater (courtesy: ESA)

The contract was signed today by Franco Ongaro, ESA Director of Technology, Engineering and Quality, and Marco Fuchs, CEO of Germany space company OHB, prime contractor of the Hera consortium. The signing took place at ESA’s ESOC centre in Germany, which will serve as mission control for the 2024-launched Hera.

Hera is the European contribution to an international planetary defence collaboration among European and US scientists called the Asteroid Impact & Deflection Assessment, AIDA. The DART spacecraft – due for launch in July 2021 – will first perform a kinetic impact on the smaller of the two bodies. Hera will follow-up with a detailed post-impact survey to turn this grand-scale experiment into a well-understood and repeatable asteroid deflection technique.

While doing so, the desk-sized Hera will also demonstrate multiple novel technologies, such as autonomous navigation around the asteroid – like modern driverless cars on Earth – while gathering crucial scientific data, to help scientists and future mission planners better understand asteroid compositions and structures.

Hera will also deploy Europe’s first ‘CubeSats’ (miniature satellites built up from 10 cm boxes) into deep space for close-up asteroid surveying, including the very first radar probe of an asteroid’s interior – using an updated version of the radar system carried on ESA’s Rosetta comet mission.

Due to launch in October 2024, Hera will travel to a binary asteroid system – the Didymos pair of near-Earth asteroids. The 780 m-diameter mountain-sized main body is orbited by a 160 m moon, formally christened ‘Dimorphos’ in June 2020, about the same size as the Great Pyramid of Giza.

DART’s kinetic impact into Dimorphos in September 2022 is expected to alter its orbit around Didymos as well as create a substantial crater. This moonlet asteroid will become unique, as the first celestial body to have its orbital and physical characteristics intentionally altered by human intervention. Hera will arrive at the Didymos system at the end of 2026, to perform at least six months of close-up study.

Hera’s mission control will be based at ESA’s ESOC centre in Darmstadt, Germany, also the home of ESA’s new Space Safety and Security programme, of which Hera is a part.

This contract signing covers the full Hera satellite development, integration and test, including its advanced guidance, navigation and control (GNC) system. Contracts for Hera’s two hosted CubeSats and relevant technology developments are already ongoing.

Hera’s European partners

The contract has been awarded to a consortium led by prime contractor OHB System AG in Bremen.

Of 17 ESA Member States contributing to Hera, Germany is in the forefront, tasked with the overall Hera spacecraft design and integration, main navigation cameras, tanks, thrusters, high-gain antenna, reaction wheels, and mass memory unit.

Italy is leading the mission’s power and propulsion subsystems, and is providing the deep-space transponder that will enable the mission’s radioscience experiment. In addition, Italy is leading the dust and mineral prospecting CubeSat, named after the late Andrea Milani, distinguished professor and leading asteroid scientist.

Belgium is developing Hera’s on-board computer and software, the brain of the spacecraft, plus its power conditioning and distribution unit – the heart of its electrical subsystem. It is also contributing to Hera’s Japanese-developed thermal imager and CubeSats operations center at ESA/ESEC.

Luxembourg is leading the radar-hosting ‘Juventas’ CubeSat and the inter-satellite communication system allowing the two Hera CubeSats to communicate with Earth through an innovative network using Hera as data relay.

Portugal and Romania are developing the laser altimeter which will provide crucial information for the autonomous navigation functions. In addition, Romania is developing the image processing unit, harness and the electrical test equipment (while also contributing to its GNC development).

The Czech Republic is responsible for the full satellite structure, payload software (to command the instruments), independent software validation and ground support equipment for pre-flight satellite testing. It is also providing components for Juventas’ low-frequency radar and data processing software on the second CubeSat.

And Spain is developing Hera’s advanced guidance, navigation and control system as well as the deep-space communication system. It is also providing the Juventas gravimeter instrument.

  • Austria is supporting with mission data analysis and processing
  • Denmark is contributing to the Juventas CubeSat and remote terminal unit
  • France is providing Juventas’ low-frequency radar, as well as star trackers and support to the CubeSats’ payload operations planning and close-proximity trajectories
  • Hungary is supporting scientific calibration of the cameras
  • The Netherlands is developing the new deep-space CubeSat deployment system and providing Hera’s Sun sensors
  • Switzerland is contributing with structural elements and mechanisms for the solar arrays
  • Finland is providing the second CubeSats’ multi-spectral imager and onboard equipment. It is also providing the data processing unit
  • Poland is contributing with Juventas’ low-frequency radar deployable antennas
  • Ireland is providing an innovative inertial measurement unit for the Hera spacecraft to support deep-space navigation
  • ESA Associate Member State Latvia is contributing a time-of-flight detector for the mission’s laser altimeter.

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Dust monitor to demonstrate pristine satellite launches

Dust monitor to demonstrate pristine satellite launches

(17 September 2020 – ESA) While on Earth, satellites are kept in immaculate cleanrooms to protect their instruments from harmful dust particles.

If those instruments fail to function properly in space, however, it could be because of particle contamination during launch. Now a British company has developed a device to identify whether this is the case.

Following successful trials of a prototype sensor, space-tech company XCAM is working with ESA to develop a flight-ready device that monitors dust contamination on payloads during and shortly after launch.

The device will provide data to demonstrate whether or not precious cargos – such as Earth-observing satellites – stay clean on their way into space.

XCAM’s prototype monitoring device (courtesy: ESA)

Payloads are protected from the elements within a secure capsule in the upper part of launcher called the fairing. Once outside the Earth’s atmosphere, the fairing separates, exposing its contents to space.

Cleanrooms protect spaceborne equipment from contamination during assembly, but vibrations and shocks during launch may shake up residues in the fairing that can affect how the payload operates.

Dust particles can contaminate optical surfaces, such as those found on Earth-observing satellites, as well as affecting the performance of sensitive mechanical equipment.

XCAM’s sensor keeps track of contamination remotely to provide continuous measurements in real-time.

The company is now working with ESA to develop a device that will be used in the fairing of the European Vega-C launcher. The gadget must be able to withstand the mechanical loads of launch such as acoustics and vibrations – and then survive in space for long enough to relay data back to Earth for analysis.

It will enable satellite launchers to provide evidence to their customers that payloads are kept spotless on their way into orbit.

“It was fantastic for XCAM to work on such an exciting project with ESA at the prototype stage, but to have been able to go beyond that, and win the contract to develop the flight qualified system is even better,” says Karen Holland, chief executive of XCAM.

“Following these achievements, XCAM has recently received several highly prestigious awards nominations for our work in the field of digital imaging systems. As a very small company of just 15 people, we are very pleased to be recognised by the awards judges.”

“Because of the very peculiar contamination mechanisms it presents, and the lack of monitoring inside the fairing, the launch phase is somewhat of an unresolved question for contamination engineers – which makes control of particulate very challenging,” says Riccardo Rampini, technical officer for the XCAM project.

“With the development of a novel sensor capable of operating before and during launch, which will provide real-time information on the particulate inside the fairing of a launcher, ESA will soon provide a solution to this problem.”

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