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Space News Update — July 1, 2016 —

Contents

In the News

Story 1: Juno switched to autopilot mode for Jupiter final approach

Story 2: Ceres Bright Spot is Salty

Story 3: Plans To Crash Land Rosetta On Comet 67P Proceed

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. Juno switched to autopilot mode for Jupiter final approach

Four days out from arriving at the solar system’s biggest planet, NASA’s Juno spacecraft received a final uplink of commands Thursday governing the robotic probe’s high-velocity braking maneuver Monday to steer into orbit around Jupiter.

Juno will run on autopilot for the rest of its approach, counting down to a series of tightly-choreographed maneuvers Monday leading to ignition of the craft’s main engine to slow its speed by 1,212 mph (541.7 meters per second), just enough to be captured in orbit by the firm grasp of Jupiter’s gravity.

Before uploading the final command sequence, ground controllers stationed at NASA’s Jet Propulsion Laboratory and at a control center run by Lockheed Martin, the spacecraft’s builder and operator, prepared the engine for Monday’s critical burn.

“Ten days ago, we opened the main engine cover so that the engine would be ready to fire when we get to July 4, and a couple of days ago we pressurized the whole system, so that the engine is ready to go, (and) all the propulsion, all the pipes and valves are all ready to fire,” said Ed Hirst, Juno mission manager at JPL.

Engineers transmitted the final command file, dubbed “ji4040,” to Juno around 3:15 p.m. EDT (1915 GMT) Thursday via an antenna in NASA’s Deep Space Network located in Goldstone, California.

“Once those commands are sent, it will be hands-off from the team here on the ground,” Hirst told reporters Thursday before sending the order for Juno to launch its Jupiter arrival sequence. “We’ll continue to monitor the spacecraft and make sure everything is executing as we expect it to execute, but the spacecraft is on its own, and it’s designed to take care of itself with all the command sequences that we’ve sent it.”

Scott Bolton, an astrophysicist from the Southwest Research Institute in San Antonio who leads the Juno science team, said Thursday he has mixed emotions as the spacecraft zips toward Jupiter on the tail end of a 1.7 billion-mile (2.8 billion-kilometer) journey.

“Yeah, I’m nervous,” Bolton said.

Bolton’s team proposed the $1.1 billion Juno mission to NASA in February 2004, and it beat out a competing concept to return samples from South Pole-Aitken basin on the far side of the moon, winning the space agency’s backing in June 2005.

Juno launched Aug. 5, 2011, from Cape Canaveral on top of the most powerful version of United Launch Alliance’s Atlas 5 rocket, and the probe returned to Earth’s vicinity in October 2013 for a gravity assist, slingshotting it toward Jupiter.

“I’m excited with anticipation, of course, because we’re finally arriving, but I also have tension and nervousness because there’s a lot riding on what happens July 4,” Bolton said.

Engineers expect to receive confirmation that Juno’s main engine, burning a mix of liquid hydrazine and nitrogen tetroxide propellants, has started its 35-minute burn at 11:18 p.m. EDT Monday (0318 GMT Tuesday).

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Radio tones broadcast by Juno will be picked up by an array of huge dish antennas on the ground. Each tone comes in at a slightly different frequency, indicating when Juno accomplishes one of the many steps during the arrival sequence.

Juno’s high-gain antenna will not be pointed toward Earth during the insertion burn, eliminating any chance engineers will receive detailed telemetry on the progress of the engine firing.

Instead, controllers will listen for tones at the start and end of the burn, and watch for a subtle fluctuation in the radio signal coming from Juno caused by the Doppler shift, a variation in the frequency of the spacecraft’s transmission as its velocity changes.

The Doppler effect is similar to the change in pitch of an emergency siren as an ambulance passes.

Heading for a point 2,900 miles (4,667 kilometers) above Jupiter, Juno will configure itself for the make-or-break engine firing beginning shortly after 9 p.m. EDT Monday (0100 GMT Tuesday), when the spacecraft will begin turning to face the right direction for the burn.

The pointing maneuver will turn Juno’s three huge solar array wings, each stretching nearly 30 feet (9 meters) long, away from the sun, forcing the probe to drain power from its batteries. Juno is the first spacecraft to travel to Jupiter’s distance, where the sun is 25 times dimmer than it is at Earth, and rely solely on solar power.

Built with lean power requirements in mind, the power-efficient space probe can run all its systems and scientific instruments on enough juice to power five 100-watt light bulbs.

About 22 minutes before ignition, Juno’s smaller pointing thrusters will increase the craft’s spin rate from 2 rpm to 5 rpm for added stability during the main engine burn.

At the time of Juno’s engine firing, Jupiter’s gravity will exert a tight tug on the spacecraft, accelerating it to approximately 150,000 mph (about 250,000 kilometers per hour), making Juno one of the fastest human-made objects in history.

Soon after the insertion maneuver is complete, Juno will spin down back to its standard two revolutions per minute, then turn back toward the sun to start recharging its batteries and beam telemetry to engineers on Earth.

Check out a detailed timeline of the major events Monday.

Juno’s Leros 1b engine, supplied by Moog-ISP in the United Kingdom, needs to fire for at least 20 minutes for the probe to reach a safe orbit around Jupiter, according to Rick Nybakken, the mission’s project manager at JPL.

Otherwise, Jupiter’s gravity will bend Juno’s trajectory and send it speeding back into interplanetary space, missing the planet entirely.

Software programmers installed safeguards to raise the probability of a good insertion burn, including an “auto restart” feature to allow the engine to quickly resume the burn if a computer fault or another anomaly interrupts it.

Monday’s engine burn, assuming it operates for all 35 minutes, will place Juno in an elongated orbit that takes the spacecraft around Jupiter’s poles once every 53-and-a-half days. A follow-up engine burn is scheduled for

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Oct. 19 to lower the high end of Juno’s orbit, placing the robot on a course around the planet that takes it as close as 3,100 miles (5,000 kilometers) over Jupiter’s cloud tops every two weeks.

During each close flyby of Jupiter, the body-mounted instruments aboard Juno will take turns looking at the planet’s clouds, measuring plasma, and quantifying the giant world’s gravitational and magnetic fields as the orbiter spins on its axis once every 30 seconds.

Ground controllers powered off Juno’s extensive science payload Thursday ahead of the July 4 arrival, but the instruments detected the probe’s crossing into the Jovian magnetosphere last week, registering a change in the environment around the spacecraft as it moved out of the solar wind and into a region dominated by Jupiter.

The sensors will be turned back on July 6 once Juno is safely in orbit, then scientists will prepare the mission’s instrument package for the orbiter’s first dive close to Jupiter on Aug. 27. Managers will treat that close-up approach, or perijove, as a rehearsal for later orbits after Juno begins full science operations in November, obtaining early data and images to help plan observations on future passes.

The mission top priorities are remotely probing inside Jupiter to determine whether the planet harbors a solid, rocky core, and measuring the amount of water held inside the gaseous world. Those clues could help scientists determine how and where Jupiter formed, and lead researchers to know more about the origins of the rest of the planets, and even life itself.

Juno is going into the most extreme environment ever visited by a spacecraft. An intense magnetic field and deadly radiation await Juno, hazards that threaten to fry the probe’s sensitive electronics. Engineers crammed Juno’s most critical computer gear inside a titanium vault to shield against the worst of Jupiter, but there are still risks.

NASA says Juno will be exposed to 20 million rads during its time at Jupiter, equivalent to more than 100 million dental X-rays. Officials say the radiation will likely strain Juno’s health, limiting it to a lifetime of about 20 months from the time the craft gets to Jupiter.

The magnetic field at Juno’s position is an order of magnitude stronger than any space vehicle has ever experienced.

“This spacecraft is going to fly in space through a magnetic field that is 10 times greater than anything we’ve ever experienced,” said Jack Connerney, Juno’s deputy principal investigator and head of the mission’s magnetometer investigation. “That is one of the curiosities. We’re going to have to see how it performs when we do that.”

Source: Spaceflight Now Return to Contents

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2. Ceres Bright Spot is Salty

Planetary scientists say they’ve finally solved the mystery of Ceres’ bright spot. The spot, a comparatively reflective blotch in the crater Occator, has been a mesmerizing topic of debate for several years now. JPL even ran a public poll asking people what they thought the spot was — with options of volcano, geyser, rock, ice, salt, and “other” — and has had more than 190,000 respondents. As of last month, the two most popular options were ice (about 28%) and other (38%).

Unfortunately for those voters, the winning answer is salt.

Scientists have suspected salts for a while. (Ice can’t survive on Ceres’ surface: it’ll sublimate.) Last December, scientists with NASA’s Dawn mission suggested the bright Occator splash — which isn’t the only one: there are many, lesser bright spots across the dwarf planet — contained magnesium sulfate. But Maria Cristina De Sanctis (National Institute of Astrophysics, Rome) and fellow Dawn scientists report June 29th in Nature that infrared spectral data instead reveal a different salt, sodium carbonate, with some ammonia mixed in.

We’ve only detected sodium carbonate on Earth and in the plumes of Saturn’s moon Enceladus. It arises when liquid water interacts with certain minerals. The team thinks brine must have welled up from below the surface, then the water would have evaporated away, leaving the salts behind. Where that liquid water came from scientists don’t know: the impact that created Occator some 80 million years ago might have heated some subsurface ice, or perhaps liquid water deeper down rose up through the crater’s fractures. It’s even possible that the liquid water would boil near the surface, creating geysers, Mikhail Zolotov (Arizona State University) speculates in a perspective piece in the July Nature Geoscience. Or maybe the salt was deposited beneath the surface and exhumed by later craters. There are plenty of options to go around.

Although not on the surface, there’s a fair amount of water ice inside Ceres. A second paper by Michael Bland (U.S. Geological Survey) and colleagues in Nature Geoscience looks at how deeply big craters dig. The more water ice in the subsurface, the faster these craters will fade away, because an ice-rich surface would “relax” with time as the ice flowed (think glacier movements). Based on the craters, the scientists conclude that Ceres’ shallow subsurface is 30% to 40% ice by volume, with the rest a mixture of rocks, salts, and other stuff.

Read more about the result in JPL’s press release.

Source: Sky & Telescope Return to Contents

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3. Plans To Crash Land Rosetta On Comet 67P Proceed

Rosetta is set to complete its mission in a controlled descent to the surface of its comet on 30 September.

The mission is coming to an end as a result of the spacecraft's ever-increasing distance from the Sun and Earth. It is heading out towards the orbit of Jupiter, resulting in significantly reduced solar power to operate the craft and its instruments, and a reduction in bandwidth available to downlink scientific data.

Combined with an ageing spacecraft and payload that have endured the harsh environment of space for over 12 years -- not least two years close to a dusty comet -- this means that Rosetta is reaching the end of its natural life.

Unlike in 2011, when Rosetta was put into a 31-month hibernation for the most distant part of its journey, this time it is riding alongside the comet. Comet 67P/Churyumov-Gerasimenko's maximum distance from the Sun (over 850 million km) is more than Rosetta has ever journeyed before. The result is that there is not enough power at its most distant point to guarantee that Rosetta's heaters would be able to keep it warm enough to survive.

Instead of risking a much longer hibernation that is unlikely to be survivable, and after consultation with Rosetta's science team in 2014, it was decided that Rosetta would follow its lander Philae down onto the comet.

The final hours of descent will enable Rosetta to make many once-in-a-lifetime measurements, including very-high-resolution imaging, boosting Rosetta's science return with precious close-up data achievable only through such a unique conclusion.

Communications will cease, however, once the orbiter reaches the surface, and its operations will then end.

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"We're trying to squeeze as many observations in as possible before we run out of solar power," says Matt Taylor, ESA Rosetta project scientist. "30 September will mark the end of spacecraft operations, but the beginning of the phase where the full focus of the teams will be on science. That is what the Rosetta mission was launched for and we have years of work ahead of us, thoroughly analyzing its data."

Rosetta's operators will begin changing the trajectory in August ahead of the grand finale such that a series of elliptical orbits will take it progressively nearer to the comet at its closest point.

"Planning this phase is in fact far more complex than it was for Philae's landing," says Sylvain Lodiot, ESA Rosetta spacecraft operations manager. "The last six weeks will be particularly challenging as we fly eccentric orbits around the comet -- in many ways this will be even riskier than the final descent itself.

"The closer we get to the comet, the more influence its non-uniform gravity will have, requiring us to have more control on the trajectory, and therefore more maneuvers -- our planning cycles will have to be executed on much shorter timescales."

A number of dedicated maneuvers in the closing days of the mission will conclude with one final trajectory change at a distance of around 20 km about 12 hours before impact, to put the spacecraft on its final descent.

The region to be targeted for Rosetta's impact is still under discussion, as spacecraft operators and scientists examine the various trade-offs involved, with several different trajectories being examined.

Broadly speaking, however, it is expected that impact will take place at about 50 cm/s, roughly half the landing speed of Philae in November 2014.

Commands uploaded in the days before will automatically ensure that the transmitter as well as all attitude and orbit control units and instruments are switched off upon impact, to fulfill spacecraft disposal requirements.

In any case, Rosetta's high-gain antenna will very likely no longer be pointing towards Earth following impact, making any potential communications virtually impossible.

In the meantime, science will continue as normal, although there are still many risks ahead. Last month, the spacecraft experienced a 'safe mode' while only 5 km from the comet as a result of dust confusing the navigation system. Rosetta recovered, but the mission team cannot rule out this happening again before the planned end of the mission.

"Although we'll do the best job possible to keep Rosetta safe until then, we know from our experience of nearly two years at the comet that things may not go quite as we plan and, as always, we have to be prepared for the unexpected," cautions Patrick Martin, ESA Rosetta's mission manager.

"This is the ultimate challenge for our teams and for our spacecraft, and it will be a very fitting way to end the incredible and successful Rosetta mission."

Background information on ending Rosetta's mission on the comet was published on the blog last year: "From One Comet Landing to Another -- Planning Rosetta's Grand Finale" (http://blogs.esa.int/rosetta/2015/11/12/from-one-comet-landing-to-another-planning-rosettas-grand-finale).

Details regarding the end-of-mission scenario are subject to change. Further information will be announced once available.

Source: SpaceRef.com Return to Contents

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The Night Sky Friday, July 1 • Is your sky dark enough for you to see the Coma Berenices star cluster naked-eye? Just after the very end of twilight, spot Jupiter in the west. The cluster is above it by 25°, about 2½ fists at arm's length. Its brightest members form an inverted Y. The entire cluster is about 5° wide — a big, dim glow in a truly dark sky. It nearly fills a binocular view.

Saturday, July 2 • If you have a dark sky, the Milky Way now forms a magnificent arch across the east after nightfall. It runs all the way from below Cassiopeia in the north-northeast, up and across Cygnus and the Summer Triangle in the east, and down past the spout of the Sagittarius Teapot in the south.

Sunday, July 3 • Three doubles at the top Scorpius.Mars and Saturn aren't the only telescopic attractions in the south these evenings, even you have heavy light pollution! The head of Scorpius — the near-vertical row of three stars upper right of Antares — stands to Saturn's right by about a fist at arm's length, as shown above.

The top star of the row is Beta (ß) Scorpii or Graffias, a fine double star for telescopes. Just 1° below it (and a little too faint for the chart above) is the very wide naked-eye pair Omega1 and Omega2Scorpii, not quite vertical. Binoculars show their slight color difference. Left of Beta by 1.6° is Nu Scorpii, another fine telescopic double. High power in good seeing reveals Nu's brighter component itself to be a close binary, separation 2 arcseconds.

Monday, July 4 • More binary bounty! After dark, Vega is the brightest star very high in the east. Barely lower left of it is one of the best-known multiple stars in the sky: 4th-magnitude Epsilon (ε) Lyrae, the Double-Double. It forms one corner of a roughly equilateral triangle with Vega and Zeta (ζ) Lyrae. The triangle is less than 2° on a side, hardly the width of your thumb at arm's length.

Binoculars easily resolve Epsilon. And a 4-inch telescope at 100× or more should resolve each of Epsilon's wide components into a tight pair.

Zeta Lyrae is also a double star for binoculars; much tougher, but plainly resolved in any telescope. Delta (δ) Lyrae, below Zeta, is much wider and easier.

• Earth is at aphelion, it's farthest from the Sun for the year (3% farther than at perihelion in January).

Tuesday, July 5 • Arcturus is the brightest star high in the west. Equally bright Vega is similarly high in the east. A third of the way from Arcturus to Vega, look for dim Corona Borealis, the Northern Crown, with its one modestly bright star, Gemma or Alphecca. Two thirds of the way, you'll find the dim Keystone of Hercules.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver:

Date Visible Max Height Appears Disappears

Tue Jul 5, 5:11 AM 2 min 12° 10° above SSE 12° above ESE

Sighting information for other cities can be found at NASA’s Satellite Sighting Information NASA-TV Highlights (all times Eastern Daylight Time)

8 p.m., Friday, July 1 - “All Night at the Museum”– the Smithsonian’s National Air and Space Museum Celebrates its 40th Anniversary (NTV-1 (Public)) 8 a.m., 5 p.m., Saturday, July 2 - 2016 NASA Honor Awards Ceremony (NTV-1 (Public)) 9 a.m., 4 p.m., Saturday, July 2 - Replay of the Orbital ATK’s SLS Booster Qualification Motor Test (QM-2) from Promontory, Utah (all channels) 11 a.m., Saturday, July 2 - Video File of the ISS Expedition 48-49/Soyuz MS-01 Vehicle Encapsulation and Crew Activities at the Baikonur Cosmodrome in Kazakhstan (Ivanishin, Rubins, Onishi; includes activities from July 1-2) (all channels) 2 p.m., 8 p.m., Saturday, July 2 - NASA Television Video File News Feed of the ISS Expedition 48-49 Crew’s Pre-Launch Activities at the Baikonur Cosmodrome in Kazakhstan (Ivanishin, Rubins, Onishi; recorded from June 24-30) (all channels) 6 p.m., 10 p.m., Saturday, July 2 - NASA Television Video File News Feed of the ISS Expedition 48-49/Soyuz MS-01 Vehicle Encapsulation and Crew Activities at the Baikonur Cosmodrome in Kazakhstan (Ivanishin, Rubins, Onishi; includes activities from July 1-2) (all channels) 8 a.m., 2 p.m., Sunday, July 3 - NASA Television Video File News Feed of the ISS Expedition 48-49/Soyuz MS-01 Vehicle Encapsulation and Crew Activities at the Baikonur Cosmodrome in Kazakhstan (Ivanishin, Rubins, Onishi; includes activities from July 1-2) (all channels) 9 a.m., 4 p.m., Sunday, July 3 - NASA Television Video File News Feed of the ISS Expedition 48-49 Crew’s Pre-Launch Activities at the Baikonur Cosmodrome in Kazakhstan (Ivanishin, Rubins, Onishi; recorded from June 24-30) (all channels) 1 p.m., 10 p.m., Sunday, July 3 - 2016 NASA Honor Awards Ceremony (NTV-1 (Public)) 5 p.m., 9 p.m., Sunday, July 3 - Replay of the Orbital ATK’s SLS Booster Qualification Motor Test (QM-2) from Promontory, Utah (all channels) 6 a.m., Monday, July 4 - Live Media Interviews on Juno Orbital Insertion at Jupiter with NASA Scientists Jim Green and Diane Brown (all channels) 11 a.m., Monday, July 4 - Video File of the ISS Expedition 48-49 Crew’s Soyuz MS-01 Mating, Rollout to the Launch Pad at the Baikonur Cosmodrome in Kazakhstan and Launch Pad Interviews (includes activities from July 3 and 4) (all channels)

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12 p.m. (live), 4 p.m. (replay), 8 p.m. (replay), Monday, July 4 - Final NASA Media Briefing on Juno Orbital Insertion at Jupiter (all channels) 5 p.m., 10 p.m., Monday, July 4 - NASA Television Video File News Feed File of the ISS Expedition 48-49 Crew’s Soyuz MS-01 Mating, Rollout to the Launch Pad at the Baikonur Cosmodrome in Kazakhstan and Launch Pad Interviews (includes activities from July 3 and 4) (all channels) 10:30 p.m., Monday, July 4 - Live Coverage of the Juno Orbital Insertion at Jupiter (all channels) 1 a.m., Tuesday, July 5 - Post Juno Orbital Insertion NASA Science Briefing (all channels)

Watch NASA TV online by going to the NASA website. Return to Contents

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Space Calendar • Jul 01 - Comet 207P/NEAT Perihelion (0.937 AU) • Jul 01 - Amor Asteroid 2016 LZ8 Near-Earth Flyby (0.059 AU) • Jul 01 - Asteroid 12773 Lyman Closest Approach To Earth (1.741 AU) • Jul 01 - Iosif Shklovsky's 100th Birthday (1916) • Jul 02 - Moon Occults Aldebaran • Jul 02 - Comet P/2005 W4 (SOHO) Perihelion (0.053 AU) • Jul 02 - Comet 208P/McMillan Perihelion (2.545 AU) • Jul 02 - Asteroid 5720 Halweaver Closest Approach To Earth (1.979 AU) • Jul 02 - Asteroid 8624 Kaleycuoco Closest Approach To Earth (2.097 AU) • Jul 02 - Hans Bethe's 110th Birthday (1906) • Jul 03 - Comet 219P/LINEAR Closest Approach To Earth (1.804 AU) • Jul 03 - Comet P/2010 B2 (WISE) At Opposition (2.282 AU) • Jul 03 - Asteroid 35977 Lexington Closest Approach To Earth (1.751 AU) • Jul 03 - Asteroid 3905 Doppler Closest Approach To Earth (2.155 AU) • Jul 03 - Robert Haag's 60th Birthday (1956)

• Jul 04 - [Jun 30] Juno, Jupiter Orbit Insertion • Jul 04 - Mars Express, Phobos Flyby • Jul 04 - Earth At Aphelion (1.017 AU From Sun) • Jul 04 - Mars Autumnal Equinox • Jul 04 - Comet P/2013 W1 (PANSTARRS) At Opposition (4.206 AU) • Jul 04 - Asteroid 7919 Prime Closest Approach To Earth (1.152 AU) • Jul 04 - Asteroid 56678 Alicewessen Closest Approach To Earth (2.069 AU) • Jul 04 - Asteroid 15783 Briancox Closest Approach To Earth (2.308 AU) • Jul 04 - Asteroid 5190 Fry Closest Approach To Earth (2.793 AU) • Jul 04 - Asteroid 365756 ISON Closest Approach To Earth (7.241 AU) • Jul 04 - 10th Anniversary (2006), STS-121 Launch (Space Shuttle Discovery, International Space

Station) • Jul 04 - Richard Garriot's 55th Birthday (1961) • Jul 05 - Comet 207P/Hill Closest Approach To Earth (1.934 AU) • Jul 05 - Comet C/2014 W5 (Lemmon-PANSTARRS) At Opposition (2.090 AU) • Jul 05 - Comet 47P/Ashbrook-Jackson At Opposition (2.391 AU) • Jul 05 - Comet 145P/Shoemaker-Levy At Opposition (2.760 AU) • Jul 05 - Comet P/2009 WX51 (Catalina) Closest Approach To Earth (2.864 AU) • Jul 05 - Asteroid 31664 Randiiwessen Closest Approach To Earth (1.481 AU) • Jul 05 - Asteroid 230975 Rogerfederer Closest Approach To Earth (1.818 AU) • Jul 05 - Asteroid 31319 Vespucci Closest Approach To Earth (2.254 AU) • Jul 05 - Kuiper Belt Object 2014 MU69 At Opposition (42.313 AU) • Jul 05 - Kuiper Belt Object 2014 PN70 At Opposition (43.028 AU) •

Source: JPL Space Calendar Return to Contents

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Food for Thought

Life in Space: Thinner Ice Shell May Mean Life on Enceladus?

Back in 2015, it was found out that Saturn’s moon Enceladus is actually an ocean world with a subsurface ocean beneath an ice shell. However, no one could come up with a model that could reconcile the different data gathered about Enceladus, especially those gathered by the probe Cassini. That is, until now.

An international team of researchers have proposed a new model that explains the seemingly disparate data sets gathered from Enceladus, and hypothesizes that it has a much thinner shell than previously thought. Initial interpretations of data from Cassini flybys of Enceladus estimated that the thickness of its ice shell ranged from 30 to 40 km at the south pole to 60 km at the equator. However, an oscillation in Enceladus’s rotation (called a libration), linked to tidal effects, reduced the hypothesized thickness to around 20 km.

Published in Geophysical Research Letters, the study provides the internal structure of the moon: a rocky core with a radius of 185 km, then an internal ocean approximately 45 km deep, finally an ice shell with a mean thickness of around 20 km, except at the south pole where it is thought to be less than 5 km thick.

GREATER POSSIBILITIES

The new model proposes an Enceladus that could better support life. The thinner ice shell means that the moon can retain less heat. Therefore, heat readings that were previously explained by tidal forces from Saturn need another explanation. Thus, the new model reinforces the idea of strong heat production in Enceladus’s deep interior that may power the hydrothermal vents on the ocean floor. The detection of complex organic molecules of unknown composition makes the possibility of life on the Saturnian moon more likely.

A far thinner shell could allow a future space exploration mission to gather data, particularly using radar, which would be far more reliable and easy to obtain than with a 40 km thick ice shell as initially calculated.

Source: Futurism Return to Contents

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Space Image of the Week

Hubble Captures Vivid Auroras in Jupiter's Atmosphere

Astronomers are using NASA's Hubble Space Telescope to study auroras — stunning light shows in a planet's atmosphere — on the poles of the largest planet in the solar system, Jupiter. The auroras were photographed during a series of Hubble Space Telescope Imaging Spectrograph far-ultraviolet-light observations taking place as NASA's Juno spacecraft approaches and enters into orbit around Jupiter. The aim of the program is to determine how Jupiter's auroras respond to changing conditions in the solar wind, a stream of charged particles emitted from the sun. Auroras are formed when charged particles in the space surrounding the planet are accelerated to high energies along the planet's magnetic field. When the particles hit the atmosphere near the magnetic poles, they cause it to glow like gases in a fluorescent light fixture. Jupiter's magnetosphere is 20,000 times stronger than Earth's. These observations will reveal how the solar system's largest and most powerful magnetosphere behaves.

The full-color disk of Jupiter in this image was separately photographed at a different time by Hubble's Outer Planet Atmospheres Legacy (OPAL) program, a long-term Hubble project that annually captures global maps of the outer planets.

Source: NASA Return to Contents