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Saturn probe will go out in a blaze of science

Cassini orbiter
An artist’s conception shows the Cassini orbiter zooming through the upper layers of Saturn’s atmosphere, heading for a fiery breakup. (NASA / JPL-Caltech Illustration)

Twenty years after its launch to Saturn, NASA has set the Cassini orbiter on a course for certain destruction on Sept. 15 – but there’s a decidedly positive spin to the $3.3 billion mission’s end.

“We’ll be saddened, there’s no doubt about it, at the loss of such an incredible machine,” Cassini program manager Earl Maize said Sept. 13 during a news briefing at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “But I think all of us are going to have a great sense of pride in .. a little bit corny, perhaps … a ‘mission accomplished.’”

The bus-sized, plutonium-powered spacecraft was launched in 1997 and reached Saturn seven years later. It’s logged 4.9 billion miles, sent back nearly half a million images of the ringed planet and its moons, and transmitted 635 gigabytes worth of scientific data so far.

It’ll continue sending data all the way to the end, when it’s expected to break apart and burn up in the upper levels of Saturn’s atmosphere.

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‘Search for Life in Space’ hits the big screen

"Search for Life in Space"
“The Search for Life In Space” touches on several frontiers in astrobiology. (MacGillivray Freeman)

What better way to celebrate 40 years of NASA’s interplanetary Voyager mission than with an eye-filling movie that brings the decades-old story up to date?

“The Search for Life in Space,” an IMAX 3-D documentary that opens at the Pacific Science Center today, begins with the twin Voyager probes’ exploration of the solar system and beyond. Voyager’s “Grand Tour” got off the ground in 1977 and continues to this day.

The film touches on astronomer Carl Sagan’s campaign to send a message to extraterrestrial civilizations that may someday come across the probe, in the form of a Golden Record that was launched aboard each of the two spacecraft.

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Hubble keeps hope alive for alien oceans

Red dwarf planet
This artist’s impression shows how the surface of a planet orbiting a red dwarf star may appear. The planet is in the habitable zone, so liquid water exists. (CFA Illustration / M. Weiss)

Do some of the Earth-sized planets around a dwarf star called TRAPPIST-1, just 40 light-years away, have liquid water? Newly reported findings from the Hubble Space Telescope give astrobiologists continued cause for hope.

The seven TRAPPIST-1 planets created a sensation in February because they’re the biggest assemblage of Earth-scale worlds known to exist in a single planetary system. What’s more, three of the planets – known by the letters e, f and g – are in an orbital region where scientists say water could exist in liquid form.

That’s thought to be a key condition for life as we know it, which is why the region is known as TRAPPIST-1’s “habitable zone.”

But is the water really there? To get at that question, astronomers used Hubble to study the amount of ultraviolet radiation received by the planets, and what that might be doing to their atmospheres.

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Scientists see hints of another unseen planet

Distant planet
An artist’s conception shows a hypothesized planet orbiting off the main plane of the solar system. The depicted orbits and planetary sizes are not shown to scale. (UA / LPL Illustration / Heather Roper)

Astronomers say they’ve found hints that an unseen planetary-mass object may lurk in the outer reaches of our solar system. And no, they’re not talking about Planet Nine, Planet X, Nibiru or any of the other previously hypothesized worlds out there.

Kat Volk and Renu Malhotra of the University of Arizona’s Lunar and Planetary Laboratory say their analysis points to an eight-degree tilt in the average planes of orbits for the most distant objects in the Kuiper Belt, a ring of icy mini-worlds that lie beyond the orbit of Neptune.

“The most likely explanation for our results is that there is some unseen mass,” Volk said in a news release. “According to our calculations, something as massive as Mars would be needed to cause the warp that we measured.”

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Juno mission reveals surprises at Jupiter

Juno view of Jupiter south pole
This image shows Jupiter’s south pole, as seen by NASA’s Juno spacecraft from an altitude of 32,000 miles. The oval features are cyclones, up to 600 miles in diameter. (NASA / JPL-Caltech / SwRI / MSSS / Betsy Asher Hall / Gervasio Robles)

NASA’s Juno orbiter has been sending back stunning pictures of Jupiter for months, but now the mission’s scientists are sharing their first peer-reviewed findings about the planet’s previously unseen polar storms and powerful magnetic field.

“The results from Juno’s initial close passes of Jupiter are understanding of this gas giant,” the Juno science team, led by principal investigator Scott Bolton of the Southwest Research Institute, reports in the journal Science.

Bolton and his colleagues laid out those results today in a set of papers published by Science and Geophysical Research Letters, and in a NASA teleconference.

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Astronomers track TRAPPIST-1’s 7th planet

TRAPPIST-1h planet
An artist’s conception shows the planet TRAPPIST-1h. (NASA / JPL-Caltech)

An international research team led by a University of Washington astronomer has worked out the intricate dance of seven planets circling an ultracool dwarf star known as TRAPPIST-1, nailing down the coordinates of the outermost world in the process.

The astronomers found that all seven exoplanets follow stable orbits thanks to a regular pattern of gravitational interactions, known as orbital resonance. And they determined conclusively that the seventh planet, called TRAPPIST-1h, is too cold for life – although it was could have been warmer in its ancient past.

The calculations, laid out today in the journal Nature Astronomy, will go down as another success story for the planet-hunting process.

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Pluto’s ocean may go deeper than Earth’s

Sputnik Planum
The left side of Pluto’s bright “heart” is known informally as Sputnik Planum. (Credit: NASA / JHUAPL / SwRI)

Scientists have been saying for months that Pluto could have a salty, sloshing ocean beneath its icy surface, but now they’ve worked out just how deep it could go. The answer? As deep as 60 miles, or nine times the depth of Earth’s deepest seas.

The estimate, based on computer modeling of the impact dynamics behind a heart-shaped region of Pluto, was published this month in Geophysical Research Letters.

The bright-colored “heart,” first seen last year by NASA’s New Horizons probe, is arguably Pluto’s best-known surface feature. But it’s actually two features. Scientists say the left lobe of the heart, known informally as Sputnik Planum, was created in the aftermath of an ancient impact. The object that made that impact is thought to have been about 120 miles (200 kilometers) wide.

In June, researchers reported that the geological features mapped on Pluto’s surface would be consistent with the presence of a liquid water ocean far below, perhaps heated by the decay of radioactive materials in Pluto’s rocky core. But they didn’t estimate the size of the ocean.

This month’s findings address that question.

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Why it’ll take years to see what Proxima b is like

Image: Proxima Centauri b
An artist’s conception shows a view of the surface of the planet Proxima b, with the red dwarf Proxima Centauri near the horizon. (Credi:t: M. Kornmesser / ESO)

University of Washington astronomer Rory Barnes says Proxima Centauri b is the biggest discovery in 20 years for planet hunters like himself, but it could take another 20 years to find out just how livable it is.

The alien planet orbits a red-dwarf star at a distance that puts it in a zone where liquid water could conceivably exist. The fact that such a world circles the sun’s nearest stellar neighbor, 4.2 light-years away, puts it on top of the list of potentially habitable planets beyond our solar system.

Barnes, however, emphasizes the word “potentially.” During a lecture at Seattle’s Pacific Science Center, set for 7:30 p.m. tonight, the UW astronomer will delve into the opportunities and obstacles for life on Proxima Centauri b.

“We’re looking at a 15- to 20-year time frame before we can answer this question of whether it’s habitable,” Barnes told GeekWire in advance of the talk.

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Hunt for Planet Nine leads to mini-worlds

Image: Planet X
An artist’s conception shows Planet X, a.k.a. Planet Nine. (Credit: Robin Dienel / Carnegie Inst.)

The hypothetical world known as Planet X or Planet Nine hasn’t yet been found, but thanks to the search, astronomers have discovered smaller worlds on the solar system’s edge.

Mapping such objects could lead to the big discovery: a planet that’s thought to be at least several times bigger than Earth, lurking at least 200 times farther away from the sun. Or it could lead to a different explanation for the puzzling, highly elongated orbits of some of the objects that lie far beyond Pluto.

Planet Nine’s existence was proposed last year as the most elegant way to account for the orbits of worlds such as Sedna and 2012 VP113 (which has been nicknamed “Biden” in honor of the veep). Ever since then, astronomers have been surveying the skies in hopes of tracking it down.

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Potentially habitable planet at the star next door

Proxima Centauri b
An artist’s conception shows Proxima Centauri b orbiting its parent star, a red dwarf, with the two other stars of the Alpha Centauri system in the far background. (Credit: M. Kornmesser / ESO)

The rumors you’ve heard are mostly true: Scientists say the star that’s closest to our solar system has a planet that could be at the right temperature for liquid water and life.

The star is called Proxima Centauri, a red dwarf that’s part of the Alpha Centauri system, 4.2 light-years away. The planet is called Proxima Centauri b, and it’s a terrestrial world whose existence has now been confirmed after 16 years of study.

It’s not yet known whether Proxima b has an atmosphere, or liquid water. But the computer models don’t rule out the possibility. That would make it the closest known exoplanet – and the closest known exoplanet with the potential for life.

As such, it could be the nearest haven for humanity in case things go horribly wrong in our own solar system. And it just so happens that scientists are working on a robotic mission to the Alpha Centauri system: The Breakthrough Starshot initiative received a $100 million kick-start from Russian billionaire Yuri Milner in April.

“We expect either to characterize it, if we get lucky, or maybe visit it in a couple of centuries,” Guillem Anglada-Escude, an astronomer at Queen Mary University of London, told reporters.

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