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Adapted from an article by Kenneth Chang published in The New York Times, September 14, 2017:

NASA’s Cassini spacecraft, the intrepid robotic explorer of Saturn’s magnificent beauty, has finally ended its 20-year journey. By design, the probe vanished into Saturn’s atmosphere, disintegrating moments after its final signal slipped away into the background noise of the Solar System. Until the end, new measurements streamed one billion miles back to Earth, preceded by the spacecraft’s last picture show of dazzling sights from around the Sun’s sixth planet.

15cassini-beforeplunge-jumbo

Credit: Credit NASA/JPL-Caltech/Space Science Institute

 

The mission for Cassini, in orbit since 2004, stretched far beyond the original four-year plan, sending back multitudes of striking photographs, solving some mysteries and upending prevailing notions about the Solar System with completely unexpected discoveries.

Even at the end, 20 years after launch, Cassini and its instruments remained in good working shape. The plutonium power source was still generating electricity. But there was not enough propellant fuel left to safely send Cassini anywhere except into Saturn.

In the very last phase of the mission, Cassini dove through the gap between Saturn and the planet’s innermost ring. This provided new, sharp views of the rings and allowed the craft to probe the planet’s interior, as another NASA’s Juno spacecraft is doing at Jupiter.

Links: read the full article; also NYT’s ‘100 Images from Cassini’ feature.

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Anthony Lydgate, editor of Elements, newyorker.com’s science-and-tech blog provides details of the September 8 launch and goals of the OSIRIS-REx mission, to collect and return about 60 g of material from the asteroid Bennu. Read the full New Yorker article here.

(Note: newyorker.com restricts how many articles non-subscribers may read each month.)

av_orex_l2

Credit: United Launch Alliance

Links: OSIRIS-REx mission homepage.

From JPL press releases, July 4, 2016:

While Americans celebrated the evening of Independence Day, 1.7 billion miles (2.7 billion kilometres) NASA’s Juno spacecraft, launched nearly five years ago, reached its final destination: the most massive planet in our Solar System, Jupiter.

juno_burn

Credit: NASA/JPL-Caltech

Juno now starts its tour of Jupiter in a 53.5-day orbit. The spacecraft saves fuel by executing a burn that places it in a capture orbit with a 53.5-day orbit instead of going directly for the 14-day orbit that will occur during the mission’s primary science collection period. The 14-day science orbit phase will begin after the final burn of the mission for Juno’s main engine on October 19.

Most of Juno’s instruments deal with Jupiter’s particles and magnetic field, which is 20,000 times more powerful than Earth’s. The main instruments are in a vault made of 400 pounds of titanium to protect them from the strong radiation. The Junocam, its imaging camera, is outside that protection, and may not last as long as other instruments; further, it will give images as it rotates that will have to be transformed to the equivalent of steady views.

Links: Full details via the JPL press release; NASA Juno mission page; NY Times: Jupiter and its moons graphic.

From an article on the Sky and Telescope website by Monica Young, originally posted on December 10, 2015.

More than half of the potential giant planets detected by NASA’s Kepler satellite might not be planets after all according to a study by Alexandre Santerne (University of Porto, Portugal, and Aix Marseille University, France). A press release following the Extreme Solar Systems III conference in Hawaii summarized the study with the headline: “Half of Kepler’s Giant Exoplanet Candidates are False Positives.”

Common-False-Positives-480

Credit: NASA/Ames Research Center

Santerne and colleagues followed up on Kepler’s long list of planet candidates during a five-year observing campaign. Between July 2010 and July 2015, the team spent 370 nights observing 129 planet candidates out of more than 4,000 that were identified by Kepler, and only 45 of these turned out to be bona fide planets. The rest fell into 3 different categories: 3 were brown dwarfs, 63 were multiple-star systems, and 18 were neither of these, but could not be confirmed as planets. Even if all of those 18 cases turned out to be planets, 51% of Kepler’s giant potential planets would still turn out not to be real.

Previous studies found a much lower ‘false-positive’ rate for Kepler’s planet candidates. However, according to experts on Kepler data, this seemingly surprising high false-positive rate is not surprising at all.

For more information on our Solar System, and others, see Chapter 9 of The Cosmos. Link to the original article here.

From an article posted on the New Horizons website on November 5, 2015.

NASA’s New Horizons spacecraft has successfully completed record-setting maneuvers that have set it on course to reach 2014 MU69, which orbits in the Kuiper Belt, in January 2019.

The four propulsive maneuvers were the most distant trajectory corrections ever performed by any spacecraft. The fourth and final maneuver started at approximately 1:15 p.m. EST on Wednesday, Nov. 4, and lasted just under 20 minutes. Data indicating that this final maneuver had been successful reached spacecraft operators at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland, just before 7 p.m. EST on Wednesday.

Credit: The Johns Hopkins University Applied Physics Laboratory

Credit: The Johns Hopkins University Applied Physics Laboratory

The maneuvers didn’t speed or slow the spacecraft, rather they “pushed” New Horizons sideways, giving it a 57 meter per second (128 mile per hour) nudge toward the KBO. 2014 MU69 is around 1 billion miles beyond Pluto, and the aim is for New Horizons to come within even closer range of MU69 than it did to Pluto on July 14, 2015.

The New Horizons team will submit a formal proposal to NASA for the extended mission to 2014 MU69 in early 2016. Curt Niebur, New Horizons program scientist at NASA Headquarters in Washington said that “this is another milestone in the life of an already successful mission that’s returning exciting new data every day. These course adjustments preserve the option of studying an even more distant object in the future, as New Horizons continues its remarkable journey.”

At the time of November 5th’s maneuver, New Horizons was approximately 84 million miles beyond Pluto and nearly 3.2 billion miles from Earth. The spacecraft is now 895 million miles from MU69, speeding at more than 32,000 miles per hour toward deeper space.

For more information on Kuiper Belt objects, see Chapter 8.2 (p. 202-204) of The Cosmos.

For the original article on the New Horizons website, click here.

Credit: Lunar and Planetary Insitute

Credit: Lunar and Planetary Insitute

Planetary Science Nuggets are PowerPoint slides that have been provided to NASA Science Mission Directorate’s Planetary Science Division by members of the scientific community to highlight important science results or mission activities. A subset of these submissions are selected by the Planetary Science Division to be presented to SMD leadership and, potentially, NASA leadership, OSTP and the White House. This collection represents those selected Nuggets.

Link: Planetary Science Nuggets hosted by the Lunar and Planetary Institute.

From a press release originally published on the John Hopkins Laboratory website on October 15, 2015.

Following the first exploration of the Pluto system in history, NASA’s New Horizons team have published their first research paper detailing their findings of the distant planet.

The paper, entitled “The Pluto System: Initial Results from its Exploration by New Horizons,” describes an unusual heart-shaped region, intriguing moons, and a surprising degree of diversity and complexity in the Pluto System.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Team members believe that some of the processes on Pluto have occurred relatively recently, including those which involve the water-ice rich crust that they have discovered. This raises fundamental questions about how small planets remain active billions of years after their formation.

NASA’s New Horizons spacecraft made it to within 7,750 miles of Pluto’s surface at its point of closest approach, gathering so much data that scientists won’t see the extent of it for another year.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Jim Green, director of planetary science at NASA Headquarters in Washington, describes the mission as only the beginning. “The New Horizons mission completes our initial reconnaissance of the solar system, giving humanity our first look at this fascinating world and its system of moons. New Horizons is not only writing the textbook on the Pluto system, it’s serving to inspire current and future generations to keep exploring — to keep searching for what’s beyond the next hill.”

For more information on what we know so far about the dwarf planet right on the fringes of our Solar system, see Chapter 8.1 of The Cosmos.

Link: for the original press release, click here.

From an article published August 28, 2015 on The New York Times website:

Credit: Alex Parker, via NASA

Credit: Alex Parker, via NASA

Fresh from its Pluto flyby in July 2015, NASA’s New Horizons spacecraft has a new mission. The next destination for the probe is to be a much smaller ice ball in the outer Solar System, almost a billion miles beyond Pluto.

If NASA approves the extension to the mission, the spacecraft will visit the icy body known as 2014 MU69 in 2019 to capture photographs and data, in a similar way as for the examination of Pluto. While the vistas of this object would not be as impressive as those of Pluto, it would provide a close-up look at another piece of debris beyond Neptune, part of what is known as the Kuiper belt (see Section 8.2, pp. 202-204 in The Cosmos).

NASA has already examined smaller icy objects like comets, some of which originate in the Kuiper belt, but the flyby of 2014 MU69 will “connect the dots”, says S. Alan Stern, New Horizons’ principal investigator. As an intermediate-size Kuiper belt object, the gap in our knowledge between smaller icy objects and the far greater Pluto will aim to be filled.

The New Horizons spacecraft is to adjust course through a series of four thruster firings in late October and early November. New Horizons would also make more distant measurements of 20 other Kuiper belt objects en route to 2014 MU69.

For more information on spacecrafts flying by comets, see Section 8.3f, pp. 210-214 in The Cosmos.

Link: Full article here

From an article published on September 30, 2015 at www.space.com:

www.space.com

Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Colorful new maps of Ceres, charted by NASA’s Dawn space probe, have been unveiled at the European Planetary Science Conference in France. The maps highlight the dwarf planet’s topography and composition, as well as a pyramid-shaped mountain and the Occator crater, where many mysterious bright spots can be found.

Dawn scientists are also discussing three bursts of energetic electrons that have them puzzled. As Dawn principal investigator Chris Russell put it, “Ceres continues to amaze”.

To learn more about the outer Solar System, see Chapter 8 of The Cosmos.

Link to the full article on www.space.com

In this NY Times slideshow, Kenneth Chang curates a selection of images from NASA’s Cassini spacecraft’s farewell tour. Cassini entered orbit around Saturn 11 years ago; last fall, the space agency granted a final extension, through 2017, when the spacecraft will have exhausted the fuel for its thrusters. On August 17, it made its last flyby of Dione, the fourth largest of Saturn’s more than 60 moons, at 700 miles wide. Dione has its own mysteries that planetary scientists hope to unravel.

See the slideshow here (external link).