Artist's concept of the hypothetical "Planet Nine." Could it have moons? Credit: NASA/JPL-Caltech/Robert Hurt
Artistic rendering shows the distant view from theoretical Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. Credit: Caltech/R. Hurt (IPAC)
The astronomer known worldwide for vigorously promoting the demotion of Pluto from its decades long perch as the 9th Planet, has now found theoretical evidence for a new and very distant gas giant planet lurking way beyond Pluto out to the far reaches of our solar system.
“X” marks the spot in this image transmitted to Earth on Dec. 24, 2015 from the Long Range Reconnaissance Imager (LORRI) from NASA’s New Horizons’ showing the highest-resolution swath of Pluto at the center of Sputnik Planum, the informally named plain that forms the left side of Pluto’s “heart.” The pattern of polygonal cells stems from the slow thermal convection of the nitrogen-dominated ices. Also visible is a a dirty block of water ice “floating” in denser solid nitrogen. Credits: NASA/JHUAPL/SwRI
“X” marks the spot that’s illustrative of “convective churning” resulting from subsurface planetary heating, as seen in a fascinating new super high resolution image received from NASA’s New Horizons spacecraft on Christmas Eve, Dec. 24, 2015. Its situated at the very center of the left ventricle of Pluto’s huge “heart” – an icy flow plain that’s informally named “Sputnik Planum.”
The “X” feature – see image above – is located in an area of intersecting cells, shaped like polygons, on the plains of “Sputnik Planum” which are mostly comprised of frozen nitrogen ices.
Planet Mercury as seen from the MESSENGER spacecraft in 2008. Credit: NASA/JPL
Virtually every planet in the Solar System has moons. Earth has The Moon, Mars has Phobos and Deimos, and Jupiter and Saturn have 67 and 62 officially named moons, respectively. Heck, even the recently-demoted dwarf planet Pluto has five confirmed moons – Charon, Nix, Hydra, Kerberos and Styx. And even asteroids like 243 Ida may have satellites orbiting them (in this case, Dactyl). But what about Mercury?
If moons are such a common feature in the Solar System, why is it that Mercury has none? Yes, if one were to ask how many satellites the planet closest to our Sun has, that would be the short answer. But answering it more thoroughly requires that we examine the process through which other planets acquired their moons, and seeing how these apply (or fail to apply) to Mercury.
Reconstruction of Voyager 2 images showing the Great Black spot (top left), Scooter (middle), and the Small Black Spot (lower right). Credit: NASA/JPL
Neptune is a truly fascinating world. But as it is, there is much that people don’t know about it. Perhaps it is because Neptune is the most distant planet from our Sun, or because so few exploratory missions have ventured that far out into our Solar System. But regardless of the reason, Neptune is a gas (and ice) giant that is full of wonder!
Below, we have compiled a list of 10 interesting facts about this planet. Some of them, you might already know. But others are sure to surprise and maybe even astound you. Enjoy!
Gerard Kuiper, founder of the Lunar and Planetary Laboratory. Credit: lpl.arizona.edu
In the outer reaches of the Solar System, beyond the orbit of Neptune, lies a region permeated by celestial objects and minor planets. This region is known as the “Kuiper Belt“, and is named in honor of the 20th century astronomer who speculated about the existence of such a disc decades before it was observed. This disc, he reasoned, was the source of the Solar Systems many comets, and the reason there were no large planets beyond Neptune.
Gerard Kuiper is also regarded by many as being the “father of planetary science”. During the 1960s and 70s, he played a crucial role in the development of infrared airborne astronomy, a technology which led to many pivotal discoveries that would have been impossible using ground-based observatories. At the same time, he helped catalog asteroids, surveyed the Moon, Mars and the outer Solar System, and discovered new moons.
Special Guest: Mike Massimino, Former Astronaut; Senior Advisor for Space Programs at the Intrepid Sea, Air & Space Museum; Full-time instructor at Columbia University; Human-machine systems, space robotics, and human space flight.
Artist's impression of NASA's New Horizons spacecraft encountering a Pluto-like object in the distant Kuiper Belt. (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Steve Gribben)
Even though the New Horizons spacecraft hasn’t officially been approved to do a flyby of a distant Kuiper Belt Object in about 3 years, the engineering team has now performed two maneuvers in a series of four to direct the spacecraft towards an ancient and distant KBO named 2014 MU69.
“Second of four engine burns to target our KBO was completed successfully!! Go New Horizons! Go NASA!” said Principal Investigator Alan Stern on Facebook.
Two more burns will occur within the next 8 days.
The 25-minute burn on October 25 was the largest propulsive maneuver ever conducted by New Horizons. The team said that the spacecraft is in excellent health as it continues to transmit data from the Pluto system flyby in July. It is currently zooming through deep space at more than 52,000 km/hr (32,000 miles per hour) and it is now about 122 million kilometers (76 million miles) past Pluto and 5.09 billion kilometers (3.16 billion miles) from Earth.
Projected path of NASA’s New Horizons spacecraft toward 2014 MU69, which orbits in the Kuiper Belt about 1 billion miles beyond Pluto. Planets are shown in their positions on Jan. 1, 2019, when New Horizons is projected to reach the small Kuiper Belt object. NASA must approve an extended mission for New Horizons to study MU69. Credit: New Horizons team.
New Horizons must travel about a billion miles to get to 2014 MU69, which is also nicknamed “PT1” (for “Potential Target 1”) and if all continues to go well, the spacecraft is expected to reach the KBO on January 1, 2019.
“2014 MU69 is a great choice because it is just the kind of ancient KBO, formed where it orbits now, that the Decadal Survey desired us to fly by,” Stern said back in August 2015 when the target was announced. “Moreover, this KBO costs less fuel to reach [than other candidate targets], leaving more fuel for the flyby, for ancillary science, and greater fuel reserves to protect against the unforeseen.”
The 2003 National Academy of Sciences’ Planetary Decadal Survey recommended that the first mission to the Kuiper Belt include flybys of Pluto and small KBOs, in order to sample the diversity of objects in that previously unexplored region of the solar system. PT1 is a completely different class of KBO than Pluto.
New Horizons has hydrazine-fueled thrusters, and it carries enough fuel for the flyby, but the team really wants to have the other two maneuvers carried out as scheduled on Oct. 28 and Nov. 4, in order to make the fuel last as long as possible.
The New Horizons team will submit a formal proposal to NASA for the KBO flyby in early 2016. NASA officials have said the discussions on whether to approve this extended mission will take place in the larger context of the planetary science portfolio, i.e., to see if it fits in the budget.
Given the success of the Pluto system flyby, and the success so far of the maneuvers to send the spacecraft to PT1, it would be a grave mistake not to take advantage of this opportunity.
This global view of Jupiter's moon, Io, was obtained during the tenth orbit of Jupiter by NASA's Galileo spacecraft. Credit: NASA
Exploring the Solar System is like peeling an onion. With every layer removed, one finds fresh mysteries to ponder over, each one more confounding than the last. And this is certainly the case when it comes to Jupiter’s system of moons, particularly its four largest – Io, Europa, Ganymede and Callisto. Known as the Galilean Moons, in honor of their founder, these moons possess enough natural wonders to keep scientists busy for centuries.
As Jupiter’s innermost moon, it is also the fourth-largest moon in the Solar System, has the highest density of any known moon, and is the driest known object in the Solar System. It is also one of only four known bodies that experiences active volcanism and – with over 400 active volcanoes – it is the most geologically active body in the Solar System.
Lucy, an SwRI mission proposal to study primitive asteroids orbiting near Jupiter, is one of five science investigations under the NASA Discovery Program up for possible funding. Credit: swri.org
In February of 2014, NASA’s Discovery Program put out the call for mission proposals, one or two of which will have the honor of taking part in Discovery Mission Thirteen. Hoping to focus the next round of exploration efforts to places other than Mars, the five semifinalists (which were announced this past September) include proposed missions to Venus, Near-Earth Objects, and asteroids.
When it comes to asteroid exploration, one of the possible contenders is Lucy – a proposed reconnaissance orbiter that would study Jupiter‘s Trojan Asteroids. In addition to being the first mission of its kind, examining the Trojans Asteroids could also lead to several scientific finds that will help us to better understand the history of the Solar System.
By definition, Trojan are populations of asteroids that share their orbit with other planets or moons, but do not collide with it because they orbit in one of the two Lagrangian points of stability. The most significant population of Trojans in the Solar System are Jupiter’s, with a total of 6,178 having been found as of January 2015. In accordance with astronomical conventions, objects found in this population are named after mythical figures from the Trojan War.
There are two main theories as to where Jupiter’s Trojans came from. The first suggests that they formed in the same part of the Solar System as Jupiter and were caught by the gas giant’s gravity as it accumulated hydrogen and helium from the protoplanetary disk. Since they would have shared the same approximate orbit as the forming gas giant, they would have been caught in its gravity and orbited it ever since.
The asteroids of the Inner Solar System and Jupiter. Credit: Wikipedia Commons
The second theory, part of the Nice model, proposes that the Jupiter Trojans were captured about 500-600 million years after the Solar System’s formation. During this period Uranus, Neptune – and to a lesser extent, Saturn – moved outward, whereas Jupiter moved slightly inward. This migration could have destabilized the primordial Kuiper Belt, throwing millions of objects into the inner Solar System, some of which Jupiter then captured.
In either case, the presence of Trojan asteroids around Jupiter can be traced back to the early Solar System. Studying them therefore presents an opportunity to learn more about its history and formation. And if in fact the Trojans are migrant from the Kuiper Belt, it would also be a chance for scientists to learn more about the most distant reaches of the solar system without having to send a mission all the way out there.
The mission would be led by Harold Levison of the Southwest Research Institute (SwRI) in Boulder, Colorado, with the Goddard Space Center managing the project. Its targets would most likely include asteroid (3548) Eurybates, (21900) 1999 VQ10, (11351) 1997 TS25, and the binary (617) Patroclus/Menoetius. It would also visit a main-belt asteroid (1981 EQ5) on the way.
The spacecraft would perform scans of the asteroids and determine their geology, surface features, compositions, masses and densities using a sophisticated suite of remote-sensing and radio instruments. In addition, during it’s proposed 11-year mission, Lucy would also gather information on the asteroids thermal and other physical properties from close range.
Artist’s concept of Jupiter’s Trojan asteroids hovering in the foreground in Jupiter’s path, with the “Greeks” at left in the background. Credit: NASA.
The project is named Lucy in honor of one of the most influential human fossils found on Earth. Discovered in the Awash Valley of Ethiopia in 1974, Lucy’s remains – several hundred bone fragments that belonged to a member the hominid species of Australopithecus afarensis – proved to be an extraordinary find that advanced our knowledge of hominid species evolution.
Levison and his team are hoping that a similar find can be made using the probe of the same name. As he and his colleagues describe it, the Lucy mission is aimed at “Surveying the diversity of Trojan asteroids: The fossils of planet formation.”
“This is a once-in-a-lifetime opportunity,” said Levinson. “Because the Trojan asteroids are remnants of that primordial material, they hold vital clues to deciphering the history of the solar system. These asteroids are in an area that really is the last population of objects in the solar system to be visited.”
The payload is expected to include three complementary imaging and mapping instruments, including a color imaging and infrared mapping spectrometer, a high-resolution visible imager, and a thermal infrared spectrometer. NASA has also offered an additional $5 to $30 million in funding if mission planners choose to incorporate a laser communications system, a 3D woven heat shield, a Deep Space atomic clock, and/or ion engines.
As one of the semifinalists, the Lucy mission has received $3 million dollars to conduct concept design studies and analyses over the course of the next year. After a detailed review and evaluation of the concept studies, NASA will make the final selections by September 2016. In the end, one or two missions will receive the mission’s budget of $450 million (not including launch vehicle funding or post-launch operations) and will be launched by 2020 at the earliest.
Pluto’s Blue Sky: Pluto’s haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC). The high-altitude haze is thought to be similar in nature to that seen at Saturn’s moon Titan. The source of both hazes likely involves sunlight-initiated chemical reactions of nitrogen and methane, leading to relatively small, soot-like particles (called tholins) that grow as they settle toward the surface. Credits: NASA/JHUAPL/SwRI
With each passing day, significant discoveries about Pluto continue piling up higher and higher as more and more data gathered and stored from this past summer’s historic flyby by NASA’s New Horizons reaches ground stations back here on Earth.
“Blue skies–Pluto is awesome!” says Alan Stern, New Horizons principal investigator from Southwest Research Institute (SwRI), Boulder, Colorado.
The bluish tint to Pluto’s skies were unexpectedly discovered after researchers examined the first color images of the high altitude atmospheric hazes returned by New Horizons last week that were taken by the probes Ralph/Multispectral Visible Imaging Camera (MVIC).
“Who would have expected a blue sky in the Kuiper Belt?” Stern said in a NASA statement.
During New Horizons flyby on July 14, 2015, it discovered that Pluto is the biggest object in the outer solar system and thus the ‘King of the Kuiper Belt.”
The Kuiper Belt comprises the third and outermost region of worlds in our solar system.
“It’s gorgeous!” exclaims Stern.
Moreover, the source of Pluto’s blue haze is different from Earth’s and more related to Titan, Saturn’s largest moon – currently being explored by NASA’s Cassini mission orbiting Saturn since 2004.
On Earth, the blue sky is caused by light scattering off tiny particles of nitrogen molecules. Whereas on Titan its related to soot-like particles called tholins.
Tholins are generated by a series of very complex sunlight-initiated chemical reactions between nitrogen and methane (CH4) high in the atmosphere. This eventually produces relatively small, soot-like particles of complex hydrocarbons.
“That striking blue tint tells us about the size and composition of the haze particles,” said New Horizons science team researcher Carly Howett, of SwRI, in a statement.
“A blue sky often results from scattering of sunlight by very small particles. On Earth, those particles are very tiny nitrogen molecules. On Pluto they appear to be larger — but still relatively small — soot-like particles we call tholins.”
As the tholins rain down on Pluto, they add to the widespread red surface coloring.
The Ralph instrument was also key in another discovery announced by New Horizons researchers.
Numerous small, exposed regions of water ice on Pluto’s surface were discovered by combining measurements from the Ralph MVIC spectral composition mapper and infrared spectroscopy from the Linear Etalon Imaging Spectral Array (LEISA) instrument.
The strongest signatures of water ice were found in the Virgil Fossa and Viking Terra regions berby the western edge of Pluto’s huge heart-shaped Tombaugh Regio feature – see image below.
Water Ice on Pluto: Regions with exposed water ice are highlighted in blue in this composite image from New Horizons’ Ralph instrument, combining visible imagery from the Multispectral Visible Imaging Camera (MVIC) with infrared spectroscopy from the Linear Etalon Imaging Spectral Array (LEISA). The strongest signatures of water ice occur along Virgil Fossa, just west of Elliot crater on the left side of the inset image, and also in Viking Terra near the top of the frame. A major outcrop also occurs in Baré Montes towards the right of the image, along with numerous much smaller outcrops, mostly associated with impact craters and valleys between mountains. The scene is approximately 280 miles (450 kilometers) across. Note that all surface feature names are informal. Credits: NASA/JHUAPL/SwRI
Water ice is only found in certain zones of Pluto for reasons yet to be understood. There may also be a relationship to the tholins, that likewise is yet to be gleaned.
“I’m surprised that this water ice is so red,” says Silvia Protopapa, a science team member from the University of Maryland, College Park. “We don’t yet understand the relationship between water ice and the reddish tholin colorants on Pluto’s surface.”
This new global mosaic view of Pluto was created from the latest high-resolution images to be downlinked from NASA’s New Horizons spacecraft and released on Sept. 11, 2015. The images were taken as New Horizons flew past Pluto on July 14, 2015, from a distance of 50,000 miles (80,000 kilometers). This new mosaic was stitched from over two dozen raw images captured by the LORRI imager and colorized. Annotated with informal place names. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Marco Di Lorenzo/Ken Kremer/kenkremer.com
As of today, New Horizons remains healthy and is over 3.1 billion miles (5 billion kilometers) from Earth.
The team hopes to fire up the thrusters later this fall to propel the spacecraft toward a second Kuiper Belt Object (KBO) in 2019 tentativley named PT1, for Potential Target 1. It is much smaller than Pluto and was recently selected based on images taken by NASA’s Hubble Space Telescope.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
