“Green” comet makes closest approach to Earth

Originating from the Oort Cloud, comet is on its first trip to the inner solar system.

A green-colored comet is making its closest approach to Earth on Tuesday, August 7, as it travels on its first ever journey through the inner solar system.

Discovered with the PanSTARRS telescopes in Haleakala, Hawaii, on September 23, 2017, and designated C/2017 S3, the comet has undergone two recent outbursts, one on June 30, and the other two weeks later.

Many comets experience outbursts in which they brighten. For this unusually large comet, which came from the Oort Cloud, a reservoir of comets in the outer solar system beyond the Kuiper Belt, these outbursts give it a greenish tinge. Its second eruption produced a large gas cloud surrounding the comet that swelled to 161,000 miles (260,000 km) in diameter.

C2017 S3’s green color is the result of the ionization of its carbon and cyanide molecules due to warming from the Sun. Ionization involves the separation of electrons and protons, which produces the trademark green glow, as explained by Brian Koberlein of the Rochester Institute of Technology (RIT) in New York.

At closest approach, the comet will come within 70 million miles (112 million km) of the Earth, then head toward the Sun. It will swing around the Sun on August 16 and then head back to the distant Oort Cloud.

While C2017/S3 is currently too close to the Sun to be visible, observers will get the chance to see it after it begins heading back toward the outer solar system later this month, noted Paul Chodas, manager of the Jet Propulsion Laboratory’s (JPL) Center for Near-Earth Object Studies (CNEOS).

Regular outbursts by comets were long thought to be caused by surface heating and pressure buildup that produce explosions on their surfaces as they head toward the Sun. However, this theory was called into question by the Rosetta spacecraft’s close observations of Comet 67P/Churyumov-Gerasimenko, whose data pointed to dust kicked up and out into space by landslides on the comet’s surface as the outbursts’ cause.

The comet’s close approach involves no threat to Earth.

A 3D interactive  visualization of the comet produced by JPL is available for public viewing.

Scientists discover 12 new moons of Jupiter

Finding brings the giant planet’s total number of moons to 79.

A group of scientists searching for a theorized planet in the outer solar system instead discovered 12 new moons of Jupiter, bringing the giant planet’s total count of moons to 79. All are small, with diameters ranging from 0.6 miles (one km) to 1.87 miles (three km).

Led by Scott S. Sheppard of the Carnegie Institute for Science, the research team found the moons in the spring of 2017 while using the Blanco 4-meter Telescope at Cerro Tololo Observatory in Chile and the American National Optical Astronomical Observatory. Because several separate observations are required to confirm an individual object is actually in orbit around Jupiter, confirmation of all 12 took a year to complete.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant solar system objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our solar system,” Sheppard explained.

Nine of the newly-discovered moons are part of a larger swarm in distant, retrograde orbits around the giant planet, which take about two years to orbit Jupiter. Having retrograde orbits mean they circle Jupiter in the opposite direction of the planet’s rotation.

Within this distant swarm, moons are divided into three separate orbital groups, each of which is theorized by scientists to be the result of an impact with a larger parent body, likely a comet, asteroid, or additional Jovian moon.

Two of the newly-found moons have prograde or direct orbits and are located much closer to Jupiter, in an inner swarm of satellites. These moons orbit Jupiter in less than one year. All moons in this swarm, based on their orbital inclinations and distances from Jupiter, are believed to be remnants of a larger single moon that broke apart in an impact.

Of all the newly discovered objects, one has a more inclined orbit than those in the inner swarm and takes approximately a year-and-a-half to orbit Jupiter. While its orbit is prograde, its inclination leads it to cross into the region of the retrograde, outer swarm of moons.

This “oddball” is the smallest of all Jovian moons, with a diameter of less than 0.6 miles (one km). Because its unusual but prograde orbit takes it into the region of the outer moons that have retrograde orbits, the chances of collisions occurring between the objects moving in opposite directions are high.

“This is an unstable situation. Head-on collisions would quickly break apart and grind the objects down to dust,” Sheppard said.

The researchers believe that this “oddball” moon may also be a remnant of a much larger moon, possibly one that caused the outer swarm to take retrograde orbits.

Scientists think these newly-found moons formed after the solar system’s main period of planet formation. Had they formed earlier, gas and dust left over from the solar nebula, as well as larger moons, would have destroyed them by driving them into the giant planet.

Ten new moons found around Jupiter

New technology has enabled researchers to detect 10 new moons in Jupiter’s orbit.

A team of astronomers from the Carnegie Institution for Science have discovered 10 previously unknown moons around Jupiter, bringing the planet’s total amount up to 79.

Researchers first found the new bodies while searching for distant objects at the edge of our solar system. During their study they noticed a handful of never-before-seen objects near Jupiter. Intrigued, they then tracked the bodies for a year and confirmed them as moons.

Two of the natural satellites orbit close to Jupiter. They are “prograde moons,” which means they orbit in the same direction as the planet spins. As a result, astronomers believe they are pieces of a larger moon that broke apart many years ago.

Seven of the new moons orbit further away and in the opposite direction, which means they are retrograde moons. The team believes those were also once apart of a much larger body.

The tenth moon is strange in that it orbits on the same path as the retrograde moons but orbits in the opposite direction. That suggests it is the remnant of a random object that Jupiter sucked in with its gravity, such as a rogue comet.

“This just shows how chaotic our Solar System was in the past,” said team leader Scott Sheppard, a researcher at the Carnegie Institute for Science, according to GizmodoThese outer moons of Jupiter are remnants of chaos.”

Scientists just recently discovered the moons because telescope technology has come a long way within the last decade or two. That has enabled researchers to take much clearer pictures of the cosmos.

In fact, as technology continues to improve there is a chance even more moons could be found around Jupiter. That may one day help scientists understand the planet’s history and perhaps gain insight into the way other gas giants first formed.

“By looking at these outer moons we can get an insight into what the objects were like that ended up forming the planets we see today,” said Sheppard, according to The Washington Post

Possible new volcano discovered on Jupiter’s moon Io

Scientists suspect 250 additional volcanoes have yet to be discovered on solar system’s most volcanically active world.

A new hot spot detected by NASA’s Juno spacecraft near the south pole of Jupiter’s moon Io may be another, as-yet undiscovered volcano.

Juno’s Jovian InfraRed Auroral Mapper (JIRAM) located the heat source on December 16, 2017, when the probe passed about 290,000 miles (470,000 km) from Io and captured an infrared image of its southern hemisphere.

The innermost of Jupiter’s four Galilean moons and fourth largest, with a diameter of 2,264 miles (3,640 km), Io is the most volcanically active world in the solar system. Jupiter’s powerful gravitational pull as well as the gravitational influence of the other three Galilean moons, Ganymede, Europa, and Callisto, power Io’s churning interior.

“The new Io hot spot JIRAM picked up is about 200 miles (300 km) from the nearest previously mapped hot spot,” said Juno co-investigator Alessandro Mura of the National Institute for Astrophysics (INAF) in Rome. “We are not ruling out movement or modification of a previously  discovered hot spot, but it is difficult to imagine one could travel such a distance and still be considered the same feature.”

Approximately 150 active volcanoes have been previously discovered on Io by numerous spacecraft, including Voyagers 1 and 2, Galileo, Cassini, and New Horizons. Some spew lava as high as 250 miles (400 km) into space.

Scientists believe as many as 250 additional volcanoes have yet to be discovered on Io.

Future flybys will come even closer to the giant planet and its moons. Data collected during those flybys will be analyzed in conjunction with that collected last December.

Since entering Jupiter orbit on July 4, 2016, Juno has traveled in an elliptical orbit around the giant planet, conducting close flybys every 53 days to study the planet’s cloud tops and look beneath them at its auroras to learn more about Jupiter’s formation, evolution, composition, magnetic fields, gravitational fields, and structure.

During these close flybys, Juno flies as low as 2,100 miles (3,400 km) above Jupiter’s cloud tops.

Currently, the $1.1 billion mission, which has flown almost 146 million miles (235 million km) since entering orbit around Jupiter, is set to end in July 2021.

The probe will begin its 13th close flyby of Jupiter starting on July 16.

Catalog identifies “light fingerprints” of 19 solar system bodies

Resource will be reference for categorizing exoplanets.

A new catalog compiled by scientists at Cornell University identifies the unique “light fingerprints” of 19 solar system objects, including 10 planets and nine moons for use as a resource to better characterize exoplanets.

Planets and moons have unique “fingerprints” in the form of their calibrated light spectra and geometric albedo, or sunlight reflected from their surfaces.

The 19 objects selected were chosen for their highly diverse compositions and characteristics and include rocky, gaseous, and dwarf planets, frozen worlds, and objects that spew lava.

Titled “A Catalog of Spectra, Albedos, and Colors of Solar System Bodies for Exoplanet Comparison,” the catalog has been published in the journal Astrobiology and will be highlighted on the December cover of its print edition.

Its contents are available to the public for free on the website of the Carl Sagan Institute.

Objects included in the resource are the solar system’s four terrestrial planets, Mercury, Venus, Earth, and Mars; its four gas giants, Jupiter, Saturn, Uranus, and Neptune; two dwarf planets, Ceres and Pluto; Earth’s Moon; Jupiter’s moons Io, Callisto, Europa, and Ganymede; and Saturn’s moons Titan, Rhea, Dione, and Enceladus.

“We use our own solar system and all we know about its incredible diversity of fascinating worlds as our Rosetta Stone,” explained Lisa Kaltenegger of the Carl Sagan Institute. “With this catalog of light-fingerprints, we will be able to compare new observations of exoplanets to objects in our own solar system–including the gaseous worlds of Jupiter and Saturn, the icy world of Europa, the volcanic world of Io, and our own life-filled planet.”

In addition to showing high- and low-resolution images of the data from which the scientists characterized these 19 worlds, the catalog also shows how the colors of each world would change if it orbited various stars other than the Sun.

Without high-resolution spectra, some exoplanets will prove difficult to categorize. For example, if Venus were observed from another solar system, the way sunlight reflects off its thick carbon dioxide atmosphere would give it the colors of an icy world even though it is actually a rocky planet.

“Planetary science broke new ground in the ’70s and ’80s with spectral measurements for solar system bodies. Exoplanet science will see a similar renaissance in the near future,” said Jack Madden of the Carl Sagan Institute, who led the study.

“The technology to directly collect the light from Earth-sized planets around other stars is currently in a clean room waiting to be assembled and trained on the right target. With the upcoming launch of the James Webb Space Telescope (JWST) and the current construction of large ground-based telescopes such as the Giant Magellan Telescope and the Extremely Large Telescope, we are entering a new age of observational ability, so we need a reference catalog of all the planets and moons we already know, to compare these new exoplanet spectra to.”

Small space crystals reveal sun’s youth

Astronomers found that the sun had an explosive and energetic start to its existence.

Microscopic space crystals known as hibonite show that the young sun was an explosive, fiery mess, new research in the journal Nature Astronomy reports.

Long before the Earth first formed, the sun jetted out constant eruptions and massive quantities of high-energy particles. Though such events took place long, long ago, hibonite trapped the energy in a way where it can still be observed today.

The tiny crystals are much too small to see with the naked eye. Even so, they contain chemical traces of the early sun that give insight into what our solar system was like long before any of the planets formed.

Stars come about in dense, cold clouds of dust and gas. During that stage, they generate intense heat and pull materials towards their center. Though the sun experiences solar flares and coronal mass ejections today, it used to be much more wild during its stellar birth.

“A young star is more active in that it has more frequent and violent eruptions that launch particles and radiation into its surroundings,” said study co-author Philipp Heck, an associate curator of meteoritics and polar studies at The Field Museum in Chicago, according to Live Science.

Stars as big as the sun typically take 50 million years to settle into their mature state. Once there, they can last for tens of billions of years before exploding.

To see if the sun had a energetic youth, researchers from the Field Museum in Chicago analyzed samples collected from the Murchison meteorite that exploded over Australia in 1969. The remains contained dust grains shaped by supernova that existed before the sun.

The team then shot hibonite crystals within the rock with lasers, a process that released the neon and helium inside them. That revealed a unique mix of isotopes that confirmed the sun was extremely energetic billions of years ago.

Such information is important because it sheds new light onto, not just the sun, but the early solar system. That in turn could help scientists get a much better understanding of the mechanisms that govern our universe.

“What I think is exciting is that this tells us about conditions in the earliest Solar System, and finally confirms a long-standing suspicion,” added Heck, according to Phys.org. “If we understand the past better, we’ll gain a better understanding of the physics and chemistry of our natural world.”

Study recommends return missions to Uranus and Neptune

Proposal also calls for flybys of several Kuiper Belt dwarf planets.

A new white paper by planetary scientists who specialize in outer solar system worlds proposes return missions to Uranus and Neptune during the late 2020s or early 2030s.

Submitted to Arxiv, the white paper is a proposal that typically constitutes the first step toward a new mission in time for NASA’s decadal study, which sets the priorities for the next decade of planetary exploration.

Written by Amy Simon and Mark Hoffstadter, NASA experts on Uranus and Neptune, and Alan Stern, principal investigator of the New Horizons mission to Pluto and the Kuiper Belt, the study proposes sending a flyby probe to Uranus and a separate Neptune orbiter.

The Uranus spacecraft would fly within the planet’s magnetic field, which strangely turns on and off for reasons not well understood. Scientists believe this happens because the planet orbits on its side, creating an unusual polar arrangement.

To study Uranus’s interior, the spacecraft would drop a probe into the giant planet’s atmosphere. It would then leave Uranus and head for the large dwarf planets Orcus and Varuna, then possibly travel on to Haumea, Makemake, and Sedna.

In contrast, the Neptune orbiter would concentrate solely on the planet and its large moon Triton, studying interactions between the two objects. Triton is the only solar system moon that orbits in the opposite direction of its parent planet, which scientists attribute to it being a captured Kuiper Belt Object that once orbited the Sun independently.

A geologically active world, Triton spews liquid geysers that likely come from a subsurface ocean.

Uranus and Neptune have each been visited just once, by the Voyager 2 spacecraft, in 1986 and 1989 respectively. Scientists have combined the Voyager data with observations of the planets by the Hubble Space Telescope (HST) in attempts to better understand these worlds, which are larger than terrestrial planets but significantly different from the gas giants Jupiter and Saturn.

While Jupiter and Saturn are both composed largely of hydrogen and helium, Uranus and Neptune have larger percentages of water ice.

According to the proposal, the cost of both missions would be capped at $3.5 billion.

“You want to fill in some of the gaps with some of the instruments we didn’t have last time,” Simon noted.

Because these worlds are so far from the Sun, solar panels cannot be used to generate power on the spacecraft. Instead, the probes are powered by RTGs, radioactive batteries whose primary source of fuel is plutonium-238.

Production of plutonium-238, halted for close to 30 years due to international nuclear proliferation treaties, resumed in 2015.


Mercury probes will launch together in October

Joint mission seeks better understanding of the ways planets near their parent stars form and evolve.

The BepiColombo mission to Mercury, which consists of one orbiter being sent by the European Space Agency (ESA) and  another being sent by the Japan Aerospace Exploration Agency (JAXA), is scheduled to launch on an Ariane 5 rocket from the Kourou Spaceport in French Guiana on October 19.

At launch, the ESA’s Mercury Planetary Orbiter and JAXA’s Mercury Magnetospheric Orbiter will be carried by a transfer module that will be positioned between them. A combination of solar and electric propulsion will power the three connected objects.

Bepi-Colombo will execute a total of nine gravity assist flybys of Earth, Venus, and Mercury to reach its destination and enter the desired orbit.

Three years after launch, the spacecraft will conduct their first scientific flybys of Mercury. Webcams on board the central transfer module will take the first, simple images of the planet before the probes’ main science cameras begin operations.

Both orbiters will be equipped with scientific instruments that will take measurements of Mercury’s surface environment, probe deeply into its interior, and study the planet’s interaction with the solar wind. Scientists hope data collected by the probes will shed light on the formation and evolution of a solar system’s innermost planet in close orbit around its parent star.

In May of this year, the three vehicles arrived at the Kourou Spaceport, where they are now undergoing deployment tests, being equipped with protective high-temperature blankets, being fitted with solar arrays, and having their nitrogen and xenon tanks checked, loaded, and pressurized.

Other preparations include planning for unexpected contingencies and computer simulations of the spacecraft’s operations. The latter are being conducted at ESA’s operations center (ESOC) in Darmstadt, Germany.

“We have had a great start to our launch campaign in Kourou, and are on track for launch in less than 90 days,” emphasized BepiColombo project manager Ulrich Reininghaus of ESA.

“We have an incredibly packed schedule, but it is great to see our spacecraft building up together for the final time.”

The launch window for the mission will remain open through November 29.


The moon may have once supported life, study reports

New evidence suggests that the moon once had the right climate and atmosphere to support small microorganisms.

Scientists from the University of London and Washington State University have found evidence that the moon could have once had the conditions needed to support life, a new study published in Astrobiology reports.

Previously, astronomers believed that Earth’s natural satellite never had the volcanoes necessary to create an atmosphere.

However, the recent findings reveal that the lunar surface may have once had the conditions to support simple life forms around roughly 4 billion years ago.  

During that time, the moon spewed out superheated gas, including water vapor, from its core. That then created an atmosphere where the escaping steam may have turned into liquid pools on the surface.

If that happened, such areas could have been the perfect place for microorganisms to flourish. 

That is significant because if scientists can drill down into the moon and find signs of such life it will give them a glimpse of what used to exist on early Earth.

“It looks very much like the Moon was habitable at this time,” explained lead author Dirk Schulze-Makuch, an astrobiologist at Washington State University, according to Telegraph UK. “There could have actually been microbes thriving in water pools on the Moon until the surface became dry and dead. If liquid water and a significant atmosphere were present on the early Moon for long periods of time, we think the lunar surface would have been at least transiently habitable.”

The findings come from combination of recent space mission data and an analysis on lunar soil samples that show the moon is not as dry as previously believed.

In fact, in 2009 and 2010 a team of astronomers discovered that the celestial body holds hundreds of millions of metric tons of water ice. There could be water in the lunar mantle as well.

Such findings support the idea that the rocky satellite once held life. While today’s moon is sterile, four billions of years ago it would have been much more active.

“It seems bizarre to think about, but there may even have been liquid water on the Moon,” added study co-author Ian Crawford, a researcher at the University of London.

New map tracks radiation levels on Europa

Map will direct future Europa missions to locations that are potentially most habitable.

A new map that tracks radiation bombarding Jupiter’s moon Europa by its parent planet will prove an important tool in future missions searching for evidence of microbial life on the large moon.

After NASA’s Galileo mission revealed the likelihood of a global ocean beneath Europa’s surface, scientists have considered the Galilean moon a top contender for hosting microbial life.

Possible missions to Europa in various stage of planning seek to find biosignatures or signs of life in the underground ocean.

However, while Europa appears to be one of the solar system’s best hopes for finding life, the moon is regularly bombarded by powerful radiation from Jupiter, which could reduce habitability by breaking down or destroying material transported from the ocean to the surface.

Now, a new study led by Tom Nordheim of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, has produced the most comprehensive map ever of radiation levels on Europa using data returned by the Galileo mission’s flybys of Europa 20 years ago and electron measurements returned by Voyager 1, which flew by the Jupiter system in early 1979.

From the data returned by these missions, Nordheim’s team found radiation levels on Europa to vary significantly depending on location, with the highest radiation levels found near the equator and the lowest levels found near the poles.

The researchers produced a map that depicts high radiation zones as ovals.

“This is our first prediction of radiation levels at each point on Europa’s surface and is important information for future Europa missions,” noted Chris Paranicas of the Johns Hopkins Applied Physics Laboratory (JHUAPL) in Laurel, Maryland, who took part in the study.

“If we want to understand what’s going on at the surface of Europa and how that links to the ocean underneath, we need to understand the radiation,” Nordheim emphasized. “When we examine materials that have come up from the subsurface, what are we looking at? Does this tell us what is in the ocean, or is this what happened to the materials after they have been radiated?”

Nordheim’s research team also measured how deeply radiation from Jupiter penetrates beneath Europa’s surface, providing important information for the Europa Clipper mission, which will conduct about 45 Europa flybys while orbiting Jupiter following an early 2020s launch.

They found that in the regions with the highest radiation levels, a probe would have to drill four to eight inches (10 to 20 cm) to find preserved biosignatures. In those with the lowest radiation levels, the probe would have to drill less than 0.4 inches (one cm).

A paper on the study has been published in the journal Nature Astronomy.