Category: Planets

Scientists trace origin of Martian dust

Similar composition of dust grains around the planet lead researchers to single source.

Mars’s abundant dust comes from one geological formation near the planet’s equator, a 621-mile (1,000-km) region that has undergone billions of years of erosion and may have once been volcanic.

Known as the Medussae Fossae Formation, this large deposit, which continues to erode over time, has been imaged by the HiRISE camera on NASA’s Mars Reconnaissance Orbiter (MRO).

Unlike dust on Earth, which is separated from rock by water, wind, glaciers, volcanoes, and even meteor impacts, dust on Mars has experienced little influence from any of these phenomena. Ancient surface water and moving glaciers had a limited impact on the dust’s movement.

With a much thinner atmosphere than that protecting Earth, Mars experiences more meteor impacts than our planet, but fragments created by meteors are significantly larger than the fine, tiny Martian dust grains.

Led by Lujendra Ojha and Kevin Lewis of Johns Hopkins University, a team of researchers studied the chemical composition of dust grains collected by landers and rovers in various locations on the Red Planet and found a distinct similarity in all the samples.

“Dust everywhere on the planet is enriched in sulfur and chlorine, and it has this very distinct sulfur-to-chlorine ratio,” Ojha noted.

NASA’s Mars Odyssey, which has been orbiting the planet since 2001, found the dust in the Medusae Fossae Formation to have the same abundance and ratio of sulfur and chlorine as the dust studied by the rovers and landers.

“Mars wouldn’t be nearly this dusty if it wasn’t for this one enormous deposit that is gradually eroding over time and polluting the planet, essentially,” Lewis stated.

The Medussae Fossae Formation is the largest known volcanic deposit in the solar system though it has been steadily shrinking due to erosion by the Martian wind.

By measuring the ridges carved by the wind over time, scientists can calculate how much of the region’s dust has eroded over three billion years, enabling them to approximate the current amount of dust on the Red Planet capable of forming a global layer between 6.6 and 39 feet (2-12 meters) thick.

Dust particles can lower ground temperatures on the Martian surface and raise them further up in the atmosphere through absorption of solar radiation. Greater discrepancy between ground and atmospheric temperatures causes stronger winds, which pick up and transport surface dust.

Every few years, regular seasonal dust storms can become global, potentially harming science instruments and their solar panels by getting stuck inside both.

Findings of the study have been published in the journal Nature Communications.

Ocean worlds could be habitable for long periods of time

Climates can be kept stable by processes other than those that occur on Earth.

Water worlds, planets covered with oceans, could be habitable for life for more than a billion years, according to a new study that conducted over a thousand computer simulations.

Until recently, scientists thought that the only planets capable of supporting life are Earth-like worlds that have land and shallow oceans. Planets completely covered in oceans do not cycle minerals and gases, a phenomenon that keeps Earth’s climate stable.

Over very long periods of time, Earth keeps itself cool by pulling atmospheric greenhouse gases into minerals, then warms itself up by releasing the gases back into the atmosphere through volcanic eruptions.

With telescopes growing more powerful, scientists have discovered numerous exoplanets orbiting stars other than the Sun. Many of these are not at all Earth-like, and some are covered in oceans with depths of up to several hundred miles.

On ocean worlds, Earth’s method of maintaining a stable climate would not work, as all the rock is covered by water, which also suppresses volcanoes.

Edwin Kite of the University of Chicago and Eric Ford of Pennsylvania State University decided to research whether ocean worlds might use a different method to maintain climate stability. They turned to a computer simulation that tracked the evolution of thousands of planets over several billion years.

The computer model showed that if planets are in ideal orbits around their parent stars, have the right amount of carbon, begin their lives with sufficient water, and cycle carbon between their atmospheres and oceans in just the right amounts, they can maintain stable climates.

Additionally, the planets cannot have too many minerals and elements dissolved in their oceans, as these would remove atmospheric carbon.

“The surprise was that many of them stay stable for more than a billion years, just by luck of the draw. Our best guess is that it’s on the order of 10 percent of them,” Kite said.

“How much time a planet has is basically dependent on carbon dioxide and how it’s partitioned between the ocean, atmosphere, and rocks in its early years. It does seem there is a way to keep a planet habitable long-term without the geochemical cycling we see on Earth,” he added.

While the simulations were done for planets orbiting Sun-like stars, their results could also apply to those orbiting smaller, dimmer red dwarf stars.

Findings of the study have been published in the Astrophysical Journal.

Most known exoplanets are water worlds, study reports

Scientists have found that most of the exoplanets on record hold quite a bit of water.

A group of international astronomers have found that many exoplanets two to four times the size of Earth have water on their surface, according to new research presented at the Goldschmidt conference in Boston.

Astronomers first uncovered exoplanets orbiting distant starts in 1992. Since that time, scientists have spent years attempting to uncover their composition. The new research — which comes from data collected by the  Kepler Space Telescope and the Gaia mission — shows that many known worlds could be up to 50 percent water.

Such exoplanets are exciting because they could well change the way researchers search for life in the universe.

“It was a huge surprise to realize that there must be so many water-worlds,” said lead researcher Li Zeng, a researcher at Harvard University, according to Science Daily.

Researchers found that almost all of the 4000 confirmed exoplanets on record fall into one of two categories. They either have an average planetary radius that is 1.5 times Earth’s, or they have one that is 2.5 times Earth’s. That distinction helped the team piece together the internal structure of the distant bodies.

Models created from the data showed that exoplanets with a radius 1.5 times Earth’s are generally rocky, while the ones that have radii 2.5 Earth’s are likely water worlds.

Though water is not as common on such places as it is on Earth, and while the surface temperatures are much too hot to support conventional organisms, the exoplanets could still offer new insight into the universe. Researchers plan to continue exploring them and potentially gain more insight into their mechanisms in the future.

That is because the presence of water, regardless of other conditions, always means there is a chance for life. Even so, the team also states that just because a world has water does not mean there is life. More research has to be done on individual world’s before such claims could be made.

“One has to realize that, although water appears to be precious and rarer on Earth and other inner solar system terrestrial planets, it is in fact one of the most abundant substance in the universe, since oxygen is the third most abundant element after hydrogen and helium,” added Zeng, according to Discover Magazine.

UV light shows which exoplanets may harbor life

A new study shows that UV light is key in providing the building blocks needed for life.

Researchers from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology have identified a group of exoplanets with the same chemical conditions that may have once allowed life to exist on Earth, according to a new study published in the journal Science Advances.

In the research, the team found that ultraviolet (UV) light sparks a series of chemical reactions that produce the essential building blocks needed to create life.

Using that idea, they then identified multiple planets that both sit inside their star’s habitable zone and get enough UV light from their host star to spark such reactions.

It is those distant worlds where life is most likely be found.

The team began the study by theorizing that cyanide helped life exist on early Earth. They argued that carbon from meteorites slammed into our planet millions of years ago and interacted with nitrogen to create hydrogen cyanide.

The cyanide then rained to the surface, where it reacted with the sun’s UV light and generated the first building blocks for RNA.

After using UV lamps to recreate such reactions in the lab, the team managed to build many of life’s essential elements, including lipids, amino acids, and nucleotides.

From there, researchers ran a series of experiments to see how quickly the mix of UV light, water, and hydrogen cyanide or sulphite ions can create those key building blocks. They then repeated the process without light.

That showed, while stars around the same temperature as our sun are able to create the right amount of light for life’s building blocks, cool stars cannot.

As a result, the team believes the only planets worth searching for life at are ones in the so-called abiogenesis zone — a region where planets get both liquid water and enough light to activate basic chemistry.

“The thing that you know best about any exoplanet system is the star,” lead author Paul Rimmer, an astrochemist at the University of Cambridge, told Space.com. “So, that seemed like a natural thing to start with.”

While only a few known exoplanets sit in that zone, the team hopes future technology will be able to track down more hanging throughout the cosmos.

“This work allows us to narrow down the best places to search for life,” added Rimmer, according to Phys.org. “It brings us just a little bit closer to addressing the question of whether we are alone in the universe.”

NASA releases image, video, of Saturn’s auroras

Data from Hubble and Cassini reveal remarkable similarities with Earth’s auroras.

Last year, while the Cassini spacecraft was still orbiting Saturn, NASA’s Hubble Space Telescope (HST) captured a stunning view of the planet’s northern aurora, which, after being combined with Cassini data, was just released as an image and video.

When Saturn experienced its summer solstice on May 24, 2017, meaning its north pole was tilted toward the Sun, both Hubble and Cassini observed and measured the northern aurora.

Although the aurora appears blue, it actually glows in ultraviolet wavelengths, which can only be seen from space. When hydrogen gas at the north pole interacts with energetic electrons generated by the planet’s powerful magnetic field, intense auroras are created. Because Saturn rotates rapidly on its axis, with a Saturn “day” taking just 11 hours, the auroras’ appearances constantly change.

The actual image and video released by NASA are composites that include images of the aurora taken in early 2018 and transformation of the May 2017 photos from ultraviolet wavelengths to visible light.

One of Cassini’s last images before it plunged into Saturn’s atmosphere last September revealed a never-previously-seen auroral storm produced by interactions between plasma in the planet’s magnetosphere and its upper atmosphere.

The spacecraft also tracked an arc-shaped structure within the aurora as it grew and eventually disappeared.

In a paper published in the journal Geophysical Research Letters, Cassini scientists noted the aurora bears a striking resemblance to auroras seen on Earth and attributed its creation to the solar wind, a stream of charged particles emanating from the Sun.

From the combined observations of both Hubble and Cassini, scientists learned that Saturn’s aurora strongly peaked just prior to the planet’s midnight, then did so again around dawn. Both midnight and dawn auroral spikes also occur on Earth.

New Horizons sets its sights on Kuiper Belt object

For the first time in history, the New Horizons spacecraft has glimpsed images of the space object Ultima Thule.

The New Horizons spacecraft has glimpsed the mysterious Kuiper Belt object known as Ultima Thule for the first time.

After spending quite a bit of time observing Pluto, NASA’s New Horizons has a new course set towards the Kuiper Belt. More specifically, its goal is the distant object Ultima Thule — an object that sits roughly 44 AU from the Sun.

Though it is still 107 million miles from Ultima Thule, the craft’s Long Range Reconnaissance Imager managed to snap roughly four dozen images of the celestial body. It then sent that data back to Earth, where NASA scientists used it to create a composite image and discern the dim object from all the background stars.

That revealed Ultimate Thule sits where astronomers originally thought it did, showing New Horizons is right on track.

“The image field is extremely rich with background stars, which makes it difficult to detect faint objects,” said Hal Weaver, a New Horizons project scientist,  according to Gizmodo. “It really is like finding a needle in a haystack. In these first images, Ultima appears only as a bump on the side of a background star that’s roughly 17 times brighter, but Ultima will be getting brighter—and easier to see—as the spacecraft gets closer.”

There are two reasons the newly compiled picture is so important. Not only does it give new insight into the Kuiper Belt, but it is also marks the most distant images ever taken from Earth. In addition, New Horizons also showed it has the ability to detect its target, which means the astronomers will be able to adjust the craft if needed.

NASA reports that New Horizons will move past Ultima Thule on January 1, 2019. That passing will mark the most distant object ever visited by a human-built spacecraft and give even more insight into Ultima Thune.

“Our team worked hard to determine if Ultima was detected by LORRI at such a great distance, and the result is a clear yes,” said Alan Stern, a researcher at the Southwest Research Institute, according to Phys.org. “We now have Ultima in our sights from much farther out than once thought possible. We are on Ultima’s doorstep, and an amazing exploration awaits!”

Scientists directly observe growth of infant exoplanet

Observation will give scientists new insights into the early stages of planet formation.

For the first time ever, scientists have observed a baby exoplanet in the process of growing by accreting material from the disk surrounding the star it orbits.

Using adaptive optics on the 6.5-meter Magellan Clay Telescope in Chile, a team of astronomers led by Kevin Wagner of the University of Arizona, Amherst College, NExSS and Earths in Other Solar Systems studied the 10-million-year old parent star, an orange dwarf known as PDS 70, located 370 light years from Earth.

Unlike most planets in the process of forming, which can be imaged only indirectly as gaps in the circumstellar disks surrounding young stars, PDS 70b has been seen directly as it accretes material from the disk surrounding its star.

“These disks around young stars are the birthplaces of planets, but so far, only a handful of observations have detected hints of baby planets in them. The problem is that until now, most of these planet candidates could just have been features in the disk,” said Miriam Keppler of the Max Planck Institute for Astronomy in Heidelberg, Germany, and leader of the group that initially discovered PDS 70b.

The researchers observed the system in hydrogen alpha and similar wavelengths on two nights last May. They detected hydrogen alpha emissions at the site of the planet, indicating hot hydrogen gas is falling onto it, a clear sign that it is still accreting material.

Even though it is a baby planet still in the process of forming, PDS 70b is already larger than Jupiter. Scientists estimate it has completed 90 percent of its growth and that it likely accreted material at a much faster rate in its early years than it is doing so now.

PDS 70b’s surface temperature is estimated to be approximately 1,382 degrees Fahrenheit (1,000 degrees Celsius), and its atmosphere is thought to be cloudy.

Being able to observe the process of a planet growing by gathering materials from a star’s circumstellar disk will give scientists new insight into the planet formation process.

The research team’s findings have been published in The Astrophysical Journal Letters.

InSight lander is now halfway to Mars

Tests indicate all its science instruments are healthy.

NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) lander passed the halfway point between Earth and Mars on August 6, and tests of its science instruments indicate all are healthy and fully functional.

Launched on May 5 of this year, the lander is scheduled to touch down in Mars’s Elysium Planitia on November 26.

Mission scientists and engineers are testing software important for landing and surface operations. InSight’s highly sensitive science instruments will probe the planet’s deep interior.

Some of the instruments’ technology s being reused from NASA’s Phoenix Mars lander, which touched down on the Red Planet’s north polar region in 2008.

The lander is equipped with a seismometer, the Seismic Experiment for Interior Structure (SEIS), which will explore Mars’s internal activity by measuring ground motions in a broad range of frequencies.

Another instrument, the Heat Flow and Physical Properties Package (HP3), will burrow 10 to 16 feet (3 to 5 meters) to measure the amount of heat escaping from the planet. It will drill into the surface using a self-hammering mechanical mole connected to sensors via a science tether that will run from the mole to the surface.

To assure HP3 operates successfully, mission team members tested its main electronics, its sensors, its internal heaters, and its electronic settings.

A third science instrument, the Rotation and Interior Structure Experiment (RISE), will study changes in Mars’s rotation axis through InSight’s radio connection with Earth. This will provide scientists with important data about the composition of Mars’s core.

Mars’s rotation axis is believed to be less stable and more changeable than Earth’s because the Red Planet does not have a large moon to act as a stabilizer.

InSight’s cameras were found to be functioning well after taking a “selfie” of the spacecraft’s interior.

“If you are an engineer on InSight, that first glimpse of the heat shield blanket, harness tie-downs, and cover bolts is a very reassuring sight, as it tells us our Instrument Context Camera is operating perfectly. The next picture we plan to take with this camera will be the surface of Mars,” said InSight Project Manager Tom Hoffman of NASA’s Jet Propulsion Laboratory (JPL).

Current plans call for the cameras to photograph Elysium Planitia within minutes after landing.

Data returned by InSight is expected to help scientists better understand the processes that shaped the solar system’s rocky planets over four billion years ago.

Exoplanet habitability connected to host star’s light

Ability to produce life’s building blocks depends on level of ultraviolet light received from the host star.

The chances of life developing on rocky, Earth-like exoplanets may be determined by both the type and intensity of the light emitted by the planets’ host stars, according to a new study published in the journal Science Advances.

A group of scientists at Cambridge University and at the Medical Research Council Laboratory of Molecular Biology (MRC LMB) identified a list of rocky exoplanets whose stars emit sufficient ultraviolet light for the chemical reactions that produce the building blocks of life to occur.

On Earth, ultraviolet light from the Sun started this series of chemical reactions.

All the exoplanets the researchers identified are located in their stars’ habitable regions, with temperatures that allow liquid water to exist on their surfaces.

“This work allows us to narrow down the best places to search for life,” said Paul Rimmer of both Cambridge University’s Cavendish Laboratory and MRC LMB. “It brings us just a little bit closer to addressing the question of whether we are alone in the universe.”

The latest study is part of an ongoing collaboration between the two above institutions combining exoplanet research with organic chemistry. It builds on a 2015 paper, also published in Science Advances, in which scientists theorized that meteorites containing carbon impacted early Earth, releasing that carbon, which then interacted with atmospheric nitrogen to produce hydrogen cyanide.

Although hydrogen cyanide itself is toxic to life, its interaction with various elements on Earth’s surface via power from ultraviolet sunlight generated the building blocks of RNA, theorized to be the first molecule of life to carry information. RNA is closely related to DNA, the self-replicating material that carries genetic information in practically all organisms.

In a series of laboratory experiments, the researchers exposed water containing hydrogen cyanide and hydrogen sulphite ions to ultraviolet light and to no light to find out how quickly the building blocks of life would form.

“There is a chemistry that happens in the dark: it’s slower than the chemistry that happens in the light, but it’s there. We wanted to see how much light it would take for the light chemistry to win out over the dark chemistry,” explained Didier Queloz, also of Cavendish Laboratory.

Under darkness, the hydrogen cyanide and hydrogen sulphite produced an inert compound that could not form the building blocks of life. However, under ultraviolet light, they did produce these building blocks.

The scientists then compared the light chemistry used in the experiment to the ultraviolet light of various stars as well as the amount of light available to those stars’ planets and found that stars with roughly the same temperature as our Sun emitted sufficient light to form life’s building blocks.

Planets with temperatures that allow liquid water on their surfaces that also receive the appropriate amount of ultraviolet light to start this chemical process were designated as being in the abiogenesis zone.

 

Martian dust storm begins to subside

Orbiters and Curiosity rover confirm decline in atmospheric dust.

The global dust storm that has raged on Mars for more than a month is beginning to subside, according to observations by orbiters circling the Red Planet as well as by NASA’s Curiosity rover.

According to scientists monitoring the storm, more dust has been falling to the planet’s surface than being raised into its atmosphere since July 23.

NASA’s Mars Reconnaissance Orbiter (MRO) recorded that temperatures in the middle section of Mars’s atmosphere have stopped rising. Warming in this part of the atmosphere is caused by dust particles absorbing solar heat, so a halt in that warming indicates levels of atmospheric dust are falling.

Both MRO’s Mars Color Imager (MARCI), a wide-angle-camera, and its Mars Climate Sounder (MCS), an instrument that profiles temperature, picked up signs of the diminishing storm.

Their data is corroborated on the ground by Curiosity, which has also detected dust levels declining at its location in the 96-mile- (154-km-) wide Gale Crater. Because Curiosity is nuclear-powered, it does not rely on solar panels and has been able to continue operating during the storm.

“It’s the beginning of the end for the planet-encircling dust storm on Mars,” noted a NASA statement released on Thursday, July 26.

Several surface features and Martian land forms that were obscured by dust for weeks are again becoming visible to orbiters, the statement added.

Scientists hope the storm will die down enough for Earth-based telescopes to view these features, as Mars is currently making its closest approach to Earth since 2003.

NASA’s 15-year-old Opportunity rover, which relies on solar panels to power its batteries, put itself into hibernation mode in June when the storm intensified and has not contacted Earth since June 10.

Members of Opportunity’s mission team, who listen daily for signals from the rover, are hopeful it will survive and eventually reawaken, as temperatures at its location in the 14-mile- (22-km-) wide Endeavor Crater never fell low enough to freeze it.

At the same time, they acknowledge the rover could take several weeks or even months to contact Earth again because the Martian skies need to be clear enough for its solar panels to recharge its batteries.