Tag: space

The Slooh community observatory will be celebrating Earth Day on Saturday (April 22), with a webcast beginning at 9 a.m. EDT (1300 GMT). During the webcast, members of the public will share the things they’d miss most about Earth if they had to go to space, while two astronauts will name the things they did miss during their journeys to space. You can watch the Earth Day webcast live via Slooh.com, or in the window below, courtesy of Slooh. 

From Slooh: 

“On Saturday, 22nd April 2017 … Slooh will host a special live show for Earth Day, sponsored by the digital release of Sony Pictures’ Passengers.  

“Over the last month, people from all over the world have sent in videos to Slooh answering one very important question: what would they would miss about our planet if they were to go into space? During the live show, Slooh will share a compilation of the best submissions and will explore what about the Earth inspires those who reach for the stars. The show will be anchored by live views of the Earth from space and with live feeds of various beautiful vistas around the world from Slooh’s observatory in the Canary Islands, as well as cameras around the globe.

“Headlining the show are NASA astronauts Doctors Tracy Caldwell Dyson and Stan Love. They will be sharing what they missed about Earth when they were away in space, how their unique perspective deepened their appreciation of the planet, and what they will be doing to honor Earth this Earth Day.
 
“Academy-award nominated production designer, Guy Hendrix Dyas, will also join the show to talk about why the concept of leaving Earth is so popular in science fiction, and his experience of capturing the contrast between outer space and Earth in his latest movie, Passengers. 

“‘No matter who we are or where we live, we all share a common home — Earth,’ says Slooh Human Spirit Editor, Helen Avery. ‘In the day-to-day, we often forget that we are all connected, as too do we often forget just how wondrous our planet is. It is the most diverse of all those in our solar system, and — as far as we yet know — in the universe. Earth Day is a wonderful time to come together to remember and to appreciate the home we all share.’

“Join with Slooh and people from around the world to celebrate the wonder of our planet, as we remind ourselves … there really is no place like home. 

“Viewers can join in on the celebration on Twitter by sending questions and comments to @Slooh or using the hashtag #noplacelikehome. Viewers are also encouraged to join the rest of the Slooh Community in expressing on Twitter what they would miss most about Earth if they had to travel into space.”

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Thursday, Dec. 6, 2012, 10:31 a.m. EST. The last or third quarter moon rises around 11:30 p.m. and sets around 12:15 p.m. It is most easily seen just after sunrise in the southern sky.

This illustration provides a comparison for how big the moons of Mars appear to be, as seen from the surface of Mars, in relation to the size that Earth’s moon appears to be when seen from the surface of Earth. Deimos, at far left, and Phobos, beside it, are shown together as they actually were photographed by the Mast Camera (Mastcam) NASA’s Mars rover Curiosity on Aug. 1, 2013. [Read the Full Story]

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NASA’s newest astronauts are meeting the press in a series of televised interviews today through 1 p.m. EDT (1700 GMT). Space.com’s Hanneke Weitering will interview astronaut candidate Robb Kulin, formerly of SpaceX, at 11:20 a.m. EDT (1520 GMT). Tune in!

Main Story: NASA Reveals 12 New Astronauts for Earth Orbit, Deep Space Missions

What’s Next for NASA’s New Astronaut Class?

Vice President Welcomes NASA’s ‘Newest Heroes’ to Astronaut Corps

Astronauts Record Awesome Welcome Video for NASA’s 2017 Recruits

What It’s Like to Become a NASA Astronaut: 10 Surprising Facts

NASA announced the 2017 astronaut class Wednesday, June 7, at the Johnson Space Center in Houston. The astronaut candidates will be presented by acting NASA Administrator Robert Lightfoot, JSC director Ellen Ochoa and Flight Operations Director Brian Kelly. Vice President Mike Pence welcomed the new astronauts to NASA and toured the agency’s Mission Control Center. He also received briefings on the agency’s current human spaceflight operations. 

Live @ 2 p.m. EDT: NASA Budget Overview with House Appropriations Committee

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At 2 p.m. EDT (1800 GMT) today, acting NASA chiefe Robert Lightfoot will give testimony before the House Appropriations Committee during a hearing on the agency’s proposed 2018 budget. The meeting follows a 10 a.m. EDT (1400 GMT) hearing on the same subject, where Lightfoot is also appearing as a witness, by the Space Subcommittee of the House Committee on Space, Science and Technology. 

The youngest exoplanet yet discovered is less than 1 million years old and orbits Coku Tau 4, a star 420 light-years away. Astronomers inferred the planet’s presence from an enormous hole in the dusty disk that girdles the star. The hole is 10 times the size of Earth’s orbit around the Sun and probably caused by the planet clearing a space in the dust as it orbits the star. Credit: NASA

Exoplanets are planets beyond our own solar system. Thousands have been discovered in the past two decades, mostly with NASA’s Kepler space telescope. 

These worlds come in a huge variety of sizes and orbits. Some are gigantic planets hugging close to their parent stars; others are icy, some rocky. NASA and other agencies are looking for a special kind of planet: one that’s the same size as Earth, orbiting a sun-like star in the habitable zone.

The habitable zone is the range of distances from a star where a planet’s temperature allows liquid water oceans, critical for life on Earth. The earliest definition of the zone was based on simple thermal equilibrium, but current calculations of the habitable zone include many other factors, including the greenhouse effect of a planet’s atmosphere. This makes the boundaries of a habitable zone “fuzzy.”  

Early discoveries

While exoplanets were not confirmed until the 1990s, for years beforehand astronomers were convinced they were out there. That wasn’t just wishful thinking, but because of how slowly our own sun and other stars like it spin, University of British Columbia astrophysicist Jaymie Matthews told Space.com. Matthews, the mission scientist of occasional exoplanet telescope observer MOST (Microvariability and Oscillations of STars), was involved in some of the early exoplanet discoveries.

Astronomers had an origin story for our solar system. Simply put, a spinning cloud of gas and dust (called the protosolar nebula) collapsed under its own gravity and formed the sun and planets.  As the cloud collapsed, conservation of angular momentum meant the soon-to-be-sun should have spun faster and faster. But, while the sun contains 99.8 percent of the solar system’s mass, the planets have 96 percent of the angular momentum. Astronomers asked themselves why the sun rotates so slowly.

The young sun would have had a very strong magnetic field, whose lines of force reached out into the disk of swirling gas from which the planets would form. These field lines connected with the charged particles in the gas, and acted like anchors, slowing down the spin of the forming sun and spinning up the gas that would eventually turn into the planets. Most stars like the sun rotate slowly, so astronomers inferred that the same “magnetic braking” occurred for them, meaning that planet formation must have occurred for them. The implication: Planets must be common around sun-like stars.

For this reason and others, astronomers at first restricted their search for exoplanets to stars similar to the sun, but the first two discoveries were around a pulsar (rapidly spinning corpse of a star that died as a supernova) called PSR 1257+12, in 1992. The first confirmed discovery of a world orbiting a sun-like star, in 1995, was 51 Pegasi b — a Jupiter-mass planet 20 times closer to its sun than we are to ours. That was a surprise. But another oddity popped up seven years earlier that hinted at the wealth of exoplanets to come.

A Canadian team discovered a Jupiter-size planet around Gamma Cephei in 1988, but because its orbit was much smaller than Jupiter’s, the scientists did not claim a definitive planet detection. “We weren’t expecting planets like that. It was different enough from a planet in our own solar system that they were cautious,” Matthews said.  

Alien Worlds Infographic 20″x60″ Poster. Buy Here
Credit: Space.com Store

Explosion of data

Most of the first exoplanet discoveries were huge Jupiter-size (or larger) gas giants orbiting close to their parent stars. That’s because astronomers were relying on the radial velocity technique, which measures how much a star “wobbles” when a planet or planets orbit it. These large planets close in produce a correspondingly big effect on their parent star, causing an easier-to-detect wobble.

Before the era of exoplanet discoveries, instruments could only measure stellar motions down to a kilometer per second, too imprecise to detect a wobble due to a planet. Now, some instruments can measure velocities as low as a centimeter per second, according to Matthews. “Partly due to better instrumentation, but also because astronomers are now more experienced in teasing subtle signals out of the data.”

Today, there are more than 1,000 confirmed exoplanets discovered by a single telescope: the Kepler space telescope, which reached orbit in 2009 and hunted for habitable planets for four years. Kepler uses a technique called the “transit” method, measuring how much a star’s light dims when a planet passes in front of it.

Kepler has revealed a cornucopia of different types of planets. Besides gas giants and terrestrial planets, it has helped define a whole new class known as “super-Earths”: planets that are between the size of Earth and Neptune. Some of these are in the habitable zones of their stars, but astrobiologists are going back to the drawing board to consider how life might develop on such worlds.

In 2014, Kepler astronomers (including Matthews’ former student Jason Rowe) unveiled a “verification by multiplicity” method that should increase the rate at which astronomers promote candidate planets to confirmed planets. The technique is based on orbital stability — many transits of a star occurring with short periods can only be due to planets in small orbits, since multiply eclipsing stars that might mimic would gravitationally eject each other from the system in just a few million years.

While the Kepler (and French CoRoT) planet-hunting satellites have ended their original missions, scientists are still mining the data for discoveries, and there are more to come. MOST is still operating, and the NASA TESS (Transiting Exoplanet Survey Satellite), Swiss CHEOPS (Characterizing ExOPlanets Satellite) and ESA’s PLATO missions will soon pick up the transit search from space.  From the ground, the HARPS spectrograph on the European Southern Observatory’s La Silla 3.6-meter telescope in Chile is leading the Doppler wobble search, but there are many other telescopes in the hunt. 

One too-neglected example, Matthews said, is NASA’s Spitzer Space Telescope. Because it is sensitive in the infrared, it can sense the temperature profile of an exoplanet and give insights into its atmosphere.

A diagram showing the relative sizes of the new alien planets discovered by Kepler, compared to Earth and Jupiter.
Credit: NASA/Tim Pyle

Notable exoplanets

With almost 2,000 to choose from, it’s hard to narrow down a few. Small solid planets in the habitable zone are automatically standouts, but Matthews singled out five other exoplanets that have expanded our perspective on how planets form and evolve:

• 51 Pegasi b: As mentioned earlier, this was the first planet to be confirmed around a sun-like star. Half the mass of Jupiter, it orbits around its sun at roughly the distance of Mercury from our Sun. 51 Pegasi b is so close to its parent star that it is likely tidally locked, meaning one side always faces the star.
• HD 209458 b: This was the first planet found (in 1999) to transit its star (although it was discovered by the Doppler wobble technique) and in subsequent years more discoveries piled up. It was the first planet outside the solar system for which we could determine aspects of its atmosphere, including temperature profile and the lack of clouds. (Matthews participated in some of the observations using MOST.)
• 55 Cancri e: This super-Earth orbits a star that is bright enough to see by eye, meaning astronomers can study the system in more detail than almost any other.  Its “year” is only 17 hours and 41 minutes long (recognized when MOST gazed at the system for two weeks in 2011). Theorists speculate that the planet may be carbon-rich, with a diamond core.
• HD 80606 b: At the time of its discovery in 2001, it held the record as the most eccentric exoplanet ever discovered. It is possible that its odd orbit (which is similar to Halley’s Comet around the sun) may be due to the influence of another star. Its extreme orbit would make the planet’s environment extremely variable.
• WASP-33b: This planet was discovered in 2011 and has a sort of “sunscreen” layer — a stratosphere — that absorbs some of the visible and ultraviolet light from its parent star. Not only does this planet orbit its star “backward,” but it also triggers vibrations in the star, seen by the MOST satellite. 

Liquid water may still flow on Mars, but that doesn’t mean it’s easy to spot. The search for water on the Red Planet has taken more than 15 years to turn up definitive signs that liquid flows on the surface today. In the past, however, rivers and oceans may have covered the land. Where did all of the liquid water go? Why? How much of it still remains?

Observations of the Red Planet indicate that rivers and oceans may have been prominent features in its early history. Billions of years ago, Mars was a warm and wet world that could have supported microbial life in some regions. But the planet is smaller than Earth, with less gravity and a thinner atmosphere. Over time, as liquid water evaporated, more and more of it escaped into space, allowing less to fall back to the surface of the planet.

Where is the water today?

Liquid water appears to flow from some steep, relatively warm slopes on the Martian surface. First identified in 2011, features known as recurring slope lineae (RSL) were confirmed to be signs of salty water running on the surface of the planet today. The dark streaks appear seasonally on Martian slopes were found in images taken by the High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter (MRO) Spectral analysis of RSL lead scientists to conclude they are caused by salty liquid water. [Related: Salty Water Flows on Mars Today, Boosting Odds for Life]

“The detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks,” the study’s lead author, Lujendra Ojha, of the Georgia Institute of Technology in Atlanta, said in a statement.

Vast deposits of water appear to be trapped within the ice caps at the north and south poles of the planet. Each summer, as temperatures increase, the caps shrink slightly as their contents skip straight from solid to gas form, but in the winter, cooler temperatures cause them to grow to latitudes as low as 45 degrees, or halfway to the equator. The caps are an average of 2 miles (3 kilometers) thick and, if completely melted, could cover the Martian surface with about 18 feet (5.6 meters) of water. 

Frozen water also lies beneath the surface. Scientists discovered a slab of ice as large as California and Texas combined in the region between the equator and north pole of the Red Planet. The presence of subsurface water has long been suspected but required the appearance of strange layered craters to confirm. Other regions of the planet may contain frozen water, as well. Some high-latitude regions seem to boast patterned ground-shapes that may have formed as permafrost in the soil freezes and thaws over time. 

The European Space Agency’s Mars Express spacecraft captured images of sheets of ice in the cooler, shadowed bottoms of craters, which suggests that liquid water can pool under appropriate conditions. Other craters identified by NASA’s Mars Reconnaissance Orbiter show similar pooling.

Evidence for water on Mars first came to light in 2000, with the appearance of gullies that suggested a liquid origin. Their formation has been hotly debated over the ensuing years.

At the center of this view of an area of mid-latitude northern Mars, a fresh crater about 6 meters (20 feet) in diameter holds an exposure of bright material, blue in this false-color image.
Credit: NASA/JPL-Caltech/University of Arizona [Full Story]

Searching for an oasis

When Mariner 9 became the first craft to orbit another planet in 1971, the photographs it returned of dry river beds and canyons seemed to indicate that water had once existed on the Martian surface. Images from the Viking orbiters only strengthened the idea that many of the landforms may have been created by running water. Data from the Viking landers pointed to the presence of water beneath the surface, but the experiments were deemed inconclusive. [Mars Explored: Landers and Rovers Since 1971 (Infographic)]

The early ’90s kicked off a slew of Mars missions. Scientists were flooded with a wealth of information about Mars. Three NASA orbiters and one sent by the European Space Agency studied the planet from above, mapping the surface and analyzing the minerals below. Some detected the presence of minerals, indicating the presence of water. Other data measured enough subsurface ice to fill Lake Michigan twice. They found evidence for the presence of hot springs on the surface and sustained precipitation at some areas. And they found patches of ice within some of the deeper craters.

Impact craters offer a view of the interior of the red planet. Using the ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter, scientists were able to study rocks ejected from the planet’s interior, finding minerals that suggested the presence of water.

“Water circulation occurred several kilometers deep in the crust some 3.7 billion years ago,” Nicolas Mangold, of the University of Nantes in France, said in a statement.

But orbiters weren’t the only objects launched toward Mars. NASA’s Curiosity rover is the fifth robot to land on the surface of the Red Planet in the last 15 years. Pathfinder, Phoenix, Spirit and Opportunity all took detailed measurements of the planet; all but Phoenix traveled across the surface collecting a treasure trove of information.

Images of one of Phoenix’s struts taken by the lander’s robotic arm camera on Sols (or Martian days) 8, 31 and 44 of th emission. The two spheroids enclosed by the circle appear to merge with each other, which some Phoenix scientists argue is a sign that the globs are liquid water.
Credit: Renno, et al., NASA

The probes dug into the ground, examining rocks and performing experiments. In 2008, Phoenix turned up small chunks of bright material that disappeared after four days, leading scientists to surmise that they were pieces of water ice. The lander went on to detect water vapor in a sample it collected and analyzed, confirming the presence of frozen water on the red planet.

Spirit and Opportunity, the twin rovers, found traces of water enclosed in rock. In a shining example of a problem becoming a solution, a broken wheel on Spirit scraped into the top of the Martian surface, revealing a layer beneath rich in silica that had most likely formed in the presence of water.

Curiosity has found yet more evidence of water flowing on ancient Mars. The 1-ton rover rolled through an ancient stream bed shortly after touching down in August 2012, and it has examined a number of rocks that were exposed to liquid water billions of years ago. 

Mars missions aren’t the only way to search for water on Mars. Scientists studying rocks ejected from the Red Planet found signs that water lay beneath the surface in the past.

“While robotic missions to Mars continue to shed light on the planet’s history, the only samples from Mars available for study on Earth are Martian meteorites,” lead author Lauren White, of the JPL, said in a statement.

“On Earth, we can utilize multiple analytical techniques to take a more in-depth look at meteorites and shed light on the history of Mars.”

Historical landforms

In addition to examining the relatively recent (geologically speaking) presence of water, the various missions have also studied the surface of the planet in a historical context. The river beds of Mars don’t run wet today, but scientists can study them to learn more about the evolution of the planet. [Photos: The Search for Water on Mars]

The flatter northern plains of Mars may once have hosted an ocean, or possibly, as the planet cycled through dry periods, two. The more recent body of water would likely have only been temporary, seeping into the ground, evaporating, or freezing in less than a million years, scientists say.

Riverbeds and gullies indicate that water ran, at least briefly, across the surface of Mars. A hundred times more water may have flowed annually through a large channel system known as Marte Vallis than passes through the Mississippi River each year, according to estimates. The gullies themselves are smaller, likely forming during brief torrential rainstorms when fast-moving water could have carved them across the land.

Curiosity found indications that at least one region of Mars, Mount Sharp, was built by sediments deposited in a lake bed millions of years ago, suggesting large pools existed on the planet for significant time periods.

“If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars,” Curiosity deputy project scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory (JPL) said in a statement.

On Earth, the land around rivers and lakes is wetter, made up of mud and clays. Such deposits exist on Mars as well, trapping water and indicating where larger bodies may have once existed.

Liquid gold

Water may seem like a very common element to those of us stuck on Earth, but it has great value. In addition to understanding how Mars may have changed and developed over time, scientists hope that finding water will help them to find something even more valuable — life, either past or present.

Only Earth is known to host life, and life on our planet requires water. Though life could conceivably evolve without relying on this precious liquid, scientists can only work with what they know. Thus they hope that locating water on celestial bodies such as Mars will lead to finding evidence for life.

With this in mind, NASA developed a strategy for exploring the Red Planet that takes as its mantra “follow the water.” Recent orbiters, landers and rovers sent to Mars were designed to search for water, rather than life, in the hopes of finding environments where life could have thrived.

That has changed, however, with the flood of evidence these robots have returned. Curiosity determined that Mars could indeed have supported microbial life in the ancient past, and the next NASA rover — a car-size robot based heavily on Curiosity’s basic design — will blast off in 2020 to look for evidence of past Red Planet life.

Additional resources

New Horizons space probe provides the highest resolution image of Pluto ever seen as presented in a NASA press conference on July 15, 2015, at the Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland. This region near Pluto’s equator surprisingly contains a range of youthful mountains rising to heights of 11,000 feet (3,500 m) above the surface. [See a video of the flyby.]