Asteroids Archives

February 2, 2015December 23, 2015 by Elizabeth Howell

Asteroids: 10 Interesting Facts About These Space Rocks

Artist's conception of asteroids and a gas giant planet. Credit: Harvard-Smithsonian Center for Astrophysics

At first glance, looking at a bunch of space rocks doesn’t sound that exciting. Like, aren’t they just a bunch of rubble? What use can they be in understanding the Solar System compared to looking at planets or moons?

Turns out that asteroids are key to figuring out how the Solar System came to be, and that they’re more interesting than they appear at first glance. Below, we have 10 facts about asteroids that will make you reconsider that biased first impression.

Asteroids are leftovers of the early Solar System.

The leading theory about how our neighborhood came to be is this: the Sun coalesced from a compressed grouping of gas that eventually began fusing atoms and creating a protostar. Meanwhile, the dust and debris nearby the Sun began to coalesce. Small grains became small rocks, which crashed into each other to form bigger ones. The survivors of this chaotic period are the planets and the moons that we see today … as well as a few smaller bodies. By studying asteroids, for example, we get a sense of what the Solar System used to look like billions of years ago.

This image shows the Themis Main Belt which sits between Mars and Jupiter. Asteroid 24 Themis, one of the largest Main Belt asteroids, was examined by University of Tennessee scientist, Josh Emery, who found water ice and organic material on the asteroid's surface. His findings were published in the April 2010 issue of Nature. Credit: Josh Emery/University of Tennessee, Knoxville — This image shows the Themis Main Belt which sits between Mars and Jupiter. Asteroid 24 Themis, one of the largest Main Belt asteroids, was examined by University of Tennessee scientist, Josh Emery, who found water ice and organic material on the asteroid’s surface. His findings were published in the April 2010 issue of Nature. Credit: Josh Emery/University of Tennessee, Knoxville

Most asteroids are in a “belt”.

While there are asteroids all over the Solar System, there’s a huge collection of them between the orbits of Mars and Jupiter. Some astronomers think that could have formed into a planet if Jupiter was not nearby. By the way, this “belt” may erroneously create the impression that it is chock full of asteroids and require some fancy Millennium Falcon-style maneuvering, but in reality there are usually hundreds or thousands of miles in between individual asteroids. This shows the Solar System is a big place.

Asteroids are made of different things.

In general, an asteroid’s composition is determined by how close it is to the Sun. Our nearby star’s pressure and heat tends to melt ice that is close by and to blow out elements that are lighter. There are many kinds of asteroids, but these are the three main types, according to NASA:

Dark C (carbonaceous) asteroids, which make up most asteroids and are in the outer belt. They’re believed to be close to the Sun’s composition, with little hydrogen or helium or other “volatile” elements.
Bright S (silicaceous) asteroids and are in the inner belt. They tend to be metallic iron with some silicates of iron and magnesium.
Bright M (metallic) asteroids. They sit in the middle of the asteroid belt and are mostly made up of metallic iron.

Illustration of small asteroids passing near Earth. Credit: ESA / P. Carril

Asteroids also lurk near planets.

NASA also has classifications for this asteroid type. Trojans stay in the same orbit as a planet, but they “hover” in a special spot known as a Lagrangian point that balances the pull of the planet’s gravity and the pull of the Sun. Trojans near Mars, Jupiter and Neptune have been discovered — as well as at least one near Earth in 2011. We also have near-Earth asteroids, which cross our orbit and could (statistically speaking) one day pose a threat to our planet. That said, no one has yet identified any one asteroid that will one day collide with our planet for sure.

Asteroids have moons.

While we think of moons as something that orbits a planet, asteroids also have smaller bodies that orbit them! The first known one was Dactyl, which was discovered in 1993 to be orbiting a larger asteroid called Ida. More than 150 asteroids are known to have moons, with more being discovered periodically. A more recent example is one discovered orbiting Asteroid 2004 BL86, which passed 750,000 miles (1.2 million kilometers) from Earth in early 2015.

Another set of images of 2004 BL86 and its moon. Credit: NAIC Observatory / Arecibo Observatory

We have flown by, orbited and even landed on asteroids. NASA says there are more than 10 spacecraft that accomplished at least one of these, so we’ll just cover a couple of examples here. NEAR Shoemaker touched down and survived for weeks on 433 Eros in 2001 despite not being designed to do it. NASA’s Dawn spacecraft spent months orbiting Vesta — the second-largest member of the asteroid belt — in 2011 and 2012. And in 2010, Japan’s Hayabusa spacecraft made an astonishing return to Earth bearing samples of asteroid Itokawa that it nabbed in 2005.

Asteroids are too small to support life as we know it. That’s because they’re too tiny to even hold on to atmospheres. Their gravity is too weak to pull their shape into a circle, so they’re irregularly shaped. To get a sense of just how small they are in aggregate, NASA says the mass of all the asteroids in the Solar System is less than our Moon — which only has a tenuous “exosphere” itself.

Impactors strike during the reign of the dinosaurs (image credit: MasPix/devianart)

Despite their small size, water may flow on asteroid surfaces. Observations of Vesta released in 2015 show gullies that may have been carved by water. The theory is that when a smaller asteroid slams into a bigger one, the small asteroid releases a layer of ice in the bigger asteroid it hit. The force of the impact briefly turned the ice into water, which streaked across the surface. (As for how the ice got there in the first place, it’s possible that comets deposited it in some way — but that’s still being investigated as well.)

An asteroid could have killed the dinosaurs. The fossil record for dinosaurs and other creatures of their era show them rapidly disappearing around 65 million or 66 million years ago. According to National Geographic, there are two hypotheses for this event: an asteroid or comet hitting the Earth, or a huge volcano eruption. The case for an asteroid comes from a layer of iridium (a rare element on Earth, but not in meteorites) that is found all over the world, and a crater called Chicxulub in Mexico’s Yucatan Peninsula that is about 65 million years old. Iridium, however, is also found inside the Earth, which lends credence to some theories that it was volcanoes instead. In either case, the resulting debris blocked the Sun and eventually starved those survivors of the impact.

At least one asteroid has rings. Called Chariklo, scientists made the surprise discovery in 2013 when they watched it pass in front of a star. The asteroid made the background star “blink” a few times, which led to the discovery that two rings are surrounding the asteroid.

January 30, 2015December 23, 2015 by Nancy Atkinson

It Looks Like an Asteroid Strike Can’t Cause a Worldwide, Dinosaur-Killing Firestorm

Computer generated simulation of an asteroid strike on the Earth. Credit: Don Davis/AFP/Getty Images

For decades, scientists have debated the cause of the mass extinction that wiped out the dinosaurs and other life 65 million years ago. While the majority of researchers agree that a massive asteroid impact at Chicxulub, Mexico is the culprit, there have been some dissenters. Now, new research is questioning just a portion of the asteroid/Cretaceous-Paleogene extinction scenario. While the scientists involved in the study don’t doubt that such an asteroid impact actually happened, their research shows it is just not possible that vast global firestorms could have ravaged our planet and be the main cause of the extinction.

Researchers from the University of Exeter, University of Edinburgh and Imperial College London recreated the vast energy released from a 15-km wide asteroid slamming into Earth, which occurred around the time that dinosaurs became extinct.

They found that close to the impact site — a 180 km wide crater in Mexico — the heat pulse would have lasted for less than a minute. This intense but short-lived heat, the team says, could not have ignited live plants, challenging the idea that the impact led to global firestorms.

However, they did find that the effects of the impact would actually be worse on the other side of the planet, where less intense but longer periods of heat could have ignited live plant matter.

“By combining computer simulations of the impact with methods from engineering we have been able to recreate the enormous heat of the impact in the laboratory,” said Dr. Claire Belcher from the University of Exeter. “This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact. This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event.”

The Cretaceous-Paleogene extinction was one of the biggest in Earth’s history and geologic evidence of the impact has been discovered in rock layers around the world from this time period. Some critics of the asteroid impact theory as a cause of the extinction have pointed to some of the microfossils from the Gulf of Mexico that show the impact occurred well before the extinction and could not have been its primary cause. Others point to volcanism that produced the Deccan traps of India around this time as a possible cause of the extinction.

But multiple models have showed such an impact would have instantly caused devastating shock waves, tsunamis, and the release of large amounts of dust, debris and gases that would have led to a low light levels and a prolonged cooling of Earth’s surface. The darkness and a global winter would have decimated the planet life and the dependent animals.

So while fire and brimstone may not have played a big role in the Cretaceous-Paleogene extinction, there was plenty of destruction and mayhem for the resulting extinction of more than 70% of known species.

Here’s a video from the researchers that shows their findings that close to the impact site, the heat pulse was too short to ignite live plant material.

Their research is published in the Journal of the Geological Society.

Source: University Exeter

January 28, 2015December 23, 2015 by Nancy Atkinson

Amazing Impact Crater Where a Triple Asteroid Smashed into Mars

A triple crater in Elysium Planitia on Mars. Credit: NASA/JPL/University of Arizona.

At first glance, you many not guess that this feature on Mars is an impact crater. The reason it looks so unusual is that it likely is a triple impact crater, formed when three asteroids struck all at once in the Elysium Planitia region.

Why do planetary scientists think the three craters did not form independently at different times?

“The ejecta blanket appears to be uniform around the triple-crater showing no signs of burial or overlapping ejecta from overprinting craters,” write scientists Eric Pilles, Livio Tornabene, Ryan Hopkins, and Kayle Hansen on the HiRISE website. “The crater rims are significantly stunted where the craters overlap.”

This oblong-shaped crater could have been created from a triple asteroid, or it could have been a binary asteroid, and one broke apart, creating the three overlapping craters. The team says the two larger craters must have been produced by asteroids of approximately the same size, probably on the order of a few hundred meters across.

“The northern crater might have been created by a smaller asteroid, which was orbiting the larger binary pair, or when one of the binary asteroids broke up upon entering the atmosphere,” the team explained. “The shape of the triple-crater is oblong, suggesting an oblique impact; therefore, another alternative would be that the asteroid split upon impact and ricocheted across the surface, creating additional craters.”

Studying craters on Mars — and there are lots of them, thanks to Mars’ sparse atmosphere — can help estimate the ages of different terrains, as well as revealing materials such as ice or minerals that get exposed from the impact.

HiRISE is the amazing camera on board the Mars Reconnaissance Orbiter.

January 19, 2015December 23, 2015 by Nancy Atkinson

Here’s Ceres Compared to All the Other Asteroids We’ve Visited

Ceres compared to asteroids visited to date, including Vesta, Dawn's mapping target in 2011. Image by NASA/ESA. Compiled by Paul Schenck.

When the Dawn mission was in its planning stages, Ceres was considered an asteroid. But in 2006, a year before the mission launched, the International Astronomical Union formed a new class of solar system objects known as dwarf planets, and since by definition a dwarf planet is spherical and travels in an orbit around the Sun, Ceres fit that definition perfectly.

But since it’s located in the Asteroid Belt, we still tend to think of Ceres as an asteroid. So, how does Ceres compare to other asteroids?

Dr. Paul Schenk, who is a participating scientist on the Dawn mission, recently put together some graphics on his website and the one above compares Ceres to other asteroids that we’ve visited with spacecraft.

Of course, Ceres is bigger (it’s the biggest object in the Asteroid Belt) and more spherical than the other asteroids. When it comes right down to it, Ceres doesn’t look much like an asteroid at all!

“Ceres is most similar in size to several of Saturn’s icy moons and may be similar internally as well, being composed of 25% water ice by mass,” Schenk noted on his website.

Comparisons of Ceres with other prominent icy objects. Dione is Ceres' closest twin in size and mass. Image credit: NASA/ESA. Compiled by Paul Schenk. — Comparisons of Ceres with other prominent icy objects. Dione is Ceres’ closest twin in size and mass. Image credit: NASA/ESA. Compiled by Paul Schenk.

And water is one of the most interesting and mysterious aspects of Ceres. A year ago, the Herschel space telescope discovered water vapor around Ceres, and the vapor could be emanating from water plumes — much like those that are on Saturn’s moon Enceladus – or it could be from cryovolcanism from geysers or icy volcano.

“The water vapor question is one of the most interesting things we will look for,” Schenk told Universe Today. “What is its source, what does it indicate about the interior and activity level within Ceres? Is Ceres active, very ancient, or both? Does it go back to the earliest Solar System? Those are the questions we hope to answer with Dawn.”

Some scientists also think Ceres may have an ocean and possibly an atmosphere, which makes Dawn’s arrival at Ceres in March one of the most exciting planetary events of 2015, in addition to New Horizon’s arrival at Pluto.

“Since we don’t know why the water vapor venting has happened, or even if it continues, it’s hard to say much more than that,” Schenk said via email, “but it is theoretically possible that some liquid water still exists within Ceres. Dawn will try to determine if that is true.”

One of the possibilities that has been discussed is that if the water vapor is confirmed, Ceres could potentially host microbial life. I asked Schenk what other factors would have to be present in order for that to have occurred?

“The presence of carbon molecules is often regarded as necessary for life,” he replied, “and we think we see that on the surface spectroscopically in the form of carbonates and clays. So, I think the questions will be, whether there is actually liquid water of any kind, whether the carbon compounds are just a surface coating or in the interior, and whether Ceres has ever been warm. If those are true then some sort of prebiotic or biotic activity is in play.”

Since we do not know the answer to any of these questions yet, Schenk says Dawn’s visit to Ceres should be interesting!

On thing of note is that Dawn is now closing in on Ceres and just today, the team released the best image we have yet of Ceres, which you can see in our article here.

Read more of Schenk’s article, “Year of the ‘Dwarves’: Ceres and Pluto Get Their Due.”

Keep tabs on the Dawn mission by following Universe Today, or see the Dawn mission website.

January 15, 2015December 23, 2015 by Ken Kremer

First SLS Engine Blazes to Life in Mississippi Test Firing Igniting NASA’s Path to Deep Space

The RS-25 engine fires up for a 500-second test Jan. 9, 2015 at NASA's Stennis Space Center near Bay St. Louis, Mississippi. Credit: NASA

NASA’s goal of sending astronauts to deep space took a major step forward when the first engine of the type destined to power the mighty Space Launch System (SLS) exploration rocket blazed to life during a successful test firing at the agency’s Stennis Space Center near Bay St. Louis, Mississippi.

The milestone hot fire test conducted on Jan. 9, involved igniting a shuttle-era RS-25 space shuttle main engine for 500 seconds on the A-1 test stand at Stennis.

A quartet of RS-25s, formerly used to power the space shuttle orbiters, will now power the core stage of the SLS which will be the most powerful rocket the world has ever seen.

“The RS-25 is the most efficient engine of its type in the world,” said Steve Wofford, manager of the SLS Liquid Engines Office at NASA’s Marshall Space Flight Center, in Huntsville, Alabama, where the SLS Program is managed. “It’s got a remarkable history of success and a great experience base that make it a great choice for NASA’s next era of exploration.”

The SLS is NASA’s mammoth heavy lift rocket now under development. It is intended to launch the Orion deep space crew capsule and propel astronauts aboard to destinations far beyond Earth and farther into space than ever before possible – beyond the Moon, to Asteroids and Mars.

The over eight minute RS-25 engine test firing provided NASA engineers with critical data on the engine controller unit, which is the “brain” of the engine providing communications between the engine and the vehice, and inlet pressure conditions.

“The controller also provides closed-loop management of the engine by regulating the thrust and fuel mixture ratio while monitoring the engine’s health and status. The new controller will use updated hardware and software configured to operate with the new SLS avionics architecture,” according to NASA.

This also marked the first test of a shuttle-era RS-25 since the conclusion of space shuttle main engine testing in 2009.

For the SLS, the RS-25 will be configured and operated differently from their use when attached as a trio to the base of the orbiters during NASA’s four decade long Space Shuttle era that ended with the STS-135 mission in July 2011.

“We’ve made modifications to the RS-25 to meet SLS specifications and will analyze and test a variety of conditions during the hot fire series,” said Wofford

“The engines for SLS will encounter colder liquid oxygen temperatures than shuttle; greater inlet pressure due to the taller core stage liquid oxygen tank and higher vehicle acceleration; and more nozzle heating due to the four-engine configuration and their position in-plane with the SLS booster exhaust nozzles.”

Watch this video of the RS-25 engine test:

Video Caption: The RS-25 engine that will drive NASA’s new rocket, the Space Launch System, to deep space blazed through its first successful test Jan. 9 at the agency’s Stennis Space Center near Bay St. Louis, Mississippi. Credit: NASA TV

The SLS core stage stores the cryogenic liquid hydrogen and liquid oxygen that fuel the RS-25 first stage engines.

“This first hot-fire test of the RS-25 engine represents a significant effort on behalf of Stennis Space Center’s A-1 test team,” said Ronald Rigney, RS-25 project manager at Stennis.

“Our technicians and engineers have been working diligently to design, modify and activate an extremely complex and capable facility in support of RS-25 engine testing.”

The Jan. 9 engine test was just the first of an extensive series planned. After an upgrade to the high pressure cooling system, an initial series of eight development tests will begin in April 2015 totaling 3,500 seconds of firing time.

A close-up view of the RS-25 engine from the test stand. Credit: NASA

The SLS core stage is being built at NASA’s Michoud Assembly Facility in New Orleans.

On Sept. 12, 2014, NASA Administrator Charles Bolden officially unveiled the world’s largest welder at Michoud, that will be used to construct the core stage, as I reported earlier during my on-site visit.

“This rocket is a game changer in terms of deep space exploration and will launch NASA astronauts to investigate asteroids and explore the surface of Mars while opening new possibilities for science missions, as well,” said NASA Administrator Charles Bolden during the ribbon-cutting ceremony at Michoud.

The core stage towers over 212 feet (64.6 meters) tall and sports a diameter of 27.6 feet (8.4 m).

NASA Administrator Charles Bolden officially unveils world’s largest welder to start construction of core stage of NASA's Space Launch System (SLS) rocket at NASA Michoud Assembly Facility, New Orleans, on Sept. 12, 2014. SLS will be the world’s most powerful rocket ever built. Credit: Ken Kremer - kenkremer.com — NASA Administrator Charles Bolden officially unveils world’s largest welder to start construction of core stage of NASA’s Space Launch System (SLS) rocket at NASA Michoud Assembly Facility, New Orleans, on Sept. 12, 2014. SLS will be the world’s most powerful rocket ever built. Credit: Ken Kremer/kenkremer.com/AmericaSpace

The maiden test flight of the SLS is targeted for no later than November 2018 and will be configured in its initial 70-metric-ton (77-ton) version with a liftoff thrust of 8.4 million pounds. It will boost an unmanned Orion on an approximately three week long test flight beyond the Moon and back.

NASA plans to gradually upgrade the SLS to achieve an unprecedented lift capability of 130 metric tons (143 tons), enabling the more distant missions even farther into our solar system.

The first SLS test flight with the uncrewed Orion is called Exploration Mission-1 (EM-1) and will launch from Launch Complex 39-B at the Kennedy Space Center.

Orion’s inaugural mission dubbed Exploration Flight Test-1 (EFT) was successfully launched on a flawless flight on Dec. 5, 2014 atop a United Launch Alliance Delta IV Heavy rocket Space Launch Complex 37 (SLC-37) at Cape Canaveral Air Force Station in Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

STS-135: Last launch using RS-25 engines that will now power NASA’s SLS deep space exploration rocket. NASA’s 135th and final shuttle mission takes flight on July 8, 2011 at 11:29 a.m. from the Kennedy Space Center in Florida bound for the ISS and the high frontier with Chris Ferguson as Space Shuttle Commander. Credit: Ken Kremer/kenkremer.com

January 13, 2015December 23, 2015 by Elizabeth Howell

What Other Worlds Have We Landed On?

As of November 2014, these are all of the planetary, lunar and small body surfaces where humanity has either lived, visited, or sent probes to. Composition by Mike Malaska, updated by Michiel Straathof. Image credits: Comet 67P/C-G [Rosetta/Philae]: ESA / Rosetta / Philae / CIVA / Michiel Straathof. Asteroid Itokawa [Hayabusa]: ISAS / JAXA / Gordan Ugarkovic. Moon [Apollo 17]: NASA. Venus [Venera 14]: IKI / Don Mitchell / Ted Stryk / Mike Malaska. Mars [Mars Exploration Rover Spirit]: NASA / JPL / Cornell / Mike Malaska. Titan [Cassini-Huygens]: ESA / NASA / JPL / University of Arizona. Earth: Mike Malaska

Think of all the different horizons humans have viewed on other worlds. The dust-filled skies of Mars. The Moon’s inky darkness. Titan’s orange haze. These are just a small subset of the worlds that humans or our robots landed on since the Space Age began.

It’s a mighty tribute to human imagination and engineering that we’ve managed to get to all these places, from moons to planets to comets and asteroids. By the way, for the most part we are going to focus on “soft landings” rather than impacts — so, for example, we wouldn’t count Galileo’s death plunge into Jupiter in 2003, or the series of planned landers on Mars that ended up crashing instead.

The Moon

Al Shepard raises the American flag during Apollo 14 in February 1971. Below is the shadow of his crewmate, Ed Mitchell. Credit: NASA

Our instant first association with landings on other worlds is the human landings on the Moon. While it looms large in NASA folklore, the Apollo landings only took place in a brief span of space history. Neil Armstrong and Buzz Aldrin were the first crew (on Apollo 11) to make a sortie in 1969, and Apollo 17’s Gene Cernan and Jack Schmitt made the final set of moonwalks in 1972. (Read more: How Many People Have Walked on the Moon?)

But don’t forget all the robotic surveyors that came before and after. In 1959, the Soviet Union’s Luna 2 made the first impact on the lunar surface; the first soft landing came in 1966, with Luna 9. The United States set a series of Ranger and Surveyor probes to reach the moon in the 1960s and 1970s. The Soviet Union also deployed a rover on the moon, Lunakhod 1, in 1970 — the first remote-controlled robot controlled on another world’s surface.

In 2013, China made the first lunar soft landing in a generation. The country’s Chang’e-3 not only made it safely, but deployed the Yutu rover shortly afterwards.

Mars

Mars is a popular destination for spacecraft, but only a fraction of those machines that tried to get there actually safely made it to the surface. The first successful soft landing came on Dec. 2, 1971 when the Soviet Union’s Mars 3 made it to the surface. The spacecraft, however, only transmitted for 20 seconds — perhaps due to dust storms on the planet’s surface.

Less than five years later, on July 20, 1976, NASA’s Viking 1 touched down on Chryse Planitia. This was quickly followed by its twin Viking 2 in September. NASA has actually made all the other soft landings to date, and expanded its exploration by using rovers to move around on the surface. The first one was Sojourner, a rover that rolled off the Pathfinder lander in 1997.

NASA also sent a pair of Mars Exploration Rovers in 2004. Spirit transmitted information back to Earth until 2010, while Opportunity is still roaming the surface. The more massive Curiosity lander followed them in 2012. Another stationary spacecraft, Phoenix, successfully landed close to the planet’s north pole in 2008.

Venus

Venera 7 — one of a series of Soviet probes sent in the 1960s and 1970s — was the first to make it to the surface of Venus and send data back, on Dec. 15, 1970. It lasted 23 minutes on the surface, transmitting weakly towards Earth. This may have been because it came to rest on its side after bouncing through a landing.

The first pictures of the surface came courtesy of Venera 9, which made it to Venus on Oct. 22, 1975 and sent data back for 53 minutes. Venera 10 also successfully landed three days later and sent back data from Venus as planned. Several other Venera probes followed, most notably including Venera 13 — which sent back the first color images and remained active for 127 minutes.

Titan

Humanity’s first and only landing on Titan so far came on Jan. 14, 2005. The European Space Agency’s Huygens probe likely didn’t come to rest right away when it arrived on the surface, bouncing and skidding for about 10 seconds after landing, an analysis showed almost a decade later.

A fish-eye view of Titan's surface from the European Space Agency's Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona — A fish-eye view of Titan’s surface from the European Space Agency’s Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona

The probe managed to send back information all the way through its 2.5-hour descent, and continued transmitting data for an hour and 12 minutes after landing. Besides the pictures, it also sent back information about the moon’s wind and surface.

The orangey moon of Saturn has come under scrutiny because it is believed to have elements in its atmosphere and on its surface that are precursors to life. It also has lakes of ethane and methane on its surface, showing that it has a liquid cycle similar to our own planet.

Comets and asteroids

Images from the Rosetta spacecraft show Philae drifting across the surface of its target comet during landing Nov. 12, 2014. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Robots have also touched the ground on smaller, airless bodies in our Solar System — specifically, a comet and two asteroids. NASA’s NEAR Shoemaker made the first landing on asteroid Eros on Feb. 12, 2001, even though the spacecraft wasn’t even designed to do so. While no images were sent back from the surface, it did transmit data successfully for more than two weeks.

Japan made its first landing on an extraterrestrial surface on Nov. 19, 2005, when the Hayabusa spacecraft successfully touched down on asteroid Itokawa. (This followed a failed attempt to send a small hopper/lander, called Minerva, from Hayabusa on Nov. 12.) Incredibly, Hayabusa not only made it to the surface, but took off again to return the samples to Earth — a feat it accomplished successfully in 2010.

The first comet landing came on Nov. 12, 2014 when the European Space Agency’s Philae lander successfully separated from the Rosetta orbiter and touched the surface of Comet 67P/Churyumov–Gerasimenko. Philae’s harpoons failed to deploy as planned and the lander drifted for more than two hours from its planned landing site until it stopped in a relatively shady spot on the comet’s surface. Its batteries drained after a few days and the probe fell silent. As of early 2015, controllers are hoping that as more sunlight reaches 67P by mid-year, Philae will wake up again.

January 8, 2015March 1, 2017 by Fraser Cain

Will We Mine Asteroids?

It’s been said that a single asteroid might be worth trillions of dollars in precious rare metals. Will we ever reach out and mine these space rocks? How hard could it be?

Here on Earth, precious metals like gold and silver are getting harder to find. Geologists are developing more elaborate ways to get at the veins of precious metals beneath the surface of the Earth. And for the truly rare metals, like platinum and iridium, forget about it. All the platinum ever mined in the history of the world would fit inside my basement, and it’s not that big of a basement.

There are asteroids out there, just floating past us, taunting us, containing mountains of precious minerals. There are iron-nickel asteroids made entirely of metal. Comets of water, dirt and organic materials, everything you’d need to make an orbital farm. Just a single 30-meter asteroid, like the recently discovered 2012 DA14, is worth $20 trillion dollars. Now, if you could just somehow get to it.

Mining here on Earth is hard enough, but actually harvesting material from asteroids in the Solar System sounds almost impossible. But almost impossible, is still possible. With enough ingenuity and a few breakthroughs in spaceflight and robotics, plus some convenient hand waving for the sake of storytelling and there could be a future of asteroid mining ahead of us.

If there are mineral rich asteroids that contain a large amount of precious elements, it just might be cost effective to deliver those elements back to Earth. $20 trillion dollars sure would help buy that space elevator you wanted for sci-fi Christmas. If we had Robotic harvesters extract the gold, platinum and iridium off the surface of the space rock and they could send return capsules to Earth.

It would make even more sense to keep this stuff in space. Future spacecraft will need rocket fuel, hydrogen and oxygen, conveniently contained in water. If you could mine water ice off a comet or asteroid, you could create fuel depots across the Solar System.

Artists's conception of a Robot space miner. Credit: NASA — Artists’s conception of a Robot space miner. Credit: NASA

Miners could extract and concentrate other materials needed for spaceflight and return them to Earth orbit. There could eventually be an orbiting collection of everything you need to survive in space, all gathered together and conveniently located … in space.

You might be surprised to know that getting to a nearby asteroid would require less energy than traveling to the Moon. Asteroids actually make better refueling stations than the Moon, and could serve as a waypoint to the other planets.

There are a few companies working to mine asteroids right now. Planetary Resources and Deep Space Industries have both developed plans for robotic missions to find asteroid targets, analyze them up close, and even return samples to Earth for study.

Artist's illustration of a robotic miner. Image credit: NASA — Artist’s illustration of a robotic miner. Image credit: NASA

Within a few decades, they should have identified some ideal candidate asteroids for mining, and we get on with the work of mining with Solar System to support our further exploration. Perhaps then we’ll become a true spacefaring civilization, or just get conquered by an uprising of our sentient robotic miner drones.

So, will this ever happen? Will we eventually mine asteroids to send material back to Earth and support the exploration of space? Who knows. Business and industry are drivers of innovation. If there’s profit to be made, somebody will figure out how to do it.

What do you think? Do you envision a future career as an asteroid miner? Can we all be like Bruce Willis? Tell us in the comments below.

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December 11, 2014December 23, 2015 by Tim Reyes

Rosetta’s Instruments Direct Scientists to Look Elsewhere for the Source of Earth’s Water

Illustration of a rocky planet being bombarded by comets. (Image credit: NASA/JPL-Caltech)

Where did all of our water come from? What might seem like a simple question has challenged and intrigued planetary scientists for decades. So results just released by Rosetta mission scientists have been much anticipated and the observations of the Rosetta spacecraft instruments are telling us to look elsewhere. The water of comet 67P/Churyumov-Gerasimenko does not resemble Earth’s water.

Because the Earth was extremely hot early in its formation, scientists believe that Earth’s original water should have boiled away like that from a boiling kettle. Prevailing theories have considered two sources for a later delivery of water to the surface of the Earth once conditions had cooled. One is comets and the other is asteroids. Surely some water arrived from both sources, but the question has been which one is the predominant source.

There are two areas of our Solar System in which comets formed about 4.6 billion years ago. One is the Oort cloud far beyond Pluto. Everything points to Comet 67P’s origins being the other birthplace of comets – the Kuiper Belt in the region of Neptune and Pluto. The Rosetta results are ruling out Kuiper Belt comets as a source of Earth’s water. Previous observations of Oort cloud comets, such as Hyakutake and Hale-Bopp, have shown that they also do not have Earth-like water. So planetary scientists must reconsider their models with weight being given to the other possible source – asteroids.

The question of the source of Earth’s water has been tackled by Earth-based instruments and several probes which rendezvous with comets. In 1986, the first flyby of a comet – Comet 1P/Halley, an Oort cloud comet – revealed that its water was not like the water on Earth. How the water from these comets –Halley’s and now 67P – differs from Earth’s is in the ratio of the two types of hydrogen atoms that make up the water molecule.

Illustration of the Rosetta spacecraft showing the location of the ROSINA mass spectrometer instrument, DFMS. The difference between a Deuterium and Hydrogen atom are also illustrated. A water molecule with Deuterium is known as heavy water due to the additional mass of D vs. H (an extra neutron). (Credit: ESA/Rosetta) — Illustration of the Rosetta spacecraft showing the location of the ROSINA mass spectrometer instrument, DFMS. The difference between a Deuterium and Hydrogen atom is also illustrated. A water molecule with Deuterium is known as heavy water due to the additional mass of Dueterium vs. Hydrogen (i.e., an extra neutron). (Credit: ESA/Rosetta)

Measurements by spectrometers revealed how much Deuterium – a heavier form of the Hydrogen atom – existed in relation to the most common type of Hydrogen in these comets. This ratio, designated as D/H, is about 1 in 6000 in Earth’s ocean water. For the vast majority of comets, remote or in-situ measurements have found a ratio that is higher which does not support the assertion that comets delivered water to the early Earth surface, at least not much of it.

Most recently, Hershel space telescope observations of comet Hartley 2 (103P/Hartley) caused a stir in the debate of the source of Earth’s water. The spectral measurements of the comet’s light revealed a D/H ratio just like Earth’s water. But now the Hershel observation has become more of an exception because of Rosetta’s latest measurements.

A plot displaying the Deuterium/Hydrogen (D/H) ratio of Solar System objects. Only asteroids have a D/H ratio that matches the Earths and comets with the exception of two so far measured have higher ratios. Objects are grouped by color. Planets & moons (blue), chrondritic meteorites from the asteroid belt (grey), Oort cloud comets(purple), Jupiter family comets(pink). Diamond markers = In Situ measurements, Circles = remote astronomical measurements(Credit: Altwegg et al. 2014) — A plot displaying the Deuterium/Hydrogen (D/H) ratio of Solar System objects. Asteroids have a D/H ratio that matches that of the Earth, while comets – except for two measured to date – have higher ratios. Objects are grouped by color: planets & moons (blue), chrondritic meteorites from the asteroid belt (grey), Oort cloud comets (purple), and Jupiter family comets (pink). Diamond markers = In Situ measurements; circles = remote astronomical measurements. (Credit: Altwegg, et al. 2014)

The new measurements of 67P were made by the ROSINA Double Focusing Mass Spectrometer (DFMS) on board Rosetta. Unlike remote observations using light which are less accurate, Rosetta was able to accurately measure the quantities of Deuterium and common Hydrogen surrounding the comet. Scientists could then simply determine a ratio. The results are reported in the paper “67P/Churyumov-Gerasimenko, a Jupiter Family Comet with a high D/H ratio” by K. Altwegg, et al., published in the 10 December 2014 issue of Science.

New Rosetta mission findings do not exclude comets as a source of water in and on the Earth's crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager) — New Rosetta mission findings do not exclude comets as a source of water in and on the Earth’s crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager)

The ROSINA instrument observations determined a ratio of 5.3 ± 0.7 × 10^-4, which is approximately 3 times the ratio of D/H for Earth’s water. These results do not exclude comets as a source of terrestrial water but they do redirect scientists to consider asteroids as the predominant source. While asteroids have much lower water content compared with comets, asteroids, and their smaller versions, meteoroids, are more numerous than comets. Every meteor/falling star that we see burning up in our atmosphere delivers a myriad of compounds, including water, to Earth. Early on, the onslaught of meteoroids and asteroids impacting Earth was far greater. Consequently, the small quantities of water added delivered by each could add up to what now lies in the oceans, lakes, streams, and even our bodies.

References:

D/H Ratio of Water on Earth Measured with DFMS

67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

Rosetta fuels the debate on the Origin of Earth’s Water

The Provenances of Asteroids, and Their Contributions to the Volatile Inventories of the Terrestrial Planets

Recent Universe Today related article:

What Percent of Earth is Water?

December 5, 2014December 29, 2015 by Fraser Cain

Weekly Space Hangout – Dec. 5, 2014: Orion’s Successful Launch!

Host: Fraser Cain (@fcain)

Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Ramin Skibba (@raminskibba)

Continue reading “Weekly Space Hangout – Dec. 5, 2014: Orion’s Successful Launch!”

December 1, 2014October 31, 2016 by Matt Williams

What Percent of Earth is Water?

The Earth is often compared to a majestic blue marble, especially by those privileged few who have gazed upon it from orbit. This is due to the prevalence of water on the planet’s surface. While water itself is not blue, water gives off blue light upon reflection.

For those of us confined to living on the surface, the fact that our world is mostly covered in water is a well known fact. But how much of our planet is made up of water, exactly? Like most facts pertaining to our world, the answer is a little more complicated than you might think, and takes into account a number of different qualifications.

Sources of Water:

In simplest terms, water makes up about 71% of the Earth’s surface, while the other 29% consists of continents and islands. To break the numbers down, 96.5% of all the Earth’s water is contained within the oceans as salt water, while the remaining 3.5% is freshwater lakes and frozen water locked up in glaciers and the polar ice caps.

Of that fresh water, almost all of it takes the form of ice: 69% of it, to be exact. If you could melt all that ice, and the Earth’s surface was perfectly smooth, the sea levels would rise to an altitude of 2.7 km.

Illustration showing all of Earth's water, liquid fresh water, and water in lakes and rivers. Credit: Howard Perlman/USGS/Jack Cook/WHOI — *Illustration showing all of Earth’s water, liquid fresh water, and water in lakes and rivers. Credit: Howard Perlman, USGS/illustraion by Jack Cook, WHOI*

Aside from the water that exists in ice form, there is also the staggering amount of water that exists beneath the Earth’s surface. If you were to gather all the Earth’s fresh water together as a single mass (as shown in the image above) it is estimated that it would measure some 1,386 million cubic kilometers (km³) in volume.

Meanwhile, the amount of water that exists as groundwater, rivers, lakes, and streams would constitute just over 10.6 million km³, which works out to a little over 0.7%. Seen in this context, the limited and precious nature of freshwater becomes truly clear.

Volume vs. Mass:

But how much of Earth is water – i.e. how much water contributes to the actual mass of the planet? This includes not just the surface of the Earth, but inside as well. In terms of volume, all of the water on Earth works out to about 1.386 billion cubic kilometers (km³) or 332.5 million cubic miles (mi³) of space.

But in terms of mas, scientists calculate that the oceans on Earth weight about 1.35 x 10¹⁸ metric tonnes (1.488 x 10¹⁸ US tons), which is the equivalent of 1.35 billion trillion kg, or 2976 trillion trillion pounds. This is just 1/4400 the total mass of the Earth, which means that while the oceans cover 71% of the Earth’s surface, they only account for 0.02% of our planet’s total mass.

*Many theories about the origins of water on Earth attribute it to collisions with comets and asteroids. Credit: NASA/JPL/Caltech*

Source of Earth’s Water:

The origin of water on the Earth’s surface, as well as the fact that it has more water than any other rocky planet in the Solar System, are two of long-standing mysteries concerning our planet. Not that long ago, it was believed that our planet formed dry some 4.6 billion years ago, with high-energy impacts creating a molten surface on the infant Earth.

According to this theory, water was brought to the world’s oceans thanks to icy comets, trans-Neptunian objects or water-rich meteoroids (protoplanets) from the outer reaches of the main asteroid belt colliding with the Earth.

However, more recent research conducted by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts, has pushed the date of these origins back further. According to this new study, the world’s oceans also date back 4.6 billion years, when all the worlds of the inner Solar System were still forming.

This conclusion was reached by examining meteorites thought to have formed at different times in the history of the Solar System. Carbonaceous chondrite, the oldest meteorites that have been dated to the very earliest days of the Solar System, were found to have the same chemistry as those originating from protoplanets like Vesta. This includes a significance presence of water.

These meteorites are dated to the same epoch in which water was believed to have formed on Earth – some 11 million years after the formation of the Solar System. In short, it now appears that meteorites were depositing water on Earth in its earliest days.

While not ruling out the possibility that some of the water that covers 71 percent of Earth today may have arrived later, these findings suggest that there was enough already here for life to have begun earlier than thought.

We’ve written many articles about the oceans for Universe Today. Here’s How Many Oceans are there in the World?, Earth Has Less Water Than You Think, Where Did Earth’s Water Come From?, Why Doesn’t Earth Have More Water?, Rethinking the Source of Earth’s Water.

If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth and Episode 363: Where Did Earth’s Water Come From?

Sources: