Posted on by Jason Major

Astronomers Measure Sunlight’s Shove

The physical force of sunlight on a moving asteroid has been measured by NASA scientists, providing information on how to better plot these Earth-passing worlds’ future paths.

First proposed by a 19-century Russian engineer, the Yarkovsky effect is the result of an object in space absorbing radiation from the Sun and emitting it as heat, thus creating a slight-but-measurable change in its movement (thanks to Newton’s first law of motion.)

By observing the 1999, 2005 and 2011 close passes of asteroid 1999 RQ36 with the Arecibo and Goldstone radar telescopes, astronomers were able to determine how much the trajectory of the half-kilometer-wide asteroid had changed.

The researchers’ findings revealed that RQ36 shifted by 160 km – about 100 miles – over the course of those 12 years. That deviation is attributed to the Yarkovsky effect. A miniscule force in and of itself, over time it has the ability to move entire worlds (albeit relatively small ones.)

“The Yarkovsky force on 1999 RQ36 at its peak, when the asteroid is nearest the Sun, is only about a half ounce — about the weight of three grapes on Earth,” said Steven Chesley of NASA’s Jet Propulsion Laboratory in Pasadena “Meanwhile, the mass of the asteroid is estimated to be about 68 million tons. You need extremely precise measurements over a fairly long time span to see something so slight acting on something so huge.”

Using measurements of the distance between the Arecibo Observatory in Puerto Rico and RQ36 during its latest pass in 2011 – a feat that was compared by team leader Michael Nolan to “measuring the distance between New York City and Los Angeles to an accuracy of two inches” – Chesley and his team were able to calculate all the asteroid’s near-Earth approaches closer than 7.5 million km (4.6 million miles) from the years 1654 to 2135. 11 such passes were found.

In addition, observation of 1999 RQ36 with NASA’s Spitzer Space Telescope found it to have about the same density as water – that’s light, for an asteroid.

Most likely, RQ36 is a “rubble-pile” form of asteroid, composed of a conglomeration of individual chunks of material held together by gravity.

These findings will be used by NASA scientists to help fine-tune the upcoming OSIRIS-REx mission, which is scheduled to launch in 2016 to rendezvous with 1999 RQ36 and return samples to Earth in 2023. Being a loose collection of rocks is expected to aid in the spacecraft’s sample retrieval process.

The findings were presented on May 19 at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan. Read more here.

(Top image: series of radar images of asteroid 1999 RQ36 were obtained by NASA’s Deep Space Network antenna in Goldstone, Calif. on Sept 23, 1999. Credit: NASA/JPL-Caltech)

Posted on by Nancy Atkinson

Big and Bright Asteroid to Pass by Earth June 14

An unusually large and bright near-Earth asteroid was recently discovered and it will make its closest approach to Earth on June 14 at about 23:10 UTC. The object is so bright, the Slooh Observatory will attempt to have a live webcast showing the object sneaking past Earth at about 5.3 million km (3.35 million) miles away, or about 14 times the distance between Earth and the Moon. The asteroid, 2012 LZ1 was discovered by Rob McNaught and colleagues on 2012 June 10/11, and is about 502 meters (1,650 feet) wide.

The team of Nick Howes, Ernesto Guido and Giovanni Sostero from the Remanzacco Observatory took this image of 2012 LZ1 on June 13. They also have an animation of the object here.

There’s no danger this asteroid will impact Earth, but it has been classified as a Potentially Hazardous Asteroid. PHAs are asteroids larger than approximately 100 meters that can come closer to our planet than 0.05 AU (7.4 million km, 4.65 million miles). None of the known PHAs is on a collision course with our planet, although, as the Remanzacco team pointed out, astronomers are finding new ones all the time.

The Slooh Observatory will use a telescope on the Canary Islands and webcast the footage beginning at 00:00 UTC on Friday (8:00 p.m. EDT Thursday), and the link to the webcast is http://events.slooh.com/. Discoverer Rob McNaught will be joining the webcast for commentary. McNaught made the discovery using the Uppsala Schmidt telescope at Siding Spring Observatory in Australia.

2012 LZ1 is just a bit smaller than asteroid 2005 YU55 (502 meters), which made a very close flyby of Earth in November, 2011 at just 32,5087km (202,000 miles) away.

Want to try and see this asteroid for yourself? Check out the Minor Planet Center’s ephemeris of this object, and for reference, it will be passing near NGC 6822 (Barnard’s Galaxy) in the constellation Sagittarius at its time of closest approach.

Sources: Remanzacco Observatory, iTelescope.net

Posted on by Nancy Atkinson

Vesta’s Amazing Technicolor Surface

A brand new 3-D video map from the Dawn mission provides a unique view of the varied surface of the giant asteroid Vesta. The animation drapes high-resolution false color images over a 3-D model of the Vesta terrain constructed from Dawn’s observations. This visualization enables a detailed view of the variation in the material properties of Vesta in the context of its topography.
Continue reading “Vesta’s Amazing Technicolor Surface”

Posted on by Jon Voisey

Earth Threatened By Glowing Green Asteroid?

Killer asteroid coming for the Earth?
Killer asteroid coming for the Earth?

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The Daily Mail is reporting that a youtube user has found a strange object while poking around in Google Sky. It looks suspiciously like a glowing green asteroid and he claims it’s heading right for us. But before we call in the experts, let’s do a little bit of critical analysis on our own.

First off, the image raises alarm bells because of the apparent size of the object. Without knowing how far away it may be, it’s hard to say how large it would actually be, but we can put some limits on it. I looked up the region on Aladin and the angular distance between the two stars just to the upper right of the object is 1 arc minute. The object seems to be about that size, so we can use that as a baseline.

Assuming that the object was somewhere in the vicinity of Pluto (roughly 6 billion km), doing a bit of quick geometry means the object would be somewhere around 580,000 km. To put that in context, that’s about 40% the diameter of the Sun. If that were the case, this wouldn’t be an asteroid, it would be a small star. The funny thing about stars is that they tend to be somewhat bright and a lot more round. So that rules out that extreme.

But what if it were very close? At the distance of the moon, that would mean the object would be about 300 km in diameter which would make this thing slightly smaller than the largest asteroid, Ceres. However, this raises another issue: With that much mass, the object should still be pretty round. Additionally, with such a size and distance, it would be very bright. And it’s not.

2011 MD on Monday, June 27, 2011 at 09:30 UTC with RGB filter. Credit: Ernesto Guido, Nick Howes and Giovanni Sostero at the Faulkes Telescope South.
Even closer we run into additional issues. Astronomical images aren’t taken as a single color image. Images like this are taken in 3 filters (RGB) and then combined to make a color image. If the object is nearby, it moves from image to image, showing up in the final image in 3 places, each as a different color. For example, here’s an image of 2011 MD illustrating the effect. Given the object in question doesn’t have this tri-color separation going on, it can’t be nearby.

So this has pretty much ruled out anything anywhere in our solar system. If it’s close, it should have color issues and be bright. If it’s far, it’s too massive to have been missed. Outside of our solar system and it wouldn’t have any apparent motion and should be visible in other images. And it’s not.

In fact, searching the various databases from which Google Sky draws its data (SDSS, DSS, HST, IRAS, and WMAP), the killer asteroid doesn’t appear at all. Thus, it would seem that this object is nothing more than a technical glitch introduced by Google’s stitching together of images. Sorry conspiracy theorists. No Planet X or Nibiru out there this time!

Posted on by Nancy Atkinson

Video: Tiny Asteroid 2012 KT42 Crossing The Sky

2012 KT42 at closest approach. Credit: Peter Lake

A few hours ago, asteroid 2012 KT42 passed by Earth at distance of a mere 14,440 kilometers (8,950 miles), the 6th closest pass on record. This is almost three times closer than geosynchronous satellites. Alex Gibbs from the Catalina Sky Survey, the discoverer of this asteroid, created this video of 2012 KT42 during its closest approach to Earth. Don’t panic, Gibbs says, as the video shows the asteroid moving at 2,000 times the actual speed. However, the asteroid was zooming along at 17km/sec (38,000 mph). Each image is a 3 second exposure, during which the object moved, creating a trail. The images were taken on May 29, 2012 between 4:30 and 6:55 UT, the latter being 6 minutes before closest approach. This asteroid was less than 10 meters across, so was far too small to make it through our atmosphere intact, even if it did intersect directly with Earth’s path. Gibbs said the asteroid was a little brighter than expected, but otherwise lived up to its predicted pass distance and size.

Other astrophotographers also got images of 2012 KT42’s close pass. Peter Lake has this 20-second image, very close to the time of closest approach:

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Lake said he actually took 15 images via a robotic telescope, of which only three had the asteroid in them. “That’s how fast it was going,” he said.

(Video Courtesy Alex R. Gibbs, Catalina Sky Survey, University of Arizona, NASA Near-Earth Object Program.)

Posted on by Nancy Atkinson

Newly Found Asteroid Buzzes Earth

Discovery images of asteroid KT42. Credit: Catalina Sky Survey/Mt. Lemmon Observatory

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A newly found space rock will give Earth a close shave on May 29, passing by at a distance of just 14,440 kilometers (8,950 miles). That distance puts the small asteroid, named 2012 KT42, in the top ten list of closest asteroid approaches. In fact, this is the sixth closest approach to date. The close pass will occur at about 07:00 UTC (03:00 EDT, midnight PDT in the US) on May 29. 2012 KT42 is estimated to be between 3-10 meters in size, and while there is no possibility this asteroid will hit Earth, even if it did, it would surely burn up in the atmosphere.

The sequence of images above were sent to us by Alex Gibbs from the Catalina Sky Survey, who made the discovery of 2012 KT42 with the 1.5 meter telescope on Mt. Lemmon, Arizona on May 28. Gibbs also discovered a similar sized asteroid earlier this year, 2012 BX34, and shared with Universe Today the behind the scenes activities in the discovery of a near-Earth asteroid.

This asteroid closely followed another close pass by a different asteroid, 2012 KP24, which passed by Earth on May 28 at a distance of about 51,000 kilometers (32,000 miles). This rock was bigger, about 25 meters (80 feet) across.

Below is an animation of images of 2012 KT42 taken by Ernesto Guido, Nick Howes and Giovanni Sostero from the Remanzacco Observatory.

An animation showing the motion of 2012 KT42. Each frame is a 5-second exposure through a 2.0-m telescope. Credit: Ernesto Guido, Nick Howes and Giovanni Sostero from the Remanzacco Observatory.

The team said that at the time they took the images on May 28, 2012 KT42 was moving at about ~3.63 “/min and its magnitude was ~17.5. The images were take with the Siding Spring-Faulkes Telescope South through a 2.0-m f/10.0 Ritchey-Chretien telescope.

An interesting note pointed out by the Remanzacco team is that on May 29 at about 10:10 UT, 2012 KT42 will transit across the face of the Sun, and this could be seen from Africa, the Middle East, Asia. But it will be hard to see, if the diameter is about 5m, then the object would only appear about 0.006 of a degree against the solar disk.

In our article about Gibbs’ earlier discovery, he noted that when astronomers look through telescopes, asteroids don’t look much different from stars – they are just points of light. But asteroids are points of light which are moving; however they are moving slow enough that to detect the motion, astronomers take a series of images, usually four images spaced 10-12 minutes apart.

Then, the observers run specialized software to examine their images for any star-like objects that are moving from one image to the next. The software removes any candidates that correspond to known objects or main-belt asteroids. Gibbs said the software has a low detection threshold to avoid missing anything, so the observer looks over what the software found and determines which are real. The remaining objects that the software determines could be interesting are then sent in to the Minor Planet Center (MPC) at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, for the team or others to follow up.

Thanks to Alex Gibbs and the Remanzacco team for sharing their images.

You can see more info about 2012 KT42 at JPL’s Small Body Database website, or at the Minor Planet Center.

Posted on by Jason Major

A New Look at Apollo Samples Supports Ancient Impact Theory

Apollo 16 astronaut Charlie Duke collects lunar samples during EVA on April 23, 1972 (NASA)

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New investigations of lunar samples collected during the Apollo missions have revealed origins from beyond the Earth-Moon system, supporting a hypothesis of ancient cataclysmic bombardment for both worlds.

Samples of Apollo 16 breccia that contain chondritic material (JSC)

Using scanning electron microscopes, researchers at the Lunar-Planetary Institute and Johnson Space Center have re-examined breccia regolith samples returned from the Moon, chemically mapping the lunar rocks to discern more compositional detail than ever before.

What they discovered was that many of the rocks contain bits of material that is chondritic in origin — that is, it came from asteroids, and not from elsewhere on the Moon or Earth.

Chondrites are meteorites that originate from the oldest asteroids, formed during the development of the Solar System. They are composed of the initial material that made up the stellar disk, compressed into spherical chondrules. Chondrites are some of the rarest types of meteorites found on Earth today but it’s thought that at one time they rained down onto our planet… as well as our moon.

The Lunar Cataclysm Hypothesis suggests that there was a period of extremely active bombardment of the Moon’s surface by meteorite impacts around 3.9 billion years ago. Because very few large impact events — based on melt rock samples — seem to have taken place more than 3.85 billion years ago, scientists suspect such an event heated the Moon’s surface enough prior to that period to eradicate any older impact features — a literal resurfacing of the young Moon.

There’s also evidence that there was a common source for the impactors, based on composition of the chondrites. What event took place in the Solar System that sent so much material hurtling our way? Was there a massive collision between asteroids? Did a slew of comets come streaking into the inner solar system? Were we paid a brief, gravitationally-disruptive visit by some other rogue interstellar object? Whatever it was that occurred, it changed the face of our Moon forever.

Curiously enough, it was at just about that time that we find the first fossil evidence of life on Earth. If there’s indeed a correlation, then whatever happened to wipe out the Moon’s oldest craters may also have cleared the slate for life here — either by removing any initial biological development that may have occurred or by delivering organic materials necessary for life in large amounts… or perhaps a combination of both.

Timeline for the Lunar Cataclysm Hypothesis (LPI)

The new findings from the Apollo samples provide unambiguous evidence that a large-scale impact event was taking place during this period  on the Moon — and most likely on Earth too. Since the Moon lacks atmospheric weathering or water erosion processes it serves as a sort of “time capsule”, recording the evidence of cosmic events that take place around the Earth-Moon neighborhood. While evidence for any such impacts would have long been erased from Earth’s surface, on the Moon it’s just a matter of locating it.

In fact, due to the difference in surface area, Earth may have received up to ten times more impacts than the Moon during such a cosmic cataclysm. With over 1,700 craters over 20 km identified on the Moon dating to a period around 3.9 billion years ago, Earth should have  17,000 craters over 20 km… with some ranging over 1,000 km! Of course, that’s if the craters could had survived 3.9 billion years of erosion and tectonic activity, which they didn’t. Still, it would have been a major event for our planet and anything that may have managed to start eking out an existence on it. We might never know if life had gained a foothold on Earth prior to such a cataclysmic bombardment, but thanks to the Moon (and the Apollo missions!) we do have some evidence of the events that took place.

Sample of lunar impact melt breccia, showing exterior and chondrule-filled interior. (Click for sample report.) Source: JSC

The LPI-JSC team’s paper was submitted to the journal Science and accepted for publication on May 2. See the abstract here, and read more on the Lunar Science Institute’s website here.

And if you want to browse through the Apollo lunar samples you can do so in depth on the JSC Lunar Sample Compendum site.

Posted on by Nancy Atkinson

Asteroid 2012 KA to Buzz Earth on May 17

Orbit diagram of asteroid 2012 KU from JPL's Small Body Database website.

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On the heels of a bus-sized asteroid that passed harmlessly between Earth and the orbit of the Moon on May 13, another asteroid between 4.5 and 10 meters (14-33 feet) wide will buzz by at about the same distance on May 17, 2012. Asteroid 2012 KA was discovered just today (May 16), and is projected to make its closest approach about 0.0015 AU, or 224,397 kilometers (134,933 miles, .6 lunar distances) from Earth’s surface at 19:43 UTC on Thursday. The asteroid was discovered by the Mt. Lemmon Observatory, and at the time of this writing, is the only observatory that has made any observations. Therefore JPL lists the uncertainty of the orbit as fairly high (9 out of a 1 to 10 scale) but orbital projections from JPL’s Small Body Database website confirms there is no chance this asteroid would hit Earth. However, most stony meteoroids up to a diameter of about 10-meters are destroyed in thermal explosions by plummeting through Earth’s atmosphere.

We’ll provide any updates as they become available.

Posted on by Nancy Atkinson

4,700 Asteroids Want to Kill You

New results from NASA's NEOWISE survey find that more potentially hazardous asteroids, or PHAs, are closely aligned with the plane of our solar system than previous models suggested. Image credit: NASA/JPL-Caltech

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There are now 4,700 asteroids out there — plus or minus 1,500 – that are considered Potentially Hazardous Asteroids (PHAs). This is the latest and best assessment yet of our solar system’s population of Near Earth Objects that have the potential to make close Earth approaches. The new results come from data obtained from the asteroid-hunting portion of the now-hibernating WISE mission, called NEOWISE.

And no, these asteroids don’t really want to harm you, but they might. “Potentially Hazardous” does not mean an asteroid will impact the Earth; it only means there is a possibility for such a threat. But only by monitoring these PHAs and updating their orbits with new observations can astronomers better predict the close-approach statistics and their Earth-impact threat. So let’s keep looking.

While previous estimates of PHAs predicted similar numbers, they were rough approximations. NEOWISE has generated a more dependable estimate of the objects’ total numbers and sizes.

“The NEOWISE analysis shows us we’ve made a good start at finding those objects that truly represent an impact hazard to Earth,” said Lindley Johnson, program executive for the NASA’s Near-Earth Object Observation Program. “But we’ve many more to find, and it will take a concerted effort during the next couple of decades to find all of them that could do serious damage or be a mission destination in the future.”

As of today, May 16, 2012, 8,874 Near-Earth objects have been discovered, with about 843 of these NEOs being asteroids with a diameter of approximately 1 kilometer or larger. 1,320 of these discovered NEOs have been classified as PHAs.

PHAs are a subset of the larger group of Near-Earth asteroids, those which have the closest orbits to Earth’s, coming within 8 million kilometers (five million miles) and they are big enough to survive passing through Earth’s atmosphere and cause damage on a regional, or greater, scale.

The WISE spacecraft did not identify and count each of these asteroids. Instead, scientists sampled 107 PHAs to make predictions about the entire population as a whole. Astronomers estimate that so far 20 to 30 percent of these objects have actually been found and cataloged. Last year, the WISE team announced they found there are likely less asteroids that are larger than 100 meters (mid-range sized asteroids) and estimate that with all the surveys combined, 93% of the asteroids larger than 1 kilometer have been found.

This diagram illustrates the differences between orbits of a typical near-Earth asteroid (blue) and a potentially hazardous asteroid, or PHA (orange). Image credit: NASA/JPL-Caltech

The new analysis also suggests that about twice as many PHAs as previously thought are likely to reside in “lower-inclination” orbits, which are more aligned with the plane of Earth’s orbit. These asteroids would be more likely to encounter Earth and therefore be easier to reach. So the new results suggest more near-Earth objects might be available for future robotic or human missions.

See our recent article on computing which asteroids might have the most potential for asteroid mining.

In addition, these lower-inclination objects appear to be somewhat brighter and smaller than the other near-Earth asteroids that spend more time far away from Earth. A possible explanation is that many of the PHAs may have originated from a collision between two asteroids in the main belt lying between Mars and Jupiter. A larger body with a low-inclination orbit may have broken up in the main belt, causing some of the fragments to drift into orbits closer to Earth and eventually become PHAs.

Brighter asteroids may be either stony — like granite — or metallic. This type of information is important in assessing the space rocks’ potential hazards to Earth. The composition of the bodies would affect how quickly they might burn up in our atmosphere if an encounter were to take place.

“NASA’s NEOWISE project, which wasn’t originally planned as part of WISE, has turned out to be a huge bonus,” said Amy Mainzer, NEOWISE principal investigator. “Everything we can learn about these objects helps us understand their origins and fate. Our team was surprised to find the overabundance of low-inclination PHAs. Because they will tend to make more close approaches to Earth, these targets can provide the best opportunities for the next generation of human and robotic exploration.”

The WISE spacecraft scanned the sky twice in infrared light before entering hibernation mode in early 2011. It catalogued hundreds of millions of objects, including super-luminous galaxies, stellar nurseries and closer-to-home asteroids. The NEOWISE project snapped images of about 600 near-Earth asteroids, about 135 of which were new discoveries. Because the telescope detected the infrared light, or heat, of asteroids, it was able to pick up both light and dark objects, resulting in a more representative look at the entire population. The infrared data allowed astronomers to make good measurements of the asteroids’ diameters and when combined with visible light observations, how much sunlight they reflect.

Read the team’s paper.

For more information, see NASA’s Near Earth Object Program website, and the WISE website.

Source: NASA

This video is from September of 2011, discussing the previous findings of the NEOWISE project:

Posted on by Nancy Atkinson

The Most Profitable Asteroid Is…

Artist impression of the Arkyd Interceptor, a low cost asteroid mission that enables accelerated exploration. Credit: Planetary Resources.

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With the recent announcement of the asteroid mining company, Planetary Resources, some of the most-asked questions about this enticing but complex endeavor include, what asteroids do we mine? Which are the easiest asteroids to get to? Could it really be profitable?

While Planetary Resources officials said they hope to identify a few promising targets within a decade, the initial answers to those questions are available now on a new website that estimates the costs and rewards of mining rocks in space. Called Asterank, the website uses available data from multiple scientific sources on asteroid mass and composition to try and compute which asteroids would be the best targets for mining operations.

So, which asteroids are most profitable, valuable, easily accessible and cost effective?

The winners are, according to Asterank:

Most Profitable: 253 Mathilde, a 52.8 km-diameter C-type (carbonaceous) asteroid that has an estimated value of over $100 trillion and estimated profit of $9.53 trillion (USD)
Most Cost Effective: 2000 BM19, a very small O-type asteroid (less than 1 km wide) that makes several close approaches to Earth. Its estimated value is $18.50 trillion and an estimated profit of $3.55 trillion.
Most Valuable: 253 Mathilde
Most Accessible: 2009 WY7, another small asteroid with regular close approaches of less than 1 AU. This is an S-type asteroid, a silicaceous or “stony” object that has a high accessibility score on Asterank of 7.6577.

Asterank combines both the economic and scientific features of over 580,000 asteroids in our solar system, looking specifically for platinum-group metals and water. It was created by Ian Webster, a software engineer in the San Francisco Bay Area.

“I’ve always had a strong interest in astronomy and especially space exploration,” Webster said via an email to Universe Today. “The commercialization of space through ventures like asteroid mining really excites me because I believe it’ll open space to the rest of us and improve human quality of life. My day job is at a startup unrelated to space, but my hobbies include building rockets and many side projects like this one. I have a lot of fun applying computer science in different ways and I hope that Asterank will educate and inspire people.”

Webster provides a caveat, however, to the rankings of the top 100 asteroids in each category.

“Scientists know shockingly little about the composition of asteroids,” he writes on the website. “Visit JPL’s Small Body Database and you will notice how sparse information is.”

So, this mean that there aren’t really ‘experts’ in this field, and even those most knowledgeable about asteroids likely don’t have the numbers needed to completely and accurately estimate the true value of an asteroid or the cost of mining it — “which is why Planetary Resources is going to spend years or even decades investing in LEO-telescopes and data-gathering flybys before they ever touch an asteroid,” Webster said.

Webster has used databases, websites, books and other publications to get as much accurate, up-to-date information as possible, but even then, he said everything on the website is a rough estimation.

“The primary purpose of this site is to broadly educate and inspire, rather than provide completely accurate data — which is currently impossible,” he said. “I created the site in response to the announcement of Planetary Resources. “I should point out that nearly all the measurements and hard data come from the scientists at NASA JPL, but I had a lot of fun putting the site together.”

And it is fun to peruse the various categories and see what asteroids make the top of each category.

The ranking takes into account the value of the materials on the asteroids such as metals, volatile compounds, and water; the costs of getting to an asteroid and moving the raw materials: and the comparative savings and potential profit, which at this point are very hypothetical, taking into account processing and moving raw material.

“We really don’t know yet how much it will cost to mine an object millions of miles away,” Webster said.

While this website is a first step, it offers an exciting and enjoyable initial look at the potential commercial viability of space mining.

Check out Asterank.