Tag: Asteroids

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There could be a lot more water out there than anyone thought. A second asteroid has been found to contain water ice. In April of this year, water ice and organics was found on 24 Themis, a 200-kilometer wide asteroid. Now, the two teams of researchers made who made the first discovery have now found the same materials on asteroid 65 Cybele.

“This discovery suggests that this region of our solar system contains more water ice than anticipated,” said University of Central Florida Professor Humberto Campins. “And it supports the theory that asteroids may have hit Earth and brought our planet its water and the building blocks for life to form and evolve here.”

Asteroid 65 Cybele is somewhat larger than asteroid 24 Themis, with a diameter of 290 km (180 miles). Both asteroids are located in the asteroid belt that sits halfway between Mars and Jupiter.

Generally, asteroids were thought to be very dry, but it now appears that when the asteroids and planets were first forming in the very early Solar System, ice extended far into the Main Belt region, which could mean water and organics may be more common near each star‘s habitable zone.

See our article from yesterday about molecules of life’s building blocks in Titan’s atmosphere and how it could add a third way for life to spring up on a planet (one being asteroid delivery, two being rising from the primordial soup thought to exist on early Earth).

The team’s paper will be published in the European Journal “Astronomy and Astrophysics,” and Campins presented his findings at the American Astronomical Society’s Division of Planetary Sciences meeting this week.

Source: University of Central Florida

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Two newly discovered asteroids will pass the Earth this week. The asteroids were discovered on September 5th of this year by Andrea Boattini using the 1.5 metre reflector at Mount Lemmon in Arizona as part of the Mount Lemmon Survey.

These two new asteroids have been given the designations of 2010 RF12 and 2010 RX30. Both are small bodies, which is why they were not discovered until mere days before they would pass the Earth. Estimates put the size of RF12 at 5 – 15 meters with a best estimate being around 8 meters (26 ft). The larger, RX30 is estimated to be 12 meters (39 ft), but the range of estimates go from 7 – 25.

Due to the large range of estimates on sizes, as well as poorly constrained relative velocities and an unknown composition, it would be difficult to predict the damage an impact from these bodies could cause. The majority of the mass for such small objects would burn up in the atmosphere with only small fragments surviving to the ground. For comparison, the estimated size of the object that caused the Tunguska event was estimated to be at least a few tens of meters in diameter at the point it exploded in the atmosphere some few miles up. Since the diameter helps to determine the volume, and thus the mass and kinetic energy, this factor increases the potential damage rapidly. However, although the bodies were just discovered this week, their orbits have already been well established for the near future and neither will collide with Earth. Both are rated at a 0 on the Torino scale (data from NASA’s NEO Program for RF12 and RX30 can be seen here and here respectively).

Although both objects will pass closer to the Earth than the moon, due to their small size, neither will be visible to the naked eye. 2010 RF12 is expected to pass the Earth at 21% of the Earth-moon distance and at maximum brightness, reach only 14th magnitude, which is just over 600 times too faint to see with the unaided eye. RX30 will approach at 66% of the Earth-moon distance and is expected to reach a similar peak magnitude. For those interested in tracking or photographing these objects, the Fawkes Telescope Project has created a page dedicated to these two objects, including best exposure times and filters for cameras that can be found here. Ephemeris for RF12 and RX30 can be found here and here respectively.

Although both of these asteroids were discovered on the same day and will be approaching near the same time, their orbits do not appear to be related. RF12’s orbit extends from 0.82 to 1.17 AU and it orbits the Sun once every year. Predictions have shown it only passes near the Earth once every one hundred years. Initially, RX30 was thought to be rotate extremely fast, but revised observations have shown that it takes at least 6 hours to rotate about its axis.

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From a University of Colorado-Boulder press release:

While the common perception of asteroids is that they are giant rocks lumbering about in orbit, a new study shows they actually are constantly changing “little worlds” that can give birth to smaller asteroids that split off to start their own lives as they circle around the sun.

Astronomers have known that small asteroids get “spun up” to fast rotation rates by sunlight falling on them, much like propellers in the wind. The new results show when asteroids spin fast enough, they can undergo “rotational fission,” splitting into two pieces which then begin orbiting each other. Such “binary asteroids” are fairly common in the solar system.

An international team of astronomers led by Petr Pravec of the Astronomical Institute in the Czech Republic found that many of these binary asteroids do not remain bound to each other but escape, forming two asteroids in orbit around the sun when there previously was just one. The study appears in the Aug. 26 issue of Nature.

The researchers studied 35 so-called “asteroid pairs,” separate asteroids in orbit around the sun that have come close to each other at some point in the past million years — usually within a few miles, or kilometers — at very low relative speeds. They measured the relative brightness of each asteroid pair, which correlates to its size, and determined the spin rates of the asteroid pairs using a technique known as photometry.

“It was clear to us then that just computing orbits of the paired asteroids was not sufficient to understand their origin,” said Pravec. “We had to study the properties of the bodies. We used photometric techniques that allowed us to determine their rotation rates and study their relative sizes.”

The research team showed that all of the asteroid pairs in the study had a specific relationship between the larger and smaller members, with the smallest one always less than 60 percent of the size of its companion asteroid.

The conclusion fits a theory of binary asteroid formation originated by co-author Daniel Scheeres, from the University of Colorado, Boulder. His theory predicts that if a binary asteroid forms by rotational fission, the two can only escape from each other if the smaller one is less than 60 percent the size of the larger asteroid. Of all the asteroid pairs in the study, the smallest of each pair was always less than 60 percent of the mass of its companion asteroid.

Scheeres’ theory predicts that if a binary asteroid forms by rotational fission, the two can only escape from each other if the smaller one is less than 60 percent of the size of the larger asteroid. When one of the asteroids in the pair is small enough, it can “make a break for it” and escape the orbital dance, essentially moving away to start its own “asteroid family,” he said. During rotational fission, the asteroids separate gently from each other at relatively low velocities.

“This is perhaps the clearest observational evidence that asteroids aren’t just large rocks in orbit about the sun that keep the same shape over time,” said Scheeres. “Instead, they are little worlds that may be constantly changing as they grow older, sometimes giving birth to smaller asteroids that then start their own life in orbit around the sun.”

Read more at the University of Colorado-Boulder.