Tag: asteroids

A large Kuiper Belt object discovered

3:55 pm

Astronomers have detected a new but very distant Kuiper Belt object.

For now, his team knows little more about their distant discovery other than its orbit and apparent brightness. Given its distance, however, the object should be sizable — anywhere from 400 km across (if its surface is bright and 50% reflective) to 1,200 km (if very dark and 5% reflective). If its true size edges toward the larger end of this range, then 2014 UZ224 would likely qualify for dwarf-planet status.

Fortunately, we should have a much better estimate of the object’s size very soon. Gerdes has used the ALMA radio-telescope array to measure the heat radiating from 2014 UZ224, which can be combined with the optical measurements to yield its size and albedo.

The object has a very eccentric 1,140 year orbit, coming as close to the sun as Pluto at its closest and almost five times farther away at its furthest.

Note: I have changed the article title because this new object is almost certainly not bigger the Pluto, as one of my readers pointed out.

3 comments

Thirty ton meteorite excavated in Argentina

9:10 am

In what is one of the largest asteroid chunks ever found on Earth, an excavation team from a local astronomy club this week excavated a thirty ton iron-nickel meteorite from the ground.

Dubbed Gancedo after a nearby town, it isn’t a record-holder, but it sure is big. What I found interesting from the article, however, is this:

Gancedo’s fall to Earth occurred between 4,000 and 6,000 years ago. Locals knew of the fall for centuries, even making iron tools from meteorites found in the strewnfield. In the 16th century, the Spanish became interested in stories of a piece of iron that fell from the sky, and in 1774 don Bartolomé Francsico de Maguna led an expedition that came across a mass of iron, referred to as Mesón de Fierro (“Table of Iron” in Spanish). Another 1,400-pound fragment from Campo del Cielo named Otumpa now resides at the British Museum in London. With more than 100 tons of meteorite recovered, Campo del Cielo is the top producer in terms of pure meteorite mass worldwide.

The Campo del Cielo strewnfield extends over an ellipse 3 km wide by 19 km long over an area northwest of Buenos Aires, and meteorites found here have a polycrystalline coarse octahedrite composition characteristic of iron-nickel meteorites. They are also unusually pure even among iron-nickel meteorites, consisting of 93% iron. Most of the remaining 7% is nickel, and less than 1% are trace elements.

The evidence here is that a very dense asteroid, weighing a minimum of 100 tons but probably several times that, smashed into the Earth about five thousand years ago. Yet, all life on Earth was not wiped out, as is repeatedly suggested might happen whenever a similarly sized asteroid zips close past the Earth. In fact, there is no evidence this impact had any significant global environmental effects.

Remember this the next time another asteroid of similar size zips past the Earth and the media doom-sayers begin to sing their siren song again.

1 comment

Ahuna Mons, Ceres’s biggest mountain, is an ice volcano

11:39 am

Ahuna Mons

Using data from Dawn scientists have concluded that Ceres’s biggest mountain, Ahuna Mons (shown on the right), was created by water volcanism.

“Ahuna is the one true ‘mountain’ on Ceres,” said David A. Williams, associate research professor in Arizona State University’s School of Earth and Space Exploration. “After studying it closely, we interpret it as a dome raised by cryovolcanism.” This is a form of low-temperature volcanic activity, where molten ice — water, usually mixed with salts or ammonia — replaces the molten silicate rock erupted by terrestrial volcanoes. Giant mountain Ahuna is a volcanic dome built from repeated eruptions of freezing salty water.

The implications of this fact are important, as it suggests that Ceres’s interior was warm enough for long periods, enough to melt ice. Where that heat came from however is a mystery, considering the dwarf planet’s small size.

1 comment

Dawn moves to higher orbit around Ceres

9:41 am

In order to save fuel as well as obtain a different view of Ceres, engineers are moving Dawn to a higher orbit.

On Sept. 2, Dawn will begin spiraling upward to about 910 miles (1,460 kilometers) from Ceres. The altitude will be close to where Dawn was a year ago, but the orientation of the spacecraft’s orbit — specifically, the angle between the orbit plane and the sun — will be different this time, so the spacecraft will have a different view of the surface.

0 comments

New and very distance outer solar system objects beyond Neptune

10:11 am

Astronomers have discovered several new objects orbiting the Sun at extremely great distances beyond the orbit of Neptune.

The most interesting new discovery is 2014 FE72:

Another discovery, 2014 FE72, is the first distant Oort Cloud object found with an orbit entirely beyond Neptune. It has an orbit that takes the object so far away from the Sun (some 3000 times farther than Earth) that it is likely being influenced by forces of gravity from beyond our Solar System such as other stars and the galactic tide. It is the first object observed at such a large distance.

This research is being done as part of an effort to discover a very large planet, possibly as much as 15 times the mass of Earth, that the scientists have proposed that exists out there.

8 comments

Costs rise on Obama’s asteroid mission

9:05 am

The year delay in Obama’s as yet unfunded unmanned asteroid mission, a preliminary to a proposed manned asteroid mission, has caused its budget to grow from $1.25 billion to $1.4 billion.

More significantly,

NASA’s cost estimate for [the unmanned] ARRM excludes launch and operations. In a March 2016 report, the Government Accountability Office (GAO) review of NASA’s major programs showed a cost of $1.72 billion. Gates explained that the $1.72 billion includes the launch vehicle cost, set at approximately $500 million as a placeholder since NASA has not determined which of three launch vehicles will be used (Delta IV Heavy, Falcon Heavy, or the Space Launch System).

…The next administration will have to decide if the costs are worth the benefits. Although NASA has decided they are, the House Appropriations Committee disagrees. It denied funding for the program in its report on the FY2017 Commerce-Justice-Science (CJS) appropriations bill, which funds NASA. The bill has not passed the House yet, however, and there is no similar language in the Senate version, so NASA is not currently prohibited from spending money on the project.

So far, NASA has been funding this Obama project by stealing money from other projects in NASA, since Congress has consistently refused to appropriate extra money for it. This approach has worked up until now, as they are only funding initial design work. Where they think they will get the money for a full mission however remains a complete mystery to me.

0 comments

Ceres lacks large craters

10:59 am

The uncertainty of science: Using data from Dawn, scientists have found that the solar system’s largest asteroid, Ceres (also called a dwarf planet by confused scientists), has a mysterious lack of large craters.

Marchi and colleagues modeled collisions of other bodies with Ceres since the dwarf planet formed, and predicted the number of large craters that should have been present on its surface. These models predicted Ceres should have up to 10 to 15 craters larger than 250 miles (400 kilometers) in diameter, and at least 40 craters larger than 60 miles (100 kilometers) wide. However, Dawn has shown that Ceres has only 16 craters larger than 60 miles, and none larger than 175 miles (280 kilometers) across.

They postulate two theories to explain the lack. First, Ceres might have formed far out beyond Neptune, though this theory is not favored because some models still say that even here Ceres should have large craters. Second,

One reason for the lack of large craters could be related the interior structure of Ceres. There is evidence from Dawn that the upper layers of Ceres contain ice. Because ice is less dense than rock, the topography could “relax,” or smooth out, more quickly if ice or another lower-density material, such as salt, dominates the subsurface composition. Recent analysis of the center of Ceres’ Occator Crater suggests that the salts found there could be remnants of a frozen ocean under the surface, and that liquid water could have been present in Ceres’ interior.

Past hydrothermal activity, which may have influenced the salts rising to the surface at Occator, could also have something to do with the erasure of craters. If Ceres had widespread cryovolcanic activity in the past — the eruption of volatiles such as water — these cryogenic materials also could have flowed across the surface, possibly burying pre-existing large craters. Smaller impacts would have then created new craters on the resurfaced area.

This theory doesn’t really work that well either, because it fails to explain why only the big craters got erased.

2 comments

More bright spots on Ceres

10:17 am

More bright spots on Ceres

Cool image time! The most recently released Dawn image of Ceres, cropped on the right, included these bright streaks running down the side of an unnamed crater. They are especially intriguing because they so much resemble the seepage lines scientists have found on slopes on Mars. On Mars the lines appear to come and go on a seasonal basis, while on Ceres they appear to have been caused by a one-time event, after which not much has changed. In both cases, however, they appear to be caused by some liquid seepage that came from below the surface.

0 comments

NASA okays New Horizons mission extension, rejects Dawn asteroid fly-by

3:48 pm

NASA has approved an extension of the New Horizons mission to fly past Kuiper Belt object 2014 MU69 on January 1, 2019.

In the same press release the agency announced that they have decided that they will get more worthwhile science by keeping Dawn in orbit around Ceres for the reminder of its life, rather then sending it on a proposed fly by of another asteroid.

0 comments
1 … 42 43 44 45 46 … 78