Weekend Feature: New Video Released of Mars' Mystery Moon, Phobos
MIT to Help Create a World-class University in Russia

Weekend Feature: Brilliant, Block-shaped 16-Story Tall Black Objects Observed on Comet Hartley 2

Comet-hartley2-first-images-2a-101104-02 (1)

After about 3.2 billion miles (5.1 billion kilometers) of deep space travel, several discoveries awaited the EPOXI mission's project and science teams. On Nov. 4, 2010, the mission spacecraft flew past a weird little comet called Hartley 2. A strane mission discovery is that on the knobby ends of Hartley 2, particularly the smaller end, the surface terrain is dotted with block-like, shiny objects, some as big as one block long and 16 stories tall. These objects appear to be two to three times more reflective than the surface average.

"From all the imaging we took during approach, we knew the comet was a little skittish even before flyby," said EPOXI Project Manager Tim Larson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It was moving around the sky like a knuckleball and gave my navigators fits, and these new results show this little comet is downright hyperactive."

The EPOXI mission found that the strong activity in water release and carbon dioxide-powered jets did not occur equally in the different regions of the comet. During the spacecraft's flyby of the comet -- with closest approach of 431 miles (694 kilometers) -- carbon dioxide-driven jets were seen at the ends of the comet, with most occurring at the small end. In the middle region or waist of the comet, water was released as vapor with very little carbon dioxide or ice. The latter findings indicate that material in the waist is likely material that came off the ends of the comet and was redeposited.

"Hartley 2 is a hyperactive little comet, spewing out more water than most other comets its size," said Mike A'Hearn, principal investigator of EPOXI from the University of Maryland, College Park. "When warmed by the sun, dry ice -- frozen carbon dioxide -- deep in the comet's body turns to gas jetting off the comet and dragging water ice with it."

Although Hartley 2 is the only such hyperactive comet visited by a spacecraft, scientists know of at least a dozen other comets that also are relatively high in activity for their size and which are probably driven by carbon dioxide or carbon monoxide.

"These could represent a separate class of hyperactive comets," said A'Hearn. "Or they could be a continuum in comet activity extending from Hartley 2-like comets all the way to the much less active, "normal" comets that we are more used to seeing."

The study provides several new twists in the unfolding story of this small cometary dynamo, including: (1) the smooth, relatively inactive waist of the peanut-shaped comet is likely re-deposited rather than primordial material; (2) Hartley 2 has an 'excited state of rotation' because it spins around one axis, but also tumbles around a different axis; and (3) on its larger, rougher ends, the comet's surface is dotted with glittering, blocky objects that can reach approximately 165 feet (50 meters) high and 260 feet (80 meters) wide.

An added surprise was a pronounced increase in the amount of CN gas in the comet's coma. For nine days in September, about 10 million times more CN gas was given off than usual. This dramatic and unexpected change, called the "CN anomaly," was analyzed by McFadden and Dennis Bodewits, a former postdoctoral fellow at NASA Goddard who is now at the University of Maryland, and their colleagues.

The amount of CN in a comet's coma is thought to hold clues to how comets formed and evolved during their lifetime. In other cases where a comet has had a big outburst, a lot of dust has been released at the same time. But in this case, the amount of dust did not change, yet the CN gas abundance exploded.

"We aren't sure why this dramatic change happened," says McFadden. "We know that Hartley 2 gives off considerably more CN gas than comet Tempel 1, which was studied earlier by a probe released by the Deep Impact spacecraft. But we don't know why Hartley 2 has more CN, and we don't know why the amount coming off the comet changed so drastically for a short period of time. We've never seen anything like this before."

EPOXI was an extended mission that utilized the already "in-flight" Deep Impact spacecraft to explore distinct celestial targets of opportunity. The name EPOXI itself is a combination of the names for the two extended mission components: the extrasolar planet observations, called Extrasolar Planet Observations and Characterization (EPOCh), and the flyby of comet Hartley 2, called the Deep Impact Extended Investigation (DIXI). The spacecraft retained the name "Deep Impact." During its approach, encounter and departure from comet Hartley 2, the spacecraft beamed back over 117,000 images and spectra.

The Daily Galaxy via Eurekalert.org and NASA/EPOXI

Get 'The Daily Galaxy' in Your Facebook News Feed!

Image top of page: This close-up view of comet Hartley 2 was taken by NASA's EPOXI mission during its flyby of the comet on Nov. 4, 2010. It was captured by the spacecraft's Medium-Resolution Instrument.
Credit: NASA/JPL-Caltech/UMD

Comments

They are the Monoliths of Space Oddessy 2001 ha ha

This article is so frustrating! Intriguing headline about 16 storied objects, but no comment on what they may be? Come on guys!

I have to agree Alex, but it's the inconsistencies that really bug me about the standard of reporting on this site - the headline says these objects are black but the body text says they are two to three times more reflective than the surface average.
I recall another recent article where something 50 million light years away was crashing into the milky way.
There are real stories behind these articles but they get eclipsed by the nonsensical headlines and lack of substance in the write-up.
Makes me wonder what the author is on.

Oops, that should have been to Steven, not Alex.

Its obvious what the 16 story item are .
They are the MONOLITHS (turn up the music).

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)