Agriculture
Getting the dirt on carbon
Where Have All the Bees Gone?
Cleaning Up Fish Farms
Amphibians
Frogs and Toads
Poison Dart Frogs
Tree Frogs
Animals
Thieves of a Feather
Color-Changing Bugs
G-Tunes with a Message
Behavior
Storing Memories before Bedtime
How Much Babies Know
Taking a Spill for Science
Birds
Cranes
Cassowaries
Crows
Chemistry and Materials
Bang, Sparkle, Burst, and Boom
Silk’s superpowers
Cooking Up Superhard Diamonds
Computers
A Light Delay
Play for Science
Programming with Alice
Dinosaurs and Fossils
Fossil Forests
The Paleontologist and the Three Dinosaurs
The bug that may have killed a dinosaur
E Learning Jamaica
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
2014 GSAT Results for Jamaican Kids
Results of GSAT are in schools this week
Earth
Petrified Lightning
A Dire Shortage of Water
Slip Slidin' Away—Under the Sea
Environment
Sea Otters, Kelp, and Killer Whales
Watching for Wildfires in Yellowstone
Little Bits of Trouble
Finding the Past
Your inner Neandertal
Salt and Early Civilization
Preserving Ancient Warrior Paint
Fish
Basking Sharks
Sturgeons
Lampreys
Food and Nutrition
Moving Good Fats from Fish to Mice
The Essence of Celery
A Pepper Part that Burns Fat
GSAT English Rules
Who vs. That vs. Which
Problems with Prepositions
Finding Subjects and Verbs
GSAT Exam Preparation Jamaica
Preparing for the GSAT Exam
March 21-22, 2013: Over 43,000 students will take the GSAT Exam
E Learning in Jamaica WIN PRIZES and try our Fun Animated Games
GSAT Exams Jamaica Scholarships
42,000 students will sit for the GSAT Exam in two weeks
GSAT Practice Papers | GSAT Mathematics | Maths
2014 GSAT Results for Jamaican Kids
GSAT Mathematics
Secrets of an Ancient Computer
GSAT Practice Papers | GSAT Mathematics | Maths
How a Venus Flytrap Snaps Shut
Human Body
Cell Phones and Possible Health Hazards
Flu Patrol
Spit Power
Invertebrates
Arachnids
Nautiluses
Snails
Mammals
Goats
Poodles
African Camels
Parents
Choosing a Preschool: What to Consider
The Surprising Meaning and Benefits of Nursery Rhymes
Children and Media
Physics
Spin, Splat, and Scramble
Black Hole Journey
The Pressure of Scuba Diving
Plants
Farms sprout in cities
City Trees Beat Country Trees
Seeds of the Future
Reptiles
Anacondas
Gila Monsters
Crocodilians
Space and Astronomy
A Whole Lot of Nothing
A Very Distant Planet Says "Cheese"
A Star's Belt of Dust and Rocks
Technology and Engineering
Drawing Energy out of Wastewater
Beyond Bar Codes
Weaving with Light
The Parts of Speech
What is a Noun
Pronouns
What is a Verb?
Transportation
How to Fly Like a Bat
Flying the Hyper Skies
Ready, unplug, drive
Weather
Arctic Melt
A Change in Climate
A Dire Shortage of Water
Add your Article

A Smashing Display

Fireworks thrilled viewers all over the United States on the Fourth of July. An even bigger display took place deep in outer space on the same day.

About 83 million miles from Earth, at 1:52 a.m. Eastern time, a projectile released by a spacecraft called Deep Impact smashed into Comet Tempel 1. In Maryland, Lucy McFadden was watching the event with about 50 coworkers. Even though it was the middle of the night, she didn’t feel sleepy at all.

“We were observing on a big screen, and all of a sudden there was a big, bright flash,” McFadden says. “I was stunned. It was just awesome to see. We were jumping up and down.” McFadden is an astronomer at the University of Maryland, College Park.

A bright flash marked the spot where a projectile launched by the Deep Impact spacecraft crashed into Comet Tempel 1.

A bright flash marked the spot where a projectile launched by the Deep Impact spacecraft crashed into Comet Tempel 1.

NASA/JPL-Caltech/UMD

The collision was no accident. Scientists first proposed a comet-slamming mission in 1996, and work on Deep Impact began in 2000. Launched in January 2005, the spacecraft was designed to release a probe that would slam into Tempel 1. The spacecraft would also take pictures and make measurements of the collision. The mission’s goal was to see, for the first time, what comets are like on the inside.

Wild orbits

A comet is a ball of ice, dust, and frozen gas that travels around the sun. A typical comet follows an orbit that brings it close to the sun, then swings it far out beyond the outer planets.

Many comets speed by Earth on a regular schedule. Halley’s comet, for instance, visits our neighborhood every 76 years. Other comets have such wild orbits that they may pass us once but never come back.

When a comet nears the center of the solar system, the sun’s heat vaporizes some of its ice, giving the comet a telltale tail.

Comet Tempel 1, as observed from a telescope at the Kitt Peak National Observatory, shows a bluish ring of gas around the comet and a pinkish dust jet (pointing toward the lower right corner of the image).

Comet Tempel 1, as observed from a telescope at the Kitt Peak National Observatory, shows a bluish ring of gas around the comet and a pinkish dust jet (pointing toward the lower right corner of the image).

Tony Farnham and Matthew Knight, University of Maryland

Ancient cultures noticed comets and either feared or admired them. Some people believed that a comet’s appearance foretold the future, hinting at major events to come on Earth.

These days, astronomers are interested in studying comets for the secrets they might hold about how our cosmic neighborhood was created.

“Comets give us a look back in time to the beginning of the solar system,” McFadden says. “They formed long ago and far away at the edge of the solar system, many hundreds of thousands of times farther away from the sun than Earth is.”

There’s even a hypothesis that water and the ingredients for life were first delivered to Earth when comets struck our planet a long time ago. So, learning more about comets could help us learn more about ourselves.

Space balls

Three previous space missions had flown past comets and taken pictures. But these pictures didn’t reveal what the icy space balls are like on the inside.

For years before the launch of Deep Impact, scientists considered a variety of possibilities. Comets could be dense and strong, hard and brittle, light and fluffy, or soft in the middle with a hard crust on the outside.

Crater expert Peter Schultz and his coworkers at Brown University did experiments to see what might happen to a comet hit by a projectile.

Crater expert Peter Schultz and his coworkers at Brown University did experiments to see what might happen to a comet hit by a projectile.

Brown University

To see how each of these types of objects would behave when pummeled, geologist Peter Schultz of Brown University and his coworkers experimented in the lab, building a variety of miniature models of comets out of sand, ice, and other materials.

In a vacuum to simulate space, the scientists used a giant gun to shoot pellets at the artificial comets from different angles. Some of the models exploded into many bits. In other cases, it looked like a space probe would just bury itself in the comet and stop, with no rebound at all.

So, what would happen when a probe actually struck a comet? If the comet were mostly solid ice, the projectile would probably gouge out a small crater. If its surface were like powdery snow, the projectile could even tunnel right through.

“I was hoping that such an impact would form a big curtain of debris that would be ejected after the shock waves hit the surface,” McFadden says. This was the scenario that looked most spectacular and beautiful in the lab.

Impact

When the space probe crashed into Tempel 1, it produced a bright flash. About a second or so later, there was a second flash, and the comet belched out a fan-shaped plume of debris.

This image, which has been colored to highlight important features, shows the plume of material kicked up by the Deep Impact probe's impact. The comet itself is silhouetted against the light reflected from surrounding dust. The plume was very bright, sugg

This image, which has been colored to highlight important features, shows the plume of material kicked up by the Deep Impact probe’s impact. The comet itself is silhouetted against the light reflected from surrounding dust. The plume was very bright, sugg

NASA/JPL-Caltech/UMD

These observations suggest that the probe ran into fluffy material—very fine dust on the comet’s surface—creating the first flash. The probe then burrowed into the comet and exploded. A high-speed plume of gas blew back out the path created by the probe, creating the second flash. A slower shock wave then reached the surface, releasing a cloud of debris.

By comparing the real explosion to what they had seen in lab experiments, the scientists concluded that Comet Tempel 1 is largely light and fluffy.

“If it were a snowball and you tried to pick it up,” McFadden says, “it would collapse.”

There’s still plenty of analysis left to do. Scientists are now looking through the images frame by frame to peel back the layers of the comet and see how different the inside is from the outside. That might reveal something about how the solar system has evolved over time.

Future mission

Meanwhile, the mission’s work isn’t yet done. Although the probe was destroyed, Deep Impact itself remains in orbit around the sun. It’s currently scheduled to fly past Earth in late December 2007. It may yet get a chance to visit another comet or to set off on some new mission.

A view of Comet Tempel 1's surface, as seen from Deep Impact's probe just 90 seconds before it slammed into the comet.

A view of Comet Tempel 1′s surface, as seen from Deep Impact’s probe just 90 seconds before it slammed into the comet.

NASA/JPL-Caltech/UMD

If you’re worried about poor, innocent comets getting smashed to bits, don’t fret, McFadden says. First of all, there are billions of comets out there, and comets get hit in space all the time. Most of them are already pockmarked with craters and other features.

Secondly, comets are not as fragile as you might think. Deep Impact’s probe weighed 820 pounds and was about the size of a washing machine. Tempel 1 is about 9 miles long and 2.5 miles wide, or about half the size of Manhattan.

“It was like a gnat running into a 747 jet,” McFadden says. The comet is still moving along on its original path as if nothing had happened.

Keep your ears open for more comet news. A spacecraft called Stardust is on its way back to Earth from the comet Wild 2, where it collected samples in January 2004. It’s scheduled to deliver its load early in 2006.

And, as scientists continue to look at the data from Deep Impact, more surprises are bound to flare up.

A Smashing Display
A Smashing Display








Designed and Powered by HBJamaica.com™