Stories tagged Earth and Space Science

Oct
13
2005

Scientists have finally solved the mystery of gamma ray bursts, the most violent explosions in the universe. Lasting a fraction of a second, they release 100,000,000,000,000 (100 trillion) times more energy than the Sun. But since they were first detected in 1970, scientists have wondered what exactly gamma ray bursts are.

Now, thanks to three satellites and four ground-based telescopes, they have figures out that the explosions occur when two neutron stars collide, or when a neutron star is swallowed by a black hole.

A neutron star is an old star that has burned off most of its fuel and collapsed under its own weight. Though they are only about 10 miles across, they weigh 1 1/2 times as much as the Sun. Gravity squeezes the atoms of together until the protons and electrons merge, forming neutrons.

Collisions between neutron stars can also create black holes. This study may give scientists their first chance to learn how black holes are formed.

Aug
23
2005

In August of 1972 one of the largest Solar Proton Events (SPEs) ever recorded crossed paths with Earth between the Apollo 16 (April 1972) and Apollo 17 (December 1972) missions to the moon. Simulations of the radiation levels an astronaut would have experienced during this SPE indicate that lethal levels would have been absorbed within 10 hours.


Image of the sun from the SOHO spacecraft of the intense solar activity taken May 15, 2005: Image of the sun from the SOHO spacecraft of the intense solar activity taken May 15, 2005Courtesy NOAA

The journal Space Weather warns that significant gaps in our current understanding and monitoring of space weather make a manned mission to Mars too dangerous for the astronauts. Satellites have been able to give advanced warnings of these SPEs, and the Coronal Mass Ejections (CMEs) that precede them, but this monitoring covers only a very small part of our solar system — only the line between the Earth and the Sun. A mission to Mars will cover significant distances that are currently not monitored. Current manned missions, like the space shuttle and International Space Station, take place in low-Earth orbits and are therefore protected from these CMEs and SPEs by Earth's magnetic field.

Scientists and engineers are working on developing new shielding plans for spacecraft to take people to Mars that are designed for protecting astronauts from high radiation levels. Still, only advance warning of these events would provide astronauts with enough time to retreat into protected areas.

University of Warwick researcher Dr Claire Foullon recommends a pre-mission launch of three satellites designed to provide space weather alerts for the Mars spacecraft crew. She also recommends that a warning device be carried aboard the spacecraft.

Earth's magnetic field protects us from solar events most of the time. However, there are times when particles do reach Earth. When blasts of solar particles arrive at the poles they can produce aurora borealis. They can also cause magnetic storms that can damage satellites and impair radio communications and navigation systems.

Want to know what the weather's like in space right now? Visit SpaceWeather.com.

Aug
05
2005


Titan's lake that wasn't: Pockmarked surface with a large black area that might look like a lake. Courtesy NASA/JPLCourtesy NASA/ESA

After hopes that Saturn's moon, Titan,
might host rivers or oceans of methane and ethane, scientists have determined that its surface is "dry as a bone."

These chemicals abound in Titan's smoggy atmosphere, which is similar to the atmosphere of early Earth. Scientists have hoped the moon might provide clues as to how life began on our planet.

Early radar studies suggested that Titan was covered with pools of methane, a flammable gas on Earth but liquid on Titan because of intense atmospheric pressure and cold (atmospheric pressure near the surface is about 60 percent greater than Earth's!). Last year, the Cassini space craft arrived at Saturn's surface and also observed liquid-like features on its moon.

Why is Titan sending mixed messages? One researcher said: "At one time, maybe a liquid water and ammonia mix flowed onto the surface of froze. That could be smooth on the scale of radar but rough on the scale we see."

Another possibility is that Titan's rivers and lakes evaporated long ago and left flat plains of organic material. Organic particles from Titan's atmosphere might also have settled in low-lying areas, creating smooth lake-like surfaces.

The latest measurements of Titan (done with the Keck II telescope in Hawaii) focused on the southern hemisphere; scientists believe it's still possible that organic material exists in the north.

Titan is the largest of Saturn's 19 moons, and the second largest moon in the solar system. It's rivaled only by Jupiter's moon, Ganymede. Although Titan is classified as a moon, it's larger, too, than the planets Mercury and Pluto. Click here to view a movie of infra-red images (representing heat variations in the atmosphere) of Titan made with the Hubble Space Telescope.

Aug
04
2005

An impressive display of meteors will move across the sky on Friday, August 12, (2005) when the Perseid meteor shower becomes most visible. Peak viewing times will be from 2 a.m. until sunrise that morning, according to NASA experts. Because of interference from urban lights, viewing is best outside of the city. The Perseid meteor shower occurs every summer, when the tail behind Comet Swift-Tuttle intersects with Earth's orbit, causing comet dust to enter Earth's atmosphere. Meteors from the comet travel from the direction of the constellation Perseus, which gives the shower its name.

Jun
08
2005

Or there will be, next year. Japanese researchers plan to drill a hole more than four miles through the Earth's rocky crust to reach the molten mantle below. This will be quite a feat — the deepest hole to date is less than a mile-and-a-half. And, just to make things interesting, they're going to do it from a boat floating a mile and a half above the sea floor. (That's where the Earth's crust is the thinnest.)

The project has several goals. They hope to learn more about undersea earthquakes, like the one that caused the Indian Ocean tsunami. They will also study the rocks and mud for records of climate change. And they will look for microbes and other signs of life in this extreme environment.

Jun
08
2005

That seems to be the conclusion of a report from the National Oceanic and Atmospheric Administration that finds the northern Gulf of Mexico is sinking much faster than previously thought.

Every year, the Mississippi and other rivers dump millions of tons of sediment into the Gulf. All that weight pushes down on the Earth, causing some shoreline areas to disappear entirely, and other to sink dangerously low. Low-lying areas are vulnerable to flooding, especially during hurricane season.

Planners need to know how high or low each area is, in order to make the proper precautions. But a recent re-measuring showed that Louisiana is sinking faster than expected. Hurricane preparations currently underway may not be enough to protect some areas.

Jun
01
2005

Last year's hurricane season sprouted an unusually high number of tropical storms — 15 in all. Some folks have blamed global climate change. But researchers at the National Oceanic and Atmospheric Administration say the increase is perfectly natural. Hurricanes follow a natural cycle, peaking every 15 to 40 years, then dropping back and becoming rarer again.

Other researchers disagree. They say rising global temperatures lead to warmer water, a key ingredient in forming hurricanes.

Few people doubt that the Earth's climate is growing warmer. But how much of that is just a natural cycle, and how much of it is caused by human activity? And what will all the effects of this change be? No one knows for sure. Meanwhile the debate, and research, go on.