Large Telescope, astronomers have gained valuable new insights about the atmosphere of the dwarf planet Pluto. The scientists found unexpectedly large amounts of methane in the atmosphere, and also discovered that the atmosphere is hotter than the surface by about 40 degrees, although it still only reaches a frigid minus 180 degrees Celsius.

These properties of Pluto’s atmosphere may be due to the presence of pure methane patches or of a methane-rich layer covering the dwarf planet’s surface.

“With lots of methane in the atmosphere, it becomes clear why Pluto’s atmosphere is so warm,” says Emmanuel Lellouch, lead author of the paper reporting the results.

Pluto, which is about a fifth the size of Earth, is composed primarily of rock and ice. As it is about 40 times further from the Sun than the Earth on average, it is a very cold world with a surface temperature of about minus 220 degrees Celsius!

It has been known since the 1980s that Pluto also has a tenuous atmosphere , which consists of a thin envelope of mostly nitrogen, with traces of methane and probably carbon monoxide. As Pluto moves away from the Sun, during its 248 year-long orbit, its atmosphere gradually freezes and falls to the ground. In periods when it is closer to the Sun — as it is now — the temperature of Pluto’s solid surface increases, causing the ice to sublimate into gas.

Until recently, only the upper parts of the atmosphere of Pluto could be studied. By observing stellar occultations (ESO 21/02), a phenomenon that occurs when a Solar System body blocks the light from a background star, astronomers were able to demonstrate that Pluto’s upper atmosphere was some 50 degrees warmer than the surface, or minus 170 degrees Celsius. These observations couldn’t shed any light on the atmospheric temperature and pressure near Pluto’s surface. But unique, new observations made with the CRyogenic InfraRed Echelle Spectrograph (CRIRES), attached to ESO’s Very Large Telescope, have now revealed that the atmosphere as a whole, not just the upper atmosphere, has a mean temperature of minus 180 degrees Celsius, and so it is indeed “much hotter” than the surface.

In contrast to the Earth’s atmosphere ^[2], most, if not all, of Pluto’s atmosphere is thus undergoing a temperature inversion: the temperature is higher, the higher in the atmosphere you look. The change is about 3 to 15 degrees per kilometre. On Earth, under normal circumstances, the temperature decreases through the atmosphere by about 6 degrees per kilometre.

“It is fascinating to think that with CRIRES we are able to precisely measure traces of a gas in an atmosphere 100 000 times more tenuous than the Earth’s, on an object five times smaller than our planet and located at the edge of the Solar System,” says co-author Hans-Ulrich Käufl. “The combination of CRIRES and the VLT is almost like having an advanced atmospheric research satellite orbiting Pluto.”

The reason why Pluto’s surface is so cold is linked to the existence of Pluto’s atmosphere, and is due to the sublimation of the surface ice; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto. In this respect, Pluto shares some properties with comets, whose coma and tails arise from sublimating ice as they approach the Sun.

The CRIRES observations also indicate that methane is the second most common gas in Pluto’s atmosphere, representing half a percent of the molecules. “We were able to show that these quantities of methane play a crucial role in the heating processes in the atmosphere and can explain the elevated atmospheric temperature,” says Lellouch.

Two different models can explain the properties of Pluto’s atmosphere. In the first, the astronomers assume that Pluto’s surface is covered with a thin layer of methane, which will inhibit the sublimation of the nitrogen frost. The second scenario invokes the existence of pure methane patches on the surface.

Small robots the size of riding mowers could prepare a safe landing site for NASA’s Moon outpost, according to a NASA-sponsored study prepared by Astrobotic Technology Inc. with technical assistance from Carnegie Mellon University’s Robotics Institute.

Astrobotic Technology and Carnegie Mellon researchers analyzed mission requirements and developed the design for an innovative new type of small lunar robot under contract from NASA’s Lunar Surface Systems group.

The results will be presented February 27 in Washington, D.C., at a NASA Lunar Surface Systems conference co-sponsored by the U.S. Chamber of Commerce and its Space Enterprise Council.

“NASA faces a challenge in planning the layout for its outpost, which is expected to begin operations in 2020,” said William “Red” Whittaker, chairman and chief technical officer of Astrobotic and a Carnegie Mellon professor of robotics. “For efficient cargo transfer, the landing site needs to be close to the outpost’s crew quarters and laboratories. Each rocket landing and takeoff, however, will accelerate lunar grit outwards from the pad. With no atmosphere to slow it down, the dry soil would sandblast the outpost.”

The research examined two potential solutions: 1) construction of a berm around the landing site, and 2) creation of a hard-surface landing pad using indigenous materials.

In the first solution, researchers found that two rovers weighing 330 pounds each would take less than six months to build a berm around a landing site to block the sandblasting effect. A berm 8.5 feet tall in a 160-foot semi-circle would require moving 2.6 million pounds of lunar dirt. Robots this size can be sent to NASA’s planned polar outpost site in advance of human expeditions. Astrobotic Technology Inc. has proposed that landing site preparation be provided by commercial ventures.

In the second solution, researchers showed how small robots could comb the lunar soil for rocks, gathering them to pave a durable grit-free landing pad, said John Kohut, Astrobotic’s chief executive officer. “This might reduce the need to build protective berms. To discern the best approach, early robotic scouting missions need to gather on-site information about the soil’s cohesion levels and whether rocks and gravel of the right size can be found at the site.”

Also at Carnegie Mellon, Whittaker is directing the development of Astrobotic’s first lunar robot, which has been undergoing field trials for several months. The company’s first mission, to win the $20 million Google Lunar X prize by visiting the Apollo 11 landing site and transmitting high-definition video to Earth, is set for December 2010.

Explosions are tricky to measure. For one, what’s the criteria? And most data on “blasts from the past” are speculation at best.

So consider this list “10 of the biggest explosions since the dawn of time,” measured by magnitude of the blast, loss of lives and impact on world history.

In no particular order:
1. Atomic blasts over Hiroshima and Nagasaki (August 6 and 9, 1945)
Ordered by U.S. President Harry S. Truman to force Japan into submission and prevent greater loss of life from an endless war, the devastating dropping of the “Little Boy” atomic bomb was the first use of a nuclear weapon in world history. The bomb contained 130 lbs. of uranium-235 and detonated at approx.

1,900 feet above the city with a force that equaled about 13 kilotons of TNT.

Scientists considered “Little Boy” to be inefficient, estimating that less than 2% of the bomb’s nuclear material actually fissioned in the blast, and yet its effect was devastating: the blast radius was about 1 mile across, killing approximately 140,000 (mostly civilians) almost instantly, with thousands more to die of radiation poisoning and other injuries in the weeks and years to come.

Three days after the Hiroshima blast, U.S. forces dropped the “Fat Man” atomic bomb over Nagasaki, prompting the Japanese to surrender on August 15. It would be the second, and to date, last use of a nuclear weapon in history, killing an estimated 80,000 Japanese.
2. Soviet Nuclear Test, Novaya Zemlya (October 1961)
In the years following the Hiroshima and Nagasaki blasts, the U.S. and Soviet Union began a Cold War campaign of nuclear one-upmanship that saw its single biggest explosion in a October 1961 Soviet-conducted test blast over the Arctic.

The detonation was caused by a 58-megaton bomb, 4,000 times more powerful than “Little Boy.”
3. MINOR SCALE, U.S. Defense Nuclear Agency, White Sands Missile Range (June 27, 1985)
The ironically named “MINOR SCALE” blast in the desert of New Mexico in 1985 consisted of up to 4,800 short tons of Ammonium Nitrate Fuel Oil (ANFO).

Considered by many to be the largest artificial, non-nuclear explosion in recorded history, the test simulated the effects of an 8-KT nuclear weapon in order to test possible responses of weapon systems and the blast’s effects on communications equipment, vehicles and buildings.

4. Krakatoa volcanic eruptions (August 26-27, 1883)
The Krakatoa eruptions of 1883 exploded with a force of approx. 200 megatons of TNT, or approximately 13,000 times the yield of the Hiroshima atomic blast, making it one of the most violent volcanic blasts in modern history.

The blast’s death toll was more than 36,400, and it’s believed to be the loudest sound ever observed, having been heard as far as 3,000 miles away.

The Krakatoa blast is also said to be the cause of the red sky in the famous painting “The Scream” by Edvard Munch.

The volcanic blast had spewed so much debris into the atmosphere that it caused deep red twilights visible in the skies over Europe (including Munch’s hometown in Norway) from November 1883 to February 1884.
5. The Halifax Cargo Ship Explosion, Nova Scotia, Canada (December 6, 1917)
A cargo ship from France carrying explosives for WWI was struck by another ship in Halifax Harbor.

The explosion hurled debris, caused fires and building collapses, killing 2,000 people and injuring 9,000 more.

The blast also caused a tsunami in the harbor, along with a pressure wave of air that devastated the shoreline and hurtled shards of the destroyed ship for many miles.
6. Explosion at Port Chicago (July 17, 1944)
Two ships loaded with more than 4,600 tons of explosives to be used in WWII collided at Port Chicago, 30 miles north of San Francisco.

This impact, coupled with an additional 400 tons of explosives sitting on adjacent railway cars, killed around 320 workers, damaged buildings, caused injury as far away as San Francisc, and caused tremors felt as far away as Nevada.
7. Chernobyl Nuclear Plant Disaster, U.S.S.R. (April 25, 1986)
The worst nuclear power plant disaster in history occurred April 25, 1986 in the U.S.S.R. region of Chernobyl.

Four inexperienced engineers conducted an electrical experiment on Chernobyl’s number 4 reactor, setting off a cataclysmic chain of events that caused the reactor to explode, blowing off its concrete and steel lid.

The blast sent more than 50 tons of radioactive material into the atmosphere, killed 32 people at the scene and led to an estimated 5,000 deaths from cancer and other radiation-caused illnesses in the following years.
8. The Yellowstone Caldera Eruption, Wyoming, USA (640,000 years ago)
Perhaps the largest explosion the Earth has known occurred approx. 640,000 years ago at the site of the Yellowstone Caldera in the northwest corner of Wyoming.

The blast was estimated to be about 2,500 times the magnitude of the 1980 Mount St. Helens eruption, affected an area of approx 34 miles by 45 miles, and spread a layer of ash over most of North America.

The area is now commonly referred to as the “Yellowstone supervolcano” referring to its potential for massive devastation that many scientists feel will re-occur some day in the distant (or not so distant) future.
9. Gamma Ray Burst, 12 billion light years from Earth (observed on Earth in 1998)
Scientists in 1998 observed an almost unfathomable burst of gamma ray energy 12 billion light years away from us.

They measured it to have released an amount of energy equaling all the estimated 10 billion trillion stars in the universe.

Its distance from our own galaxy prevented the blast from affecting us or our sun, yet the scale of the explosion has led astronomers to label it the biggest documented explosion in history.
10. The Big Bang, Birth of the Universe (13.7 billion years ago)
Though still the subject of debate in the scientific and theological communities, the “Big Bang” would have to be considered the largest explosion EVER.

The forces involved may not meet a strict definition of “explosion,” yet Georges Lemaitre’s Big Bang theory postulates that all the mass in the universe began as a condensed “primeval atom” that burst forth with such dense energy and high temperature and pressure to give birth to everything within the universe

. While initially discounted by his peers when Lemaitre introduced the concept in 1931, other related discoveries such as the cosmic microwave background radiation in 1964 helped solidify the Big Bang as the most well-reasoned theory on the origin of the cosmos.