August 31, 2016

On August 24, scientists from the European Southern Observatory (ESO) announced that they had discovered an extrasolar (beyond our solar system) planet, or exoplanet, that may harbor conditions favorable to life. This exoplanet, called Proxima b, orbits Proxima Centauri, the star closest to the sun. Astronomers have nicknamed Proxima b the “pale red dot,” a play on Earth’s appearance as a “pale blue dot” in a distant photo taken by the Voyager 1 space probe in 1990. Astronomers believe that Proxima Centauri, a red dwarf star, will cast its close-orbiting planet in a pale red glow. The search for a planet orbiting Proxima Centauri, which began just seven months ago, was dubbed the “Pale Red Dot” campaign.

This artist’s impression shows the red dwarf star Proxima Centauri, the closest star to our solar system, on the red horizon of Proxima b, a planet scientists think could support life. The double star Alpha Centauri AB appears to the upper right of Proxima Centauri. Credit: ESO/M. Kornmesser

Proxima Centauri is part of a three-star system called Alpha Centauri. Two of the stars, Centauri A and Centauri B, are roughly the size of the sun and orbit each other. Proxima Centauri is a much smaller red dwarf star and orbits the larger pair of stars every million years or so.

Proxima b (nicknamed the “pale red dot” by astronomers) and its orbit around Proxima Centauri are compared with the same region of our own solar system. Proxima Centauri is smaller and cooler than the sun, and Proxima b orbits much closer to its star than Mercury orbits the sun. A planet in the green habitable zone could possibly have liquid water, which could possibly support life. Credit: ESO/M. Kornmesser/G. Coleman

The newly discovered exoplanet, Proxima b, is at least 1.3 times the size of Earth. Its size indicates that it is probably a rocky planet, like Earth and Mars. It orbits Proxima every 11 Earth days (Mercury, the closest planet to the sun, completes a year every 88 Earth days). If Proxima Centauri were a star like our sun, the planet would be little more than a charred husk. But red dwarf stars are small and relatively cool. Consequently, it is possible that liquid water could exist on the exoplanet’s surface. Scientists call this region around a star, where temperatures are suitable for liquid water, its habitable zone. Liquid water is a necessary building block for life as we know it.

If red dwarf stars can harbor habitable worlds, then the odds that life exists elsewhere in the universe increase significantly. Red dwarfs make up about 70 percent of the stars in the universe. They also burn slowly and steadily, for up to 10 trillion years. In contrast, the sun has a stable lifespan of only 10 billion years. As a result, if favorable conditions exist, life could have countless chances to form over countless eons.

Astronomers still have a lot to learn about Proxima b and whether it can host life. It might lack an atmosphere or get bombarded by powerful X ray blasts from Proxima. The James Webb Space Telescope (JWST), to be launched in 2018, should answer some of these questions. It will be able to determine the exoplanet’s composition and whether it has an atmosphere. JWST will also gather more information on the planet’s size and makeup. Future space telescopes may even be powerful enough to see the “pale red dot” directly.

Most exoplanets are too far away to be explored by spacecraft from Earth. They orbit stars many light-years away. A light-year is the distance light travels in a year, or about 5.88 trillion miles (9.46 trillion kilometers). Nothing can travel faster than the speed of light. Proxima Centauri, however, is just 4.2 light-years away, tantalizingly close in astronomical terms. But the fastest spacecraft ever created have reached just tiny fractions of the speed of light. Using such technology, a traditional space probe would still take thousands of years to reach the system.

A private initiative called Breakthrough Starshot, however, has proposed launching a tiny spacecraft to the system that would take as little as 20 years to get there. The probe would be only a gram or two (the equivalent of less than an ounce on Earth) and be propelled by large Earth-based lasers to 20 percent of the speed of light. There are many technical hurdles to be overcome, however, and the group does not anticipate launching a probe for at least another 20 years, but there is hope that the planet could be explored close-up before 2100. Soon, we may get to say hello to our closest potential neighbor. Will it say hi back?

August 11, 2016

It is going to storm tonight—but don’t worry, you won’t get wet. The Perseid meteor shower peaks in the evening hours tonight and early tomorrow morning. Sky watchers in the Northern Hemisphere may be able to see bright streaks flashing across the night sky. Thanks to the mighty influence of the planet Jupiter, the Perseids are more numerous than they’ve been for several years.

The Perseid meteor shower lights up the night sky each year in August.
Credit: NASA/JPL

Meteor showers occur when Earth travels through a stream of meteoroids. A meteoroid is a piece of matter that enters Earth’s atmosphere at a high speed. The rate at which meteors appear generally increases, peaks, and then decreases as Earth moves in and out of a stream. As seen from the ground, all meteors in a particular shower appear to come from the same direction in the sky. This direction is called the radiant of the shower.

The Perseids are an annual meteor shower caused by a dusty trail of debris left by Comet Swift-Tuttle. As the comet orbits the sun, it sheds rock and dust particles. As Earth travels through this ring of debris, meteoroids crash into the atmosphere. Their high speed heats up the air, causing it to glow. Almost all these meteoroids are too small to reach Earth’s surface and instead burn up in the atmosphere. The Perseids get their name because the radiant of the shower lies near the constellation Perseus.

Comet Swift-Tuttle leaves a wide swath of debris, so meteors have been visible for several weeks already and should be visible for several more. The frequency of meteor sightings is expected to peak tonight, however, as Earth passes through the thickest part of the debris cloud. Astronomers estimate that there may be as many as 200 visible meteors per hour! What’s the reason for this abnormally heavy shower? The intense gravity of Jupiter sometimes tugs at debris streams left by comets. In the case of this year’s Perseids, Jupiter has pulled the center of the stream closer to Earth’s orbit, nearly doubling the usual meteor shower.

Look toward Perseus tonight after sunset to catch the show (it is best seen when the constellation is directly overhead). If possible, get away from urban light pollution, but some shooting stars can be seen even near a city’s glow. Astronomers think the brightest meteors may even outshine the stars tonight—for only a fraction of a second, of course!

Other World Book articles:

• Astronomy
• Famous comets
• Stones From Space (a Special report)

August 10, 2016

In a sleepy section of the visible universe there lurks a huge galaxy with a bizarre patchwork of features. The galaxy was known to astronomers, but its large size and strange attributes went unnoticed for decades. Research spearheaded by Lea Hagan, a graduate student at Pennsylvania State University, University Park, has found there is more to galaxy UGC 1382 than meets the eye. Hagen and her colleagues published their findings last month in The Astrophysical Journal.

At left, in optical light, UGC 1382 appears to be a simple elliptical galaxy. But spiral arms emerged when astronomers incorporated ultraviolet and deep optical data (middle). Combining that with a view of low-density hydrogen gas (shown in green at right), scientists discovered that UGC 1382 is huge, about 718,000 light-years wide.
Credit: NASA/JPL/Caltech/SDSS/NRAO

A galaxy is a vast system of stars, gas, dust, and other matter held together in space by their mutual gravitational pull. Astronomers classify galaxies into three main types based on shape: (1) spiral galaxies, (2) elliptical galaxies, and (3) irregular galaxies. Spiral galaxies feature a thin, disklike structure with sweeping arms of stars wrapped about the galaxy’s center. Elliptical galaxies have forms like centrally concentrated spheres or flattened globes. Irregular galaxies are those that don’t have spiral or elliptical forms.

In visible-light images, UGC 1382 appears to be a modestly sized elliptical galaxy, uninteresting to all but the most serious astronomer. Ultraviolet images of the galaxy gathered by the orbiting Galaxy Evolution Explorer (GALEX) telescope, however, hinted that UGC 1382 had a more complicated structure. Hagen and her team noticed previously unseen huge spiral arms billowing out from the elliptical center. The team then used observations from other telescopes to learn more about this mysterious galaxy.

Hagen’s team found that UGC 1382 is over 700,000 light-years across with its spiral arms. A light-year is the distance light travels in a year in the vacuum of space, or about 5.88 trillion miles (9.46 trillion kilometers). The Milky Way, the spiral galaxy that contains our solar system, is only about 100,000 light-years across. The scientists also found UGC 1382 to possess a puzzling structure. They determined that the stars in the spiral arms are older than the stars in the galaxy’s bright core. This arrangement is opposite of what is seen in most spiral galaxies.

The team thinks that this odd formation arose from the combination of several galaxies long ago. Billions of years ago, a group of small galaxies formed, containing much gas and dark matter. Dark matter is a substance thought to make up most of the matter in the universe but does not give off, reflect, or absorb light rays. Much later, a kind of elliptical galaxy called a lenticular galaxy formed near the group. A lenticular galaxy spins, but has no spiral arms. This galaxy floated through the group of older galaxies. The lenticular galaxy’s gravity warped and pulled at the older galaxies, eventually twisting them around itself to form spiral arms. Because these galaxies were composed mostly of gas and dark matter, the spiral arms are dim and do not appear in visible-light images of UGC 1382.

Hagen and her colleagues think this kind of galaxy could only form in emptier sections of the universe, without gravitational interference from other galaxies. They hope to do more research to better understand UGC 1382, a sort “Frankenstein” galaxy cobbled together from cosmic spare parts, and to find more oddball galaxies that are stranger than they first appeared.

July 20, 2016

On Saturday, July 16, a South African meerkat made international news, but it wasn’t one of the cute and cuddly critters of TV’s “Meerkat Manor.” This meerkat—or, rather, MeerKAT—is a radio telescope complex under construction near Carnarvon, South Africa, south of where the TV series studied actual meerkats in the Kalahari Desert. On Saturday, images from the first 16 MeerKAT reflectors (dish antennas)—in operation for only a few hours and looking at only a tiny corner of the universe—revealed black holes some 200 million light-years away and hundreds of previously unknown galaxies. A radio telescope consists of a radio receiver with an antenna fixed on a wide bowl-shaped reflector that records radio waves coming from stars and other objects in outer space. A radio receiver amplifies the signals and sends them to a computer. The computer then analyzes the radio spectrum of the wave source to produce an image.

A MeerKAT dish antenna scans the night sky above the dry Karoo region of South Africa.
Credit: © SKA South Africa

The KAT in MeerKAT stands for Karoo Array Telescope, which refers to the complex’s location in South Africa’s remote Karoo semidesert region. MeerKAT, which will have 64 reflectors when completed late next year, is the first phase of Square Kilometer Array (SKA) South Africa that will eventually have 250 antennas. SKA South Africa will then pair with a SKA complex of 256 antennas being built in Western Australia. Together, they will explore and measure the universe at different radio frequencies. If the first few hours of the first 16 SKA reflectors are any indication—which glimpsed less than 1/100^th of 1 percent of the celestial sphere—imagine what 64, then 250, then 506 antennas mapping huge areas of the sky might find!

This portion of MeerKAT’s first radio image shows more than 200 astronomical radio sources (white dots). Previous mapping of this area showed just five sources, marked here by the violet circles.
Credit: © SKA South Africa

But wait, there’s more! This is only SKA Phase 1. SKA Phase 2—scheduled to be operating by the mid-2020’s—will eventually include thousands of radio telescope antennas throughout Africa and Australia. The SKA project will no doubt enhance our understanding of the universe and may possibly even change it. It will also test our current understanding of physics and expand our technological grasp. SKA has a number of key objectives, such as investigating the origins and structure of the universe and studying gravitational waves and astrobiological (the search for and study of life in the universe) possibilities. But the project’s statement purpose, “Exploration of the Unknown,” reflects the expectation that SKA will discover things we cannot yet conceive.

July 5, 2016

Traditionally, Independence Day in the United States—yesterday, July 4—is celebrated with fireworks. This Fourth of July, the National Aeronautics and Space Administration (NASA) celebrated with fireworks of the deep space variety as its probe Juno fired its engine for 35 minutes to enter into orbit around Jupiter. After being launched in 2011, Juno has finally reached its destination.

Launched from Earth in 2011, the Juno spacecraft arrived at Jupiter on July 4, 2016, to study the giant planet from an elliptical polar orbit.
Credit: NASA/JPL

Jupiter is the largest planet in our solar system. It has a mass (amount of matter) that is greater than the masses of all the other planets in the solar system added together. Astronomers call Jupiter a gas giant because the planet consists mostly of hydrogen and helium, and it has no solid surface. Jupiter is named for the king of the gods in Roman mythology. Juno was Jupiter’s wife and queen of the gods.

Juno will study Jupiter from an elongated polar orbit. The probe will be 4,900 miles (7,200 kilometers) from Jupiter at the farthest point in its orbit, and dive to within 2,600 miles (4,200 kilometers) of the Jovian clouds, flying over the planet’s north and south poles. Mission scientists planned this orbit to keep Juno out of Jupiter’s radiation belts as much as possible. Jupiter emits a powerful magnetic field, much stronger than that produced by Earth. This strong magnetic field traps high-energy charged particles in belts around the planet. Any spacecraft entering these belts would be bombarded by huge doses of radiation. Such radiation is just as dangerous to electronics as it is to living things: it can damage computer chips and fry circuits.

Scientists shielded Juno’s most important electronics in a thick titanium case to protect them from radiation. But no spacecraft can stand exposure to such highly charged particles for long. NASA scientists do not expect the craft to survive much longer than its 20-month mission, even with its titanium vault and elliptical orbit. Consequently, they have already scheduled the probe to crash into Jupiter in February 2018.

Before it smashes into its object of study, Juno will probe the makeup of Jupiter. Scientists hope it will help determine whether Jupiter has a rocky core, and why the planet has a higher concentration of elements heavier than hydrogen and helium than the sun. Juno will also study Jupiter’s famous Great Red Spot, a storm that has been churning around the atmosphere for at least 300 years. Scientists think that answering these questions will help us better understand Jupiter’s history and the formation of our solar system. It may even give us a better idea of how other solar systems form and behave. Rather than a grand finale, Juno’s fireworks are the start of some amazing science!

December 22, 2015

Last night, Space Exploration Technologies Corporation (commonly called SpaceX) made history when it landed a rocket on Earth. Although landing probes on other bodies or placing people into orbit is usually the goal of space travel, SpaceX’s achievement promises to make spaceflight cheaper and more accessible in the near future.

SpaceX’s Falcon 9 rocket lifts off from Cape Canaveral Air Force Station in Florida on Dec. 21, 2015. The private space exploration company made history after the rocket successfully delivered communications satellites into orbit and then landed back on Earth. Credit: SpaceX

A rocket is a type of engine that pushes itself forward or upward by producing thrust. Unlike a jet engine, which draws in outside air, a rocket engine uses only the substances carried within it. As a result, a rocket can operate in outer space, where there is no air. The word rocket can also mean a vehicle or object driven by a rocket engine.

SpaceX is a private space exploration company founded by South African entrepreneur (business developer) Elon Musk. One of the company’s multistage Falcon 9 rockets lifted off from Cape Canaveral Air Force Station in Florida last night in a successful attempt to deliver communications satellites into orbit. In traditional multistage rockets, discarded stages fall to Earth and burn up in the atmosphere. Last night, however the first stage of SpaceX’s rocket descended back to Earth, slowed by its engines, and landed vertically on a pad using three large retractable legs.

The landing is a major victory for SpaceX, which had made two earlier unsuccessful landing attempts. In June, the company suffered embarrassment when a rocket launched to resupply the International Space Station exploded shortly after takeoff.

The (relatively) gentle landing should allow much of the first stage to be reused in future launches. For now, SpaceX employees are inspecting the rocket and studying how its parts can be safely reused. But as such landing and reuse become more routine, they will allow the cost of spaceflight to plummet. In November, space company Blue Origin, owned by American businessman Jeff Bezos, successfully landed a small rocket after a brief suborbital flight. But SpaceX’s rocket was far larger and part of a more complex orbital flight. Both companies are engineering new ways to make spaceflight cheaper and more reliable.

Additional World Book articles:

• Boeing Company
• Space exploration (2012) – A Back in Time article
  

December 18, 2015

On Tuesday, the United Kingdom sent its first publicly funded astronaut to the International Space Station (ISS). Tim Peake, an astronaut of the European Space Agency (ESA), arrived at the station six hours after launch aboard a Russian Soyuz spacecraft. During his six-month stay at the ISS, he will help conduct scientific experiments and perform public outreach. Peake joins American astronaut Scott Kelly and Russian cosmonauts Sergey Volkov and Mikhail Korniyenko aboard the station. He flew up together with Russian cosmonaut Yuri Malenchenko and American astronaut Timothy Kopra. Together, the six men make up the 46^th expedition to the ISS.

Tim Peake became the first publicly funded British astronaut aboard the International Space Station on Dec. 15, 2015. Credit: Victor Zelentsov, NASA/ESA Credit: Victor Zelentsov, NASA/ESA

An astronaut is a person who pilots a spacecraft or works in space. Astronauts operate spacecraft and space stations, launch and recapture satellites, and conduct scientific experiments. The word astronaut comes from Greek words meaning sailor among the stars. Cosmonaut is a Russian word that means sailor of the universe.

Peake is not the first British citizen to be launched into space. In 1991, chemist Helen Sharman visited the Russian space station Mir as part of a project funded partly by British companies. Several other astronauts with dual British and United States citizenship have worked in space as members of the United States’ National Aeronautics and Space Administration (NASA).

In the past, the British government was reluctant to participate in manned spaceflight. It formally rejected training astronauts in 1986. But over time, decreasing costs and safety concerns, combined with the chance to bolster national pride and public interest in the sciences, caused the government to change course. In 2008, the British National Space Centre released a new space strategy document in which it expressed an openness to manned missions. After many years of difficult training, Tim Peake blasted off wearing the Union Jack flag patch on his spacesuit. The United Kingdom, known for its daring exploration of remote parts of the world in centuries past, has now begun manned exploration of space.

Additional World Book articles:

• Space exploration (1994) – A Back in Time article
  
• Space exploration (2000) – A Back in Time article
• Space exploration (2003) – A Back in Time article
• Space exploration (2008) – A Back in Time article

September 4, 2014

American aerospace firm Lockheed Martin and a telescope company based in Canberra, Australia—Electro Optic Systems (ELO)—have partnered to track junk. Space junk.

Space seems like a silent, empty place in movies. While it may be silent, it is certainly not empty. It is filled with  junk—human-made, nonworking objects that orbit Earth. The National Aeronautics and Space Administration (NASA) estimates there are more than 20,000 pieces of such debris of a size larger than a softball (12 inches [30 centimeters] in circumference) orbiting our planet.

Space junk clutters low Earth orbit, the region of space within about 1,200 miles (2,000 kilometers) of the planet’s surface. The white dots in this computer-generated image of Earth mark the locations of objects in orbit. About 95 percent of the objects shown are debris—that is, they are not functional satellites. The dots appear larger than the objects they represent, which are too small to be seen at this scale (NASA Orbital Debris Program Office).

The junk circling Earth is composed of many things. When astronauts threw out a bag of garbage from the International Space Station or Mir, that bag became space junk. When an astronaut working outside a spacecraft dropped and lost a tool, that floating tool became more space junk. Even tiny items, such as specks of paint and drops of frozen liquid, become part of the debris circling in space.

All of this debris matters because it can be dangerous. Space junk travels at speeds up to 17,500 miles (27,000 kilometers) per hour—the speed required for objects to stay in an orbit around Earth. At such speeds, even tiny objects can damage or destroy a satellite or spacecraft. For example, in 2009, a nonfunctioning Russian satellite collided with and destroyed a functioning U.S. commercial satellite. Satellites are expensive, so the loss of the commercial satellite was bad enough. But, when such events happen, they also add to the problem. The collision between the Russian and American satellites created thousands of pieces of new space junk. According to experts, one satellite a year is lost on average, owing to a collision with debris.

Space junk is currently tracked using several radar systems, including the U.S. Air Force Space Fence system. The new system to be built by EOS will use advanced optical and laser technology to track pieces as small as a golf ball (1.68 inches [4.27 centimeters] in diameter)—a much smaller size than current technology permits. The site to track space junk will be housed in western Australia and it is estimated that it will cost $75 million to build. The hope is that this new system will save satellites worth millions of dollars and will increase safety for humans traveling through the region where much of the debris exists.

Additional World Book articles:

• Space debris

January 14, 2013

The administration of President Barack Obama has officially rejected an online petition from citizens urging the United States to add a Star Wars-like Death Star to the country’s military arsenal. The Death Star, which appeared in several of the movies in the Star Wars series, is a moon-sized space vehicle equipped with an energy-emitting superweapon capable of destroying an entire planet with one blast.

The request was submitted to the White House’s “We the People” website, established in 2011 “to create and sign petitions that call for the federal government to take action on a range of issues.” Petitions that receive a certain number of signatures within a specified period of time are guaranteed an answer from the White House. The Death Star petition collected 34,435 signatures. The right of the people “to petition the government for a redress of grievances” is guaranteed by the First Amendment to the U.S. Constitution.

Paul Shawcross, chief of the Science and Space Branch at the White House Office of Management and Budget, rejected the petition with an answer titled, “This Isn’t the Petition Response You’re Looking For.” In his response, Shawcross listed three main reasons for the rejection.

“The Administration shares your desire for job creation and a strong national defense, but a Death Star isn’t on the horizon. Here are a few reasons:
•    The construction of the Death Star has been estimated to cost more than $850,000,000,000,000,000. We’re working hard to reduce the deficit, not expand it.
•    The Administration does not support blowing up planets.
•    Why would we spend countless taxpayer dollars on a Death Star with a fundamental flaw that can be exploited by a one-man starship?”

Imperial storm troopers from the Star Wars movies appear on a United States stamp. (Credit: United States Postal Service)

After listing some existing space projects, Shawcross wrote, “We are living in the future! Enjoy it. … If you do pursue a career in a science, technology, engineering or math-related field, the Force will be with us! Remember, the Death Star’s power to destroy a planet, or even a whole star system, is insignificant next to the power of the Force.”

Additional World Book articles:

• Bill of Rights
• George Lucas
• Science fiction
• Strategic Defense Initiative

July 24, 2012

United States astronaut Sally Ride died on July 23 at the age of 61. Ride was the first American woman–and, at the age of 32, the youngest American–to fly in space. Her flight aboard the space shuttle Challenger in 1983 inspired many young women to pursue careers in science, mathematics, and technology at a time when men still overwhelmingly dominated those fields.

Sally Kristen Ride was born on May 26, 1951, in Los Angeles. She studied at Stanford University, where she earned bachelor’s degrees in English and physics in 1973, a master’s degree in physics in 1975, and a Ph.D. in astrophysics in 1978. During her time at Stanford, Ride became a nationally ranked tennis player and briefly considered a career as a professional. However, she instead answered a job advertisement posted by the U.S. National Aeronautics and Space Administration (NASA) and was accepted as an astronaut candidate in January 1978. By that time, the Soviet Union had already sent a woman into space. Cosmonaut Valentina Tereshkova orbited Earth 48 times in 1963.

Sally K. Ride became the first U.S. woman in space on June 18, 1983. In this photograph, Ride eats a meal on the shuttle Challenger during her second shuttle flight in October 1984. (courtesy of NASA)

In her early years at NASA, Ride studied engineering and contributed to the development of a robotic arm for the space shuttle. That work, in part, brought her to the attention of Captain Robert L. Crippen, who chose her to serve as a mission specialist aboard the Challenger mission he commanded in 1983. A crowd of some 250,000 people at the Kennedy Space Center in Cape Canaveral, Florida, chanted “Ride, Sally Ride” as the shuttle took off on June 18. During the nearly six-day mission, Ride used the robotic arm to deploy and retrieve a satellite. She flew a second mission aboard Challenger in 1984 and was slated to fly a third. However, when Challenger exploded shortly after liftoff in January 1986, future flights were suspended, and Ride retired from NASA in 1987. Then-President Ronald Reagan appointed her to serve on the commission investigating the tragedy, in which seven crew members were killed. Ride later also served on the federal panel investigating the second shuttle disaster–the disintegration of Columbia in February 2003 as it reentered the atmosphere after a mission. All seven crew members aboard were killed.

In 1989, Ride became a professor of physics at the University of California, San Diego, and director of the California Space Institute. In 2001, she founded a company called Sally Ride Science that creates science programs for upper elementary and middle school students, their teachers, and their parents. According to Ride, she wanted to “make science and engineering cool again.”

Upon hearing of her death, President Barack Obama called Ride “a national hero and a powerful role model.” But perhaps Gloria Steinem, co-founder of Ms. magazine and a leading supporter of the women’s liberation movement in the United States, best captured the impact of Ride’s achievement when she said in 1983, “Millions of little girls are going to sit by their television sets and see they can be astronauts, heroes, explorers, and scientists.”

Additional World Book articles:

• Space exploration 1983 (Back in Time article)
• Space exploration 1984 (Back in Time article)