Space and astronomy news
As part of his ongoing (and always entertaining) “Science Off the Sphere” series, Expedition 31 flight engineer Don Pettit experiments in orbit with a classic bit of summertime fun: water balloons.
Captured in real-time and slow-motion, we get to see how water behaves when suddenly freed from the restraints of an inflated latex balloon… and gravity. With Don NASA doesn’t only get a flight engineer, it gets its very own Mr. Wizard in space — check it out!
Everyone loves a long weekend, this weekend will be officially one second longer than usual. An extra second, or “leap” second, will be added at midnight UTC tonight, June 30, 2012, to account for the fact that it is taking Earth longer and longer to complete one full turn, or one a solar day. Granted, it the additional time is not very long, but the extra second will ensure that the atomic clocks we use to keep time will be in synch with Earth’s rotational period.
“The solar day is gradually getting longer because Earth’s rotation is slowing down ever so slightly,” says Daniel MacMillan of NASA’s Goddard Space Flight Center.
So, rather than changing from 23:59:59 on June 30 to 00:00:00 on July 1, the official time will get an extra second at 23:59:60.
About every one and a half years, one extra second is added to Universal Coordinated Time (UTC) and clocks around the world. Since 1972, a total of 24 seconds have been added. This means that the Earth has slowed down 24 seconds compared to atomic time since then.
However, this doesn’t mean that days are 24 seconds longer now, as only the days on which the leap seconds are inserted have 86,401 seconds instead of the usual 86,400 seconds.
This leap second accounts for the fact that the Earth’s rotation around its own axis, which determines the length of a day, slows down over time while the atomic clocks we use to measure time tick away at almost the same speed over millions of years.
NASA explains it this way:
Scientists know exactly how long it takes Earth to rotate because they have been making that measurement for decades using an extremely precise technique called Very Long Baseline Interferometry (VLBI). VLBI measurements are made daily by an international network of stations that team up to conduct observations at the same time and correlate the results. NASA Goddard provides essential coordination of these measurements, as well as processing and archiving the data collected. And NASA is helping to lead the development of the next generation of VLBI system through the agency’s Space Geodesy Project, led by Goddard.
From VLBI, scientists have learned that Earth is not the most reliable timekeeper. The planet’s rotation is slowing down overall because of tidal forces between Earth and the moon. Roughly every 100 years, the day gets about 1.4 milliseconds, or 1.4 thousandths of a second, longer. Granted, that’s about 100 or 200 times faster than the blink of an eye. But if you add up that small discrepancy every day for years and years, it can make a very big difference indeed.
“At the time of the dinosaurs, Earth completed one rotation in about 23 hours,” says MacMillan, who is a member of the VLBI team at NASA Goddard. “In the year 1820, a rotation took exactly 24 hours, or 86,400 standard seconds. Since 1820, the mean solar day has increased by about 2.5 milliseconds.”
By the 1950s, scientists had already realized that some scientific measurements and technologies demanded more precise timekeeping than Earth’s rotation could provide. So, in 1967, they officially changed the definition of a second. No longer was it based on the length of a day but on an extremely predictable measurement made of electromagnetic transitions in atoms of cesium. These “atomic clocks” based on cesium are accurate to one second in 1,400,000 years. Most people around the world rely on the time standard based on the cesium atom: Coordinated Universal Time (UTC).
Another time standard, called Universal Time 1 (UT1), is based on the rotation of Earth on its axis with respect to the sun. UT1 is officially computed from VLBI measurements, which rely on astronomical reference points and have a typical precision of 5 microseconds, or 5 millionths of a second, or better.
“These reference points are very distant astronomical objects called quasars, which are essentially motionless when viewed from Earth because they are located several billion light years away,” says Goddard’s Stephen Merkowitz, the Space Geodesy Project manager.
For VLBI observations, several stations around the world observe a selected quasar at the same time, with each station recording the arrival of the signal from the quasar; this is done for a series of quasars during a typical 24-hour session. These measurements are made with such exquisite accuracy that it’s actually possible to determine that the signal does not arrive at every station at exactly the same time. From the miniscule differences in arrival times, scientists can figure out the positions of the stations and Earth’s orientation in space, as well as calculating Earth’s rotation speed relative to the quasar positions.
Originally, leap seconds were added to provide a UTC time signal that could be used for navigation at sea. This motivation has become obsolete with the development of GPS (Global Positioning System) and other satellite navigation systems. These days, a leap second is inserted in UTC to keep it within 0.9 seconds of UT1.
Normally, the clock would move from 23:59:59 to 00:00:00 the next day. Instead, at 23:59:59 on June 30, UTC will move to 23:59:60, and then to 00:00:00 on July 1. In practice, this means that clocks in many systems will be turned off for one second.
Proposals have been made to abolish the leap second and let the two time standards drift apart. This is because of the cost of planning for leap seconds and the potential impact of adjusting or turning important systems on and off in synch. No decision will made about that, however, until 2015 at the earliest by the International Telecommunication Union, a specialized agency of the United Nations that addresses issues in information and communication technologies. If the two standards are allowed to go further and further out of synch, they will differ by about 25 minutes in 500 years.
In the meantime, leap seconds will continue to be added to the official UTC timekeeping. The 2012 leap second is the 35th leap second to be added and the first since 2008.
Lead image credit: Rick Ellis
Sources: NASA, TimeandDate.com
A pulsar may have been spotted racing through space at over 6 million miles per hour (9.65 million km/h), setting a new speed record for these curious cosmic objects. If observations are what they appear to be, astronomers will have to recalculate the incredible forces created by supernova explosions.
Seen in observations made with 3 different telescopes — NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, and the Parkes radio telescope in Australia — the x-ray-emitting object IGR J11014-6103 appears to be racing away from the remnants of a supernova in the constellation Carina, 30,000 light-years from Earth.
The comet-shaped object is thought to be a pulsar, the rapidly-spinning, superdense remains of a star. The facts that it’s dim in optical and infrared wavelengths and hasn’t changed in x-ray brightness between XMM-Newton observations in 2003 and Chandra measurements in 2011 support the claim.
IGR J11014’s comet-like shape may be the result of its breakneck speed through space as its pulsar wind nebula gets blown back by the high-energy bow shock created at the forefront of its passage.
Pulsar wind nebulae are the results of charged particles streaming out from the pulsar itself. The particles, traveling at nearly light-speed, are rapidly decelerated by the interstellar medium and create a visible shock wave. In the case of IGR J11014, the pulsar wind is formed into a “tail” by its bow shock — effectively a sonic boom in front of it.
Further observations will be needed to confirm that IGR J11014 is indeed a pulsar, especially considering that actual pulsations have not yet been detected. If it is a pulsar, and is really traveling at the record-breaking speeds it appears to be — between 5.4 and 6.5 million miles per hour, more than 12 times faster than the Sun travels around the center of the galaxy — a new model of supernova explosions may be required.
Read more on the Chandra news release here.
Image: X-ray: NASA/CXC/UC Berkeley/J.Tomsick et al & ESA/XMM-Newton, Optical: DSS; IR: 2MASS/UMass/IPAC-Caltech/NASA/NSF. Video: NASA/CXC/A. Hobart.
Image caption: An upgraded Delta 4 Heavy rocket and super secret spy satellite roar off pad 37 on June 29, 2012 from Cape Canaveral, Florida. Credit: Ken Kremer
A super secret spy satellite for the National Reconnaissance Office (NRO) soared spectacularly to space today (June 29) aboard a Delta 4 Heavy Booster – America’s most powerful rocket following the retirement of NASA’s venerable Space Shuttle Orbiters.
Liftoff of the mammoth Delta 4 Heavy rocket – composed of a trio of liquid fueled common core boosters – finally came at 9:15 a.m. EDT about 3 hours late after a variety of technical issues halted the countdown three times at less than 4 minutes from liftoff from Space Launch Complex 37 on Cape Canaveral Air Force Station, Florida.
Heavy rains and flooding from Tropical Storm Debby had forced a 1 day launch delay from June 28.
The 232 foot tall United Launch Alliance (ULA) Delta lifted off into a magnificent clear blue sky atop the rumbling thunder of three upgraded boosters strapped together side by side and it gradually arced over to the East on the way to orbit.
Both side attached boosters jettisoned as planned. After the second stage engine ignited and the payload fairing separated, the flight went into a preplanned communications black out for the remainder of the flight to orbit and the entire intelligence mission ahead for the hush, hush NROL-15 satellite.
“Today’s successful launch of the NROL-15 mission is the third of four launches for the NRO this year and the second EELV launch for the NRO in just nine days,” said Jim Sponnick, ULA vice president, Mission Operations. “We congratulate the combined NRO , U.S. Air Force and ULA team along with our mission partners for their continued focus on mission success as we deliver the critical capabilities to support the soldiers, sailors, airmen and Marines.”
Just last week on June 20, a ULA Atlas 5 booster lofted the secret NROL-38 satellite for the NRO.
This was only the 6th launch of the Delta 4 Heavy booster and the inaugural flight featuring the upgraded RS-68A Liquid Hydrogen/Liquid Oxygen first stage engines. Each improved engine delivers some 797,000 pounds of thrust vs 758,000 pounds in the prior version – an increase of 39,000 pounds. A single RL 10 engine powered the second stage.
“The upgraded Delta IV Heavy vehicle was developed with an extremely thorough and comprehensive system engineering process by the ULA and Pratt-Whitney Rocketdyne teams, along with substantial involvement by our U.S. government customers,” said Sponnick. “Congratulations to the entire team on today’s successful inaugural flight of the upgraded Delta IV Heavy launch vehicle and the RS-68A engine.”
Wildfires continue to rage across the western United States, burning forests and property alike, and even the most remote have sent up enormous plumes of smoke that are plainly visible to astronauts aboard the Space Station.
The photo above was taken by an Expedition 31 crew member on June 27, showing thick smoke drifting northeast from the Fontenelle fire currently burning in Wyoming. More plumes can be seen to the north.
Utah’s Great Salt Lake can be seen at the bottom right of the image. Its two-tone coloration is due to different species of algae that live in the lake, which is split by the physical barrier of a railroad causeway.
You can watch a video of the wildfires in the west taken from the ISS here, and see more “fire and smoke” news and images from space here.
Image: NASA
With shifting continents, rain, and wind, finding traces of ancient impact craters on Earth has been, literally, astronomically low. Now, an international team of scientists say they have found a massive impact crater in Greenland a billion years older than other known asteroid impact on Earth.
Scientists found the remains of the giant 100-kilometer (62 mile) wide crater near the Maniitsoq region of West Greenland and they believe it’s three billion years old. The largest and previously oldest known crater is the 300 kilometer-wide Vredefort crater in South Africa. Tipped on its side, the edges of the Maniitsoq crater would extend from the surface of the Earth to the edge of space.
“This single discovery means that we can study the effects of cratering on the Earth nearly a billion years further back in time than was possible before,” according to Dr. Iain McDonald of the School of Earth and Ocean Sciences at Cardiff University, who was part of the team.
Finding the crater wasn’t an easy task. Today, the Moon still shows marks of the massive bombardment that took place between three and four billion years ago. The early Earth, with its greater gravitational attraction, would have experienced even more collisions. But the land around Maniitsoq has been eroded over the eons to expose crust that originally was 25 kilometers (16 miles) below the surface. Effects of the immense shockwave produced on impact penetrated deep into the crust and remain visible.
Evidence at that depth had never been observed before, says McDonald. “The process was rather like a Sherlock Holmes story,” said McDonald. “We eliminated the impossible in terms of any conventional terrestrial processes, and were left with a giant impact as the only explanation for all of the facts.”
Only about 180 impact craters have been discovered on Earth. Around 30 percent of them contain important natural resources, including nickel, gold, oil and natural gas. It was during an exploration of natural resources that evidence for the crater was discovered. “It has taken us nearly three years to convince our peers in the scientific community,” said McDonald. “But the mining industry was far more receptive. A Canadian exploration company has been using the impact model to explore for deposits of nickel and platinum metals at Maniitsoq since the autumn of 2011.”
The international team, led by Adam Garde, a senior research scientist at the Geological Survey of Denmark and Greenland, or GEUS, contains members from Cardiff, Lund University in Sweden, and the Institute of Planetary Science in Moscow. Their work was recently published in the jounal Earth and Planetary Science Letters.
Image caption: An artistic expression of how a large meteorite impact into the sea might have looked in the first second of the impacting. We do not know if the area that was hit was actually covered by water or if there was just a sea nearby. Source: Carsten Egestal Thuesen, GEUS
Map caption: Black circle on map shows the location of the meteorite impact structure near the town Maniitsoq in Greenland.
Read more about the Maniitsoq structure.
On July 1, 1962, the Launch Operations Center in Florida officially became operational. The name was later changed to John F. Kennedy Space Center in honor of the president and his vision of Americans visiting the Moon. This video looks back at the many launches and space exploration highlights that occurred at KSC, so enjoy this look back from where many journeys to space began. If you are going to be near KSC during the US’s 4th of July holiday, NASA is hosting some special events in commemoration of the 50th anniversary. The KSC Visitor Complex is offering rare behind-the-scenes tours for its 50th anniversary year, including one taking visitors inside the massive, 525-foot-tall Vehicle Assembly Building, where the Apollo rockets and space shuttles were assembled.
You can find out more info about the events at the KSC Visitor’s Center website
Here is the first image taken by the newest space mission, NuSTAR, or the Nuclear Spectroscopic Telescope Array, the first space telescope with the ability to see the highest energy X-rays in our universe and produce crisp images of them.
“Today, we obtained the first-ever focused images of the high-energy X-ray universe,” said Fiona Harrison, the mission’s principal investigator. “It’s like putting on a new pair of glasses and seeing aspects of the world around us clearly for the first time.”
With the successful “first light” images, the mission will begin its exploration of the most elusive and energetic black holes — as well as other areas of extreme physics in our cosmos — to help in our understanding of the structure of the universe.
The first images show Cygnus X-1, a black hole in our galaxy that is siphoning gas off a giant-star companion. This particular black hole was chosen as a first target because it is extremely bright in X-rays, allowing the NuSTAR team to easily see where the telescope’s focused X-rays are falling on the detectors.
NuSTAR launched on June 13 and its lengthy mast, which provides the telescope mirrors and detectors with the distance needed to focus X-rays, was deployed on June 21. The NuSTAR team spent the next week verifying the pointing and motion capabilities of the satellite, and fine-tuning the alignment of the mast.
The mission’s primary observing program is expected to start in about two weeks. But before it does, the team will continue tests and point the NuSTAR at two other bright calibration targets: G21.5-0.9, the remnant of a supernova explosion that occurred several thousand years ago in our own Milky Way galaxy; and 3C273, an actively feeding black hole, or quasar, located 2 billion light-years away at the center of another galaxy. These targets will be used to make a small adjustment to place the X-ray light at the optimum spot on the detector, and to further calibrate and understand the telescope in preparation for future science observations.
Other targets for the mission include the burnt-out remains of dead stars, such as those that exploded as supernovae; high-speed jets; the temperamental surface of our sun; and the structures where galaxies cluster together like mega-cities.
“This is a really exciting time for the team,” said Daniel Stern, the NuSTAR project scientist. “We can already see the power of NuSTAR to crack open the high-energy X-ray universe and reveal secrets that were impossible to get at before.”
Lead image caption: NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has taken its first snapshots of the highest-energy X-rays in the cosmos (lower right), producing images that are much crisper than previous high-energy telescopes (example in upper right). NuSTAR chose a black hole in the constellation Cygnus (shown in the skymap on the left) as its first target due to its brightness. Image credit: NASA/JPL-Caltech
When galaxies collide, stars are thrown from orbits, spiral arms are stretched and twisted, and now scientists say galaxies ring like a bell long after the cosmic crash.
A team of astronomers from the United States and Canada say they have heard echoes of that ringing, possible evidence of a galactic encounter 100 million years ago when a small satellite galaxy or dark matter object passed through the Milky Way Galaxy; close to our position in the galaxy, as if a rock were thrown into a still pond causing the stars to bounce up and down on the waves. Their results were published in the Astrophysical Journal Letters.
“We have found evidence that our Milky Way had an encounter with a small galaxy or massive dark matter structure perhaps as recently as 100 million years ago,” said Larry Widrow, professor at Queen’s University in Canada. “We clearly observe unexpected differences in the Milky Way’s stellar distribution above and below the Galaxy’s midplane that have the appearance of a vertical wave — something that nobody has seen before.”
Astronomers took observations from about 300,000 nearby stars in the Sloan Digital Sky Survey. Stars move up and down at 20-30 kilometers per second while see-sawing around the galaxy at 220 kilometers per second. By comparison, the International Space Station putters around Earth at 7.71 kilometers per second; Voyager 1, the fastest man-made object, currently is leaving the solar system at about 17.46 kilometers per second. Widrow and colleagues at the University of Kentucky, The University of Chicago and Fermi National Accelerator Laboratory found that the positions of nearby stars is not quite as regular as previously thought. The team noticed a small but statistically significant difference in the distribution of stars above and below the midplane of the Milky Way.
“Our part of the Milky Way is ringing like a bell,” said Brian Yanny, of the Department of Energy’s Fermilab. “But we have not been able to identify the celestial object that passed through the Milky Way. It could have been one of the small satellite galaxies that move around the center of our galaxy, or an invisible structure such as a dark matter halo.”
Susan Gardner, professor of physics at the University of Kentucky added, “The perturbation need not have been a single isolated event in the past, and it may even be ongoing. Additional observations may well clarify its origin.”
Other possibilities considered for the variations were the effect of interstellar dust or simply the way the stars were selected in the survey. But as those events failed to explain fully the observations, the astronomers began to explore possible recent events in the history of the galaxy.
More than 20 visible satellite galaxies circle the Milky Way. Invisible satellites made up of dark matter, hypothetical matter that cannot be seen but is thought to make up a majority of the mass of the Universe, might also orbit our galaxy. Scientists believe that most of the mass orbiting the galaxy is in the form of dark matter. Using computer simulations to explore the effects of a small galaxy or dark matter structure passing through the disk of the Milky Way, the scientists developed a clearer picture of the see-saw effects they were seeing.
In terms of the nine-billion lifetime of the Milky Way Galaxy, the effects are short-lived. This part of the galaxy has been “ringing” for 100 million years and will continue for 100 million years more as the up-and-down motion dissipates, say the astronomers – unless we are hit again.
Image caption: The Small Magellanic Cloud is one of 20 visible satellite galaxies that orbit the Milky Way Galaxy. Astronomers report that a smaller counterpart or dark matter object passed through the Milky Way near our position about 100 million years ago.
Londoners awoke this morning to news of a meteorite which struck a taxi in the heart of the city’s busy shopping district Covent Garden. Witnesses were left stunned by what looked like a scene straight out of a science fiction film. An incident team arrived almost immediately to cordon off the meteorite and keep the public at a safe distance.
No one was injured as a result of the incident, but it’s a cosmic harbinger of things to come…
Of course, the “things to come” turn out to be 4 weeks of science programs on Eden TV’s Science Month, which starts up in July.
The incident was in fact a well-orchestrated publicity stunt by the UK’s Eden TV (Sky 532 Virgin 208). Science Month will run all day every day during the month of July. Highlights in the first week include Wonders of the Universe (Monday 2 July at 9pm), Finding Life Beyond Earth (Monday 2 July at 10pm), The Code (Wednesday 4 July at 10pm) and Deadliest Volcano (Thursday 5 July at 7pm).
Sure, after all’s said and done it was a PR stunt. But it was a cool PR stunt (even if not quite scientifically accurate!)
Come on, we all know that meteorites aren’t steaming hot when they land. 😉