A wide angle view of Discovery and the payload canister on the rolled back Rotating Service Structure. Credit: Alan Walters (awaltersphoto.com) for Universe Today
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Over the weekend, NASA engineers will conduct additional tests to determine if Discovery can launch “as is” or have to be rolled back for repairs — which would mean a three-month delay for the STS-131 mission. Helium regulator assemblies downstream from a failed isolation valve in the shuttle’s right rear maneuvering engine pod must work perfectly to provide a system redundancy that would justify proceeding with the flight. If they don’t, then the regulator assemblies and the valve would need to be repaired or replaced, and neither can be done at the launchpad – meaning Discovery would have to be rolled back to the Vehicle Assembly Building, de-mated from the SRBs and external tank, and sent to the Orbiter Processing Facility for repairs. But if the regulators check out, and no other problems arise, mission managers could give the ‘go’ to launch Discovery as is on April 5, 2010.
Today on the launchpad, said NASA Payload Manager Joe Delai was optimistic about the tests. “It’s looking good,” he said. “They will do a test on Saturday to make sure the two valves farther down the line work, and if that looks good, we’ll put the payload on board.”
Close-up of Discovery. Image Credit: Alan Walters (awaltersphoto.com) for Universe Today
Engineers will evaluate the data and discuss options at a readiness review Tuesday morning.
Nancy on the launchpad. Credit: Alan Walters (awaltersphoto.com) for Universe Today.
In anticipation of a good report on the regulator tests, the canister carrying the payload for Discovery’s STS-131 mission to the International Space Station was brought to Launch Pad 39A early on March 19. Later, reporters were allowed an unusual visit right on the pad and close to Discovery to see the work in progress and talk with Delai and Boeing payload flow manager, Mike Kinslow.
Enjoy these great close-up images by Universe Today photographer Alan Walters of Discovery on the on launchpad, with the Rotating Service Structure rolled back, allowing a view of the payload canister. Discovery ready to receive the payload for the STS-131 mission. Image Credit: Alan Walters (awaltersphoto.com) for Universe Today.
Discovery on the pad. Note the bird soaring overhead. Credit: Alan Walters (awaltersphoto.com) for Universe Today.On Feb. 18, 2010, workers in the Space Station Processing Facility at KSC finished packing the Leonardo module for the STS-131 mission. Credit: Nancy Atkinson
STS-131 will be a three-spacewalk space station assembly and resupply mission. The Leonard Multi-purpose Logistics Module that will be installed in Discovery’s payload bay will bring up 5,000 kg (11,000 lbs) of food, water, clothes, parts, science experiments, supply units for the oxygen generation system, and five science utilization racks.
New crew quarters for the ISS.
Other very interesting additions to the ISS on this flight include: , the fourth crew sleep station (CQ4)– which is a phone booth-like small crew quarters, the MARES (Muscle Atrophy Research and Exercise System) – which Delai compared to a Bowflex for the ISS crew, a new Minus Eighty-degree Laboratory Freezer for ISS (MELFI) which will be used to support science experiments, and a “dark room” for photography called WORF – Window Observational Research Facility, allowing for better images to be taken from the observation window in the US lab Destiny.
Before the invention of the telescope in the early 1600’s, man just knew of the Moon — a round, mysterious astronomical object that people would gaze up to in the night sky. As time progressed however, astronomers discovered that the moon isn’t exactly unique to earthlings, and other planets had their own moons. So exactly what is a moon?
A moon is defined to be a celestial body that makes an orbit around a planet, including the eight major planets, dwarf planets, and minor planets. A moon may also be referred to as a natural satellite, although to differentiate it from other astronomical bodies orbiting another body, e.g. a planet orbiting a star, the term moon is used exclusively to make a reference to a planet’s natural satellite.
The first moons to be discovered outside of the Earth’s moon were the Galilean moons of Jupiter, named after astronomer and discoverer Galileo Galilei. The moons Io, Europa, Ganymede, and Callisto are Jupiter’s largest and only the first four to be revealed, as to date, the planet has 63 moons.
Other than the four Galilean moons, Saturn’s Titan and Neptune’s Triton are two other moons which are comparable in size to the Earth’s Moon. In fact, these seven moons are the largest natural satellites in the solar system, measuring more than 3,000 kilometers in diameter. Only the inner planets Mercury and Venus have no moons.
An interesting fact about some of the solar system’s largest moons that most people may not be aware of is that a few of them are geologically active. While we may not see the Moon spewing lava or displaying any evidence of tectonic activity, Jupiter’s Io and Europa, Saturn’s Titan and Enceladus, and Neptune’s Triton have been found to be volcanically active bodies.
If the moon count had a grand total of just one in the olden times, that number has ballooned to 336 as of July 2009, with 168 moons orbiting the six planets, while the rest are moons of dwarf planets, asteroids moons, and natural satellites of Trans-Neptunian objects.
As more and more discoveries are made however, astronomers may find it more difficult to put a really defining line on what can or what can’t be classified as a moon. For instance, can you consider a 10-inch rock that’s orbiting Jupiter a moon? If yes, then there could be thousands or even millions of moons out there. If not, then where do you draw the line? Obviously, even the size of an “official” moon is still up for debate, so other than the simple definition of it being a natural satellite of a planet, there really is no clear cut answer to the question, “What is a moon?”.
Here in Universe Today, we have a nice collection of articles that explain why the Moon landings could not have been faked. Here are some of them:
Moon Rocks – Discusses how the Moon rocks are one of the most tangible objects that prove the landings took place.
Moon Landing Hoax – An explanation that counters some of the points raised by skeptics
Apollo 11 Hoax – another point for point discussion by Jerry Coffey
TV – Alert: Mythbusters and the Moon Hoax Myth – a teaser for the Mythbusters episode featuring the so-called hoax. You’ll find the comments below that article equally interesting, by the way.
Here’s an article from NASA that debunks the hoax theory using the Moon rock arguments. Another article about Moon rocks from the same site.
Episodes about the moon from Astronomy Cast. Lend us your ears!
Annotated graphic of Lunokhod 2's travels from Phil Stooke's International Atlas of Lunar Exploration.
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The saga of the Soviet Union’s Lunokhod moon rovers keeps getting more interesting! If you missed the update on our article about finding the “missing” Russian landers and rovers among the newly released Lunar Reconnaissance Orbiter images, the Lunokhod 2 rover was not exactly where one researcher initially thought – so there’s now an updated image, which you can see at this link. But among all the research and poring over images that has been done since NASA released six month’s worth of LRO data to the public earlier this week, Emily Lakdawalla from the Planetary Society uncovered an interesting tidbit about the Lunokhods which she generously passed on to me. After a little research, I found out more about an “extracurricular activity” the two Lunokhod rovers were commanded to do along their traverses on the lunar surface. They each created “memorials” to women on the Moon.
Since the early 1900’s, International Women’s Day has been observed each year by several countries around the world on March 8. The day marks the economic, political and social achievements of women. Russia has been celebrating this holiday since 1913, and in the 1970’s the crews who “drove” the Lunokhod rovers decided to honor women by commanding the rovers to create figure 8’s in the lunar regolith — 8 as in March 8.
Lunokhod 1. Credit: Goddard Spaceflight Center
Lunokhod 1 landed on the Moon November 17, 1970 and roved the surface for nearly a year (322 days.) Lunokhod 2 landed on January 15, 1973 and operated four months.
Apparently both rovers made a figure 8 in the regolith, although the documentation is a little fuzzy. A Russian scientist recalls that Lunokhod 1 made the figure 8, and one of the newly released LRO images shows a faint figure 8 in the regolith (see image left), which could only have been made by Lunokhod 1, but there is better documentation for Lunokhod 2’s memorial.
“To the extent I know, that was Lunokhod 1 which the crew made an 8 by Lunokhod tracks to congratulate our women on March 8 1973,” said Alexander “Sasha” Basilevsky, a veteran Russian planetary scientist, who responded to my queries about the significance of the figures 8’s. “Even in that Soviet time March 8 practically lost its political significance and we men just congratulated our women with little gifts. We continue to do this even now when our political system is far from communistic. For us it is just Women’s Day.”
Also, after scanning through all of Lunokhod 1’s panoramic images, I found this possible image of the figure 8, but I have not yet confirmed this is it:
Possible figure 8 in a Lunokhod 1 panoramic image. Credit: Laboratory of Comparative Planetology. Click image to see all the panoramas from Lunokhod 1.
Dr. Phil Stooke from the University of Western Ontario compiled “The International Atlas of Lunar Exploration.” “In my atlas I show a feature like this at Lunokhod 2’s site,” he said in response to my questions. “I didn’t know about this one at Lunokhod 1, but apparently it’s there as well.”
Here’s what Stooke wrote about the Lunokhod 2’s figure 8:
“On 18 January Lunokhod 2 was driven to a point on the north rim of the 25 m crater where it photographed the landing stage and the hill Le Monnier Alpha in the distance to the southwest. Here it was turned in place to create a circular mark with its wheels, and then moved a few meters where it made a second circle. The resulting figure 8 marking was later described as a memorial to commemorate International Women’s Day, 8 March, which was a holiday in the Soviet Union and is in Russia today.”
Addendum: Stooke told me that after seeing the new images from LRO, he will likely have to re-do the map of Lunokhod’ 2’s travels (top image). “Lunokhod images were often printed mirror-imaged left to right, and it’s often hard to know which is which,” he said. “In this case that map was constructed using at least one image the wrong way round, so it has to be corrected.”
So, it is unclear whether the decision to create these two memorials was in any way political, or simply a kind gesture by the Soviet space agency, or a unique choice made by the rover drivers, or – as was suggested to me by a couple of people – a visual play on an anatomical feature unique to women.
But more importantly, the accomplishments of the Lunokhod rovers are amazing considering the era in which they operated. While the Soviet Union’s exploration of the Moon was not well publicized outside of Russia — and now is often downplayed when compared to the Apollo missions – the ground-breaking technological achievements should be lauded for the innovative sample return missions and rovers that to this day hold the distance record that any vehicle has traveled on another celestial body. Together, they roved further than even the long-lasting Mars Exploration Rovers.
Lunokhod 1 Rover in its final parking spot, as seen by LRO. Credit: NASA/GSFC/Arizona State University. Click for larger version
Lunokhod 1 traveled 10.5 km (6.5 miles) and returned more than 20,000 TV images and 206 high-resolution panoramas. In addition, it performed twenty-five soil analyses with its x-ray fluorescence spectrometer and used its penetrometer at 500 different locations.
Lunokhod 2 covered a whopping 37 km (23 miles) of terrain, including hilly upland areas and rilles. It sent back 86 panoramic images and over 80,000 TV pictures. Many mechanical tests of the surface, laser ranging measurements, and other experiments were completed during this time.
Many thanks to Emily Lakdawalla, Phil Stooke and Alexander Basilevsky for helping me learn more about this interesting piece of space exploration history!
In case you are wondering, International Womans Day is an official holiday in Angola, Azerbaijan, Belarus, Burkina Faso, Cambodia, Equatorial Guinea, Eritrea, Georgia, Guinea Bissau, Kazakhstan, Kyrgyzstan, Laos, Moldova, Mongolia, Nepal, Russia, Tajikistan, Turkmenistan, Uganda, Ukraine, Uzbekistan.
A cut away graphic of the Orion Crew Module... with six seats (NASA)
The Space Shuttle, which has been used since 1982, is ready to be replaced. The fleet of Space Shuttles has completed over 130 missions and made numerous discoveries; however, the shuttles are nearing the end of their lifespan. They are scheduled to be decommissioned in 2010 or soon after. There are a number of replacements that have been proposed for the Space Shuttle in both the public and private sectors.
Although NASA had plans to retire the Space Shuttle, for many years they proposed no definite alternative. In 2004 though, the government announced its proposal for the Space Shuttle’s replacement. The major design that NASA is working on is the Orion, which is being built by Lockheed Martin for the government. The creation of the Orion was partly influenced by the Space Shuttle Columbia disaster. Originally, NASA hoped to have Orion ready by 2013, but that date has already been pushed back a year. Congress has set 2015 as the time when the spacecraft should be ready for its first flight.
The Orion is designed to hold between four and six crew members; the Space Shuttles held as many as seven. The Orion consists of the launch abort system, the crew module, the service module, and the spacecraft adapter. The Orion would be launched using the Ares rocket, which was named the 2009 invention of the year by Time magazine. NASA is also developing a larger version of the Ares to carry supplies.
The Orion and Ares are both being developed under NASA’s Constellation program. The plan was that these spacecraft would be used to take astronauts back to the Moon and eventually to Mars. The first missions were going to be trips to resupply the International Space Station. Recently however, there have been proposals to cut the Constellation program due to its enormous cost. If the government does end up scrapping the Constellation program though, it will be left with no replacement for the Space Shuttle in the near future. This is a serious matter because the Space Shuttles are already considered beyond their lifespan by many.
Advances are also being made in the private sector. In 2004, the first non-government spacecraft, SpaceShipOne, reached space and won the Ansari X Prize. The company, Scaled Compositions, also produced a SpaceShipTwo, which was unveiled to the public recently. The development of these spacecraft has fueled the belief that space tourism is in the near future.
[/caption]Radiation from the Sun, which is more popularly known as sunlight, is a mixture of electromagnetic waves ranging from infrared (IR) to ultraviolet rays (UV). It of course includes visible light, which is in between IR and UV in the electromagnetic spectrum.
All electromagnetic waves (EM) travel at a speed of approximately 3.0 x 10 8 m/s in vacuum. Although space is not a perfect vacuum, as it is really composed of low-density particles, EM waves, neutrinos, and magnetic fields, it can certainly be approximated as such.
Now, since the average distance between the Earth and the Sun over one Earth orbit is one AU (about 150,000,000,000 m), then it will take about 8 minutes for radiation from the Sun to get to Earth.
Actually, the Sun does not only produce IR, visible light, and UV. Fusion in the core actually gives off high energy gamma rays. However, as the gamma ray photons make their arduous journey to the surface of the Sun, they are continuously absorbed by the solar plasma and re-emitted to lower frequencies. By the time they get to the surface, their frequencies are mostly only within the IR/visible light/UV spectrum.
During solar flares, the Sun also emits X-rays. X-ray radiation from the Sun was first observed by T. Burnight during a V-2 rocket flight. This was later confirmed by Japan’s Yohkoh, a satellite launched in 1991.
When electromagnetic radiation from the Sun strikes the Earth’s atmosphere, some of it is absorbed while the rest proceed to the Earth’s surface. In particular, UV is absorbed by the ozone layer and re-emitted as heat, eventually heating up the stratosphere. Some of this heat is re-radiated to outer space while some is sent to the Earth’s surface.
In the meantime, the electromagnetic radiation that wasn’t absorbed by the atmosphere proceeds to the Earth’s surface and heats it up. Some of this heat stays there while the rest is re-emitted. Upon reaching the atmosphere, part of it gets absorbed and part of it passes through. Naturally, the ones that get absorbed add to the heat already there.
The presence of greenhouse gases make the atmosphere absorb more heat, reducing the fraction of outbound EM waves that pass through. Known as the greenhouse effect, this is the reason why heat can build up some more.
Here’s a simplified explanation of the greenhouse effect on the EPA’s website. There’s also NASA’s Climate Change page.
Relax and listen to some interesting episodes at Astronomy Cast. Want to know more aboutUltraviolet Astronomy? How different is it from Optical Astronomy?
X-Ray image of Proxima Centauri. Image credit: Chandra
[/caption]As the nearest star from our Solar System, Proxima Centauri is a prime candidate for future interstellar travel and space colonization missions.
In the meantime, scientists are trying to determine whether this star has super Earths orbiting within its habitable zone. Habitable zones are regions around a star where planets are believed to receive just the right amount of heat. For instance, Earth is within the Sun’s habitable zone.
If we were slightly nearer, say on Venus’ orbit, the heat would have evaporated all our oceans. On the other hand, if we were slightly farther, the temperature would have been too cold to support life.
So far, searches in the neighborhood of Proxima Centauri have revealed nothing. Even companion stars or supermassive planets that may be accompanying the star have not yet been discovered (if they are ever there at all). Although the search continues, some scientists believe Proxima Centauri’s flares can be a big obstacle for life even inside the star’s habitable zone.
Proxima Centauri’s flares are believed to be caused by magnetic activity. When a flare occurs, the brightness of all electromagnetic waves emitted by the star increases. This includes radio waves as well as harmful X-rays. The most common flare stars are red dwarfs, just like Proxima Centauri.
Now, even if Proxima Centauri is the nearest star, it is still 4.2 light years away. That’s about 4 x 10 13 km. The spacecraft that would take the first explorers to that system would have to rely on a virtually unlimited supply of energy. Furthermore, sufficient shielding against cosmic radiation should be in place.
Proxima Centauri is smaller than our Sun with a mass of approximately 0.123 solar masses and a radius of only about 0.145 solar radii. Its interior is believed to be totally dependent on convection when it comes to transferring heat from the core to the exterior.
Discovered in 1915 by Robert Innes, the Director of the Union Observatory in Johannesburg, South Africa, the star was observed to have the same proper motion as Alpha Centauri. Further studies confirmed that it was in fact very close to Alpha Centauri. The current distance between the two is estimated to be about only 0.21 light years.
Here are some articles in Universe Today that talk about Proxima Centauri:
Greetings, fellow SkyWatchers! As one hemisphere warms, another cools… and so our passion for astronomy can sometimes wax and wane. Why not rekindle your viewing spirit by enjoying some lunar targets this weekend? If you don’t think identifying lunar features with a small pair of binoculars is exciting – then think on this: Using the most simple form of optics, you are viewing details on a distant world that’s a quarter of a million miles away! So what are you waiting for? Get out your binoculars and get ready to enjoy… and I’ll see you in the backyard.
March 19, 2010 – We begin our binocular and small telescope explorations tonight by looking near the center of the lunar terminator to identify and take a closer look at Mare Fecunditatis. Its expanse covers 1463 kilometers in diameter. The combined area of this mare is equal in size to the Great Sandy Desert in Australia—and almost as vacant in interior features. It is home to glasses, pyroxenes, feldspars, oxides, olivines, troilite and metals in its lunar soil, which is called regolith. Studies show the basaltic flow inside of the Fecunditatis basin perhaps occurred all at once, making its chemical composition different from other maria. The lower titanium content means it is between 3.1 and 3.6 billion years old. Stretching out across an area about equal in size to the state of California, the Sea of Fertility’s western edge is home to features we share terrestrially – grabens. These down-dropped areas of landscape between parallel fault lines occur where the crust is stretched to the breaking point. On Earth, these happen along tectonic plates, but on the Moon they are found around basins. The forces created by lava flow increase the weight inside the basin, causing a tension along the border which eventually fault and cause these areas. Look closely along the western shore of Fecunditatis where you will see many such graben features. They are also bordered by parallel fault lines and are quite similar to such terrestrial features as Death Valley in the western United States.
Now aim towards the earthen shore of Mare Fecunditatus and identify the flat, bright oval of a previous study, Langrenus. This is an opportunity to challenge yourself by identifying two small craters just slightly northwest of the mare’s central point – Messier and Messier A – named for the famous French comet hunter – Charles Messier. Scan along the terminator over Mare Fecunditatis about 1/3 its width from west to east for a pair of emerging bright rings. These twin craters will be difficult in binoculars, but not hard for even a small telescope and intermediate power. The easternmost crater is somewhat oval in shape with dimensions of 9 by 11 kilometers. At high power, Messier A to the west appears to have overlapped a smaller crater during its formation and it is slightly larger at 11 by 13 kilometers. For a challenging telescopic note, you’ll find another point of interest to the northwest. Rima Messier is a long surface crack which runs diagonally across Mare Fecunditatis’ northwestern flank and reaches a length of 100 kilometers. Keep the Messiers in mind, for in a few days you will see a pair of “rays” extending out from them.
March 20, 2010 – On the lunar surface tonight, let’s begin with a look at Mare Serenitatus – the “Serene Sea”. On its northeast shore, binoculars will have no trouble spotting the shallow ring of crater Posidonius. Almost flat from eons of lava flows, this crater shows numerous variations in texture along its floor in small telescopes. This huge, old, mountain-walled plain is considered a class V crater and could be as much as 3 billion years old. Spanning 84 by 98 kilometers, you can plainly see Posidonius is shallow – dropping only 2590 meters below the surface. Tonight it will resemble a bright, elliptical pancake on the surface to smaller optics with its ring structure remaining conspicuous to binoculars throughout all lunar phases. However, a telescope is needed to appreciate the many fine features found on Posidonius’ floor. Power up to observe the stepped, stadium-like wall structure and numerous resolvable mountain peaks joining its small, central interior crater. It has its own interior rimae that is especially prominent to the east and a smashing view of trio Posidonius O, I and B on the north crater rim. Adding crater Chacornac to the southeast makes things even more interesting! Did you spot the small punctuation of Daniell to the north?
Now, look a bit south of and east of Posidonius and almost parallel to the terminator for a curious feature known as the Serpentine Ridge, or more properly as Dorsa Smirnov and the accompanying Dorsa Lister. Can you detect the very tiny crater Very in its center? This thin, white line wanders across the western portion of Mare Serenitatus for a distance of about 134 kilometers. In some places it rises as high as 305 meters above the smooth sands. This lunar “wrinkle” is an amazing 10 kilometers wide! Power up in a telescope. The northern portion of the Serpentine Ridge is Dorsa Smirnov until it branches west and becomes Dorsa Lister. If the shadow play is good at your time, you might be lucky enough to resolve Dorsum Nicol, which connects the two. Only about 51 kilometers long, Dorsum Nichol will appear almost as a circular, crater-like feature – but it isn’t. As part of the Mare Serenitatis / Mare Tranquilitatis border, it’s not much more than a just an area where the two distinct lava flows cooled and contracted, causing the surface to heave up, but you’ll also find it’s connected to the Rima Plinius as well.
March 21, 2010 – Tonight on the lunar surface, all of Mare Serenitatis and Mare Tranquillitatis will be revealed, and so it is fitting we should take an even closer look at both the “Serene” and “Tranquil” seas. Formed some 38 million years ago, these two areas of the Moon have been home to most of mankind’s lunar exploration. Somewhere scattered on the basalt landscape on the western edge of Tranquillitatis, a few remains of the Ranger 6 mission lie tossed about, perhaps forming a small impact crater of their own. Its eyes were open, but blinded by a malfunction…forever seeing nothing. To the southwest edge lie the remnants of the successful Ranger 8 mission which sent back 7137 glorious images during the last 23 minutes of its life. Nearby, the intact Surveyor 5 withstood all odds and made space history by managing to perform an alpha particle spectrogram of the soil while withstanding temperatures considerably greater than the boiling point. Not only this, but it also took over 18,000 pictures!
Now let’s go to the southwest edge of Tranquillitatis and visit with the Apollo 11 landing area. Although we can never see the “Eagle” telescopically, we can find where it landed. For telescopes and binoculars the landing area will be found near the terminator along the southern edge of Mare Tranquillitatis. No scope? No problem. Find the dark round area on the lunar northeastern limb – Mare Crisium. Then locate the dark area below that – Mare Fecundatatis. Now look mid-way along the terminator for the dark area that is Mare Tranquillitatis. The bright point west where it joins Mare Nectaris further south is the target for the first men on the Moon. We were there! Telescopically, start tracing the western wall of Tranquillitatis and looking for the small circles of craters Sabine and Ritter which are easily revealed tonight.
Once located, switch to your highest magnification. Look in the smooth sands to the east to see a parallel line of three tiny craters. From west to east, these are Aldrin, Collins, and Armstrong – the only craters to be named for the living. It is here where Apollo 11 touched down, forever changing our perception of space exploration.
“That’s one small step for [a] man, one giant leap for mankind.”
Until next week? Ask for the Moon… But keep on reaching for the stars!
This week’s awesome images are (in order of appearance): Crescent Moon and Venus In the Trees courtesy of Mike Romine, Mare Fecunditatus courtesy of Virtual Moon Atlas, Craters Messier and Posidonius courtesy of Damien Peach, “Serpentine Ridge” and Six Day Moon courtesy of Peter Lloyd, Lunar History Area courtesy of Virtual Moon Atlas and “Footstep” courtesy of NASA. We thank you so much!
Illustration of the X-37 Advanced Technology Demonstrator during flight. Credit: NASA
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It’s cute. It’s little. It’s also top secret. The X-37B orbital test vehicle is at Cape Canaveral in Florida, and the word is that it will be launched on board an Atlas V rocket on Monday April 19, 2010 at around 10 pm EDT. Other than that, the Air Force isn’t saying much about this mini-space shuttle look-alike. The reusable unmanned vehicle is capable of staying in orbit for 270 days, but the mission duration hasn’t been announced. Additionally, the ship has a payload bay for experiments and deployable satellites, but no word if any payloads will be included on the inaugural flight of this mini space plane.
X-37B. Credit: US Air Force
The X-37B is 9 meters long and 4.5 meter wide (29 X 15 ft) and its payload bay is 2.1 by 1.2 meters (7 by 4 feet). The vehicle was built at Boeing Phantom Works, based on an orbital and re-entry demonstrator design initially developed by NASA, then handed over to the Pentagon.
Rumors of an X-37B launch have been circulating since 2008.
Originally the vehicle was scheduled for launch in from the payload bay of the Space Shuttle, but that plan was axed following the Columbia accident. The X-37A carried by WhiteKnightOne in 2005 (Alan Radecki)
DARPA, the Defense Advanced Research Projects Agency completed a series of approach and landing drop tests in 2007 of an experimental X-37B vehicle using the White Knight airplane from Scaled Composites as a mothership.
It will land like the space shuttle, with the primary landing site at Vandenberg Air Force Base in California. Edwards Air Force Base is the backup landing site.
The project is managed by the Air Force Rapid Capabilities Office.
The X-37B’s mission is to “demonstrate a reliable, reusable, unmanned space test platform for the United States Air Force,” according to a fact sheet put out by the military. “Objectives of the OTV program include space experimentation, risk reduction and concept of operations development for reusable space vehicle technologies.”
It will be interesting to ascertain the capabilities and uses for this vehicle.
Artist’s impression of Corot-9b. Credit: ESO/L. Calçada
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Chalk up another exoplanet discovery for the CoRoT satellite. But this planet, while a gas giant, could have temperatures cool enough to host liquid water. Corot-9b orbits a sun-like star at a distance similar to Mercury – one of the largest orbits of any extrasolar planet yet found, and may have an interior that closely resembles Jupiter and Saturn. “This is a normal, temperate exoplanet just like dozens we already know, but this is the first whose properties we can study in depth,” said Claire Moutou, who is part of the international team of 60 astronomers that made the discovery. “It is bound to become a Rosetta stone in exoplanet research.”
Corot-9b (unofficial nickname Carrot Nimby) regularly passes in front of its star, located 1,500 light-years away from Earth towards the constellation of Serpens (the Snake), allowing astronomers to view the planet for 8 hours at a time. The transits occur every 95 days.
“Our analysis has provided more information on Corot-9b than for other exoplanets of the same type,” says co-author Didier Queloz. “It may open up a new field of research to understand the atmospheres of moderate- and low-temperature planets, and in particular a completely new window in our understanding of low-temperature chemistry.”
The star Corot-9b orbits is slightly cooler than our sun, so the astronomer estimate that Corot-9b’s temperature could lie somewhere between -23°C and 157°C.
Corot-9b has a radius around 1.05 times that of Jupiter but only 84% of the mass. This leads to a density of 0.90 g/cc, or 68% that of Jupiter.
More than 400 exoplanets have been discovered so far, 70 of them through the transit method. Astronomers say Corot-9b is special in that its distance from its host star is about ten times larger than that of any planet previously discovered by this method. And unlike all such exoplanets, the planet has a temperate climate. The temperature of its gaseous surface is expected to be between 160 degrees and minus twenty degrees Celsius, with minimal variations between day and night. The exact value depends on the possible presence of a layer of highly reflective clouds.
“Like our own giant planets, Jupiter and Saturn, the planet is mostly made of hydrogen and helium,” said team member Tristan Guillot, “and it may contain up to 20 Earth masses of other elements, including water and rock at high temperatures and pressures.”
Princeton University scientists (from left) Reinabelle Reyes, James Gunn and Rachel Mandelbaum led a team that analyzed more than 70,000 galaxies and demonstrated that the universe - at least up to a distance of 3.5 billion light years from Earth - plays by the rules set out by Einstein in his theory of general relativity. (Photo: Brian Wilson)
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Published in 1915, Einstein’s theory of general relativity (GR) passed its first big test just a few years later, when the predicted gravitational deflection of light passing near the Sun was observed during the 1919 solar eclipse.
In 1960, GR passed its first big test in a lab, here on Earth; the Pound-Rebka experiment. And over the nine decades since its publication, GR has passed test after test after test, always with flying colors (check out this review for an excellent summary).
But the tests have always been within the solar system, or otherwise indirect.
Now a team led by Princeton University scientists has tested GR to see if it holds true at cosmic scales. And, after two years of analyzing astronomical data, the scientists have concluded that Einstein’s theory works as well in vast distances as in more local regions of space.
A partial map of the distribution of galaxies in the SDSS, going out to a distance of 7 billion light years. The amount of galaxy clustering that we observe today is a signature of how gravity acted over cosmic time, and allows as to test whether general relativity holds over these scales. (M. Blanton, SDSS)
The scientists’ analysis of more than 70,000 galaxies demonstrates that the universe – at least up to a distance of 3.5 billion light years from Earth – plays by the rules set out by Einstein in his famous theory. While GR has been accepted by the scientific community for over nine decades, until now no one had tested the theory so thoroughly and robustly at distances and scales that go way beyond the solar system.
Reinabelle Reyes, a Princeton graduate student in the Department of Astrophysical Sciences, along with co-authors Rachel Mandelbaum, an associate research scholar, and James Gunn, the Eugene Higgins Professor of Astronomy, outlined their assessment in the March 11 edition of Nature.
Other scientists collaborating on the paper include Tobias Baldauf, Lucas Lombriser and Robert Smith of the University of Zurich and Uros Seljak of the University of California-Berkeley.
The results are important, they said, because they shore up current theories explaining the shape and direction of the universe, including ideas about dark energy, and dispel some hints from other recent experiments that general relativity may be wrong.
“All of our ideas in astronomy are based on this really enormous extrapolation, so anything we can do to see whether this is right or not on these scales is just enormously important,” Gunn said. “It adds another brick to the foundation that underlies what we do.”
GR is one, of two, core theories underlying all of contemporary astrophysics and cosmology (the other is the Standard Model of particle physics, a quantum theory); it explains everything from black holes to the Big Bang.
In recent years, several alternatives to general relativity have been proposed. These modified theories of gravity depart from general relativity on large scales to circumvent the need for dark energy, dark matter, or both. But because these theories were designed to match the predictions of general relativity about the expansion history of the universe, a factor that is central to current cosmological work, it has become crucial to know which theory is correct, or at least represents reality as best as can be approximated.
“We knew we needed to look at the large-scale structure of the universe and the growth of smaller structures composing it over time to find out,” Reyes said. The team used data from the Sloan Digital Sky Survey (SDSS), a long-term, multi-institution telescope project mapping the sky to determine the position and brightness of several hundred million galaxies and quasars.
By calculating the clustering of these galaxies, which stretch nearly one-third of the way to the edge of the universe, and analyzing their velocities and distortion from intervening material – due to weak lensing, primarily by dark matter – the researchers have shown that Einstein’s theory explains the nearby universe better than alternative theories of gravity. Some of the 70,000 luminous galaxies in SDSS analyzed (Image: SDSS Collaboration)
The Princeton scientists studied the effects of gravity on the SDSS galaxies and clusters of galaxies over long periods of time. They observed how this fundamental force drives galaxies to clump into larger collections of galaxies and how it shapes the expansion of the universe.
Critically, because relativity calls for the curvature of space to be equal to the curvature of time, the researchers could calculate whether light was influenced in equal amounts by both, as it should be if general relativity holds true.
“This is the first time this test was carried out at all, so it’s a proof of concept,” Mandelbaum said. “There are other astronomical surveys planned for the next few years. Now that we know this test works, we will be able to use it with better data that will be available soon to more tightly constrain the theory of gravity.”
Firming up the predictive powers of GR can help scientists better understand whether current models of the universe make sense, the scientists said.
“Any test we can do in building our confidence in applying these very beautiful theoretical things but which have not been tested on these scales is very important,” Gunn said. “It certainly helps when you are trying to do complicated things to understand fundamentals. And this is a very, very, very fundamental thing.”
“The nice thing about going to the cosmological scale is that we can test any full, alternative theory of gravity, because it should predict the things we observe,” said co-author Uros Seljak, a professor of physics and of astronomy at UC Berkeley and a faculty scientist at Lawrence Berkeley National Laboratory who is currently on leave at the Institute of Theoretical Physics at the University of Zurich. “Those alternative theories that do not require dark matter fail these tests.”
Sources: “Princeton scientists say Einstein’s theory applies beyond the solar system” (Princeton University), “Study validates general relativity on cosmic scale, existence of dark matter” (University of California Berkeley), “Confirmation of general relativity on large scales from weak lensing and galaxy velocities” (Nature, arXiv preprint)
