Category Archives: NASA
Last year I had the privilege of writing a short piece about the Dark Sky Festival in Harmony, Florida. I really enjoyed learning about the town of Harmony and the Festival they host every year so when I was asked again this year I jumped at the opportunity. This year’s Dark Sky Festival promises to be the most successful yet.
Once again the town of Harmony, Florida is pleased to present to you the 10th annual Dark Sky Festival! For the last ten years Harmony, a small town southeast of Orlando, has hosted a festival to celebrate the wonder of the Earth’s most beautiful natural resource, the night sky. On the night of February 2nd, 2013 the public is invited to attend a night of celebration and education focused on learning about the night sky and the benefits of living under a night sky free from the effects of excessive artificial lighting. The effects of excessive artificial lighting are scientifically proven to have negative effects on human and wildlife health, to damage the nighttime ecosystem, and of course mask the beauty of the starry night sky.
Harmony, Florida was founded in 2003 by Orlando’s former Humane Society/SPCA director Martha Lentz with the goal of creating a community where humans can live in harmony with nature and the environment. The town was master planned into one of the most unique communities in Florida. One of the goals of the community is to limit its impact on light pollution to preserve a natural view of the night sky. Light pollution is the sum of all the wasted artificial light that is shined into the sky as a result of poorly designed lighting fixtures. This wasted light produces the all too familiar sky glow effect that turns the sky pink near the horizon and washed out overhead. The effects of light pollution can be limited, and even reversed as residents of Harmony know. By taking simple and inexpensive steps to ensure all outdoor lighting fixtures are fully-shielded (meaning no light escapes upward from its source) Harmony has created a very aesthetically pleasing and environmentally friendly lightscape. Furthermore, the lighting regulations created for Harmony are so impressive that the surrounding county which includes parts of Walt Disney World has adopted them as a lighting ordinance.
This year’s Dark Sky Festival promises to be the most successful one yet. Over 5,000 people attended the 2012 Festival and again the town expects to see growth in attendance. Attractions of this year’s Festival include the following:
- Public stargazing with over 50 telescopes
- Speakers from NASA, Seminole State College Planetarium, the International Dark Sky Association, and more
- Two mobile planetariums with presentations and NASA Exhibits
- Variety of kids activities including Mad Science, demos from high school robotics clubs, glow-in-the-dark mini-golf and the Kids Zone
- Music, food, specialty booths, and presentations from scientists
This year’s speakers include International Dark Sky Association’s Executive Director Bob Parks and Jon Cowart, Deputy Partner Manager of NASA’s Commercial Crew Program. If you stick around long enough you might even run into some Star Wars characters from the famous 501st Legion!
Don’t miss this wonderful opportunity to learn more about astronomy and the dark sky movement as well as a chance to explore the universe first-hand through some incredible telescopes! Astronomers from around the state have their telescopes set up for free, public viewing. If you’re completely new to the field of astronomy or a seasoned pro the Dark Sky Festival at Harmony surely has something for everyone. Make sure you stop by the beautiful town of Harmony on Saturday February 2, 2013 to enjoy this rapidly growing annual celebration of the night sky. Festivities begin at dusk at 5 pm and continue until 10 pm.
To learn more about the town of Harmony please visit the town’s website www.harmonyfl.com.
If there is one probe in the last decade that was by far the most under-appreciated and most deserving of worldwide acclaim it was the Huygens probe that landed on Saturn’s largest moon Titan back in 2005. Granted I was only sixteen year old at the time, but I don’t remember much being made about Huygens except by NASA. Admittedly nowadays, the things that excite NASA rarely, if ever, excite the average U.S. citizen. What a shame that is. I know it’s rather daft to compare the 1969 Moon landing with the Huygens mission but the spirit of the first moon landing was surely present within NASA when Huygens touched down on Titan. The mission was historic for several reasons. It was the first time a man-made probe had landed on a moon. It was, and still is, the most distant body a man-made probe has landed on. Huygens also had great scientific value also from the brief glimpse it got of the surface of the alien moon. It was the first time we had ever touched down on a world that was truly “alien”, in that we had little to no idea what to expect.
Huygens was part of a mission to Saturn that was 22 years in the making. The Cassini spacecraft was the main probe that would visit Saturn for the first time since Voyager 1 passed by in 1980. One moon in particular caught the attention of NASA during its Saturnian encounter, Titan. Titan is Saturn’s largest moon and bears a striking similarity to Earth. It has a dense atmosphere. The first images of Titan showed the famous ‘thin blue line” that shows the presence of an atmosphere. As the picture below shows, Titan’s atmosphere looks incredibly like our own atmosphere when seen from space. From that point on NASA resolved that it would eventually send a probe there.
The Cassini probe was launched on October 15, 1997 and arrived at Saturn on July 1, 2004. The European Space Agency built Huygens probe was carried along with Cassini and during its first approach of Titan jettisoned the tiny probe on December 25, 2004. It took another 20 days for Huygens to reach Titan but on January 14, 2005 NASA has finally achieved its goal of sending a probe to Titan. It took two and a half hours for Huygens to descend through Titan’s atmosphere and took hundreds of images from its Descent Imager/Spectral Radiometer. Once below the haze and clouds Titan revealed a surface that was very Earth-like in many ways. Large mountains and hills covered with a lacework of what looked like streams and runoff flows of some kind of liquid, and even a shoreline of massive bodies of liquid. It was later determined that the bodies of liquid were not water since the surface of Titan is a frigid -179°C. The only element known to exist as a liquid at that extreme temperature is methane. Methane also exists as a solid and a gas on Titan, the same way water exists as a solid, liquid, and gas on Earth. The discovery revealed that the same way that Earth has a hydrological cycle, Titan has a methanological cycle. There are vast lakes and oceans of liquid methane which evaporate and form methane clouds. There is also even methane rain on Titan that falls in huge, slow moving rain drops due to the low gravity. Life as we know it couldn’t exist on Titan, but if we were to find even single-cell organisms or bacteria growing there it would cause us to radically re-think our understanding of biology and the possibility of alien life.
Long story short, Huygens was a huge success and tons of extremely valuable scientific data was produced from the tiny little probe that was the caboose of Cassini for six years. After the success of Huygens there should have been headline news stories about it on the 6 o’clock news across the world and front page news in all the newspapers. There should have been parades celebrating the historic landing from New York to Hong Kong. But alas, the world doesn’t get excited about space anymore. Huygens will go down as one of mankind’s most successful missions as well as one of the most under-rated mission of all time.
For your viewing pleasure here are some of NASA/ESA’s images received from Huygens during its descent and once it touched down. Enjoy.
This morning marks an historic achievement for private spaceflight. At 9:56 am EDT SpaceX’s unmanned Dragon capsule docked with the International Space Station marking the first time a private spacecraft has rendezvoused with the orbital lab. The time of nation-state dominance in space has come to an end with this historic link-up. SpaceX has shown the world that space is open for all of humanity, not just governments. What was once done by clandestine government agencies motivated by one-upmanship is now achievable for citizens for the advancement of space exploration and colonization.
Image Credit: NASA/SpaceX
During the docking, astronaut Don Petit on-board the space station used the giant 58-foot grapple arm called Canadarm2 to reel Dragon in for berthing. After grabbing a hold of the capsule, Petit said to Mission Control in Houston, “Houston, station, it looks like we’ve got us a dragon by the tail” followed by applause in Houston and SpaceX’s headquarters in Hawthorne, CA. The operation was done in almost total darkness during orbital night using only the ISS’s exterior lights to illuminate the capsule and the grappling arm. However, the rendezvous was not without a hiccup. On Dragon’s approach to the space station, its navigation system experienced a glitch. Dragon uses a system called LIDAR (light detection and ranging) to measure distances. The LIDAR uses laser beams to measure the distance to objects by observing how long it takes the beams of light to reflect back off an object. The LIDAR experienced a glitch when stray light reflections from another module on the space station were being gathered by device. Dragon’s mission control was quick on its feet and resolved the problem by narrowing LIDAR’s field of view to eliminate the stray light. All went smoothly from there.
SpaceX founder Elon Musk is one step closer to realizing the dream of his company, to make humanity a multi-planet species. Although that goal is a very long way off, this historic accomplishment’s importance cannot be overlooked. Whether a SpaceX craft is the vehicle that takes humans to Mars or not, SpaceX has helped NASA by freeing up precious budget room that can now be devoted to planning for a Mars mission. Now NASA doesn’t have to build and fund another transport vehicle to low-Earth orbit. Now we can look forward to a future when governments and private companies cooperate in space to achieve massive goals once possible only in dreams. Now, we can, to use the common phrase, boldly go where no man has gone before!
Last night NASA decided to delay their Anomalous Transport Rocket Experiment (ATREX) launch yet again. I’m personally beginning to get sick of hearing this over and over again. The rocket experiment which is going to eventually launch from NASA’s Wallops Island, VA facility has been delayed due to poor weather three times now. The plan is for five sounding rockets to launch in rapid succession to just shy of 65 miles which is the recognized edge of space to study the mysterious ultra high altitude winds that can reach 200-300 miles per hour. Each rocket will release a tracer chemical that can be observed by ground-based observers and cameras. The chemical, trimethylaluminum, for lack of better word, will glow in the atmosphere and the cameras can observe how the winds swirl it around. The only trick is that the launch must happen on a clear night. Not just a clear night in Wallops Island, but a clear night at the observation sites in North Carolina and New Jersey as well. This has proved complicated as you could expect. The original launch date was March 14th but bad weather at Wallops delayed the launch by a couple days. The second launch was also delayed due to poor conditions and NASA set a third window for last night from 12am – 3am EDT. The skies were clear at Wallops but New Jersey was cloudy.
I was originally excited by the launch because NASA widely publicized the visibility of the tracer chemical from Massachusetts to North Carolina. But after three unsuccessful launch windows I’ve pretty much given up on this mission and my hopes of seeing it. I stayed up last night watching Apollo 13 and listening to the webcast stream from the launch pad and after they said they were “red” for at least an hour and a half around 1:30 I shut the computer and went to bed frustrated. I understand that this method of experimentation is probably the lowest cost option but the launch window only extends until April 3rd, which is only another ten days. They’re ten days into the window and they’ve had rotten luck so far. If I’m frustrated with the experiment I’m sure the folks at NASA are too, if not more so. The next attempt at a launch will be no sooner than Sunday night 3/25, and if that doesn’t work out then they’ve only got a week to launch these birds. If you still want to follow this mission, visit the NASA/ATREX website. Happy Friday and clear skies!
This is probably old news to many informed astro and space nerds (and Martians) but it still blows my mind every time I think about it. As we know, NASA launched its massive Martian science laboratory named “Curiosity” late last year. The one-ton rover will make the 570 million kilometer journey to Mars and enter the atmosphere on August 5, 2012. Apart from the never before attempted method of landing using sky crane to lower the huge rover onto the surface, this landing is exciting for another reason. Once the heat shield on the capsule is jettisoned, the small camera on the rover’s body will begin recording the last mile or two of the descent to the Martian surface shooting 1.3 millisecond exposures at 5 frames per second for approximately 2 mintues. I’m imagining myself five months from now sitting in front of my computer with my face just inches away from the screen completely enamored with the live video coming in from another world! It’s going to be a total geek out moment for me! I’m not sure where the video will be viewed from, but my guess would be the Jet Propulsion Laboratory website.
Also exciting about the video is that if it’s live NASA won’t be able to false color anything so it’ll be 100% authentic footage of the surface of Mars! If that doesn’t excite you, I’m sorry. I’m basically cursing the fact that it’s only March! On the other hand, today is the first day of spring and the Vernal equinox so that’s pretty cool. Get your eggs out today and try to stand them on edge.
More Mars-related news keeps coming in! On Friday last week a potential supernova was discovered in Messier 95, a beautiful barred spiral galaxy in the constellation Leo and a part of the nearby Leo I group of galaxies. M95 is easy to find right now because it is a mere 1/2° away from Mars. That makes it visible in the same field of view as Mars in most telescopes at lower power. The only trouble is that Mars is so bright this time of year that it floods the M95 area with light making it more difficult to spot. The bright speck believed to be a supernova is located in one of the spiral arms of the galaxy so once located it is an easy find. While unconfirmed as of yet, the supernova is believed to be a Type II which are common in spiral arms. The nova is currently about magnitude 12 so it is invisible to the naked eye but should be easily discerned with a 6″ or bigger scope under dark skies. There’s currently no moon so that should definitely aid your quest. Happy hunting!
After watching the 60 Minutes segment on SpaceX last night I’m convinced that 2012 truly is the year of the “Dragon”. As SpaceX founder and Chief Development Officer Elon Musk says, “We are at the dawn of a new age”. That new age is the beginning of private spaceflight taking over what only governments could do for fifty years, launching astronauts into space. In the 60 Minutes segment CBS anchor Scott Pelley interviewed Musk and toured the SpaceX facility in Los Angeles. Musk is a daring young entrepreneur who isn’t a stranger to uncharted territory. Musk founded PayPal back in 1999, which at the time was revolutionary. He is also the CEO of Tesla Motors which produces all-electric luxury cars. At age 40 he is a naturalized U.S. citizen and one of America’s most successful entrepreneurs. In 2002, Musk’s ambitions shifted to the aerospace industry and he founded SpaceX with the vision of lowering the cost of building rockets and spaceships to transport astronauts to low Earth orbit and beyond.
Now in its tenth year, SpaceX is competing for a NASA contract to build America’s next fleet of spaceship. Musk considers himself a little kid battling against sumo wrestlers to win the contract but he believes that his company will emerge victorious. Having already invested $100 million of his own money into SpaceX, Musk is determined to see the honors given to his spaceship. Back in 2010 SpaceX officially became the first private company to launch an unmanned ship into orbit and return it safely to Earth. After two near-misses involving timing glitches and software bugs, the unmanned capsule sat aboard a Falcon 9 rocket designed by SpaceX and orbited the Earth two times before successfully splashing down in the Pacific. The Falcon 9 rocket is a multi-stage rocket much like the Saturn class rockets used by NASA in the Gemini and Apollo programs. But unlike the Saturns, the Falcon series rockets are fully reusable. This was a part of Musk’s early goal of lowering the cost of spaceflight as each component can be recovered and reused multiple times.
SpaceX is primed to make history again on April 30th when they send their unmanned capsule named “Dragon” to the International Space Station to dock and deliver supplies. This will be the first private docking with the ISS and will surely usher in a long line of firsts in private spaceflight. The Dragon capsule is currently being used for unmanned missions, but as Pelley inquired on his visit to SpaceX’s facility, it has windows. ”Why put windows on a cargo capsule?” he asks. Why? Because it’s not a cargo capsule, Musk responds. Dragon’s ultimate design is to carry astronauts. SpaceX is currently exploring the possibility of seating for seven, as many as the Space Shuttle.
When asked about American space heroes Neil Armstrong and Eugene Cernan’s disapproval of the government’s transitioning of space exploration to private enterprise, Musk says he’s saddened to hear men who he regards as personal heroes disapproval of his work. He believes that if they were to visit SpaceX’s facility and see the over 1,000 employees and how hard they work they would change their minds. Regardless of what critics say, Musk remains focused on fulfilling his goal of landing that NASA contract to build the next fleet of spacecraft for human exploration. Extending human presence in space is a fundamental belief of Musk’s. His vision for eventually making humans a multi-planet race would allow us to greatly increase our knowledge of the universe and survive a potential extinction scenario on Earth.
Musk, along with everyone at SpaceX is striving towards the goal set ten years ago by the daring entrepreneur to make 2012 the year of the Dragon Capsule. Americans need to get back into space and SpaceX is certainly on the brink.
Since yesterday was the 50th anniversary of John Glenn’s historic spaceflight that made him the first American to orbit the Earth it got me thinking. We’ve come a long way from 1962. A long way. We’ve sent men to the moon, send robots to other planets, gazed at the oldest known parts of the universe, and have sent spacecraft to all of the planets in our solar system. You might have seen the meme that’s gone around the internet that has a picture of Neil Armstrong standing next to the Eagle lunar excursion module that says “Your phone has more computing power than Apollo 11″. While that’s true, your smart phone is more advanced than the Apollo era spacecraft, it has a bitter aftertaste to it…Despite all the advances in space technology and human technology in general, the United States is currently unable to send humans into space…at all.
I believe NASA and our government have really dropped the ball in letting the Space Shuttle retire. I wrote about this in an earlier post but I think it is embarrassing that the United States, the once proud leader in manned space exploration, is currently unable to send a single man to space. President Kennedy would be appalled at our lack of interest in manned space exploration! I know that people much smarter than me state that Shuttle was a superb craft that did everything we hoped it would do, and more, but that it did have its limitations. Shuttle was not designed for trips out of low Earth orbit. The Apollo crafts were. Shuttle represented a shift in focus from NASA from manned exploration to scientific observation. We had achieved the goal of the late President Kennedy and it was time to move on to the next step. While some of the most amazing discoveries in space were made during Shuttle’s reign, we were limited by its flight capabilities. It did not pack a multi-stage rocket system to propel it all the way to the moon without having to refuel. NASA was, however, working on developing a new manned deep space vehicle before the announcement of Shuttle’s retirement was made. The Constellation program was supposed to be the successor to the Apollo program with expanded capabilities. Constellation was supposed to be our return to the moon, the ISS, and beyond. The program was cut in 2010 by President Obama. Instead, now we have the Space Launch System (SLS) on the books. It is similar to Constellation but it integrates all the components into one vehicle much like an Apollo craft. The problem is that valuable time and resources have been wasted in the development of Constellation and SLS when there should have been clear leadership and vision from the government from the beginning. The estimated first SLS mission isn’t until 2017 and a manned mission wouldn’t be possible until 2025. By that time the ISS will likely have been decommissioned and sleeping in the Pacific, and with no definite plans to construct a new orbital station there could be no human presence in space for up to five years!
There seems to be a major lack of unified vision and planning going on at NASA and our federal government. The fact alone that we retired the Space Shuttle with no ready to go replacement is just woeful. So yes we’ve come very far in our understanding of space flight in the 50 years since John Glenn orbited the Earth. But we’ve also shown that we haven’t applied that knowledge to translate it into achievement…something that alarmingly lacking when compared with the Apollo days.
Last week NASA announced that it expects to concede lunar exploration to its oldest rivals Russia and perhaps soon China. Well they didn’t actually say that. But it can certainly be implied quite easily.
NASA has released its expectations for its 2013 budget, which will be about $59 million smaller than the current fiscal year. The proposed FY 2013 budget, which runs from October 2012-September 2013, will be NASA’s lowest level of funding in four years and will leave the agency rather flat-looking in 2013. While the proposed budget totals at $17.7 billion, a large amount of funds are likely to be shifted to suit the Obama administrations desires. Programs such as research for human spaceflight and commercial spaceflight are getting a 22% bump over the 2012 budget while only $1.5 billion will be allocated to the planetary sciences budget, which represents a 15% decrease from 2012. Planetary sciences is the mastermind behind planning for robotic missions to Mars such as the coveted sample-return mission to search for advance the search for signs of life on the red planet.
Funding for the next-gen manned spaceflight vehicles, the Space Launch System (SLS) and the Orion Multi-Purpose Crew Vehicle, is due to receive $2.9 billion, 3% less than 2012. The Obama administration has expressed its desire for NASA to devote itself to research for landing astronauts on an asteroid and eventually Mars. While this is quite a lofty and admirable goal it completely leaves our closest neighbor out of the equation…the Moon.
The entire government seemingly doesn’t care that 2012 marks the 40th anniversary of the last manned moon mission. In fact, no human has left low-earth orbit since the Apollo 17 mission on December 7th, 1972. The furthest distance from Earth traveled by humans is still the Apollo 13 flight that took the craft to the lunar far side in an effort to save the ship and the crew after the crippling explosion on the service module. Since the first lunar landing in 1969 humans have only spent a mere couple of days in total elapsed time exploring the surface of the moon. All the moon landings have been American in case you work for the government and have forgotten.
With the Obama administration’s direction of the budget for 2013, it seems that the moon will play little or no part in the goals of the agency. Ever since the cancellation of the Constellation program in Obama’s first year manned lunar exploration has been on the back burner. Instead we are focusing on sending humans deeper into space than ever before, to Mars and beyond. While that’s not a bad thing it seems strange that we would so easily neglect our closest neighbor in space. Despite its proximity to our home we know so little about the moon. I find it sad that we’re overlooking the moon in favor of landing on an asteroid. Last September famous moon-lander Neil Armstrong and three other space experts including Apollo 17 moon lander Eugene Cernan told Congress that they were embarrassing the United States by cutting funding of lunar missions. I would have to agree. America once held an inspiring dominance on spaceflight and lunar capability but now that dominance is all but lost. We won the space race, we completed the challenge of President Kennedy to land a man on the moon and return him safely. Now we’ve completely forgot about what that feels like. In my lifetime I’ve never seen a human stand of the surface of another world, and I’m not likely to for at least another 13 years.
Everybody loves stamps, right? We all love space here too, so this one’s right up your alley! I found this pretty cool article while browsing through Universe Today written by Ray Sanders yesterday. The New Horizons mission which was launched in 2006 will be the first mission to explore Pluto in July 2015. The folks at NASA and New Horizons are hoping to commemorate this first is human spaceflight with a specialized stamp from the U.S. Postal Service. Since it usually takes a year or two for the Postmaster General to approve new stamp designs (testament to the outdated nature of the USPS) New Horizons has already begun work to get the design approved by the time the probe reaches Pluto on July 14, 2015. One of the deciding factors behind a new stamp design appeal is whether or not there is a large group of people who want to see it as a stamp. So New Horizons has created a petition and is collecting signatures for all those who want to see the first flyby mission of Pluto commemorated on a postage stamp to go into your collection or to stick your tongue to as slap on ye olde envelope and put in yonder mailbox. Please read Mr. Sanders’ article on Universe Today for more information which also includes a link to the petition. Their goal is 100,000 signatures on the petition before they deliver it to the Postal Service. In my opinion, although stamps seem trivial and insignificant to many, we need as many people as possible to be aware of what our country is doing in space and to be interested. This stamp campaign would be a great way for NASA to get some attention for the ground-breaking work they do everyday!
“What a wonderful smell you’ve discovered!” cried Han Solo to Chewbacca after jumping down the chute into the trash compactor. The compactor was full with Death Star junk and Han, Chewie, Luke and Leia could barely walk for all the trash. Then the creepy dianoga grabs Luke and the walls start to compact. C-3PO has neglected his comm link and death by pancaking is narrowly avoided! (All this while “Ben Kenobi’s Death/TIE Fighter Attack” begins to play on iTunes!) This might be exaggerated slightly but I think that it represents a very real problem that our planet is facing.
Low-Earth orbit (LEO) and our geosynchronous orbit is becoming increasingly dangerous because of the many thousands of pieces of debris left over from jettisoned spaceship parts, broken satellites, and other random pieces of junk, not to mention the thousands of satellites already orbiting the planet. The sheer amount of debris that is hanging out in orbit would pose a big threat to the future of space travel, and in particular space tourism. Both of the Republican primary front-runners, Romney and Gingrich, have plans to ramp up America’s space presence, albeit in the private sector. Speaker Gingrich’s plan involves a sizable space tourism and moon colonization effort by the end of his second term in 2020 which would mean constant travel back and forth along the Earth-moon transit.
Every satellite launched into orbit adds another potential threat of collision to a spacecraft. There is also the threat of two satellites loosing communication with the ground and loosing orbital velocity and crashing into another satellite, or spaceship. Now while an incident like that involving loss of life would at least be sustainable by NASA or any other government operation, the private sector would not be able to handle a death in space. If a spaceship full of tourists en route to the moon collides with a rogue satellite or piece of junk and all the passengers are lost chaos would ensue on the ground. Cries for the end of space tourism and stricter debris management would never end! Space tourism might be nixed altogether and space would once again be the realm of governments only.
I guess the proper Star Wars illustration for how the situation could end up would be from The Empire Strikes Back when Han, Chewie, and Leia are flying the Millennium Falcon through the asteroid field and C-3PO cries, “Sir, the odds of successfully navigating an asteroid field are approximately 3,720 to 1!” While the Hoth asteroid field is not representative of our solar system’s asteroid field because of the erratic nature of it, it could one day represent the clutter of space junk collected in our planet’s orbit.
What should be done? Well I’m no physicist or engineer at the Jet Propulsion Laboratory, but there seems to be a couple solutions. One would involve a sort of “kill-switch” on all new satellites that causes them to fall back to Earth and burn up in the atmosphere when the ground can’t re-establish communication or if they pose a danger to other satellites or spaceships. A recovery mission would most likely be far too costly and lengthy, not to mention the risk of handling the defunct satellites or debris. Equipping new satellites with the ability to maneuver away from threatening debris to avoid collisions is another viable option.
No matter what solution presents itself, it will take a concerted effort from all the spacefaring nations to address the problem. We must take the necessary steps to ensure the safety of future generations of space travelers whether government or private.