The Big Crunch may sound like a slogan for crackers or potato chips, but it’s actually an astronomical theory with a gloomy twist.

We’ve all heard of the Big Bang, a widely accepted theory that proposes the entire universe began from a single point about 13.7 billion years ago and has been expanding ever since.

But will it expand forever? Or could it stop and reverse that process?

One possible fate of the universe is the Big Crunch, the idea that the cosmos could one day begin contracting and eventually collapse back on itself or return to a single point.

If it ever happens, this anti-Big Bang would take place so far in the future that Earth might even not exist anymore, according to experts writing for Cornell University’s Curious About Astronomy Web site.

But the experts also took a stab at what a contracting universe could look like to an observer billions of years into the future.

“As the present-day observable universe started to get really small, the observer would most likely see some of the things that happened in the early universe happen in reverse. Most notably, the temperature of the universe would eventually get so high that you could no longer have stable atoms, in which case the hypothetical observer wouldn't be able to hold himself together.”

Yikes. But fear not. It turns the expansion of the universe has been accelerating rather than slowing.

Astronomers believe that’s caused by a mysterious dark energy pulling galaxies apart, according to NASA.

“Dark energy is this idea that not only is the universe expanding, dark energy is actually making that expansion happen even faster,” said Marla Geha, as assistant professor of astronomy at Yale University. “The dark energy will actually continue the expansion of the universe forever, so there probably will not be a Big Crunch if we have the numbers right.”

But the continuous expansion would have other consequences. Over tens of billions of years, the galaxies that we see around us would get farther and farther away, making the universe more of a lonely place, Geha said.

Famous for its reddish color, Mars has long fascinated astronomers, ordinary sky gazers and science-fiction writers.

But its strange, tiny moons also deserve plenty of attention, especially since one of them has been suggested as a way for humans to get to the planet itself.

“To reach Mars, we should use comets, asteroids and Mars’s moon Phobos as intermediate destinations. No giant leaps this time. More like a hop, skip and a jump,” Buzz Aldrin, the second man on the moon, wrote recently in an article in Popular Mechanics. Read more about the moon vs. Mars debate

Phobos is one of two Martian moons, with Deimos keeping it company in space.

Just 13 miles across, Phobos orbits so close to Mars that it may be shattered by the Red Planet’s gravitational tidal forces in about 100 million years, according to NASA.

You can see its battered, pockmarked surface in the photo above, taken by the Mars Reconnaissance Orbiter last year. The Stickney Crater, which takes up almost half its diameter, is on the lower right.

Some astronomy Web sites call Phobos potato-shaped and that’s a good way to describe it!

Think Phobos is small? Deimos is even tinier, at about 7.5 miles in diameter. If you were to stand on the surface of Mars, it would look light a bright star, NASA says.

And here’s a bit of mythology to add to your astronomy knowledge. You may know that Mars was named after the Roman god of war. So in keeping with the tone, Phobos (“Fear”) and Deimos (“Terror”) were named after the horses that pulled the chariot of Ares, the Greek god of war and the counterpart to Mars.

Only 12 men have had the honor of walking on the moon, but six astronauts were in charge of getting them there and bringing them home safely. These were the command service module pilots, whose job it was to circle the moon and return to Earth - without setting a foot on the lunar surface.

These six people are often overshadowed by the moonwalkers. Their stories are worth telling, though, especially in honor of the upcoming 40th anniversary of the first lunar landing.

The first CSM pilot is the most famous. Michael Collins flew on the Apollo 11 mission, carrying Neil Armstrong and Buzz Aldrin to the moon for the first lunar landing. He circled the orb for nearly a day in solitude. For 48 minutes out of each orbit he was out of radio contact with Earth.

In his autobiography, Collins wrote "this venture has been structured for three men, and I consider my third to be as necessary as either of the other two." He also said he never felt lonely, but "awareness, anticipation, satisfaction, confidence, almost exultation."

Richard Gordon, commander of the Yankee Clipper – the Apollo 12 CSM, was the second to orbit the moon while others walked on the surface. While he circled, he mapped out potential landing sites for future missions. He was slated to walk on the moon in the Apollo 18 mission, but that mission was canceled.

Stuart Roosa spent 33 hours in orbit during Apollo 14. His skill as the CSM pilot was needed after initial attempts to dock with the lunar module failed.

Alfred Worden was listed in the Guinness Book of World Records as the “most isolated human being” while he was orbiting the moon during the Apollo 15 mission. When the Endeavour was at its greatest distance from the lunar crew, Worden was 2,235 miles away from any other human being.

Ken Mattingly is probably well known for his actions on the ground of the ill-fated Apollo 13 mission, but he finally did get to go to the moon for the Apollo 16 launch. Mattingly used instruments aboard Casper to map a stretch of the lunar surface all around its equator.

The final mission, Apollo 17, put Ronald Evans in control of the command module, America. Evans holds the record of more lunar time in orbit than anyone else: 147 hours, 48 minutes.

Each of these men spent countless days training next to their more-heralded moonwalker colleagues. Yet, while their capsule brethren actually touched another heavenly body, these brave astronauts could only stare out their window and marvel at the view.

– Larry Frum

John Stoll lives amongst about 38,000 hours worth of audio recordings.

As NASA's lead audio engineer, it's his job to take care of these tapes and files, which record every second of every NASA mission since the U.S. space agency started sending chimpanzees into space, he said.

On Thursday, Stoll will start playing what amounts to his opus.

He will share with the world the audio recordings from the Apollo 11 mission, which put the first man on the moon. All 190 hours of the mission will stream on NASA's Web site, coinciding exactly with the dates and times of the original mission - only on a 40-year delay.

The mission recordings will begin playing at about 7:30 a.m. ET on Thursday and will continue for eight days, ending at 12:30 p.m. ET on Friday July 24, NASA says.

Those who don't want to listen to the whole, 190-hour broadcast can find some highlight clips here.

In their entirety, the recordings offer a gritty, real-life take on history that you can't find in books or old television footage, Stoll said.

His favorite part, of course, is the moon landing, which happened at 4:18  p.m. ET on July 20, 1969, and will be broadcast at the same time on Monday.

On the recording, you hear the NASA flight director in one ear and the audio feed from the moon in the other. At about the time Neil Armstrong announces that "the Eagle has landed," Stoll said, the flight director's voice is tense as he has to figure out whether to declare the landing a success or to pull back. Stoll said he never felt that tension until he listened to the raw recordings.

"That call, it was just really cool to listen to because everything is just happening so fast," he said, "and you don’t get to hear that, especially if you see it from the outside."

Stoll said he and other NASA employees in Houston, Texas, are in the process of digitizing NASA's entire audio collection, most of which is on old-fashioned tape. The older tapes, like the ones from Apollo missons, are in great conditon and are kept under strict environmental controls, he said. But newer tapes, like those from the 1980s, tend to gum up reel players. He has to heat those tapes to 130 degrees with a small oven before he can play them.

All of that work will soon culminate in a public Web site where people can listen to NASA audio from many other U.S. space missions.

That site should go up in two months or so, he said.

But it's probably best to get through the eight days of Apollo recordings before you worry about more.

After a decade of costly construction, the International Space Station is nearing completion. But NASA won't have long to enjoy the achievement.

According to an article from the Washington Post, NASA space station program manager Michael T. Suffredini raised eyebrows when, at a public hearing last month, he declared flatly that NASA plans to de-orbit the station in 2016.

That means the $100 billion research facility, which has been circling Earth since 1998, will ultimately burst into flames as it reenters the Earth's atmosphere and crashes into the Pacific Ocean.

Budget constraints and the lack of a shuttle program, which is set to retire in 2010, may have persuaded NASA to end the space station program.

The Washington Post explains:

The rap on the space station has always been that it was built primarily to give the space shuttle somewhere to go. Now, with the shuttle being retired at the end of 2010, the station is on the spot. U.S. astronauts will be able to reach the station only by getting rides on Russia's Soyuz spacecraft.

There is no official lobbying to extend the mission, but NASA's plans have met with criticism. Sen. Bill Nelson (D-FL) argues, "If we've spent a hundred billion dollars, I don't think we want to shut it down in 2015."

While speaking to a panel charged by the Obama administration with reviewing the entire human spaceflight program, Nelson affirmed, "My opinion is it would be a travesty to de-orbit this thing... If we get rid of this darned thing in 2015, we're going to cede our leadership in human exploration."

What do you feel should be done with the International Space Station? Does the initial $100 billion investment justify extending the program, or should we simply cut our losses and look toward a new future of space exploration?

I recently spent a miserable 10 hours on a flight from Europe to the U.S. and it made me think of how wonderful it would have been to be able to take the Concorde and cut that time in half.

My misery, and a conversation with a colleague about it, inspired an article on the status of supersonic flight six years after the Concorde fleet was retired from service.

Those planes flew at twice the speed of sound, but what if you could travel even faster?

Research continues into hypersonic flight, defined as least five times faster than the speed of sound. The first human to travel at hypersonic speeds was Russian Major Yuri Gagarin 1961 during the world's first piloted orbital flight, according to the U.S. Centennial of Flight Commission.

Future generations might one day zip around the globe in planes that reach those speeds with the help of supersonic combustion ramjets. Also known as scramjets, these engines use external air for combustion, according to NASA.

But there are lots of obstacles to overcome.

“It really comes down to the faster you go, the higher the temperatures associated with the external shape of the airplane,” said Peter Coen, principal investigator for NASA’s supersonic fundamental aeronautics program.

To illustrate, the temperature on the surface of an object that is traveling at five times the speed of sound reaches 1,800° F, according to the U.S. Centennial of Flight Commission.

“That really requires an airframe that has the life that would be associated with commercial success. That material has not been envisioned yet, never mind invented,” Coen said.

The crew of the International Space Station (ISS) tasted their own urine Wednesday - and NASA didn't even have to double-dog dare them.

Astronauts celebrated by "clinking" their drinking bags together in a traditional cheers before sipping water composed of recycled urine, sweat and atmospheric moisture. The cheers marked the initiation of a closed loop water recycling system aboard the ISS.

NASA claims each crew member creates about a gallon of water from urine every six hours, but the source water doesn't just come from the space station's human occupants. "Lab animals on the ISS breathe and urinate, too, and we plan to reclaim their waste products along with the crew's. A full complement of 72 rats would equal about one human in terms of water reclamation," Layne Carter, a water-processing specialist with NASA, said in a statement released by the space agency.

On NASA TV, Flight Engineer Mike Barrett confirmed "the taste is great," as another astronaut swam through the air catching floating bubbles of the recycled water. "This has been the stuff of science fiction," Barrett said on the program. "Everybody's talked about recycling water in a closed loop system, but nobody's ever done it before. Here we are today with the first round of recycled water."

Tom's Hardware is less enthusiastic about drinking the potent potable:

While it might sound completely gross to us, the water is probably cleaner than what we drink on earth. That being said, I’d rather take my chances with Earth water than drink the purified urine of a rat. Really.

Similar water purification technology was employed after the Asian tsunami in 2004, but with large scale use there is typically a much larger gap between urine and tap.

Would you be willing to drink reclaimed urine, or are you sticking to bottled water while Evian is available?

Okay, that headline is the only joke in this post about turning astronaut waste into drinking water.

So please get the "yuck" factor out of your system and read on.

Among tons of equipment that the space shuttle Endeavour hauled to the International Space Station (ISS) is a new water-purification system that recycles everything - humidity, condensation, sweat and yes, even urine - into purified drinking water.

(CNN's intrepid space correspondent Miles O'Brien sampled an earth version of the H20 during his coverage of Endeavour's launch on Friday. Other than a hint of an iodine aftertaste.... he pronounced it OK.  Miles did several live shots on CNN TV, and eventually finished the bottle.)

The WRS, or water recovery system, includes two refrigerator-sized racks packed with a distiller and filters.

"We use some traditional technology, such as filtration systems, but some of the technology is unique to our operation, like working without gravity," said Bob Bagdigian of the Marshall Space Flight Center in Huntsville, Alabama. He's the project manager for NASA's Environmental Control Life Support System (ECLSS).

Each crew member on the ISS uses just under a gallon of water a day. Water is needed for drinking, brushing teeth, flushing toilets, showering, and washing hands, clothes and dishes. About two thirds of that water now comes from Russian Progress resupply vehicles, the European Space Agency's Jules Verne automatic transfer vehicle, and NASA space shuttles. The remaining third comes from a small water processor on the Russian side of the station. That system captures sweat, and other water vapor in the air as it passes through the air-conditioning system, filtering it and turning it into drinkable water.

With the planned doubling of the station crew from three to six, there's a need to look for more efficiency in handling supplies - especially water, that is plenty heavy and therefore plenty expensive to bring up from the ground.

Any long-term outpost on the moon or Mars will have no choice but to recycle liquids. So it made sense that an early version of such a system be tested on the space station. If this system works as planned, it should cut the need for water delivery by 65 percent, producing 6,000 pounds of potable water each year.

The environmental team at Marshall in Huntsville, Alabama, does more than just water purification. These microbiologists, chemists, materials, chemical, mechanical, and software engineers are part plumbers, part HVAC workers and part environmental police for the space station crew. Their systems do everything from providing oxygen and potable water to removing carbon dioxide from the cabin air and maintaining cabin temperature and humidity levels.

So how sure will the station residents be that the water is fit for human consumption?

They won't drink a drop until several samples have been flown back to Earth and are tested and re-tested.

The purification technology design also has provided assistance on Earth. Similar equipment has been used in aid centers after earthquakes in Iraq and Pakistan, said Bagdigian.

Does Bagdigian, trained as a biologist and chemical engineer, ever get tired of the bathroom humor?

He laughed. Non-scientists, especially kids, can identify with such a basic human function, he said.

"Everybody is interested in living in space and how that is going to become a reality."

–Marsha Walton, Producer, CNN Science and Technology

Dozens of bloggers kept their thoughts flowing during the countdown to the launch of Endeavour on Friday. Only one person did it from Firing Room 3 of the Launch Control Center at the Kennedy Space Center.

Steve Siceloff in the Firing Room the day before the launch of STS-126. His Endeavour launch blog Friday was the first written from this nerve center of the countdown. NASA photo

“It’s a great environment. The only better seat would be on the shuttle itself,” said Steve Siceloff, public affairs web writer at KSC.

Bloggers around the world got much of their countdown information from Launch Commentator Candrea Thomas on NASA TV.

Siceloff had a lot more raw information to process.

“I’m listening to eight different audio loops. That takes some training of its own,” he said.

The rocket scientists talking on all those other channels are monitoring the orbiter, three main engines, an external fuel tank, two solid rocket boosters, and oh, a couple million other parts.

So what’s the atmosphere in the firing room?

“It’s actually very calm. Everybody’s into their books and into their own world. They’ve all got headsets on so they don’t talk loudly,” he said.

Siceloff, who says he’s been a space geek since he was a kid, used to cover NASA for the Fort Pierce Tribune and Florida Today.

He’s been blogging, writing and producing for the NASA web pages for a year and a half.

Endeavour’s launch blog got underway at 2:30pm. For the most part, it was a very quiet countdown.

“The launch team is working no technical issues” was a very common refrain on NASA TV.

But about 15 minutes before the scheduled 7:55pm eastern launch, we “civilians” in the NASA press room suddenly displayed the loud, rough, somewhat chaotic personality of most newsrooms.

There were a few words on NASA TV about a technical issue. Something about a door not being latched.

After miles of checklists and a near flawless countdown, could an open door stop this launch?

Here’s how Siceloff handled that first flare of a problem on the launch blog:

7:40 p.m. – Launch controllers are discussing a potential issue with a door in the White Room. There is concern whether the door has been pinned back. The door in question is not on Endeavour.

(The White Room is an environmental chamber that mates with the orbiter, where the Closeout Crew assists the astronauts in boarding and getting strapped into their seats on the shuttle.)

While scores of us in the press room were on the phone with our editors with a “Danger Will Robinson… this COULD be a showstopper” tone in our voices, Siceloff said the scene was far more serene in the Firing Room.

“It was very calm, very confident, very thorough. I never heard anyone on a loop sound excited,” said Siceloff. His next entry:

7:46 p.m. – T-9 minutes and counting . . . Launch controllers have cleared the door issue, saying it does not pose a hazard to Endeavour as it climbs away from the launch pad. All launch teams are go for launch.

So do rocket scientists ever get excited?

“When the shuttle clears the tower, there’s a whole lot of clapping,” said Siceloff.

And yes, said Siceloff, the stuff they say about rocket scientists is true.

“They really are the smartest people in the world,” he said.

By Marsha Walton, CNN Science and Technology Producer

As the shuttle Endeavour pursues its expansion and re-supply mission to the International Space Station, the political world still turns nearly 200 miles below. Will a President Barack Obama and a fractured economy spell change for NASA and space exploration?

The space shuttle Endeavour blasts off successfully Friday night.

The agency's $17 billion annual budget - about a third of which goes to fund the shuttle and other space missions  – may be under scrutiny, along with everything else, in our new financial climate.

On the campaign trail this year, Obama said, "We cannot cede our leadership in space.  That's why I'm going to close the gap, ensure our space program doesn't suffer when the shuttle goes out of service."

But skeptics raise multiple questions, starting with the fact that the president-elect made that statement in the heat of a tight campaign and in NASA's Florida backyard. It wouldn't be the first time that a president abandoned a lofty promise to reach for the stars.  In his 2004 State of the Union speech, President Bush announced an ambitious effort for manned missions to the Moon and Mars.   But the money never came through, and it's rarely been mentioned since.

With the shuttle slated for retirement in 2010, how long will it take to get the replacement vehicle ready?  Many think the 2015 deadline for the Orion craft and its Ares rocket is too rosy.

Can we afford it?  NASA's budget is only about two-thirds of one percent of the Federal budget, but is it high enough on our national priority list?

And just what are we getting back for our dollars?  Is the science we're getting from the Shuttle and the ISS going to pay for itself?

Proponents say it would be shortsighted to ditch our science and exploration efforts because America can't afford to fall farther behind in tech and science literacy.

To be sure, NASA's had its triumphs and tribulations in recent years.  On the down side, there's been uncertainty over the shuttle, the Columbia disaster, a couple of failed Mars missions, the earth-bound controversy over political censorship of the agency's climate scientists and NASA's first successful launch into the tabloid world with last year's bizarre astronaut love-triangle story.  

NASA's victories, however, are unmistakable:  The Hubble Space Telescope has led what's now routinely called "The Golden Age of Astronomy;" the Mars Rovers' unexpected five years of service; and groundbreaking research in space, on land, and in the oceans.

So let's hear from you:  What should the Obama Administration do?  Has NASA earned our continued support?  Does the mission need to be corrected?  Or should we put the money elsewhere?

Watch CNN's Situation Room Monday at 5 p.m. ET for a report from Miles O'Brien on Obama and the future of space policy.

And you can read the Obama campaign's space policy here.

– Peter Dykstra, Executive Producer, CNN Science, Technology, and Weather