A small asteroid the size of a city bus zoomed between Earth and the moon’s orbit Friday, just days after its discovery, but it never posed a threat to our planet, NASA says.

The asteroid 2012 BX34 passed within 36,750 miles (59,044 kilometers) of Earth when it made its closest approach at 10:30 a.m. ET. The space rock is about 37 feet (11 meters) wide and would have broken apart in Earth’s atmosphere long before it reached the ground, if it had reached the planet at all, NASA scientists said.

“Asteroid 2012 BX34 is small,” astronomers with NASA’s Asteroid Watch at the Jet Propulsion Laboratory in Pasadena, Calif., said in a Twitter message. “It wouldn’t get through our atmosphere intact even if it dared to try.”

The space rock passed Earth at a distance that is only about 0.17 times that between Earth and the moon. For comparison, the moon typically orbits Earth at a distance of about 240,000 miles (386,000 kilometers).

Asteroids this small are hard to spot, and luckily they pose the least concern,” Asteroid Watch scientists explained. “Our goal is to find the bigger ones.” [Video and image of asteroid 2012 BX34's orbit]

In September, NASA announced that it has spotted about 90 percent of the largest asteroids (the size of a mountain or bigger) that can come near Earth. About 911 such giant space rocks have been confirmed. Astronomers estimate there are about 981 big near-Earth objects that occasionally creep close to our planet.

Asteroid 2012 BX34 was the second space rock to fly relatively close by Earth this week, Asteroid Watch scientists said. On Jan. 23, another small asteroid — called 2012 BS1 — passed by the planet at a range of about 745,000 miles (1.2 million kilometers), which is about 3.1 times the Earth-moon distance.

“Asteroid 2012 BS1 is so small (about 7 meters) it would disintegrate in our atmosphere if it were to come close to Earth,” the Asteroid Watch team wrote.

Astronomers with NASA and other science teams routinely scan the skies in search of near-Earth asteroids that could pose a danger to the planet. Experts estimate that asteroids about 460 feet (140 meters) across and bigger can cause widespread devastation near their impact sites, though a larger space rock would be required to cause destruction on a global scale.

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This week, scientists from around the world are also discussing how Earth should respond to the threat of an asteroid impact. The so-called NEOShield project is a European commission led by the German Aerospace Center and includes scientists from universities and industrial partners in Germany, France, the United Kingdom, Spain, the United States and Russia.

You can follow Tariq Malik on Twitter @tariqjmalik. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

• Photos: Asteroids in Deep Space
• Unprepared for Asteroid Attack!
• When Space Attacks: The 6 Craziest Meteor Impacts

© 2012 Space.com. All rights reserved. More from Space.com.

NASA’s first major disaster, the Apollo 1 fire that killed three astronauts 45 years ago today, marked a dark day for the space agency. But it also marked the beginning of NASA’s continual process of learning from its own mistakes.

And what a costly mistake it was. On Jan. 27, 1967, Virgil “Gus” Grissom, Edward White and Roger Chaffee, the first crew of America’s manned moon program, Apollo, were suited up and strapped inside their new space capsule for a dress rehearsal of their upcoming launch — a mission to fly the Apollo capsule to Earth orbit to test the vehicle for moon flights. This was to be a ground test only, and wasn’t thought to pose much risk.

But when an electrical spark ignited a fire, flames and smoke swept through the capsule, and the crew was unable to escape. An investigation later was unable to pinpoint the exact initiation spot of the fire, but determined that the plethora of flammable materials (especially Velcro) and pure oxygen environment inside the capsule were partly to blame.

In the 45 years since that day, spacecraft builders have learned a lot about constructing safer space vehicles.

“From a human safety perspective, I think because of the shock that the industry went through following the Apollo 1 fire, I think they set a great foundation and since the recovery from Apollo 1 I think people have been able to make good refinements,” said Bill Johns, chief engineer at Lockheed Martin for the Orion capsule, NASA’s next-generation spaceship being designed to carry astronauts to deep space.

Examining the evidence

The fact that the disaster occurred on the ground rather than in space made a big difference to those hoping to understand what went wrong, and do better next time. In this case, all the evidence was sitting there waiting to be examined, which would have been impossible for an accident after launch.

One of the most incriminating finds made by the investigation team was that the 100 percent oxygen environment of the capsule, originally intended to reduce the weight of the vehicle, made fire extremely easy to start.

NASA soon put a stop to that, and redesigned Apollo to fly with a mix of about 34 percent oxygen in its pressurized modules.

“The biggest single change that they made, and they made it phenomenally within the next year, was that they had to go from pure oxygen environment to an air environment,” Johns told Space.com. “Materials exposed to pure oxygen are just looking for an excuse to burn.”

In addition to changing the mix of gas in the cabin, engineers had had to redesign many aspects of the vehicle to accommodate the change, including making the spacecraft’s walls significantly thicker to handle the increased pressure.

Fire safety lessons

Another major finding was that the prevalence of flammable materials inside the Apollo 1 cabin further increased the risk of fire.

After the accident, NASA reduced the amount of flammable Velcro in the crew cabin, and tested many of the capsule’s materials for flammability.

Now, as a result of the lessons learned from Apollo 1, many new materials have been developed for spaceflight with fire safety in mind. The insulation surrounding wires, for instance, is now made of a special coating so fire-resistant that it can’t burn even when put in a pure oxygen environment.

The hatch

A particularly tragic aspect of the Apollo 1 fire was the fact that the astronauts inside the capsule tried to open the hatch to escape, but couldn’t.

The investigation later revealed that the hatch opening procedures were way too difficult and took too long to be executed in an emergency. Furthermore, the inward-opening hatch was impossible to open under any pressure higher than normal atmospheric pressure — and the fire had boosted the cabin pressure significantly.

Ironically, NASA had considered installing explosive bolts on the hatch for emergency openings, but opted against it out of fear that the door might open accidentally, putting the astronauts at risk. (The hatch had prematurely opened on Grissom’s previous Mercury flight, when his Liberty Bell 7 landed in the ocean).

However, after the fire crew capsule hatches were significantly redesigned. NASA changed Apollo’s hatch to an outward-opening design, and that same choice persists today in Orion.

“It’s the minimum entry — if you want to deal with carrying humans to space, you need to have a hatch that opens outward so that the crew has a chance to open it,” Johns said. “Those rules have carried forth to this day.”

Additionally, the Orion capsule includes an alternate escape option through the docking hatch, and an explosive system to blow out the hatch in an emergency.

Ultimately, though, while spacecraft safety has improved leaps and bounds since Apollo 1, the business of flying in space is still risky, and NASA aims to remember that. The Apollo 1 fire was not the last of NASA’s deadly space accidents. Two fatal space shuttle accidents, one in 1986 and the other in 2003, killed 14 astronauts in all, forcing NASA each time to re-examine its spacecraft safety.

“In the face of our greatest accomplishments, it’s easy to lose sight of the fact that each time men and women board a spacecraft, their actions carry great risks, along with the opportunity for great discoveries and the chance to push the envelope of our human achievement,” NASA administrator Charles Bolden said in a video message to commemorate the Apollo 1 anniversary this week.

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“In memory of our colleagues, I ask all of you in the NASA family once again to always make your opinions known and be unafraid to speak up to those in authority so that safety can always be our guiding principle and the sacrifices of our friends and colleagues will not have been in vain.”

You can follow Space.com assistant managing editor Clara Moskowitz on Twitter @ClaraMoskowitz. Follow Space.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

• Apollo 1 Remembered – Report from the Archives
• Space Travel: Danger at Every Phase
• Photos: NASA’s Orion Space Capsule Test Flight

© 2012 Space.com. All rights reserved. More from Space.com.

The United States may start working toward establishing a moon colony by 2020, or an asteroid may remain the next target for manned exploration; it depends on who wins this November’s presidential election.

America’s space policy tends to change on four- or eight-year cycles, often shifting dramatically when a new commander-in-chief is sworn in. With the next election less than 10 months away, it appears that incumbent Democrat Barack Obama will take on one of two Republicans — former Massachusetts Gov. Mitt Romney or former Speaker of the House Newt Gingrich. Romney and Gingrich are currently leading the Republican primaries, ahead of Rick Santorum and Ron Paul.

Here’s a brief look at the vision the president and each of the two Republican frontrunners have professed for NASA and the nation’s space activities.

Barack Obama: The status quo

President Obama announced his administration’s space policy in 2010, one year after taking office. The plan called for a radical change in direction for NASA.

Obama canceled George W. Bush’s Constellation program, which had instructed NASA to return astronauts to the moon by 2020. Instead, Obama directed the space agency to focus on getting humans to an asteroid by 2025, then on to Mars by the mid-2030s.

The president’s vision entails, in part, the development of a new heavy-lift rocket. In response, NASA has begun working on a booster called the Space Launch System, which it hopes will be operational by late 2021.

Obama’s policy also seeks to jump-start commercial spaceflight capabilities. Since the space-shuttle fleet was grounded last year, NASA has relied on Russian Soyuz vehicles to ferry astronauts to and from the International Space Station.

But over the long haul, Obama wants private American spaceships to take over this taxi role. So the president promised NASA an extra $6 billion over five years, which the agency would use to help companies develop these new craft.

NASA has said it hopes some of these commercial vehicles will be up and running by 2017 or so.

Newt Gingrich: Grand plans

Newt Gingrich has big ideas for American spaceflight, which he laid out in a speech Wednesday on Florida’s Space Coast.

The self-professed space geek said that, if elected president, he would push for a permanent manned lunar colony by 2020. He also wants a bustling commercial spaceflight industry by that year, as well as a next-generation propulsion system capable of sending astronauts to Mars quickly and efficiently.

But Gingrich wouldn’t count on NASA to make all of this happen. Instead, he would look to develop the capabilities of private industry by establishing a system of cash prizes. As an example, he said he’d propose a $10 billion prize for the first company or entity to get a human to Mars.

“You put up a bunch of interesting prizes, you’re going to have so many people showing up who want to fly, it’s going to be unbelievable,” Gingrich said. “So the model I want us to build is largely the model of the ’20s and ’30s, when the government was actively encouraging development (in the aviation industry), but the government wasn’t doing it.”

Gingrich announced he would set aside 10 percent of NASA’s budget to help fund these prizes. He seems keen to cut the space agency’s funding overall, saying repeatedly that he wants NASA to be “leaner” and less bureaucratic.

Mitt Romney: Steering NASA by committee

Mitt Romney hasn’t been as voluble on space policy as Gingrich, but he shares his Republican rival’s desire to shift more of the spaceflight burden from NASA to private industry.

In fact, Romney wants the business community to help chart NASA’s course and provide part of its funding. At a Republican primary debate in Florida on Monday, he suggested that leaders from the private sector, academia and the military should work together with the president and NASA officials to map out the nation’s space activities.

“Bring them together, discuss a wide range of options for NASA, and then have NASA not just funded by the federal government but also by commercial enterprises,” Romney said. “Let’s have a collaborative effort, with business, with government, with the military as well as with our educational institutions.”

Compared with a Gingrich presidency, a Romney administration would likely place less weight on exploring and exploiting the final frontier. However, the former Massachusetts governor has said that he views space exploration as a priority.

We need to “have a mission, once again excite our young people about the potential of space, and the commercial potential will pay for itself down the road,” Romney said.

Calling all visionaries

These presidential hopefuls are following in the footsteps of past leaders by declaring sweeping visions for our nation’s space program. Most famously, John F. Kennedy said on May 25, 1961, “I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth.”

Those words prompted a countrywide push to carry out the Apollo program, culminating in the landing of Neil Armstrong and Buzz Aldrin on the moon in 1969.

Ever since, leaders have been trying to reproduce the Kennedy effect.

“I have been puzzled for years by a statement that goes something like, ‘If we just had a president with the vision and foresight of John F. Kennedy to announce a bold space initiative, all would be well with NASA,’” said Roger Launius, space history curator at the Smithsonian’s National Air and Space Museum in Washington, D.C.

The problem is that Apollo succeeded because of the very specific political, technological and economic environment of the time, Launius said. It’s not necessarily for a lack of vision that NASA hasn’t quite reached those heights since.

“We have had those national leaders who made those bold proclamations,” Launius told Space.com in an email. “Twenty years to the day after the Apollo 11 landing, President George H.W. Bush made another Kennedy-like speech announcing the ambitious Space Exploration Initiative (SEI) that was intended to return people to the moon by 2000, establish a lunar base, and then, using the space station and the moon, reach Mars by 2010. The price tag for this effort was estimated at a whopping $400 billion over two decades and the initiative never gained traction in Congress or with the American people.”

The giant asteroid Vesta may contain a vast supply of water ice, a supply that has sat frozen for billions of years, a new study reveals.

The surface of Vesta — the second-largest object in the main asteroid belt between Mars and Jupiter — appears to be quite dry. But water ice may lurk underground over roughly half of the huge space rock’s area, particularly near the poles, researchers said. And it may have been there for billions of years.

“Near the north and south poles, the conditions appear to be favorable for water ice to exist beneath the surface,” study co-author Timothy Stubbs,  of NASA’s Goddard Space Flight Center in Greenbelt, Md., said in a statement.

Asteroid ice underground?

Vesta has an average diameter of about 330 miles (530 kilometers). It probably doesn’t have any permanently shadowed craters where water ice could stay frozen at the surface, researchers said.

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That’s because the asteroid is tilted on its axis at about 27 degrees, giving Vesta seasons akin to the ones we experience on Earth. So every part of the space rock’s surface likely sees the sun at some point during a Vestan year.

However, the research team — using models based on data gathered by NASA’s Hubble Space Telescope and other instruments — determined that average annual temperatures near Vesta’s poles are probably less than minus 200 degrees Fahrenheit (minus 129 degrees Celsius). Below this threshold, water ice is thought to be able to survive in the top 10 feet (3 meters) or so of Vestan soil, or regolith.

The average temperatures near Vesta’s equator, however, are roughly minus 190 degrees Fahrenheit (minus 123 Celsius), according to the study — too high to allow water to remain within a few meters of the surface.

This band of relatively warm temperatures extends from the equator to about 27 degrees north and south latitude, researchers said.

“On average, it’s colder at Vesta’s poles than near its equator, so in that sense, they are good places to sustain water ice,” Stubbs said. “But they also see sunlight for long periods of time during the summer seasons, which isn’t so good for sustaining ice. So if water ice exists in those regions, it may be buried beneath a relatively deep layer of dry regolith.”

Water ice might be stable at the bottom of some craters for much of the Vestan year (about 3.6 Earth years), the study found. But at some point during the summer, sunlight would probably drive it off the surface, either to be lost into space or redeposited somewhere else on the asteroid.

A spacecraft’s view of Vesta

Modeling results such as those presented in the new study could soon be vetted by a robotic visitor to Vesta.

NASA’s Dawn spacecraft entered into orbit around the huge space rock in July 2011 and has been studying it ever since. Part of the probe’s work involves searching for water with its gamma ray and neutron detector (GRaND) spectrometer, and Dawn recently spiraled close enough to Vesta to get a good look.

“The Dawn mission gives researchers a rare opportunity to observe Vesta for an extended period of time, the equivalent of about one season on Vesta,” Stubbs said. “Hopefully, we’ll know in the next few months whether the GRaND spectrometer sees evidence for water ice in Vesta’s regolith.”

Dawn will stay at Vesta until July, when it will depart and journey to Ceres, the largest object in the asteroid belt. It should arrive there in February 2015.

Both Vesta and Ceres are so large that scientists consider them protoplanets — baby planets whose growth was interrupted when Jupiter formed. Scientists hope Dawn’s observations shed light on the role water has played in the evolution of planets.

“Our perceptions of Vesta have been transformed in a few months as the Dawn spacecraft has entered orbit and spiraled closer to its surface,” said Lucy McFadden, a planetary scientist at NASA Goddard and a Dawn mission co-investigator. “More importantly, our new views of Vesta tell us about the early processes of solar system formation. If we can detect evidence for water beneath the surface, the next question will be is it very old or very young, and that would be exciting to ponder.”

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• The 7 Strangest Asteroids in the Solar System
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© 2012 Space.com. All rights reserved. More from Space.com.