[AK47rulz]

Manned interplanetary missions on NASA's agenda
by Boris Pavlishchev
Moscow, Russia (Voice of Russia) Aug 29, 2012

Illustration only.


After dropping plans to return to the Moon, the American space agency NASA has set its sights on Mars. But before venturing there, it is going to test out its latest interplanetary technologies during a manned mission to Asteroid Itokawa, expected to take place before 2025.

Dr Igor Lisov is a Russian spaceflight expert: "The Itokawa mission will travel on board the Orion spaceship, which is unlikely to be operational before 2019. NASA plans to use the intervening seven years for practising aspects of this mission on a variety of simulators. In 2005, Itokawa was studied in some detail by a Japanese probe.

"It is a 530-metre potato-shaped rock with a very uneven gravitational field. Accordingly, studying the conditions on it could be helped by computer simulation."

A simulation exercise of this kind is currently under way in a big hangar at NASA's centre in Houston. The trainees are 'orbiting' Itokawa, 'approaching' it, 'touching down' and carrying out 'surface walks' - everything with the help of a computerized simulator equipped with a giant screen. The 'walks', which include 'hovering', are being carried out with the help of hammocks and 3D goggles.

In June, a team of American, European and Japanese astronauts practised Itokawa walks by carrying out scuba ventures from board the Aquarius sea lab, which is resting on the seabed off Florida at a depth of about 19 metres. For collecting rock samples, they attached themselves to the bottom with ropes and hooks.

In Moscow last autumn, six international volunteers successfully completed a mock mission to Mars. They had spent 520 days in complete isolation on space-type life support. Russia, too, is mulling a manned marsshot.





http://www.space-travel.com/reports/...genda_999.html

[Aminkaoo]

Hints of a violent Solar System from asteroid Itokawa
Samples returned by a Japanese mission to the asteroid Itokawa show that it …




Asteroids are laboratories that astronomers can use to study the history of our Solar System. They provide a means to understand the current environment as well: since they have no atmosphere and (in most cases) relatively little mass, they are good proxies for what interplanetary spacecraft will experience on longer trips, such as missions to Mars.

The Hayabusa mission, conducted by the Japan Aerospace Exploration Agency (JAXA), traveled to the near-Earth asteroid known as Itokawa. The probe collected samples from the surface and returned them to Earth for analysis. As reported by Eizo Nakamura et al. in PNAS, Haybusa's samples showed the effects of the interplanetary environment, especially signs of impacts from tiny rocky particles. As a result, the JAXA scientists were able to piece together the impact history of Itokawa, showing that that the asteroid had survived and been shaped by collisions with objects ranging in size from 10 kilometers down to a nanometer.

While some asteroids (such as Vesta) are solid objects with complex structure, many others are looser clumps of rocky material, colloquially known as rubble piles. Near-Earth asteroid 25143 Itokawa is a rubble pile, and is typical of objects in this part of the Solar System. It is somewhat potato-like in shape, about 550 meters across on its longest side, and roughly half that in other directions. Its small size and relatively low density gives it such a tiny gravitational pull that a human could launch herself into an orbit around the asteroid merely by jumping off the surface.

The Hayabusa spacecraft collected a number of small pieces of rock from the surface of the asteroid, five of which were analyzed in detail for the current study. Earlier experiments showed that the surface of Itokawa is similar to many meteorites that have struck the Earth known as chondrites. Imaging the samples using a scanning electron microscope (SEM) found a great deal of "space weathering." The weathering takes the form of tiny holes from micrometeorite impacts, as well as signs of more extreme impacts from higher-mass intruders.

Micrometeorite impacts leave crater holes less than a micron (10-6 meters, or one millionth of a meter) in diameter. The edges of the craters are marked by spherical blobs, indicating the micrometeorites melted the rock, which is only possible if they were moving at high speeds. Why they are moving so rapidly relative to Itokawa is uncertain; models predict that the smallest meteorites are propelled by radiation pressure from the Sun, but that is insufficient to accelerate them to the speeds required to melt the surface of the grain samples.

In the case of larger impact events, the grains showed the effects of shock heating that melted the rock temporarily, transforming it from a crystalline solid to a glassy state. (Glasses are materials that have no regular structure ordering the placement of atoms, while atoms are arranged in strict repeating patterns within a crystal.) The rock also exhibited signs of compression, where it had been squeezed by the high pressure of a strike by larger rocks and small asteroids.

As a result of all the signs of stress, Nakamura et al. argue that Itokawa is the remains of a much larger asteroid that was shattered by one or more impacts after it formed. Only a catastrophic event has the energy required to melt the rocks in this way.

The researchers conclude that the rubble surface of Itokawa has been shaped by impacts on all scales. Major events included the hypothetical impact that shattered the original asteroid, from which the current form of Itokawa emerged; others fractured and melted the rock on smaller scales, turning solid chondrite into glass. Micrometeorites moving at high velocity punctured the rock, melting small holes.

Together, these impacts reveal that our Solar System can be a fairly violent environment. Studies of other asteroids will provide us a better picture of just how many impacts from objects small and large can be expected as we venture further from Earth's sheltering atmosphere.




http://arstechnica.com/science/2012/...eroid-itokawa/

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from the article:
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Near-Earth asteroid 25143 Itokawa is a rubble pile, and is typical of objects in this part of the Solar System. It is somewhat potato-like in shape, about 550 meters across on its longest side, and roughly half that in other directions. Its small size and relatively low density gives it such a tiny gravitational pull that a human could launch herself into an orbit around the asteroid merely by jumping off the surface.
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Hmmmm....Would it be possible for this to break apart? Even just the presence of the Orion craft, could affect something held together so loosely I would have thought.
Obviously I'm wrong.

And I find it unusual that a Russian writer from "the voice of Russia" is reporting this.

[HwoRas1]

'orbiting' Itokawa, 'approaching' it, 'touching down' and carrying out 'surface walks'
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Their surface walks would need to be slow and deliberate with such flimsy gravity on it....Like it says elsewhere, you would be able to literally jump into orbit on this body.......

[Hankie]

> Manned Mission

Did you say "MANNED mission"? Ain't we got fun!

> Near-Earth asteroid 25143 Itokawa is a rubble pile

Yes.

> the grains showed the effects of shock heating that melted the rock temporarily, transforming it from a crystalline solid to a glassy state.

This is seen to some extent in all asteroids and all comets, it happened very very early in the life of the solar system. The reason has been a mystery for many years to those scientists who study meteorites. It was recently resolved, and the reason is as given in the post above - caused by larger impact events.

[carletoxtrs]

Manned Mission

Did you say "MANNED mission"? Ain't we got fun!
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Well, no, I never said it, NASA did.
I was also surprised it had such plans.
My question though still remains. With its very minimal gravity, the Astronauts would need to be treading very lightly.

[pupyississido]

4,700 POTENTIALLY HAZARDOUS ASTEROIDS LURKING


Generally speaking, there's a collective sigh of relief when any large hulk of space rock flies past Earth -- except, perhaps, for the smaller asteroids that scatter precious meteorites over California's 'Gold Country.' But when one of the estimated 4,700 potentially hazardous asteroids (PHAs) glides by, we really should count our lucky stars: Those things could kill you.



PHAs are asteroids larger than 100 meters (330 feet) wide that drift close enough to Earth's orbit to be considered a threat. They come within eight million kilometers (five million miles), or around 20 times the Earth-moon distance, of our planet and should they be on a collision course with Earth, they could survive the atmospheric burn and wipe out a city (or worse).

They are an extra-special subset of a larger family of near-Earth asteroids (NEAs), space rocks that give astronomers a reason for pause.

The new estimate of 4,700 (plus or minus 1,500) PHAs comes courtesy of observations by NASA's Wide-field Infrared Survey Explorer (WISE) -- specifically, its near-Earth object-hunting mission: NEOWISE. There's no real big surprise with this number -- it does, after all, fall in line with most previous estimates -- but WISE sampled 107 known PHAs to give a more precise idea of the total population of dangerous asteroids in our neighborhood. But here's the kicker: Only 20-30 percent of these asteroids have been discovered thus far.

ANALYSIS: Capturing Lazy Asteroids to Plunder

"The NEOWISE analysis shows us we've made a good start at finding those objects that truly represent an impact hazard to Earth," said Lindley Johnson, program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington. "But we've many more to find, and it will take a concerted effort during the next couple of decades to find all of them that could do serious damage or be a mission destination in the future."

The NEOWISE analysis has turned up something interesting about PHAs. Generally, they possess much lower inclination orbits than the wider population of NEAs. This means that they have orbits around the sun more likely to collide with Earth. But there's a flip-side to this doomsday coin; their low inclination orbits make PHAs easier for future robotic and possible manned missions to track, land on and deflect, if necessary.

Another oddity noted by NEOWISE is that PHAs are generally brighter, yet smaller, than the greater NEA population. This information provides clues as to the composition of these particular asteroids. They are most likely composed of granite-like rock or metals. These materials make PHAs hardier and more likely to survive atmospheric entry should they collide with Earth -- flip that doomsday coin back over. But once again, there's a plus side (flip it again).

ANALYSIS: Nuking Asteroids: It's a Megaton Of Fun!

As recently announced by the start-up company Planetary Resources, it is hoped asteroids may be hiding trillions of dollars of precious metals. Asteroid mining could therefore be an industry of the future. Although I have misgivings about such a business venture in the near-term, this NEOWISE data would surely help companies such as Planetary Resources' prospects for high-value asteroid targets that are easily accessible.

How they propose to carry out the expensive business of refining and transporting the materials back to Earth is open to debate, but the technologies they'd need to develop in the pursuit of profit could ultimately be used to safeguard life on Earth. The ability to rendezvous with a PHA is the first step in asteroid deflection (unless we decide to nuke 'em, instead), so the more information we can gather as to the nature of these dangerous asteroids, the better.

Source: JPL




http://news.discovery.com/space/dont...ds-120518.html