我剛開始看NASA網站, 沒看年份, 所以也中招了~ 哈哈…. 現在的火星位於太陽的另一邊 (2006年8月), 想看也看不到嚕~ 上次火星比較接近地球是去年十月底. 下次應該是2007年底, 當然不會像2003的時候那麼亮囉.

相關網站:
- NASA – Beware the Mars Hoax
- Close Encounter with Mars (2006 Version)
- Mars Hoax Returns

傳來傳去的訊息如下:

8月26日剛好是星期六，那天大家可以到高一點的地方等到凌晨看月亮！
兩百七十二年後才會再出現一次，機會難得！
請記下這一天並且不要錯過這次難得的機會。
從八月份開始，火星將會在晚上呈現出最明亮的時候。
從肉眼來看，它會像月亮那麼大。
繞著地球走了34.56英里後，它的大小將在2006年8月27號達到最大。
在2006年8月27日淩晨00:30一定要觀看哦！那時天空會看上去有兩個月亮！
相同的景觀再出現將會在2278年。一定要轉發給你的朋友因為一旦錯過這次，我們沒有機會再次見到這樣的景觀了。

新的行星definition:
Planet: A round thing orbiting a star. More precisely, according to the draft definition: “A planet is a celestial body that (a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (b) is in orbit around a star, and is neither a star nor a satellite of a planet.”

Related link: Planet debate: Proposed new definitions
右邊的連接是New Scientist相關報導的PDF.

Pic 1: If the new definition is adopted, the solar system will have 12 planets (Image: IAU/Martin Kornmesser)
Pic 2: A dozen candidate objects are being considered for possible planet status (Image: IAU/Martin Kornmesser)

(from newscientist.com)
Huge asteroid threatening Earth
From: Agence France-Presse From correspondents in Paris
March 03, 2006

AN asteroid capable of devastating an area the size of a sub-continent has about a one in 1000 risk of hitting Earth early next century, NASA said today.

The rock, 2004 VD17, is about 500m long and has a mass of nearly a billion tonnes.

If it hit Earth it would deliver 10,000 megatonnes of energy, equivalent to all the world’s nuclear weapons. Spotted on November 27 2004, VD17 was identified as potentially crossing Earth’s orbit, with a one in 3000 risk of collision on May 4, 2102.

Further observations and calculations have prompted the risk on that day to be upgraded to “a bit less than one in 1000″, said NASA Near-Earth Object (NEO) expert David Morrison in an emailed circular.

“The risk of an impact within the next century (is) higher than that of any other known asteroid,” he said, stressing however that the likelihood of a hit was small.

“Fortunately, it is nearly a century before the close pass from VD17. This should provide ample time to refine the orbit and, most probably, determine that the asteroid will miss the Earth.”

Collisions by large asteroids or comets are extraordinarily rare, but can be watershed events when they happen.
The reign of the dinosaurs is believed to have ended 65 million years ago by a rock that smashed into the Yucatan peninsula in Mexico.

The theory is that the impact kicked up vast clouds of dust that were borne around the globe on high-altitude winds and filtered out light and heat from the sun, inflicting climate change that changed Earth’s biodiversity.

Image: Asteroid … the impact from an asteroid this size could obliterate half a continent / supplied

以上都是一些電影裡的情節 = = 現實也說不定是這樣喔. 不過科學家有證實到最”流行”的核武炸隕石方法, 可能對地球的傷害會反而更大. 說可能放一顆夠重量的東西在隕石的軌道上, 這樣說不定隕石會被吸過去, 也就不會直接撞到地球了….. 不知道這方法可不可以. 只希望永遠都沒機會去證實!

‘Gravity tractor’ to deflect Earth-bound asteroids
18:00 09 November 2005
(NewScientist.com news service)
Zeeya Merali

NASA scientists have come up with a surprisingly simple yet effective way to deflect an Earth-bound asteroid – park a large spacecraft close by and let gravity do the work.

Previous suggestions have focused on deflecting an incoming asteroid with nuclear explosions. But NASA experts believe a “gravity tractor” should be able to perform the same feat by creating an invisible towline to tug the rock off its deadly course.

“Most people think of the Hollywood treatment – throw a nuclear weapon at it,” says Edward Lu, a NASA scientist and astronaut who developed the idea. But this would produce shattered pieces, some of which might still head towards Earth. “That’s the blast-and-hope strategy,” Lu adds.

Pots of paint
Another proposal is to detonate nuclear bombs close to the asteroid. The resulting blast of radiation should nudge it off track but there is the same risk of wayward fragments if the asteroid shatters.

A more novel idea is to paint the surface of the asteroid white. This should change the amount of solar energy it radiates and change its course. However, the amount of paint required could be huge.

Lu and colleagues originally thought about landing a spacecraft on the surface of an asteroid, in order to gently push it off course. But a lack of gravity means the craft would have to attach itself to the surface of the rock and this could prove complicated because the asteroid might be little more than a pile of rubble, Lu explains.

To make matters worse, asteroids often rotate, so pushing on one could simply set it spinning faster, rather than altering its course.

Hands down winner
Lu’s team finally realised that the spacecraft might not need to land at all. Placing a heavy enough object near the asteroid for long enough could produce sufficient gravitational tug to change its orbit.

For a 200-metre-wide asteroid, the spacecraft would need to weigh about 20 tonnes and lurk 50 metres from its target for about a year to change its velocity enough to knock it off course.

“This is hands down the best idea I have seen,” says Erik Asphaug, a planetary scientist at the University of California at Santa Cruz. “This will work, but you need to put a large enough spacecraft out there at the right time.”

Taking the hit
Such large spacecraft are perfectly feasible, says Lu. In fact, NASA’s multi-billion-dollar Prometheus programme, which was set to explore the outer solar system but which has been delayed, planned to develop just such a vehicle, propelled by nuclear fission.

The strategy crucially relies on our ability to detect an asteroid threat about 20 years in advance. For larger asteroids this is realistic. But Asphaug says many smaller asteroids – less than about 500 metres across – may go unnoticed until only a few years before impact.

Asphaug suggests it may be better to invest in predicting when and where smaller asteroids could strike, than on massive hazard-averting spacecraft. Governments could then prepare to evacuate affected regions. “In many cases it makes more economic sense to just let the thing hit,” he says

Journal reference: Nature (vol 438, p 177)

(from New Scientist)
Deep Impact collision ejected the stuff of life
13:10 07 September 2005
Maggie McKee

Millions of kilograms of fine dust particles and water and a “surprisingly high” amount of organic molecules sprayed into space when NASA crashed its Deep Impact spacecraft into Comet 9P/Tempel 1 on 4 July 2005, reveal a trio of new studies.

The observations bolster theories that comets may have seeded Earth with the raw materials for life and suggest they may be sponge-like – rather than hardened – at their cores.

On 4 July, about 80 telescopes on Earth and in space trained their sights on Comet Tempel 1 when a 370-kilogram copper impactor was sent hurtling into its path. Just after the smash, a bright vapour plume spewed from the surface at about 5 kilometres per second, followed quickly by a stream of particles that spread into a cone.

The cone appeared to remain attached to the comet’s surface for about 22 hours before separating into a detached arc. Researchers used this gravitational attraction to estimate the mass and density of the comet’s main body, or nucleus. They found that the 72 trillion kilogram-nucleus was extremely porous, with as much as 80% of its volume taken up by empty space.

“That tells me there is no solid layer all the way down to the centre,” says Mike A’Hearn, the mission’s principal investigator at the University of Maryland in College Park, US. He says he had expected that the ice might become denser towards the core of the nucleus, but that instead “probably all the way in, ice is all in the form of tiny grains”.

A touch crumbly

“It’s like a sponge, with a lot of cavities,” agrees Horst Uwe Keller, an astronomer at the Max-Planck Institute for Solar System Research in Germany. He observed the event with Europe’s Rosetta spacecraft and says the discovery confirms previous observations suggesting other comets are also porous. “When you touch it, it just crumbles under your hands.”

Observers estimate the impact released about 5 million kilograms of water from beneath the comet’s surface and between two and five times as much dust. There was so much dust, in fact, that mission members have not been able to see the impact crater with the high-resolution camera on the mission’s flyby spacecraft, about 500 km away.

To add to the problem, that camera was malfunctioning but now image-processing techniques may have revealed a glimpse of the crater and team members may release the image later on Wednesday.

Building blocks

The team estimates the impact blasted away a crater about 100 metres wide and up to 30 m deep. Crucially, organic molecules were among the material ejected. Neither the full range of molecules nor their abundances have been determined yet, but researchers say they have found a surprisingly high amount of methyl cyanide, a molecule seen in large quantities in another comet.

This supports theories that comets may have brought water and the building blocks of life to Earth, and the team hopes to eventually “identify all the species comets brought in abundance to early Earth”, says A’Hearn.

The observations have also apparently ruled out another theory – that impacts with other objects may be responsible for the occasional stream of gas and dust seen coming off of comets. Although Tempel 1′s surface is pockmarked with craters ranging from 40 m to 400 m across, astronomers watching the comet both before and after the impact noticed that it released the streams relatively often in spurts of activity apparently triggered by sunlight.

“I don’t think the hypothesis that outbursts are caused by impacts is really valid,” says A’Hearn. “Probably comets undergo outbursts like this very frequently and the fact that everyone was looking intensively [at this comet] for an extended period allowed us to see phenomena that are probably common and weren’t seen before.”

Journal reference: Science (DOI: 10.1126/science.1118923)

(from ninemsn.com.au)
Hotspot found on one of Saturn’s moons
20:35 AEST Wed Aug 31 2005

There is a hotspot on one of Saturn’s moons which should not be there and has yet to be explained, scientists said.

It is located at the south pole of Enceladus, a moon with a diameter of just 500 km which orbits Saturn at a distance of around 238,000 km.

The hotspot is unusual because it occurs at the pole, scientists said. Usually, the hottest part of any planet or moon is around the equator, as is the case with the earth.

This suggests that the heat at Enceladus’ southern pole is generated from within, said scientists from the Cassini-Huygens mission to Saturn and its moons.

But they acknowledged they had no idea how.

“It shouldn’t be that warm,” said John Spencer, one of the scientists working on the project.

“It’s like flying past Antarctica and finding that it’s warmer than the earth’s equatorial regions. It’s that strange.”

Spencer, of the Southwest Research Institute in Colorado, is one of a group of scientists examining data sent back to earth from the Cassini spacecraft, which was launched in 1997 to examine Saturn.

The spacecraft has flown past Enceladus three times – most recently on July 14 when it passed within just 175 km of the small, icy orb.

The scientists expected to find that the temperature was around 80 degrees Kelvin (minus 193 degrees celsius), at its hottest point, which they assumed would be near the equator.

Instead, they found that the heat was concentrated at the south pole, where the temperature hit 91 degrees Kelvin near a series of fissures, or “tiger stripes” on the moon’s surface.

“It is an extremely conspicuous hot region,” Spencer told a news conference. “Something is different about that area.”

The scientists have two theories to explain the hotspot. The first is that the heat comes from decaying radioactive material below the moon’s surface and the second is that it is caused by gravitational tides.

But they say neither theory adequately explains the heat.

“We don’t have anything we could call a complete hypothesis yet,” said Torrence Johnson from NASA, which is working on the project alongside the European and Italian space agencies.

The team says the hotspot suggests there might be volcanoes and geysers on Enceladus.

If this is true, it would be one of only three “active” moons known to man. The others are Io, which orbits Jupiter, and Triton, which circles Neptune.

The Cassini spacecraft has been sending spectacular images back from Saturn, its rings and its moons since last year, when it reached the planet. It also launched a probe which landed on the surface of Titan, another of Saturn’s 31 known moons.

(from ninemsn.com.au)
Space Penguin could hop around moon
20:36 AEST Wed Aug 31 2005

A robotic Lunar Penguin explorer could be hopping around on the moon by 2009, maker Raytheon Co said as it unveiled the concept lander at an aerospace conference.

The unmanned lunar device, in development for two years, is a metre tall and weighs approximately 104 kg “hops” by reigniting small propulsion engines.

The Penguin, unveiled at the American Institute of Aeronautics and Astronautics Space 2005 Conference, can make a single jump of about 1 km and could be adapted to make additional jumps, possibly over greater distances.

US President George W Bush last year refocused the space program on sending people to the moon, Mars and beyond.

Raytheon said the Penguin could be a robotic precursor to future manned space missions and was being proposed to NASA.

While still in the concept stage, the explorer could be launched as early as 2009, said Karleen Seybold, a senior systems engineer for Raytheon, based in the Waltham, Mass.

The Lunar Penguin, originally intended to land on the South Pole of the moon to search for ice, is based on tactical weapons technologies, which should make it much more affordable, Raytheon said, without disclosing a price.

The lander sits on four legs, much like a small version of the original landers that brought astronauts to the moon. The squat, compact unit has a few tiny jump boosters protruding below and on its sides and looks nothing like an actual penguin.

The Penguin uses rocket engines from ground-based missile defence systems and the guidance system of a Tomahawk cruise missile.

“Since we could set it down in such a precise location, the Penguin could be the delivery vehicle for the science community,” said Seybold said.

Raytheon is a major military defence technology company but has only a small share of NASA contracts.

———-

Robotic space penguin to hop across the Moon
18:20 31 August 2005
(NewScientist.com news service)
Will Knight

The first lunar colonists may not be a humans but compact robots capable of jumping more than a kilometre in a single bound.

Engineers at US defence contractor Raytheon, in Massachusetts, have developed a robot, dubbed the Lunar Penguin, that could one day bounce across perilous craters and imposing mountains on the Moon’s craggy surface using a set of compact rocket boosters.

US president George W Bush has made returning to the Moon, and later reaching Mars, a crucial part of his vision for future US space exploration. But, in order for humans to make the Moon a second home, robotic scouts will need to search for safe landing spots and useful minerals for colonists to mine.

“Since we could set it down in such a precise location, the Penguin could be the delivery vehicle for the science community,” Raytheon engineer Karleen Seybold, who is leading the Penguin project, told Reuters.

Jumping craters
The robot, in fact, bears no physical resemblance to a real penguin, but looks like a simple, squat, four-legged lunar lander. It is just under 1 metre tall and weighs 104 kilograms.

The design borrows technology from Raytheon’s missile systems – the rockets come from a ground-based missile defence system and the guidance system is taken from a Tomahawk cruise missile. Although Raytheon has yet to receive an order to develop the Lunar Penguin further, Seybold says the bot could feasibly be launched as soon as 2009.

“The hopping penguin is an interesting concept,” says Max Meerman, a researcher at UK space company Surrey Satellites. “Jumping a mile means that crater edges, like the ones that cause problems for the Mars rovers, are not a big issue.”

Difficult landing
But Meerman adds that leaping such distances across the surface of the Moon could subject any instruments aboard the robot to severe stress. “Landing on the Moon is notoriously difficult,” he says. “Much more so than on Mars, so doing it multiple times will be a big engineering challenge.”

The Lunar Penguin was publicly demonstrated for the first time on Tuesday at the American Institute of Aeronautics and Astronautics’ 2005 SPACE Conference and Exhibition in California, US.

The event, which takes place between 30 August and 1 September, provides a showcase for many new technologies, from supercharged jet engines to giant hot air balloons.

Leaps and bounds
For the Lunar Penguin to be a viable Moon probe, some of the prototype’s features would need to be redesigned. For example, the guidance system would need to be reconfigured for navigation on the Moon rather than on Earth. It currently uses a Global Positioning System (GPS) receiver, which would not work on the surface of the Moon, as it uses Earth-orbiting satellites.

Returning to the Moon is unlikely to be straightforward process, says Ian Wright, a researcher at the UK’s Open University and one of the team behind the failed Beagle 2 Mars mission. Wright notes that the last human mission took place more than 30 years ago. But to reach out to the stars, he says scientists will need to try out novel concepts. “The robotic penguin sounds like an excellent opportunity to help us do this,” he told New Scientist.

Meerman says the Lunar Penguin’s unique approach to lunar locomotion could prove a useful way of exploring the Moon’s hostile landscape. “If it’s successful, perhaps we could find astronauts on the next manned Moon mission using the same system to jump over hills,” he says.