29 September 2009
One big step for India, a giant leap for mankind
One big step for India, a giant leap for mankind
Srinivas Laxman & Prashanth G N, TNN 25 September 2009, 12:47am IST
BANGALORE/MUMBAI: It is a giant leap for India's space programme and the biggest scientific discovery of the 21st Century. India's maiden moon mission, Chandrayaan-1 has found water, a discovery that scientists say will upend thinking about space and boost research. And, of course, it has helped shake off the failure tag from the Rs 386-crore Chandrayaan-I project that was aborted last month.
The historic development, that TOI in a global newsbreak reported in Wednesday's edition, took place just prior to the termination of the mission on August 30, 2009. Although water was spotted by the Moon Mineralogy Mapper (M3), a NASA probe and one of the 11 payloads on the spacecraft, glory shone on ISRO for the discovery that was made after nearly five decades of lunar exploration by Western nations.
``If it weren't for them (ISRO), we wouldn't have been able to make this discovery,'' Carle Pieters, the Brown University researcher who analyzed the data from the NASA probe.
Pieters, a planetary geologist, has told scientists the discovery ``opens a whole new avenue of lunar research but that we have to understand the physics of it to utilize it''. A Brown University statement on Thursday said, ``The discovery by M3 promises to reinvigorate studies of the moon and potentially upend thinking of how it originated.''
Water molecules (H20) and hydroxyl ^ a charged molecule consisting of one oxygen atom and one hydrogen atom ^ were discovered across the surface of the Moon. The M3 had covered almost 97% of the Moon before Chandrayaan-1 was terminated.
Brown University scientists say that while the abundance is not precisely known, ``as much as 1,000 water molecule parts-per-million could be in the lunar soil: harvesting one tonne of the top layer of the Moon's surface would yield as much as 32 ounces of water''.
ISRO chairman Madhavan Nair described it a path-breaking event and Chandrayaan-I project director Mylswamy Annadurai called it one of the greatest examples in international collaboration in space.
Chandrayaan's surprise find triggered tremendous excitement among Indian space scientists who were disappointed that the mission had to be terminated because of a communication breakdown.
Narendra Bhandari, who is associated with Chandrayaan, told TOI from Ahmedabad: ``It is a good observation and after all it was one of the main aims of the Indian Moon programme. According to well-known astrophysicist, S M Chitre, water on the Moon could have been deposited by the comets several billion years ago. ``The comets are like water carriers,'' he told TOI.
Regarding the significance of the discovery, Chitre said that it will have far reaching consequences with regard to the human colonization of the Moon and future rocket launches from the lunar surface. ``The real significance of this mission is that it surveyed the entire moon. Nasa's Apollo manned missions between 1969 and 1972 did not find any water at all because they surveyed only a bare 25% of the lunar surface,'' he said.
President of National Space Society (NSS), Suresh Naik, told TOI finding water will help in making rocket fuel.
``Launching rockets from the Moon definitely have an advantage because the escape velocity is much less than on Earth,'' he said. On Earth, the escape velocity, ie, the speed a rocket needs to escape the Earth's gravity, is 11km per second. With the Moon's gravity being one-sixth that of the Earth's, the escape velocity would be much less, he explained. In plain terms, it means less energy is needed to launch rockets from the Moon.
The US, Russia and China are exploring the possibility of building human habitats on the Moon after 2020. Space experts said that in this race, India cannot lag behind and Isro officials also have not ruled this out.
Pieters said findings from M3 reveal new questions about ``where the water molecules come from and where they may be going''. Scientists have for long speculated that water molecules may migrate from non-polar regions of the Moon to the poles, where they are stored as ice in ultra-frigid pockets of craters that never receive sunlight. If, indeed, the water molecules are mobile, there is then the possibility of getting water to the permanently shadowed craters. She said: ``When we say water on the Moon, we are not talking about lakes, oceans or even puddles. Water on the Moon means molecules of water and hydroxyl that interact with molecules of rock and dust specifically in the top millimeters of the Moon's surface,'' she explained. The M3 team found water molecules and hydroxyl at diverse areas of the sunlit region of the Moon's surface as well as at the Moon's higher latitudes where it seemed more definitive in presence. The M3 discovery has been confirmed by data from two NASA spacecrafts ^ the Visual and Infrared Mapping Spectrometer (VIMS) ^ on the Cassini spacecraft and High-Resolution Infrared Imaging Spectrometer on the EPOXI spacecraft.
The M3 is a joint project of Nasa's Propulsion Laboratory (JPL) and Brown University.
The Indian Space Research Organisation (ISRO) and US space agency NASA should deploy surface robotic penetrator in 'Chandrayaan-II' mission to study more about the presence of water molecules on moon, former President APJ Abdul Kalam has suggested.
"I suggested to both ISRO and NASA to work on future mission of Chandrayaan-II using moon surface robotic penetrator during my recent visit to California Institute of Technology in US, where NASA scientists presented the findings of Moon Mineralogy Mapper (M3) to Indian scientists," Kalam told students during an interaction on Saturday.
26 September 2009
Asteroid attack: Putting Earth's defences to the test
(See the outstanding video)
IT LOOKS inconsequential enough, the faint little spot moving leisurely across the sky. The mountain-top telescope that just detected it is taking it very seriously, though. It is an asteroid, one never seen before. Rapid-survey telescopes discover thousands of asteroids every year, but there's something very particular about this one. The telescope's software decides to wake several human astronomers with a text message they hoped they would never receive. The asteroid is on a collision course with Earth. It is the size of a skyscraper and it's big enough to raze a city to the ground. Oh, and it will be here in three days.
Far-fetched it might seem, but this scenario is all too plausible. Certainly it is realistic enough that the US air force recently brought together scientists, military officers and emergency-response officials for the first time to assess the nation's ability to cope, should it come to pass.
They were asked to imagine how their respective organisations would respond to a mythical asteroid called Innoculatus striking the Earth after just three days' warning. The asteroid consisted of two parts: a pile of rubble 270 metres across which was destined to splash down in the Atlantic Ocean off the west coast of Africa, and a 50-metre-wide rock heading, in true Hollywood style, directly for Washington DC.
The exercise, which took place in December 2008, exposed the chilling dangers asteroids pose. Not only is there no plan for what to do when an asteroid hits, but our early-warning systems - which could make the difference between life and death - are woefully inadequate. The meeting provided just the wake-up call organiser Peter Garreston had hoped to create. He has long been concerned about the threat of an impact. "As a taxpayer, I would appreciate my air force taking a look at something that would be certainly as bad as nuclear terrorism in a city, and potentially a civilisation-ending event," he says.
The latest space rock to put the frighteners on us was 2008 TC3. This car-sized object exploded in the atmosphere over Sudan in October last year. A telescope first spotted it just 20 hours before impact - at a distance of 500,000 kilometres - and astronomers say we were lucky to get any warning at all.
Thankfully, 2008 TC3 was far too small to do any damage on the ground, but we are nearly as blind to objects big enough to do serious harm. We have barely begun to track down the millions of skyscraper-sized asteroids zipping around Earth's neighbourhood, any one of which could unleash as much destructive power as a nuclear bomb on impact.
Asteroid impacts are not as rare as you might think. It is widely accepted that an asteroid or comet 30 to 50 metres across exploded over Tunguska in Siberia in 1908, flattening trees for dozens of kilometres all around. The chance of a similar impact is about 1 in 500 each year (Nature, vol 453, p 1178). Put another way, that's a 10 per cent chance of an impact in the next 50 years (see "Should we panic?").
"Fifty-metre asteroids scare me to death," says Timothy Spahr, director of the Minor Planet Center in Cambridge, Massachusetts. "I could easily see a 50-metre object hitting in three days causing absolute pandemonium."
During the US air force planning exercise, the participating scientists explained that with so little warning there would be no hope of preventing an impact. Even Innoculatus's smaller 50-metre asteroid would weigh hundreds of thousands of tonnes, requiring an enormous push to change its trajectory appreciably - so much so that detonating a nuke near it in space would not provide a sufficient impulse so late in the game to cause a miss. To deflect an asteroid sufficiently, force would need to be applied years in advance (see "Could we nuke it?").
In fact, it could make things worse by breaking the asteroid into pieces, some of which could be large enough to do damage, and even create a blizzard of meteors that would destroy satellites in Earth orbit.
Panic on the streets
Realistically, though, the nuclear option would not be on the table in the first place: the nuclear-tipped missiles sitting patiently in silos around the world are not designed to track and home in on an asteroid or even survive for more than a few minutes in space. Instead, we would simply have to brace ourselves for the impact.
The good news is that even a little warning makes a big difference, simply because it would allow us to predict the time and location of impact. In the case of 2008 TC3, just a few hours after the asteroid's discovery, NASA scientists completed calculations that predicted an atmospheric plunge over an unpopulated desert area of northern Sudan, with timing accurate to within a minute.
But participants in the planning exercise worried that if an asteroid posing an imminent threat to a populated area were discovered, and the situation were not handled properly, panic and lack of coordination could lead to chaos on the roads.
Spahr was not involved in the exercise, but shares those concerns. "With a three-day warning, you can walk away and be safe. But it scares me, given how poorly we've handled things of this nature in the past," he says, citing the failure to fully evacuate New Orleans ahead of hurricane Katrina in 2005. "I'm picturing people panicking and driving the wrong way on the freeway, screaming 'Oh my god, it's going to kill us!'"
To prevent panic and disorganised movement, it is crucial for authorities to develop an evacuation plan and communicate it to the public as soon as possible after discovery of the dangerous object, since such discoveries are posted automatically online and would cause a media firestorm.
Such measures should ensure the streets would be very quiet as an object such as Innoculatus plunges into the atmosphere and makes its final approach to Washington DC. The compression of the atmosphere in front of the asteroid and friction with the air would cause rapid heating. At lower altitudes, where the air is denser, the heating becomes so intense that the asteroid vaporises and explodes. For the Tunguska event, this happened at about 8 kilometres above ground.
Supersonic shock wave
If you were unfortunate enough to be looking up from directly below, the explosion would be brighter than the sun. The visible and infrared radiation would be strong enough to make anything flammable ignite, says Mark Boslough of Sandia National Laboratory in Livermore, California. "It's like being in a broiler oven," he says. Anyone directly exposed would quickly be very badly burned.
Even before the sound of the blast reaches you, your body would be smashed by a devastating supersonic shock wave as the explosion creates a bubble of high-pressure air that expands faster than the speed of sound. Planetary scientist Jay Melosh of Purdue University in New York once experienced a shock wave from an experiment that exploded 500 tonnes of TNT, a tiny blast in comparison with the blast from an asteroid. "I was standing on top of a hill about 1.5 kilometres away wearing earplugs," he recalls. Melosh says you would see the shockwave in the air due to the way it refracts light. "It's a shimmering bubble," he says. "It spreads out in complete silence until it reaches you, then you hear a double boom."
Melosh was at a safe distance, but at ground zero below an exploding asteroid, the shock wave would be powerful enough to knock down buildings. It would arrive about 30 seconds after the blazing hot flash of light, and could also knock any nearby planes out of the sky, Boslough says. Any surviving buildings would be pummelled by raging winds blowing faster than any hurricane can muster.
Of course, two-thirds of Earth's surface is ocean. While our atmosphere is likely to protect us from asteroids smaller than 100 metres across, anything larger hitting the ocean - including chunks of Innoculatus's rubble pile - would cause a giant splash that could smash coastal buildings with high-speed volleys of water. The tremendous damage and loss of life that would ensue if multiple cities around an ocean basin were flooded led NASA scientists in 2003 to rate ocean impacts by asteroids as far more dangerous than those on or over land.
Recent computer simulations offer some hope, though. They suggest that the monster waves generated by ocean impacts would typically break far from shore, dissipating most of their energy before they could reach cities - unless the impact was very close to the coast, of course. Another ray of hope is that 100-metre asteroids hit Earth only about one-tenth as often as 30-metre objects.
Lasting just one day, the 2008 US air force exercise could barely scratch the surface of the incoming-asteroid problem. Not surprisingly, it discovered that should the nightmare come true, there is no plan for how to coordinate the activities of NASA, emergency planners, the US military and other parts of government. Further planning exercises are needed: the time saved through early preparation will be crucial if an evacuation is ever required at short notice.
Our chance of having any prior warning at all for an approaching 30-metre asteroid is no better than 25 to 35 per cent with existing sky surveillance, calculates astronomer Alan Harris of the Space Science Institute in Boulder, Colorado (see graphic). The sun washes out half of the sky with daylight, blinding us to 50 per cent of threatening objects. Even glare from the moon can hide unwelcome incoming guests.
What's more, two of the world's three leading asteroid surveys are based in Arizona, including the Catalina Sky Survey, which discovered 2008 TC3. The region tends to cloud over between July and September. "Shift 2008 TC3 back to July and forget it. It wouldn't have been seen," says Spahr.
Now picture this ugly scenario, which worried some participants in the air force exercise: an asteroid flies out of nowhere and explodes over a sensitive nuclear-armed region, like South Asia or the Middle East. There's a reasonable chance that such an airburst could be misinterpreted as a nuclear attack. Both produce a bright flash, a blast wave and raging winds.
An asteroid flying out of nowhere and exploding over a sensitive region like the Middle East could be misinterpreted as a nuclear attack
Such concerns were one reason why, when NASA found 2008 TC3 in its sights, it not only issued a press release but also alerted the US State Department, military commanders, and White House officials, says Lindley Johnson at NASA headquarters, who oversees the agency's work on near-Earth objects. "If it had been going down in the middle of the Pacific somewhere, we probably would not have worried too much more about it, but since it was [going to be] on land and near the Middle East, we did our full alerting," he says.
There is one major way to improve our prospects - point more eyes at the skies. The European Space Agency wants to get into the monitoring game and may set its telescopes at the European Southern Observatory in Chile on the problem. This could fill a gap in the NASA-funded surveys, which are limited to watching the skies of the northern hemisphere, says Richard Crowther of the UK's Science and Technology Facilities Council, who is a consultant for ESA and heads a United Nations working group on near-Earth objects.
"Up to now, the US has taken the majority of the responsibility for dealing with this issue and I think it's time for other states to take on a more equitable share of that," he says.
Help will also come from two new US observatories designed to survey the entire sky visible from their locations every few days. The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), will consist of four 1.8-metre telescopes, the first of which is already up and running in Hawaii. Plans are afoot to construct the 8.4-metre Large Synoptic Survey Telescope in Chile by 2015, though the project is still raising funds. These will improve the chances of an early detection and potentially extend warning times for 30-metre objects to more than a month. But even so, every ground-based lookout suffers from interference from the sun and moon.
A dedicated space telescope would fix this problem, but such a mission could cost more than a billion dollars. "We're talking about investing in an insurance policy," says Irwin Shapiro of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
Shapiro is leading a US National Research Council panel that by year's end will recommend a strategy to better address the threat from near-Earth objects. That study, along with the air force's report on its asteroid impact exercise, is intended to help the White House develop an official policy on the near-Earth object hazard by October 2010, which Congress has requested.
While asteroid impacts are much rarer than hurricanes and earthquakes, they have the potential to do much greater damage, Johnson warns: "It's not something I think there needs to be billions of dollars per year spent on, but it does warrant some priority in the list of things that we ought to be worried about." The cash would at least give us a better idea of when the next asteroid might strike. "From what we know today," he says, "it could be next week."
Should we panic?
An asteroid blast like the one that flattened Tunguska in Siberia in 1908 is expected only once every 500 years or so, on average. It is likely to be a lot longer than that before one hits a populated area, given how small a fraction of Earth's surface is taken up by cities and towns. A NASA study in 2003 concluded that only one in four Tunguska-like impacts would kill anyone, and only one in 17 such impacts would have a death toll of 10,000 or more, comparable to severe earthquakes and tsunamis.
Can we nuke it?
The fastest way to deflect an asteroid away from Earth would be to send a nuclear bomb aboard a spacecraft, à la the film Deep Impact, though we'd still need several years' warning.
The spacecraft would have to be able to home in on the asteroid and to trigger the explosion at just the right distance. Precision is needed to avoid breaking up the hurtling rock while still giving it enough of a nudge to prevent the Earth impact years down the line.
That assumes we're already prepared. Designing and building new spacecraft typically takes a few years. With current rocket technology, it would probably take several additional years to reach a threatening asteroid. And since the explosion would need to occur years ahead of the predicted impact in order to make the asteroid miss Earth, we'd need decades of lead time if we hoped to deflect Armageddon. A confounding factor is that nukes in space are forbidden by the Outer Space Treaty of 1967, signed by the US, Russia, and other nuclear powers, though they might agree to turn a blind eye on this one.
With several decades of warning time, other deflection technologies could come into play. The gravity tractor, for example, would see a spacecraft hover near the asteroid for several years, gradually pulling the asteroid off its collision course using the tiny gravitational pull of the spacecraft's mass.
Another option would be to focus sunlight on a spot on the asteroid using a fleet of mirror-bearing spacecraft, heating it enough to vaporise rock. The escaping gases would act like the exhaust from a rocket engine, giving the asteroid a slight push in the opposite direction that could produce a substantial course change over many years.
David Shiga is New Scientist's physical sciences reporter in Boston
Find the Air Force Report Here:
19 September 2009
The Sky is Falling Now
Every asteroid that will ever strike Earth is already out there and already on course to strike Earth. Every future asteroid impact event is already an event in progress.
This note is in reply to Mike Treder’s recent article (with which I generally agree) about the threat of near-Earth objects.
Here are my responses to a few of the points made:
You’ll notice, though, that these things happen periodically; not on a regular basis, but every so often…
This seems self contradictory. Periodic means to occur at regular intervals. I think you wanted to say non-periodically, or aperiodically, or at random, without a recursive pattern. Maybe “You’ll notice, though, that these things happen; not on a regular basis, but every so often,” would have been better. However “You’ll notice, though, that these things happen ‘at random’; not on a regular basis, but every so often,” would have been best.
The reason I would pick on this semantic is that the leading astronomy ‘experts’ in this issue have seemed to come to believe in their own intellectual artifacts: population estimates, average relative frequencies, statistical probabilities, power law distribution curves, as if they were hard empirical definitive evidence and not simply academic fabrications. When portrayed to the public or government, the consequence is a gross misapprehension of the threat. Clark Chapman even recently used the phrase ‘known frequency’ in arguing against the possibility of a given large asteroid event 12,000 years ago.
I’m just sayin’, words are symbols for ideas. And here, there has never been a more critical time in the life of mankind for us to get the ideas right.
(If astronomers and aerospace engineers were as sloppy with their mathematical semantics as they are with their linguistic semantics we would still be observing the Sun as it revolved around the Earth.)
...and somewhat predictably. Most of them result from impacts of asteroids or comets. And guess what—those “planet killers” are still out there.
I don’t know what other extinction events you may be referring to here but speaking for asteroid impact events, at least in this context they are wholly unpredictable. In referencing the past occasion of these events or the systemic geometric dynamics of these objects there is no recursive pattern or potential for recursive pattern in their occasion.
The problem with predictability is that every asteroid that will ever strike Earth is already out there and already on course to strike Earth. Every future asteroid impact event is already an event in progress—there is simply nothing to predict! Which and when and how large the next one will be is a never-ending matter of seeing it coming soon enough and with a high enough degree of certainty for us to mount and effective response. The current and proposed observational efforts can only do that as a matter of very good luck.
We can state with absolute certainty that another large impactor will be on a collision course with Earth at some point in the relatively near future. It could be a hundred years from now, a thousand years, a million years, ten million years—or it could be, metaphorically, tomorrow.
Why ‘metaphorically’? Tomorrow is true, precise and literal—and as such the threat is evergreen. If we expect more money from the public and government to address this issue we must scare them better. No Fear = No Funding. No Funding = No Planetary Defense. No Planetary Defense = No More Mankind. This much ain’t rocket science… okay, maybe a little.
Thousands of near-Earth objects (NEOs) are in orbits that bring them into close proximity with the Earth. In addition, there are millions of icy and rocky objects out in the Kuiper belt, any one of which could be jostled from its orbit and sent plummeting toward the Earth at any time. It is estimated that at least 70,000 of these objects are more than 100 km in diameter, large enough to cause the next major extinction event.
Deflecting impending comet impact threats (Oort Cloud/Kuiper Belt Objects) would be virtually impossible from Earth. Perhaps from the orbit of Mars—and at 100 km, not without something a lot bigger than nukes. Probably why none of the proposed discovery surveys even try to look for comets. For now, our response to comet impact threats is the same as to the threat of Rogue Black Holes or Gamma Bursts… Hope!
FYI: At 25 meters (the floor of the threat/harm threshold) or greater, the estimated NEO asteroid population is ~10 million. And whereas extinction level threats begin at 10 km for asteroids, given their greater velocity it is only 6 km for comets.
However the number of asteroids or comets in itself is strategically irrelevant. After all, how many 10 km asteroids or 6 km comets does it take to constitute one extinction level event?
The search for NEOs can be conducted at relatively low cost, especially if it’s done on a cooperative international basis and involves government, academic, and individual volunteer efforts.
In this context you could say that seeing them coming’individually, a few decades before impact, is as close to predictably as we can get.
I trust you understand that if we are going to respond to this threat, and do so successfully, then the detection element will be only a small fraction of the cost in terms of human endeavor. And that when you say ‘relatively low cost’ it would be relative to the cost of deflection or perhaps relative to the magnitude of the loss of our species due to extinction by NEO.
To attempt to deflect a 10 km asteroid with nuclear ablation today, all things considered, would require 10,000 megatons (twice the worlds current nuclear arsenal) delivered by 1,000 Aries V (on the drawing board) heavy launch vehicles. And through 1,000 launch windows…
We can build more nukes and rockets. But even one launch window is a matter of chance and we would need 1,000 of them. If we are to succeed here we need to build and pre-position such a capability to some circumstellar orbit (orbit of Mars?) before we see it coming. And ‘before’ we see it coming begins… Now! Then we can afford to worry about comets.
(For a 100 km object multiply everything above by 1,000 times.)
Although the odds of detecting and stopping a major comet or asteroid that could threaten civilization are small, they are greater than zero, and the cost of ignoring the search is, well, potentially everything.
If you mean exactly what you say here I agree. I’m just surprised that anyone else would say it!
In other words: As things stand, our failure, so far, to develop our conceptual abilities into manifest capabilities will most likely result in a failure of any effort to respond to and deflect any extinction level threat.
However, if you were in fact somehow referring to some academic random-chance probabilistic assessment of the next extinction level event any time soon, then that would be irrelevant, strategically speaking.
See Mike Treder's article at: http://ieet.org/index.php/IEET/more/3408/
"Although the odds of detecting and stopping a major comet or asteroid that could threaten civilization are small, they are greater than zero, and the cost of ignoring the search is, well, potentially everything.
Roller coaster rides are fun. But when the survival of human—and posthuman—civilization is at stake, it’s imperative that we set a high priority on detecting and then deflecting the next planet killer before it gets here."