Asteroids are fascinating – not just because they can destroy humanity

Look up in the night sky, if you are lucky you might be able to see Vesta, the only asteroid—among millions that lurk between Mars and Jupiter—bright enough to be visible to the naked eye from the Earth. Given their dull (non)appearance in the sky, it is no wonder that the first asteroid was only discovered in 1801 when relatively powerful telescopes started to be built.

However, in the two centuries since, we have learnt a lot about these celestial bodies. They could prove to be both a curse and a blessing. A curse because they could bring about the end of human existence, and a blessing because they could be the launchpad for building human colonies in outer space.

The definition of an asteroid has changed over the years, but today we know them as small bodies found in the inner solar system. Asteroids can also be called failed planetesimals—tiny fragments that had the potential to grow larger under the influence of gravity and become a planet when the solar system was being formed billions of years ago, but couldn’t.

Living on a pale blue dot

We now know that these “failures” pose a high risk to life on the Earth. Only last week a half-kilometre wide asteroid passed by the Earth. If it had hit us, it could have caused human extinction. Fortunately it was about 1 million km away, which is three times the distance between the Earth and the moon. But the risk is real. In the past one such asteroid impact was responsible for extinction of dinosaurs and an older one caused even more destruction and made all the oceans boil.

4927597266_275e355960_oThe good news is that, with enough warning, we already have the technology to deflect asteroids. But the bad news is that we may not get enough warning, because there are thousands of asteroids—some of which could be on a collision course with the Earth right now—that we have not yet discovered.

This threat has spurred some to take matters in their hands, rather than wait for government agencies to do the work. The B612 foundation, for instance, is planning to launch a private space mission in 2018 that will discover and track hundreds of thousands of such asteroids.

If you can’t beat ’em, profit from ’em

Leaving the stories of doom behind, asteroids are fascinating for another reason: they hold clues about the formation of our solar system. For instance, according to theory, when the Earth formed into a planet, the process would have been too hot to have left any liquid water on the surface. So the current hypothesis is that water-rich celestial bodies, such as comets, brought the water when many crashed into the Earth during its early days.

A current space mission, called Rosetta, to the comet 67P recently tested this hypothesis. It found that the water on that comet was not of the same composition as that on the Earth. So if not comets, then the other celestial body that could achieve this feat are asteroids. This hypothesis will be tested by the Hayabusa-2 mission, launched in December by the Japanese space agency, when it will land three rovers on the asteroid 1999 JU3, and also collect and return a sample from the asteroid back to the Earth in 2020.

Even if they aren’t the source of terrestrial water, asteroids could be habitable, or at least resource-providing, stations for human colonies in outer space. And this isn’t just a crazy idea. Two private companies, Planetary Resources and Deep Space Industries, are currently working on projects to mine asteroids. They aim to harvest not just water, but also metals such as iron, nickel, platinum and palladium. Apart from the moon, few celestial bodies can boast of having such a close relationship with humanity.

First published in Lokmat Times. Lead image by ESA and ATG media lab. Asteroid image by Emily Lakdawalla (under CC-BY-NC-SA).

Curious Bends – Vandana Shiva, antibiotics in chicken, asteroid hunters and more

Few technologies, not the car, the phone, or even the computer, have been adopted as rapidly and as widely as the products of agricultural biotechnology. The tools of genetic engineering have allowed a good proportion of the current population to survive and prosper. But such statistics (or any scientific argument) does not stop Vandana Shiva from thinking that the root of all evil lies in GM technology. (42 min read)

2. Chicken consumption is at an all-time high in India. It may be contributing to antibiotic resistance

An investigation of chicken from around Delhi shows that they contain antibiotics beyond the limits setup by international bodies. These antibiotics are used not to treat diseased chicken but to prevent them. However, there are no regulations in India for their use in poultry. This means the amounts used are often excessive, probably contributing to increasing antibiotic resistance. (21 min read)

3. India’s outdated approach to education is hurting students and academia

The University Grants Commission wants to reign in elite institutions, such as the Indian Institute of Science and the Indian Institutes of Technology, by making their courses shorter. This decision, however, isn’t based on any sound research. If such institutions aren’t allowed to experiment with education, then how would you know what works best for Indian students and academics? (5 min read)

+ The author, Vishu Guttal, is an assistant professor at the Indian Institute of Science.

4. India has an asteroid search mission made up of mostly students

“Four years, 260 teams across India, 1200 observations of celestial bodies and 21 discoveries of asteroids. All India Asteroid Search Campaign was started by SPACE, an NGO in India, in 2010 with an aim to increase the love for science, astronomy and scientific research in Indian students. SPACE provides training to students and amateur astronomers to hunt for asteroids.” (2 min read)

5. An interview with Manjul Bhargava, winner of the 2014 Fields Medal

The first Indian-origin mathematician has won the Fields Medal, which is considered to be the Nobel Prize of mathematics. In an interview, he talks about growing up in India, Canada and the US and how his upbringing shaped up his desire to pursue mathematics, tabla and sanskrit. His hope is that Indian youth will take up research in basic science.

Chart of the week

You must have heard that even today half of India’s population lives off agricultural activities. But how true is that? Turns out that estimating how many cultivators and agricultural labourers India has is no easy task. Here’s an attempt by Hindustan Times.

Massive asteroid may have kickstarted the movement of continents

Earth was still a violent place shortly after life began, with regular impactors arriving from space. For the first time, scientists have modelled the effects of one such violent event – the strike of a giant asteroid. The effects were so catastrophic that, along with the large earthquakes and tsunamis it created, this asteroid may have also set continents into motion.

The asteroid to blame for this event would have been at least 37km in diameter, which is roughly four times the size of the asteroid that is alleged to have caused the death of dinosaurs. It would have hit the surface of the Earth at the speed of about 72,000kmph and created a 500km-wide crater.

At the time of the event, about 3.26 billion years ago, such an impact would have caused 10.8 magnitude earthquakes – roughly 100 times the size of the 2011 Japanese earthquake, which is among the biggest in recent history. The impact would have thrown vapourised rock into the atmosphere, which would have encircled the globe before condensing and falling back to the surface. During the debris re-entry, the temperature of the atmosphere would have increased and the heat wave would have caused the upper oceans to boil.

AGU

Donald Lowe and Norman Sleep at Stanford University, who published their research in the journal Geochemistry, Geophysics, Geosystems, were able to say all this based on tiny, spherical rocks found in the Barberton greenstone belt in South Africa. These rocks are the only remnants of the cataclysmic event.

According to Simon Redfern at the University of Cambridge, there are two reasons why Lowe and Sleep were able to find these rocks. First, the Barberton greenstone belt is located on a craton, which is the oldest and most stable part of the crust. Second, at the time of the event, this area was at the bottom of the ocean with ongoing volcanic activity. The tiny rocks, after having been thrown into the atmosphere, cooling, and falling to the bottom of the ocean, then ended up trapped in the fractures created by volcanic activity.

This impact may have been among the last few major impacts from the Late Heavy Bombardment period between 3 and 4 billion years ago. The evidence of most of these impacts has been lost because of erosion and the movement of the Earth’s crust, which recycles the surface over geological time.

However, despite providing such rich details about the impact, Lowe and Sleep are not able to pinpoint the location of the impact. It would be within thousands of kilometres of the Barberton greenstone system, but that is about all they can say. The exact location may not be that important, Lowe argued: “With this study, we are trying to understand the forces that shaped our planet early in its evolution and the environments in which life evolved.”

One of the most intriguing suggestions the authors make is that this three-billion-year-old impact may have initiated the the movement of tectonic plates, which created the continents that we observe on the planet.

The continents ride on plates that make up Earth’s thin crust; the crust sits on top of the mantle, which is above a core of liquid iron and nickel. The heat trapped in the mantle creates convection, which pushes against the overlying plates.

All the rocky planets in our solar system – Mercury, Venus, Earth and Mars – have the same internal structure. But only Earth’s crust shows signs of plate motion.

A possible reason why Earth has moving plates may be to do with the heat trapped in the mantle. Other planets may not have as much heat trapped when they formed, which means the convection may not be strong enough to move the plates.

However, according to Redfern: “Even with a hot mantle you would need something to destabilise the crust.” And it is possible that an asteroid impact of this magnitude could have achieved that.The Conversation

First published on The Conversation.

Asteroids likely source of Earth’s water

Bad Science examples from the media: Indian Express, April 29, 2010

Ice asteroids likely source of Earth’s water: Study

Astronomers have for the first time detected ice and organic compounds on an asteroid, a pair of landmark studies.

The discovery bolsters the theory that comets and asteroids crashing into Earth nearly four billion years ago seeded the planet with water and carbon-based molecules, both essential ingredients for life.

Working separately, two teams of scientists using NASA’s Infrared Telescope Facility in Hawaii found that the 24 Themis, which orbits the Sun between Mars and Jupiter, is literally covered in a thin coating of frost.

It had long been suspected that the massive space rocks that bombarded our planet after the formation of the solar system contained frozen water, but the two studies, published in Nature, provide the first hard evidence.

Still, a mystery remained: How could frozen water persist over billions of years on an asteroid hot enough to vapourise surface ice?

Only if that layer of frost were continually replenished by the slow release of water vapour released from ice in the asteroid’s interior, the researchers reasoned.

In other words, 24 Themis some 200 kilometres (125 miles) in diameter almost certainly contains far more water locked in its minerals than anyone suspected.

===========

This article has many flaws. At the very outset, the headline itself is misleading. Unfortunately the piece has fallen to the common temptation of sensationalising the news with an unholy bargain of the truth. Unlike what the headline implies, the asteroid Themis 24 is very much a solid mass covered with a thin layer of ice and not wholly made out of ice. If you want a sensational title, isn’t it good enough to just say “Asteroids likely source of water on Earth”?

Secondly, the article has been sadly stripped of so many important data points that it fails to make the point. For example, when asking the question “How could frozen water persist over billions of years on an asteroid hot enough to vapourise surface ice?” the writer gives no background to the reader about why is it hot enough to vaporise the surface ice. If the piece of rock is in between Mars and Jupiter then a common man would assume that the surface temperature compared to the Earth (which is much closer to the sun) would be lower. Thus, if Earth can have surface ice, then why can’t an asteroid? Although this logic is flawed in itself, it raises many more questions in a reader’s mind such as, is it because the asteroid has no atmosphere? or is it because it travels at a greater speed than earth? and so on. Also, the mystery question is wrongly posed as it should be ‘millions’ (what authors claim by their modelling) instead of ‘billions‘.

Thirdly, there is no mention of the timeline in any of the Nature articles and points to the classic error of ‘making up information’ for the sake of it. I suppose that the writer has come to a conclusion (if at all he has given this article any thought) that first sign of life was seen 3.5 billion years ago thus obviously, water would have come to Earth sometime before that. Thus, the use of “nearly four billion years ago.”

Fourthly, “Only if that layer of frost were continually replenished by the slow release of water vapour released from ice in the asteroid’s interior, the researchers reasoned.” This sentence will only confuse the readers ever more. Why does the ice in the interior of the asteroid sublime only to deposit back as frost on the surface? The more probable reason, as mentioned by the researchers, is ‘impact gardening’ which is the phenomenon of small bodies hitting the surface of the asteroid and churning up the subsurface ice. The impact might also be able to trigger the sublimation of subsurface ice, the authors believe. There is no mention of that in this article!

Finally, “24 Themis — some 200 kilometres (125 miles) in diameter — almost certainly contains far more water locked in its minerals than anyone suspected” is absolutely wrong. Humberto et. al clearly mention that “Although many asteroids show absorptions in this region, they are well matched by hydrated minerals. The spectral features of 24 Themis are significantly different from those in other asteroids and we show that it is accurately matched by small ice particles.” The point the authors make is exactly opposite. There isn’t hydrated minerals or ‘high concentration hydrated minerals’ that the authors observe but water in it’s free form as small ice particles.

As science writers we have the responsibility to communicate science correctly and such obvious mistakes will only create more doubts and lead the readers astray.

ResearchBlogging.org Rivkin, A., & Emery, J. (2010) Detection of ice and organics on an asteroidal surface. Nature, 464(7293), 1322-1323. DOI: 10.1038/nature09028 & Campins, H., Hargrove, K., Pinilla-Alonso, N., Howell, E., Kelley, M., Licandro, J., Mothé-Diniz, T., Fernández, Y., & Ziffer, J. (2010) Water ice and organics on the surface of the asteroid 24 Themis. Nature, 464(7293), 1320-1321. DOI: 10.1038/nature09029