asteroid – Akshat Rathi

Asteroids are fascinating – not just because they can destroy humanity

February 4, 2015February 4, 2015 Akshat RathiLeave a comment

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.

The 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

September 7, 2014 Akshat RathiLeave a comment

1. Why India’s fiercest anti-GM activist has found a big following abroad

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

April 14, 2014April 14, 2014 Akshat RathiLeave a comment

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.

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.

First published on The Conversation.