Category Archives: Real World Problems

Could asteroids bombard the Earth to cause a mass extinction in 10 million years?

Sanna Alwmark, Lund University and Matthias Meier, Swiss Federal Institute of Technology Zurich

Scientists have spent decades debating whether asteroids and comets hit the Earth at regular intervals. At the same time, a few studies have found evidence that the large extinction events on Earth – such as the one that wiped out the dinosaurs 66m years ago – repeat themselves every 26m to 30m years. Given that there’s good evidence that an asteroid triggered the dinosaur extinction, it makes sense to ask whether showers of asteroids could be to blame for regular extinction events.

The question is extremely important – if we could prove that this is the case, then we might be able to predict and even prevent asteroids causing mass extinctions in the future. We have tried to find out the answer.

Today, there are approximately 190 impact craters from asteroids and comets on Earth. They range in size from only a few meters to more than 100km across. And they formed anywhere between a few years ago and more than two billion years ago. Only a few, like the famous “Meteor crater” in Arizona, are visible to the untrained eye, but scientists have learned to recognise impact craters even if they are covered by lakes, the ocean or thick layers of sediment.

Meteor crater, Arizona.
Kevin Walsh/wikipedia, CC BY-SA

But have these craters formed as a result of regular asteroid collisions? And if so, why? There have been many suggestions, but most prominently, some scientists have suggested that the sun has a companion star (called “Nemesis”) on a very wide orbit, which approaches the solar system every 26m to 30m years and thereby triggers showers of comets.

Nemesis would be a red/brown dwarf star – a faint type of star – orbiting the sun at a distance of about 1.5 light years. This is not an impossible idea, since the majority of stars actually belong to systems with more than one star. However, despite searching for it for decades, astronomers have failed to observe it, and think they can now exclude its existence.

Difficult dating

Yet, the idea of periodic impacts persists. There are other suggestions. One idea is based on the observation that the sun moves up and down slightly as it orbits the galaxy, crossing the galactic disk every 30m years or so. Some have suggested that this could somehow trigger comet showers.

But is there any evidence that asteroid impacts occur at regular intervals? Most research so far has failed to show this. But that doesn’t mean it isn’t the case – it’s tricky getting the statistics right. There are a lot of variables involved: craters disappear as they age, and some are never found in the first place as they are on the ocean floor. Rocks from some periods are easier to find than from others. And determining the ages of the craters is difficult.

A recent study claimed to have found evidence of periodicity. However, the crater age data it used included many craters with poorly known, or even incorrect and outdated ages. The methods used to determine age – based on radioactive decay or looking at microscopic fossils with known ages – are continuously improved by scientists. Therefore, today, the age of an impact event can be improved significantly from an initial analysis made, say, ten or 20 years ago.

Another problem involves impacts that have near identical ages with exactly the same uncertainty in age: known as “clustered ages”. The age of an impact crater may be, for example, 65.5 ± 0.5m years while another is be 66.1 ± 0.5m years. In this case, both craters might have the same true age of 65.8m years. Such craters have in some instances been produced by impacts of asteroids accompanied by small moons, or by asteroids that broke up in the Earth’s atmosphere.

The Manicouagan crater in Canada seen from the International Space Station/
NASA/Chris Hadfield

The double impact craters they produce can make it look like they hit a time when there were lots of asteroid impacts, when actually the craters were formed in the same event. In some cases, clustered impact craters are spaced too far apart to be explained as double impacts. So how could we explain them? The occasional collision of asteroids in the asteroid belt between Mars and Jupiter might trigger short-lived “showers” of asteroids impacting the Earth. Only a few of these showers are necessary to lead to the false impression of periodicity.

Fresh approach

In contrast to previous studies, we restricted our statistical analysis to 22 impact craters with very well defined ages from the past 260m years. In fact, these all have age uncertainties of less than 0.8%. We also accounted for impacts with clustered ages.

Our article, recently published in Monthly Notices of the Royal Astronomical Society, shows that, to the best of our current knowledge, asteroid impacts do not happen at regular intervals – they seem to occur randomly.

Of course, we can’t be sure that there isn’t any periodicity. But the good news is that, as more impact craters are dated with robust ages, the statistical analysis we did can be repeated over and over again – if there is such a pattern, it should become visible at some point.

The ConversationThat means that there is presently no way to predict when a large asteroid collision may once again threaten life on Earth. But then when it comes to facing the apocalypse, maybe not knowing is not so bad after all …

Sanna Alwmark, Doctoral Candidate of Lithosphere and Biosphere Science, Lund University and Matthias Meier, Swiss National Science Foundation Ambzione Fellow in Geochemistry, Astrophysics, Swiss Federal Institute of Technology Zurich

This article was originally published on The Conversation. Read the original article.

Can industrialists publish scientific papers?

This forum is part of the MISTA conference series web site.

If you look at the scientific literature you might think that most of the work that is reported is theoretical in nature. It depends, of course, how you define theoretical but you would probably be right. And the scientific community makes no apologies for this as, by its nature, it is what they do.

However, there is a need for practitioners to report their results and experiences in the scientific literature so that the community is aware of real world applications and what is happening outside of the theoretical world that many academics occupy.

Indeed, some scientific journals welcome articles that essentially describe case studies so that we can all learn from these experiences. Some of the journals that spring to mind are the Journal of the Operational Research Society, Interfaces and the Journal of Scheduling (if you know of others, please feel free to post them as a reply to this post)

The benefits of publishing in the scientific literature include the following:

  1. It gets your message out there, so that others might benefit from it.
  2. It places a marker in the sand, that indicates that you reported this work before anybody else (in a scientific sense).
  3. You might be able to use the scientific paper in your marketing material to show that the approaches you are using have been validated by the scientific community.
  4. It might enable engagement with the scientific community which might improve your systems even more.
  5. It might prompt interest from the media who regularly look at what is being published in the hope of getting a story.

The barriers to industrialists publishing in the scientific literature include:

  1. You may not know what the scientific literature is, let alone how to access it.
  2. You simply don’t have enough time, or maybe even the motivation, to write a scientific paper.
  3. Even if you are able to read at a scientific paper, it might not be obvious how to go about writing one.
  4. If you have an idea for a paper, how do you go about getting it published, after you have written it?
  5. Of the thousands of journals out there, how do you choose which one to target?
  6. If you submit a paper to a journal what do you do if you get critical reviewer comments or, even worse, the paper is rejected?

So, how can the industrial community write scientific papers, and be better represented in the scientific literature?

Here are just a few ways that might work for you:

  1. Respond to this post if you are interested in accessing the scientific literature. There might be people reading this forum who would be willing to work with you to help get your work published.
  2. Google (other search engines are available) your idea and see if anything comes up which is associated with a university. Then try contacting the academic who seems to be involved in that project.
  3. Take a look at Google Scholar (as opposed to just Google). This just searches scientific papers and you might find an academic who has expertise in your area of interest.
  4. Most universities have a Business Engagement department. Try contacting them.
  5. The MISTA conference series is interested in seeing more papers and presentations that describe real world problems, and solutions to those problems. If you are interested in discussing such a paper, please feel free to contact one to the conference chairs. The worst they can say is that the suggestion is not suitable for MISTA.

Writing a scientific paper for the first time can be daunting (in fact it is!) but it could be just what your company needs to promote itself to a wider community that you probably don’t have access to otherwise. And, if you need help and advice, then there are plenty of people around who would be more than happy to assist.

Respond to this forum post and see if it leads to anything.