What can we learn from comets and asteroids, the universe’s most misunderstood objects?
According to Natalie Starkey, a space scientist who was a co-investigator for the European Space Agency’s Rosetta Mission, quite a bit. In her new book, “Catching Stardust” (Bloomsbury Sigma, 2018), Starkey aims to reach everyone from scientists to science enthusiasts and explain what makes asteroids and comets so strange and remarkable and why it’s so important to study them. Often confused for one another, comets and asteroids have been misunderstood for centuries. But comets aren’t just dirty snowballs and, as Starkey explained in her book, we now know that asteroids can look just as much like comets as comets can look like asteroids.
Space.com talked with Starkey about the evolving definitions of comets and asteroids, how a comet might have sparked modern civilization, the lucrative prospects of space mining, and whether we’re prepared for an asteroid impact — according to Starkey, we aren’t.
Natalie Starkey: Yes. I mean, that is one of the big things I wanted to get across in this book.
[There was a] turning point with the Stardust Mission: [The solar system object it visited] was a comet, we knew it was a comet, it looked like a comet, it acted like one, it had a beautiful coma, or tail, out the back and everything. But actually, when they got the samples back, they found out that they looked a little bit like an asteroid — what we thought should be in an asteroid.
It really turned around the thinking on the classical view of how these objects formed and where they formed. There’d always been inklings of it in the scientific literature, but we had no real proof [of] what was actually in these objects.
We can still go with that classical view that comets are cold and they live in the far outer reaches of the solar system, and asteroids are kind of the hot, leftover objects from the planet- building phase. [However] there is a lot of overlap still. We have objects that sit right in the middle that are as much comet as they are asteroid. So, I think it’s still useful to have the definitions. It’s important to know if they’ve got a tail, if they’ve got ice, and if we therefore think they’re an asteroid or a comet. It isn’t that simple but we still need those definitions because, inherently, they are different objects and they did form in different locations in the solar system and probably at different times.
Space.com: Early in the book, you mention that a comet impact on Earth could have sparked agriculture and human civilization — could you speak a bit more to that?
Starkey: This was something I found a little bit after I read [proofread] the main draft. I came across this, and it was a really interesting idea — it’s not proven, I have to add. It was a comet that had been observed … it was depicted in stone drawings in temples. They interpreted this to be something like a comet in the sky back in the times, and it looks like this comet collided with the Earth. And when we go back through the ice cores in Greenland, it actually shows that this event coincided with a sudden drop in global temperature.
The idea really is that it kind of forced communities to come together because they needed to maintain crops and work out how they were going to feed themselves. The idea is that, if that hadn’t happened, then the modern age of agriculture couldn’t have started, because they needed that push, that sudden drop in temperature, which looks like it came from the comet impact.
Space.com: Do you feel that we, right now, as a society, are prepared in case of an asteroid impact?
Starkey: I would say no. I think most people are not really aware that we could get impacted by an asteroid or comet. But at the same time, the chances of us being impacted in the next 100 years is almost zero. We know that we’re pretty safe for now. So, it’s one of those problems which I tried to kind of get across in the book, that although we really don’t need to worry about it for ourselves, we need to worry about it for our descendants, because almost certainly, they are going to be affected. Maybe not the next generation or even the one after that, but, you know, somewhere down the line, we’re going to be affected by an impact from space.
I think at this stage, at the moment, if we had a decade’s notice that something was coming for the planet, we could potentially launch a mission in that time frame to do something about it. I think if we had less than a decade’s notice, it seems at the moment that we don’t have the technology in place to currently protect ourselves.
Space.com: If you could have people who read this book take just one thing away from it, what would that be?
Starkey: It’s got to be that we need to explore the solar system more with spacecraft.
I don’t necessarily think we need humans to go out there at the moment, but that’s my personal belief. At the moment, if we can make robotic instruments that can go out into space and explore…We can achieve so much. We’ve learnt so much about so the solar system just since the 1950s when we first started exploring it. And I think the only way for us to understand our planet and to understand the planets around us, how it formed, how humans got to Earth, or how organic material got to Earth, how we got our water, how everything formed, the only way to do that is to go out into space to explore these objects.
We need to support space missions — of course I’m going to say that, because I’m a space scientist — but I really think it’s important that we understand where we came from.