Our Place in Space: Breakthrough Starshot

Hello, friends!  Welcome to Our Place in Space: A to Z!  For this year’s A to Z Challenge, I’ll be taking you on a partly imaginative and highly optimistic tour of humanity’s future in outer space.  If you don’t know what the A to Z Challenge is, click here to learn more.  In today’s post, B is for…


So it’s several hundred years into the future.  Human civilization has spread out across the Solar System.  Large numbers of people are living on the Moon and Mars.  We even have successful colonies on Venus and Mercury (more on that later this month) and a few smaller settlements on the various moons of the outer Solar System.  Does this mean we’re done exploring space?  Heck no!  There’s still plenty more outer space stuff to explore!

Just as NASA scientists here in the 21st Century send robotic space probes to our neighboring planets, scientists in the future will be keen to send robotic probes out to neighboring star systems.  And the model for a robotic mission to another star system already exists.  In 2016, venture capitalist Yuri Milner, theoretical physicist Stephen Hawking, and Facebook C.E.O. Mark Zuckerberg announced funding for a new research project called Breakthrough Starshot.

The idea is to build a swarm of teeny-tiny space probes, use high energy laser pulses to accelerate these probes straight out of the Solar System, and then sit back and wait for our probe swarm to transmit data back from another star system.  Specifically, Breakthrough Starshot wants to visit Proxima Centauri, the nearest star system to our own.  Proxima Centauri is known to have at least one planet, an Earth-sized world known as Proxima b.

Get it?  Because the C.E.O. of Facebook is involved in this project!

Could we actually build space probes that small?  Well, computer chips are pretty gosh darn small at this point, and they keep getting smaller.  So do cameras and other advanced electronic devices.  So yeah, this part of Breakthrough Starshot’s plan seems plausible enough.

What about that whole high energy laser pulse thing?  That part does seem more speculative to me, but experiments in Earth orbit have shown that light sail technology does work.  Just as the sail on a sailboat catches the wind, a light sail can catch light and use that light-pressure to propel a spacecraft through space.  A high energy laser aimed at a light-sail-equipped space probe… yeah, that sounds plausible to me, too.

Of course, a lot could go wrong with a space probe traveling through interstellar space.  That’s why we’d send a swarm of these things, rather than just one.  Most of the probes probably won’t make it to Proxima b, but the few that do survive the trip will send us some spectacular images and data.

Personally, I don’t like seeing headlines predicting that Breakthrough Starshot will be launching by such and such date (typically, a date in the late 2020’s or early 2030’s).  Breakthrough Starshot does seem to be founded on good science.  It’s the kind of program that really could work, someday.  But is it going to happen in the next ten to fifteen years?  No, I don’t think so.  That seems overoptimistic, in my opinion.

In the more distant future, however, Breakthrough Starshot (or a program very much like it) absolutely could happen.  This sort of thing could definitely work.  And looking ever further into the future, to a time when humans have thoroughly explored our own Solar System, the idea of sending swarms of microchip space probes to neighboring star systems might become routine.

Want to Learn More?

Click here to visit Breakthrough Starshot’s website.  They’ve got lots of information and videos explaining how they intend to get to Proxima b.

I’d also recommend clicking here to see a list of challenges that the Breakthrough Starshot team know they will need to overcome in order to make their plan work.

And for those of you who are looking for some heavier reading, click here to read “A Roadmap to Interstellar Flight,” a scientific paper that essentially serves as Breakthrough Starshot’s founding document.

Touring Proxima Centauri’s Asteroid Belts

Hello, friends!

As you know, sometimes things don’t go according to plan.  For today’s post, I was planning to draw a really pretty picture of a really planet—a planet that astronomers may (or may not) have found in the Proxima Centauri system.  But as I did my research about this possible planet, I realized I needed to draw something else for you first.

As reported in this 2017 paper, temperature readings indicate that Proxima Centauri may have at least one and as many as three asteroid belts.  Based on what I’ve read, it sounds like the presence of these belts has not been definitively proven yet.  But no one seems to be able to definitively disprove them either.

So here is a map of everything we currently know or suspect exists in the Proxima Centauri system.

As you can see, the planet Proxima b is in an extremely tight orbit around its star.  But since Proxima Centauri is much smaller and cooler than our Sun, Proxima b is technically in the star’s habitable zone.  Click here for my post on whether or not Proxima b could actually support life.

Beyond the orbit of Proxima b, we find our first possible asteroid belt.  In that 2017 paper I cited above, this innermost belt is described as the warm dust belt.  It appears to be located approximately 0.4 AU away from its star (roughly equivalent to the orbit of Mercury in our Solar System).

A little farther out, we find a second possible asteroid belt, which the authors of that 2017 paper describe as the cold dust belt.  Remember: we suspect these dust belts exist because of temperature measurements, hence the names.  The cold dust belt appears to be spread out between 1 AU and 4 AU (roughly equivalent to the space between the orbits of Earth and Jupiter in our Solar System).

And then farther out still, there appears to be a third belt, referred to as the outer dust belt (in my opinion, it should have been named the colder dust belt).  The outer dust belt appears to be located approximately 30 AU away from its star (roughly equivalent to the orbit of Neptune).

I want to emphasize again: as far as I can tell from my own research, no one has definitively proven or disproven these dust belts exist.  All we have are some temperature measurements that suggest something might possibly be there.

But if all those dust belts do exist, that tells us there should be planets orbiting in the gaps between the belts.  It would take a planet’s gravity to keep those gaps empty.  And now that you know that, I think we’re ready to take a closer look at Proxima c.

Except tomorrow is Insecure Writer’s Support Group day, so our trip to Proxima c will have to wait.  But I promise the wait will be worth it.  Science predicts that if Proxima c really exists, it must be the most gorgeous planet you’ve ever seen!

Next time on Planet Pailly, the unexpected benefits of having your manuscript edited.

How Proxima b Lost Its Ozone Layer

Hello, friends!

Today we’re visiting Proxima Centauri, one of three stars in the Alpha Centauri system, the star system right next door to our own.  And it turns out Proxima has at least one planet.  Not only that: Proxima’s planet is orbiting within the habitable zone.  That planet may have liquid water on its surface, and perhaps even life!

Proxima’s planet, known officially as Proxima b, orbits about 0.05 AU away from its star.  That puts Proxima b closer to its star than Mercury is to our Sun.  But that’s okay.  Proxima Centauri is much smaller, dimmer, and colder than our own Sun, so everything balances out.

But I have bad news.  The temperature might be right for life, but the radiation environment is all wrong.  Proxima Centauri is a very angry little star.  It’s much angrier than our Sun.  Solar flares, solar wind, and solar radiation are a whole lot worse than anything Earth would normally have to worry about.

In March of 2016, Earth-based astronomers observed a “superflare” on Proxima Centauri.  As you can see in the highly technical diagram below, that superflare would have done serious damage to Proxima b’s ozone layer (assuming Proxima b had an ozone layer in the first place).

According to this 2018 paper on ozone loss, if superflares like that are normal for Proxima Centauri, we should expect Proxima b to lose 90% of its ozone layer in just five years (again, assuming Proxima b had an ozone layer in the first place).  Without an ozone layer, incoming ultraviolet radiation would thoroughly sterilize Proxima b’s surface (much like it does on Mars).

And it gets worse.  Earth’s magnetic field deflects a lot of harmful solar and cosmic radiation away.  But according to this 2016 paper on space weather, Proxima b’s magnetic field (assuming Proxima b has a magnetic field) is taking a real beating.  The magnetic field would be badly weakened and compressed.  As a result, Proxima b’s atmosphere would start eroding away, due to the solar wind, and if those UV rays haven’t already killed everything on the surface, all that solar and cosmic radiation would have a chance to finish the job.

Even the most extreme of extremophiles here on Earth would have a tough time surviving on Proxima b.  But the situation is not hopeless.  That 2016 paper on space weather and that 2018 paper on ozone loss both acknowledge that there are still plausible scenarios where life could evolve and thrive on Proxima b.  But in order to do it, the Proxima b-ians must have done one of two things:

  • Life on Proxima b must be very specifically adapted to that radiation environment, or…
  • Life on Proxima b must have found a good hiding place, perhaps deep underwater or underground, where the radiation can’t reach it.

Next time on Planet Pailly, it’s a bird!  It’s a plane!  It’s… oh no, it’s a killer asteroid!!!