Could solar panels in space be the energy source of the future?

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Hello, this is the podcast of Inside Science, first broadcast on the 21st of August, 2025.

I'm Marnie Chesterton.

Coming up on the show, heartbreaking science stories from the siege of Leningrad, how to save a species by hunting it, and Caroline Steele joins me to share this week's science news you need to know.

Hi, Caroline.

Hello!

What have you got for us?

So, turns out one of Jupiter's moons could be a huge dark matter detector.

Birds are as lazy at communicating as we humans are, and I think we should use maths to win at guess who.

That all sounds fantastic.

Before all that, let's talk solar power.

It was way back in 1839 when French physicist Edmond Becquerel first suggested that you could get electricity by shining light on certain materials.

He, alongside many of us alive today, probably would be surprised to learn that by the 2030s it's forecast to be our dominant energy source on this planet.

With such a huge market predicted, it's probably not surprising that scientists are thinking beyond our roofs and fields and calculators.

Even so, solar panels in space?

Well, that's new research out today, making both the financial and environmental case for extraterrestrial solar panels, potentially reducing European reliance on wind and land-based solar power by up to 80%.

Its lead author is Dr.

Wei He, Senior Lecturer in the Department of Engineering at King's College London.

One key challenge for using normal, like renewable energy, which is solar and wind, because they are very intermittent.

Power generation depends on the weather.

So space-based solar power could be a green technology which can have nearly continuous power generation.

Depends on how technology will be developed.

It could never be cost-effective.

It could play a minor part as a complementary to the, you know, like our current solar and winds technology, or it can make a very major role in our system.

So I think there is still great uncertainty, but hopefully this study can open,

you know, this research topic and we can explore more about this exciting technology.

Dr.

Wei He

sounds sci-fi, but is it?

Are we really at the point with solar panels that we're ready to launch them into space?

And will we be trailing the longest ever extension cable back to the planet?

Professor Henry Snaith is the Binks Professor of Renewable Energy at Oxford University, and he joins me now.

So that projection is based on a NASA design for solar energy generation by 2050.

How is this going to work?

If you have solar panels in space, how do you get the energy back to Earth?

So you mentioned about a very long cable.

That would obviously be pretty impractical.

But the way the energy would be transmitted back to Earth is via microwave.

So there would be a big microwave source emitter and microwave receivers on the Earth to then convert that microwave radiation back into electrical energy.

And how workable is this technology?

Well, it's sort of down to economics and need.

So it's questionable.

As the lead author just mentioned, it's uncertain.

There's a lot of uncertainty as to what's going to make sense in 2050.

The bit of work that's been published is sort of pitching the need in terms of the intermittency of renewables.

Actually, the renewable energy, solar and wind, do need storage, but that is other technology that's advancing.

So whether it's economically feasible to put solar in space really depends on how rapidly the storage technologies advance and get cheaper.

Putting things into space is notoriously expensive.

Are you seeing this as at all viable?

So my personal opinion is that solar in space is potentially useful post-2050.

So it's not what's going to help us reach the carbon targets and to get to net zero by 2050.

But it could be important after 2050.

The reason I think it could be important is actually not due to intermittency, because I do believe storage technologies and transmission on the Earth will solve that, but due to the amount of land we do actually need to cover in solar panels.

So just as a very brief statistic, if we want to produce all our power, 100% of our power from solar energy, then we need between 1% to 2% of our land.

That sounds, it is a lot of land, but if you compare it, for instance, to farming, we farm 50% of our land at the moment.

So it's a relatively small fraction.

but still quite significant.

That's feasible.

If we then have an increase in demand for power, which is almost certainly going to happen between now and 2050, then that percentage of land needed starts to increase.

And that's when, in my view, it makes sense to start to really think about putting large arrays in space.

So, for putting solar panels in space, there was some fantastic work that came out recently looking at origami shapes for folding up these solar panels.

And then you put them out and then they kind of spring out into a flat surface.

How big would we need to make these solar panels out in space?

I mean, the total area, so you can consider it in terms of

radiance in space versus on Earth.

You've got more radiance, but it's only sort of under a bright sunlight.

It's let's say it's one.

In space, it's 1.3, but you're in the sun all the time.

So it's like five times as much as it is in terms of over the day or over the year as it is on a typical place on Earth.

Earth.

So that means instead of 1% of the area of the land, let's say, you'd need a fifth of the area of surface of Earth.

But that's, and I don't know how many square kilometers or

the area of the surface of the Earth is.

I could calculate it.

Someone will know.

But it's a lot.

So we're talking about massive areas in space full of solar panels or solar foils.

But I should also point out, you know, solar in space is not new per se.

It's how all the satellites are powered it's been we've had solar power in space since the first satellites were put into space and since the 1950s when the bell labs developed the first silicon cells so we it's not new and in fact solar in space is is accelerating there's more and more satellites and objects going up into space and this whole origami approach is what's used today in terms of you don't want to send a big extended panel up in a spacecraft it has to to be something that's folded up.

So, Henry, back here on Earth, I'm just wondering what other kinds of solar generation might we see coming on board.

Okay, so the technology we use today is predominantly based on silicon.

It's a semiconducting material.

It absorbs light, generates electricity.

This concept works very well, and they're pretty efficient.

Modules are between sort of 22 to 24 percent efficiency.

The next generation of technologies will be based on what we call tandem cells and this is where we stack different materials on top of each other.

So we have multiple solar cells technologies on top of each other and by doing that we can increase the efficiency.

So

the efficiency could in principle go up towards 50% efficiency.

So I'm slightly biased towards one specific material type and that's called perovskite because I've had a lot of work in that area.

And there we can now make tandem cells where we have perovskite actually on top of silicon.

So we use silicon, but add perovskite.

And those cells are now already 35% efficiency.

So what we're going to see is this higher efficiency cell technology starting to be deployed over the next sort of three to five to ten years.

And this will then become the dominant technology.

What that means is the overall power per square metre, per square kilometre, per unit area of solar farm increases.

so we need less land to produce the electricity we need.

Professor Henry Snaith, thank you so much for joining us.

Thank you very much.

In other news, many ecologists believe we are living in an era of human-caused mass extinction.

The African big five, lions, rhinos, buffaloes, elephants and leopards are all under threat, facing the loss of most of their habitat and climate changes that affect what is left.

So it might be a surprise to hear conservation scientist Adam Hart make the case that one way to help them is to hunt them.

Let's hear him out.

I first went to Africa 25 years ago.

Like many, I'd grown up watching nature documentaries.

So it was a shock to land in Malawi and not be greeted by lions lazing in the grass at the airport.

It was only when I got to a friend's remote family farm in Zambia that Attenborough's Africa appeared.

There was the herd of Impala I'd wanted to see.

Under the shade of a tree was a huge male kudu with spectacular spiral horns.

Antelope, snakes, birds, frogs, insects, there was life everywhere.

And for a zoologist like me, it was paradise.

Why, I asked my friend's uncle, was there so much wildlife here and so little elsewhere?

The answer was something I struggled to understand.

You see, the answer was because we hunt.

How, I asked incredulously, can hunting animals, killing them, possibly lead to what I could see all around me?

Well, like so many things, it came down to money.

Hunters from around the world would pay to come to the huge property to hunt.

Some would hunt for meat, but the big money came from trophy hunters, after particularly spectacular antelope.

They would take the skull, horns, and sometimes the whole skin back home.

This meant that the property did far better economically by having wildlife roaming around than it would do with cattle or crops, which was the alternative.

Hunting was a better return than agriculture, And as a consequence, habitat was a better land use than fields and pastures.

And that is the key to understanding the role of trophy hunting in conservation.

It makes habitat and wildlife more valuable than the alternatives.

Trophy hunting was big news ten years ago, when an American hunter killed a lion in Zimbabwe known as Cecil.

Since then there have been countless calls to ban trophy hunting or the import of hunting trophies.

The problem is that those calling for bans seldom have evidence on their their side.

A common statement is that trophy hunting is driving species to extinction, but this simply isn't true.

Recent studies have shown that legal trophy hunting is not a major threat to any hunted species imported to the UK or to any CITES listed species.

In fact, hunting potentially directly benefits at least 20 species and subspecies as well as communities.

It also conserves vast tracts of wider habitat in southern Africa, far more land than national parks cover.

Another statement is that trophy hunting revenue doesn't reach communities.

Yet there are several open letters from communities that rely on trophy hunting income, calling for those considering bans to listen to them and rethink.

Many communities see our attempts to dabble in African conservation as neo-colonial.

I agree with them, it is.

In this debate, well-intentioned outrage has drowned out evidence-based argument.

When, in 2022, a bill was introduced in UK Parliament to ban imports from trophy hunting, analysis conducted by me and other conservationists showed that nearly three quarters of factual claims made in Parliament by supportive MPs were false.

Those calling for bans have embraced misinformation in a way that should greatly concern anyone who values an evidence-based approach to policy or cares about habitat and wildlife.

Trophy hunting is deeply offensive to many and if poorly regulated it can be hugely problematic.

It's very far from perfect, but well regulated trophy hunting is a vital part of the conservation toolkit for nations that are enormously successful in protecting habitat and wildlife, like Botswana, Namibia, Zambia and Zimbabwe.

In a study of conservation effort, four of the five top nations were African hunting nations.

Eight of the top ten have hunting as part of the bigger picture.

The UK for reference?

Well we came 123rd.

In 2019, the Joint Nature Conservation Committee, the government's advisory group on conservation, concluded that, in the absence of trophy hunting in Africa, wildlife populations and local communities are likely to suffer.

We do not see any evidence which suggests that an overall ban on trophy hunting is warranted.

Indeed, much of the evidence suggests that such a ban might have unintended and perverse consequences for wildlife conservation.

Many conservation scientists, including me, agree.

But successive governments seem to prefer optics over facts.

We need better ways to conserve wildlife, but misinformed bans will most likely harm species, reduce habitat, and impoverish communities.

And that means there will be even less of the Africa we know from Attenborough's documentaries left to see.

Be careful what you wish for.

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Professor Adam Hart there.

Are you persuaded?

Do send us your thoughts.

The address is insidescience at bbc.co.uk.

Sticking with thorny conservation dilemmas, what if you could save your life by destroying not only your life's work, but also a common good?

That was the dilemma faced by a group of wartime scientists during the infamous siege of Leningrad during World War II.

Their stories are the subject of a book shortlisted for the annual Royal Society Trivedi Book Prize, which is right up our street.

So over the next six weeks, Inside Science will be hearing from the six shortlisted authors and the judges who shortlisted them.

Beginning with one of the UK's most successful crime writers.

I'm Val McDermott and I'm one of the judges for the Royal Society Book Prize.

The shortlist book I'm representing is The Forbidden Garden of Leningrad by Simon Parkin.

And it's set during the siege of Leningrad, 900 days when the city was surrounded by Nazi troops, was cut off.

There was no food coming into the city.

People were literally dying in the streets of starvation.

And at the heart of the city, there was a seed bank.

And these scientists were determined to preserve this seed bank for posterity because they understood the value of having these seed banks so they could develop new varieties, ones that work better in different climates.

And in spite of the pressures around them, they saved these seeds.

Many of them died in the course of this.

And it raises lots of interesting moral and ethical questions about what people will do when they are absolutely committed to a scientific principle.

I found it really moving

and irresistible, really.

Hi, I'm Simon Parkin.

I'm a British author and journalist and I'm here today at the Millennium Seed Bank.

Behind panelled glass around the perimeter of the room we can see botanists behind the glass tapping out seeds from brown envelopes and then sorting through them with tweezers.

It's pretty amazing seeing the scale of the operation here.

Below us is the vault itself which is behind a huge almost one of those bank vault doors that swings open from heist movies and then yeah the sort of latent life held within them to guarantee the future and I suppose a library of all of the seeds is pretty incredible.

I want to talk to you about your book, which is a crucial part of this story of the science of seed collecting.

I think we should go somewhere a little more quiet and less echoey, though.

We are in the seed bank.

The science of preserving seeds is going on all around us, but not just in this building, in buildings like this all around the world.

And it feels like that's a legacy of the world's first seed

which is what your book is about.

Tell us why you wanted to bring it to life.

This story is not well known at all.

Among seed bankers, most of them know it because it's an inspiring story of how four fathers and four mothers of seed bankers believed in the mission so much that they gave their lives to sustain it.

But among even historians of the Siege of Leningrad, the story is not that well known.

So I really wanted to try to put as much detail and texture in, to try to tell the story on a week-by-week basis.

It's kind of in a way the ultimate dedication to your science that people faced with death and seeds that they could just eat, they chose death.

Tell me a bit more about who worked there.

There are, in fact, you know, physical acts of heroism.

And in fact, on the day that Pavlovsk is invaded by the Nazis, which is where one of the experimental stations is on the outskirts of Leningrad.

Abram Camaraz is there digging out the plots and trying to rescue the potatoes and he's struck by an artillery shell or in the blast of one and knocked unconscious and when he comes to a few hours later he checks his body, sees it's not wounded and

hoists the sack of potatoes onto his shoulder and carries it for two days back to the middle of the city.

The botanists start to put the collection into two rooms in their big institute on the first floor to try and shield them from looters who might be trying to get in to get some food.

And at the same time, they're drawing up a schedule

to essentially be on fire watch.

So, four of the botanists would stand on the roof waiting for German incendiary bombs to be dropped.

And more than 60 bombs are dropped on the roof whenever they're dropped.

One of the botanists will kick it off into the courtyard where other botanists down the bottom will put it out, extinguish it with sand.

Tell me about city gardens because you know you've got a city that's starving, you've got this pioneering institute full of seeds, so it makes sense to plant them.

The winter of 1941 was notoriously harsh, extremely low temperatures,

very difficult to grow anything, obviously.

You're reliant on your grain stores which the Germans specifically target.

So this is why the level of death and starvation in that first winter is so severe and

it certainly touches the life of the Institute itself.

On Christmas Day for example

Nikolai Ivanov, who's the leader of the Plant Institute at that time, knocks on the door of one of his staff members, Alex Stutchkin, opens the door, sees Alex at his desk motionless, goes over, tries to rouse him and it's clear that Stutchkin has died.

A packet of almonds falls out of his hands and spills onto the desk, showing I I suppose, his dedication in these winter months.

Spring comes in 1942, and the arrival of spring changes everything.

You can now start planting out some of the seeds, and the botanists have a renewed sense of purpose.

I'm trying not to well up as you're talking.

It's not, I have to say something, it's not often that you read a science book and it makes you cry, but there's something at the back of your book which is a staff roll call, and it's

names and titles and dates of death and pictures where you could find them of all of the members of the Plant Institute.

How did you find all of that information?

The Plant Institute is still going, it's still there in St.

Petersburg doing its work.

It's notoriously underfunded at the moment and there's sort of lots of financial struggles for them, but it is still there.

So I was planning to visit and do it all in person, but then world events conspired to make that impossible.

But thankfully there was an archivist at the Plant Institute and she very kindly agreed to scan and photograph every document, every list that they had in their archives and to send them to me.

Well it's a fabulous book, a very vivid companion I guess to a

brutal period in history and some very, very brave people.

Simon Parkin, thank you so much for writing The Forbidden Garden of Leningrad.

Thanks.

Caroline Steele is still here in the studio with me and

yeah, you're coming off the back of the siege of Leningrad.

So need some good cheer, please.

This is exciting, spacey news.

So a researcher at the University of Maryland in the US has published a paper proposing that the largest moon in our solar system, which is Jupiter's moon Ganymede, could be a massive dark matter detector.

What?

How?

Well, we're mostly looking for dark matter by looking for tiny lightweight particles that just about interact with normal matter.

And to do this, you have to put huge detectors underground where there's not much sort of background particle noise.

It's really expensive.

We haven't found direct evidence for dark matter yet.

But there are some theories that suggest that dark matter particles could actually be huge, like bigger than a basketball size, but there would be very few of them.

So to detect them, you need a massive surface and a really long period of time.

We basically can't do that experiment here on Earth.

But Ganymede is about twice as big as our moon.

It's basically not changed for the last two billion years.

And if a dark matter particle collided with it, it would leave a distinctive crater, because it could basically pass through Ganymede's icy shell into the ocean below, and it would sort of spew out distinct minerals.

And that sort of trace could last for a really long time, because it's not tectonically active like here on Earth, where a collision would sort of get lost by tectonic plate movement and that kind of thing.

So, according to the paper, upcoming space missions could basically just survey Ganymede and look for evidence of these collisions.

Yeah, just to clarify, this paper hasn't been peer-reviewed or aka torn to shreds by theoretical physicists who are like, what a ridiculous notion.

Yes, let's see what happens when it's peer-reviewed.

I really like it as an idea.

I think it's quite exciting.

Any theoretical physicists listening, do get in touch with the show and tell us what you think.

Shortcuts in bird song, lazy birds.

Yeah, so a new study led by researchers at the University of Manchester and published in PLOS Computational Biology has found that birds appear to follow Zip's law of abbreviation.

What?

Which is basically the idea that more frequently used sounds tend to be shorter, making communication more efficient.

So if we think about human language, what do you reckon the three words we use most are?

Hi,

bi,

mum.

Zero out of three, sorry Marnie.

No.

The three most frequently used words are the,

of,

and and.

They're all really short, right?

Okay, yeah.

And then long words we don't tend to use that often.

Things like photosynthesis, onomatopoeia, we're efficient and we've chosen small, short sounds for things that we use regularly.

Okay, that makes sense.

And it turns out birds follow the same pattern, which also sort of makes sense because birds and humans share similarities in terms of genes and brain structures when it comes to learning to communicate.

And the way the researchers did this is they basically analyzed 600 songs from seven different species of birds and found that more frequently used sort of song phrases were on average shorter.

Moving on, you promised me a game.

Yes, I've got guess who with me in the studio.

I thought we could play it.

I unfortunately only have the dinosaur version, not the version with human faces on, so this might just make this whole section slightly more complicated, but let's give it a go.

I'm such a nerd.

Yeah.

I mean, I say that we're playing board games on Radio 4.

I refer listeners back to our Christmas episode, which was all about board games.

I think we should probably explain how Guess Who Works, just in case anyone hasn't played it.

So you've got two players, and in secret, each player chooses a person, or in this case, dinosaur, from a set of unique characters, and then you take turns asking yes-no questions to try and guess the opponent's secret character.

Now, mathematicians at the University of Manchester have worked out how to maximise your chances of winning.

How would you try and win?

What kind of questions would you ask me?

And I can tell you if that agrees with what the mouse says.

So I'd pick something that half of these, in this case, dinosaurs have.

Yes, perfect.

So the best way to play is to try and split your characters in half each time, except for in four specific situations.

So when either you or your opponent only has one option left, or when your opponent has four possible options left and you have four, six or ten, and then you shouldn't try and split your characters in half.

You should try and split them into say three and one where essentially you're hedging your bets.

You're saying I'm unlikely to win at this point.

I instead have to try and split my characters into uneven groups and really hope that my character lies in the smaller group because that's my best shot at winning.

And then I have an overall strategy which massively increases your chance of winning in general.

But I don't recommend doing this if you want to remain friends with the person you're playing with.

Go on.

Is your dinosaur yellow or are they green?

And the answer to this question is no.

No.

Your dinosaur is a different colour.

It's neither yellow or green.

Is that right?

Yes.

Okay.

So I basically cheated there and got extra information by still asking a question that gives a yes-no answer.

And that's because I sort of introduced three options.

Either, if your dinosaur's yellow, you say yes.

If your dinosaur's a different colour, you say no.

If your dinosaur is green, the person will just totally panic because there's no answer to that question that is correct.

So if you ask that consistently through the game, your chances of winning are two-thirds, which is pretty good.

Okay, I'm not actually listening because what you're saying counts as game instructions and I just don't listen to the instructions.

I think we should just get on and play a game.

Oh great, I'm going to be at a massive advantage because I listen to the instructions clearly.

But I don't think that's something that the Radio 4 listeners need to join us for.

So it is us out of time.

From Caroline and me, bye from you.

Bye-bye.

And from me, bye for now.

You've been listening to BBC Inside Science with me, Marnie Chesterton.

The producers were Claire Salisbury and Jonathan Blackwell.

Technical production was by Matt Chamberlain and Steve Greenwood.

The show was made in Cardiff by BBC Wales and West.

When the right team comes together at the right time, the potential is unlimited.

In the world of biotech, that time is right now.

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