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It looks unremarkable, but this system at the end of a runway can stop an aircraft overrun from becoming a disaster Plus: the hunt for falling satellites and a new space telescope set to explore the universe.
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00:06For anyone watching this show in an airplane high above the clouds, flying at high altitude
00:12is very safe.
00:15It's the landing that, statistically speaking, is where an accident is more likely to take
00:20place.
00:24All that and more on this edition of DW Science Show.
00:28Welcome to Tomorrow Today.
00:34A close call.
00:36The aircraft landed safely, but pilots and passengers aren't always as lucky as they were
00:41on the island of Zyd that day.
00:43Sometimes disaster is only meters away.
00:46Warsaw, September 14, 1993.
00:50Lufthansa Flight 2904 landed on a rain-soaked runway.
00:53The aircraft aquaplaned and ran out of room to stop.
00:56It crashed into an embankment.
00:59Two people died.
01:01After this and other serious accidents, aviation authorities concluded that runways should have
01:05a safety area, extending at least 300 meters beyond the runway.
01:12One example is the 2005 Air France accident.
01:16The aircraft overshot the runway in rain and difficult conditions.
01:20It finally came to a stop 300 meters beyond the runway.
01:25As air traffic grew, the number of accidents increased, too.
01:29Like here in Miami.
01:32And in Alaska.
01:34Runway overruns are one of the most common aviation accidents.
01:41But what if an airport doesn't have enough space for a safety area?
01:45That's the problem the U.S. Federal Aviation Administration set out to solve.
01:50Its answer was EMAS, the Engineered Materials Arresting System.
01:55And it looks surprisingly simple.
02:00These are foam glass stones made entirely from recycled glass.
02:05They're very light and brittle, a lot like pumice.
02:08If an aircraft rolls onto our EMAS, there's a braking effect.
02:14If an aircraft overshoots the runway, it rolls onto a thin concrete layer that breaks under its weight.
02:20The wheels sink into the foam glass, slowing it to a stop.
02:26Zabrücken Airport's 85-meter EMAS bed can stop an aircraft traveling at up to 102 kilometers an hour.
02:33Larger systems can handle speeds of up to 130 kilometers an hour.
02:40The system is barely visible from the cockpit.
02:44Many pilots have never encountered one.
02:46But if an aircraft overruns the runway, keeping straight is key.
02:51Turning away from the arrestor bed could mean missing the chance to stop safely.
02:59Zabrücken became Germany's first airport to install EMAS in 2019.
03:03It's still the country's only airport with a system.
03:09So far, its only visitor has been a fox.
03:15Our runway is a bit like an aircraft carrier.
03:18The ground drops away steeply at both ends of the runway, so we're working with only two kilometers.
03:24But they're two very, very safe kilometers.
03:32An accident in Brazil showed what can happen.
03:35In 2007, an Airbus 320 overshot the runway at Sao Paulo's Cangones Airport.
03:41It slid down a slope and crashed into an air cargo building.
03:45199 people died.
03:47The runway had no EMAS system.
03:51These recordings from Key West and Boca Raton show the difference EMAS can make.
03:56The FAA has documented more than 25 successful EMAS stops in the U.S.
04:02Everybody walked away unharmed, and only one aircraft suffered serious damage.
04:07Today, Swedish company Runway Safe is the only producer of EMAS systems.
04:12It also supports California's Burbank Airport.
04:14So Burbank had an overrun with a 737 in about the year 2000, and it went over the fence into
04:24a gas station.
04:25And the airport decided to buy the gas station, close it down, and install EMAS.
04:31And a decade later, there was almost the same thing happening.
04:36But this time, the 737 was arrested by the EMAS system.
04:42Two overruns at Burbank with very different outcomes.
04:45The first aircraft was destroyed.
04:48The second, in 2018, was stopped by EMAS and returned to service.
04:53Saarbrücken's system cost over 4 million euros.
04:56A new ATR passenger aircraft is over 20 million.
04:59Yet Saarbrücken is still the only airport in Germany with EMAS.
05:03In our assessment, we identified 8 out of 29 major German airports
05:08that don't provide the full, obstacle-free safety area on all runways.
05:13At those airports, we believed installing EMAS would make sense.
05:18Stopping a runway overrun from turning into a catastrophe.
05:23Konkonas has added that extra layer of protection.
05:26In 2022, it became the first airport in South America to install EMAS.
05:33Eventually, every flight comes to an end.
05:39And that's also true for satellites.
05:46It all starts in Frankfurt.
05:49Three space transport researchers embark on a mission halfway around the world.
05:55They're going satellite hunting.
06:01Preparations actually began in Stuttgart at the university's Institute of Space Systems.
06:06For years, the team has used a plasma wind tunnel
06:10to study how materials melt and vaporize as spacecraft fall back to Earth.
06:16Now they're trying to find out what really happens when a satellite burns up.
06:29Most satellites have to be brought down within five years at the latest.
06:34They burn up, but are they really gone?
06:36Do parts reach the ground?
06:38We now have models that predict what happens,
06:41and measurements help us see if those predictions are right.
06:45The researchers want to know what survives re-entry, what doesn't, and why.
06:51The answers could influence the design of future satellites.
06:55And they matter here on Earth.
06:57In March 2024, part of a discarded ISS battery pallet crashed through the roof of a house in Florida.
07:04On the right is a replica used in lab tests.
07:07Even carefully planned re-entries can go wrong.
07:11In 2004, a NASA capsule crashed into the Utah desert.
07:16As more satellites are launched, more and more are burning up overhead.
07:21What do they leave behind in the atmosphere, and does that affect the climate?
07:25The team's measurements could help answer that question.
07:31ESA is also studying satellite re-entries that can be predicted with precision.
07:38The Stuttgart researchers have a long journey ahead of them.
07:42Their observation flight will leave from Tonga in the South Pacific.
07:46The remote region is often chosen for re-entries,
07:50keeping any surviving debris far from populated areas.
07:54One famous example, Russia's former space station Mir in March 2001.
08:00Its re-entry left behind some streaks of light visible from Fiji and nothing else.
08:06A business jet, capable of flying at over 15.000 meters,
08:11has been equipped as a flying observation station.
08:14In September 2024, an earlier observation campaign produced these recordings.
08:20This time, the researchers hope to collect even better data.
08:25From the aircraft, they'll track satellite re-entries using a range of scientific instruments,
08:30including 28 camera systems developed in Stuttgart.
08:35We've actually got five cameras here, each doing something different.
08:39The small cameras at the top use different color filters,
08:42allowing us to isolate specific parts of the spectrum.
08:47And the long assembly underneath has a single camera,
08:51which we want to use to record the complete spectrum of light.
08:56The mix of colors, coming from the glowing satellite.
09:03The re-entry will happen during the daytime,
09:06so this camera will capture how that light changes from moment to moment.
09:15Unlike a normal video camera, each pixel here works independently.
09:19It only reacts when the light at that pixel becomes brighter or darker by more than a certain amount.
09:31The equipment is packed and ready.
09:34Just before departure from Frankfurt, excitement is beginning to build.
09:38First stop, Bangkok.
09:40Then Sydney, Australia.
09:42And then the final destination, Tonga.
09:50We've prepared well and we'll see how it goes.
09:55It's a long way to go for a glimpse of what happens when space comes back to Earth.
10:04They've now arrived in Sydney and are fitting out an aircraft chartered by ESA,
10:09a Falcon 900 business jet carrying specialist cameras.
10:14A final polish of the windows, then take off from Tonga.
10:18Their target is the exact spot where a retired satellite will plunge back through the Earth's atmosphere.
10:24Reaching it is a challenge.
10:27We had to make lots of small corrections to get the timings exactly the way the team needed them.
10:35So it was a whole lot of little precise inputs that is not normally how you fly an aircraft like
10:42this.
10:42It was up about 45 degrees and it was sort of coming towards the nose of the aircraft,
10:48but obviously a lot further away.
10:51T minus one minute.
10:52Just before re-entry, the tension is palpable.
10:56Wonderful.
10:57Now?
10:59Then the satellite appears, unusually close.
11:02The onboard cameras record it all.
11:04For the Stuttgart researchers, it's the moment they've been chasing.
11:08Yeah!
11:09Oh yeah!
11:10Oh yeah!
11:11Woo!
11:12It's going down here.
11:13It's going down.
11:14It's going down.
11:15Spectacular images captured over the South Pacific.
11:19Even in its final moments, the satellite is still transmitting telemetry, relayed to the European Space Operations Center in Darmstadt.
11:28As it descends, the trajectory begins to flatten, a sign it's moving deeper into the atmosphere.
11:37Then it's back to Tonga.
11:39A first look at the recordings confirms the mission was a success.
11:4629 of 30 instruments recorded data.
11:49Every camera picked up a huge cloud of fragments.
11:52In all, two terabytes of images, video, and spectral data.
11:57Filth material, video, spectral data.
12:01Helping researchers improve satellite design and better understand how burning space debris affects the atmosphere and the ozone layer.
12:11But not everything that ventures into space ends up as space junk.
12:15Like the Roman Space Telescope, our new eye on the sky, with technology made in Heidelberg.
12:24The Max Planck Institute for Astronomy in Heidelberg has contributed to major space missions, including the James Webb Space Telescope.
12:34Now NASA has again turned to the Institute for key parts of Roman's coronagraph.
12:40One goal of Roman is to study planets beyond our solar system.
12:44The coronagraph will help make some of those exoplanets visible directly.
12:54Imagine Earth beside the Sun, seen from outside our solar system.
12:58Earth would be very faint.
13:00To see it, you'd have to block out the Sun's light.
13:04That's what the coronagraph does.
13:08The Heidelberg mechanisms move filters, masks, and mirrors into position.
13:13Special masks block glare, while shape-changing mirrors suppress stray light.
13:18The instrument can reveal planets up to 100 million times fainter than their stars.
13:26The coronagraph is very complex and costs half a billion euros.
13:29It's probably the most complex optical instrument ever built.
13:34The components were tested to ensure they could withstand radiation, extreme temperatures, and launch vibrations.
13:42Oliver Krause personally delivered the instruments to the United States in a sealed, dust-free container.
13:48The completed coronagraph reached NASA's Goddard Space Flight Center in 2024.
13:54KAUSA was also in Florida for the August 2026 launch, which went smoothly.
14:02We're proud to be part of the Nancy Grace Roman mission in Heidelberg.
14:07We supplied six mechanisms that move the coronagraph's optical elements, and we're confident they'll work.
14:15Watching the launch was wonderful.
14:19The solar panels, antenna, and aperture cover, all deployed successfully.
14:27Roman will travel nearly one million miles away from Earth to Lagrange Point L2
14:32and begin transmitting imagery and data back home that will contribute to world-changing science,
14:37along with all of the captivating imagery like we see from Hubble and James Webb.
14:44I have no doubt that Roman will become a household name alongside those great instruments of discovery.
14:50Roman is expected to reach its destination in December 2026,
14:54with first scientific images due in early 2027.
14:58Heidelberg scientists hope their technology will help us better understand worlds beyond our solar system.
15:05When we capture the spectra of exoplanets, we can identify molecules and atoms.
15:12Their atmospheres can also offer clues about what's happening inside the planets.
15:17To me, exotic means unlike our solar system, different, almost unimaginable.
15:23Water worlds, lava planets, things that sound like science fiction.
15:30More than 6,000 exoplanets have been found, and Roman could discover 100,000 more.
15:35It's field of view is about 100 times larger than Hubble's, allowing it to survey vast areas of the sky.
15:48Nancy Grace Roman, known as the Mother of Hubble, was NASA's first chief of astronomy.
15:54Now the telescope that bears her name could help reveal thousands of new worlds across our galaxy.
16:04And here's another crew that's reaching for the sky.
16:13Most students spend their time studying.
16:16For five years now, this group has spent its spare time testing rocket engines.
16:24Making its own rocket fuel and casting its own rocket nozzles.
16:34They've built rocket after rocket, even traveling to the United States, all in pursuit of a dream.
16:44Our ultimate goal is to reach the Karman line 100 kilometers up, and bring the world altitude record home to
16:50Bremen.
16:53What we're planning is definitely something no student team has ever pulled off in quite this way before.
16:59The Bremen team wants its homemade rocket, Transcendence, to reach the Karman line, the threshold of outer space.
17:07But reaching 100 kilometers isn't enough.
17:10To break the student altitude record, they'll need to climb even higher, to 103.6 kilometers.
17:18It's an ambitious goal.
17:20To keep the project alive, the students cover much of the costs themselves.
17:26And right from the start, they faced setbacks.
17:30In 2023, they took their first rocket to a competition in Portugal.
17:34But the judges found fault with the construction, and refused to let it launch.
17:41They had to pack up and go home.
17:47A year later, they got another chance.
17:50Launch sites are much cheaper in the United States than in Europe.
17:54So a group headed to California's Mojave Desert.
18:02There, finally, they got their breakthrough.
18:10The Bremen team successfully launched its first rocket, Phoenix.
18:21It's soared nine kilometers into the sky, and since then, they've kept pushing forward.
18:27In 2025, and again in 2026, the team launched near Bremen.
18:34These flights only reached about one kilometer.
18:40But they weren't chasing records.
18:43They were gathering data for their next big goal.
18:55What if other airborne machines and devices could help solve problems here on Earth?
19:00We've certainly got challenges to spare.
19:03Trees and forests, for example, are suffering under rising temperatures.
19:07Researchers are looking to help.
19:12A forest from the sky.
19:15This drone drops seeds.
19:17Tree seeds, just as trees do themselves.
19:20But the drone is much faster and more flexible.
19:27We're out of time.
19:29Forests store carbon, give us places to unwind, supply timber, shelter wildlife, and much more.
19:35With climate change, we need them as allies, so we have to reforest fast.
19:42The drone can sow a hectare in about 10 minutes, far faster than a planting crew.
19:47It can reach places people can't.
19:49And once programmed, it works almost by itself.
19:54Ole Seidenberg developed the idea with two friends.
19:58In the town of Lüdenscheid in western Germany, they launched a pilot project in 2021.
20:05The land belongs to Gabriel von den Busche.
20:08He owns this forest, or what the bark beetles left of it.
20:12It's 2,000 hectares in all.
20:15He had high hopes the drone could restore his woodland.
20:18But the first field trial showed it wouldn't be that simple.
20:24We dropped Douglas fir seed pellets on a fairly exposed, south-facing slope.
20:29It looked much like this bare ground.
20:33What we couldn't have foreseen was just how dry 2022 would be.
20:38The drought left the surface layer hard as a board, so the seeds in the ground didn't stand a chance.
20:49It was a hard lesson for the forest owner and for Ole's team.
20:53Simply scattering tree seeds wasn't enough.
20:56The real challenge wasn't the drone, it was the soil.
21:05Without shrubs and trees for shade, the sun beats straight onto the ground.
21:10Surface temperatures can climb to 70 degrees Celsius.
21:14Mosses and other ground cover dry out, and much of the life in the soil disappears.
21:20Even the remaining moss can become a problem.
21:26We quickly found that a pellet landing on moss might germinate beautifully.
21:31But the seedling can't push its roots through the moss.
21:36So ideally, we always need contact with the mineral soil.
21:41This dark, almost black-brown layer here, so the seedling can take root, survive and grow.
21:50The verdict from the first trials was clear.
21:53Too few seeds sprouted and survived.
21:56The team had to rethink the process from the ground up.
22:02That was a real disappointment.
22:05We want to deliver a forest for the owners.
22:08And that motivated us to keep working, to adjust and improve whatever we could.
22:17We borrowed an idea from farming.
22:20Farmers place seeds a few centimeters below the surface, then tamp the soil down again.
22:26That gives the seed the best possible contact with the soil.
22:33But how can you do that in a forest? A drone can't.
22:37They needed a completely different approach.
22:40Eighteen months later, they had one.
22:42Working with a specialist partner, they brought a farming technique into the forest.
22:48The result is this specially adapted tracked machine.
22:55In a single pass, it loosens the soil, sows the seeds and firms the ground down again.
23:07There are other advantages. We can sow larger seeds like these acorns.
23:13Ecologically, that's great.
23:16We can get a whole range of tree species into the ground.
23:20Another big advantage is that a drone can't fly through dense areas like these.
23:25But the tracked machine can drive through easily, helping us transform the forest.
23:34Building more resilient forests means moving away from monocultures and creating diverse,
23:40mixed woodland.
23:41Direct seeding is a well-established method and has advantages over planting nursery-grown trees.
23:47A study by Bavaria's State Institute of Forestry shows why.
23:53Trees grown directly from seed usually develop strong, natural root systems.
23:59But when it comes to nursery-grown trees, 71 percent have stunted, poorly developed roots.
24:08Over time, Ziemann and his colleagues learned another lesson.
24:12Their original seed coating, known as pelleting, wasn't doing enough to help the seeds germinate.
24:23Our old pellets contained a lot of clay. We found that it restricted air flow,
24:28leaving the seed without enough air to breathe.
24:32So we switched to cellulose.
24:37Now the seed can breathe freely, and the coating also draws water from the soil, like a sponge.
24:44The cellulose channels that water straight to the seed.
24:52This year Gabriel von den Busche is trying the new direct seeding method with the tracked machine.
24:59It's much faster and more effective than sowing by hand.
25:06We want to try different methods side by side.
25:09This is a first for our business.
25:12We've never done anything like it.
25:15It'll be fascinating to see how the trees develop.
25:18In 40 years, will they be more resilient than planted trees?
25:23We're trying to learn.
25:25I can't say yet whether it'll work, but nothing ventured, nothing gained.
25:32Here, on the drone-seated slopes, the tracked machine could still help fill the gaps.
25:38After years of trial and error, these nearly bare hillsides may become a diverse, resilient woodland again.
25:49And that's all for now on DW's Science Show.
25:53Thanks for watching, and see you again soon on Tomorrow Today.
25:58Goodbye.