- We live in an age where telescopes have become time machines, letting us see all the way back to the beginnings of our universe.

The Hubble Space Telescope and the James Webb are still giving us stunning images of nebula and galaxies by focusing on small patches of sky, capturing light that traveled billions of years to reach us.

And from the ground, the Rubin Observatory is now beginning to sweep the sky repeatedly, building a moving map of the cosmos in visible light.

- We're seeing a very distorted version of the universe.

- The thing is, even with all that, we're still not seeing 95% of what's there.

The forces that shape the universe, dark matter and dark energy, remain invisible and still not understood.

So what if we sent something up that may just give us a chance to see the rest of it?

Enter the Nancy Grace Roman Space Telescope, NASA's wide-field survey mission, targeted ♪ NASA's wide-field survey mission, targeted ♪ for launch as early as 2026.

♪ Its wide field will deliver an unprecedented flood of data, ♪ so NASA is preparing now with a simulated universe, a ♪ dress rehearsal before Roman ever opens its eye in space.

- Every picture has about two billion photons that are coming ♪ to us from these extragalactic objects.

♪ - For us, survey means lots of data across ♪ the sky very quickly.

♪ It's delivering data for the whole community at once.

♪ ♪ So it's a different mode for NASA.

♪ - And we can take this and transform it.

♪ - Michael Troxel and Dan Scolnic lead Duke's ♪ new space initiative, working with teams around ♪ the world to prepare for Roman's coming survey of the cosmos.

♪ One of the key projects is called Open Universe, ♪ a massive simulation of how Roman's and Ruben's ♪ surveys will see the sky, so scientists can practice with ♪ realistic data and refine their analyses before the ♪ telescope starts.

♪ Roman will sweep huge swaths of sky over about five years ♪ from Lagrange Point II, about a million miles from Earth, near ♪ the James Webb, far above the atmosphere where the view is ♪ sharper, darker, and uninterrupted.

♪ - I mean, the Roman Space Telescope has this ♪ amazing history where it was essentially, ♪ originally, a military spy satellite that was sitting in ♪ a hangar and gathering dust.

♪ Someone in the military, for the National Reconnaissance ♪ Office, reached out to someone high up at ♪ NASA and said, "Hey, any chance that you guys ♪ would be interested in this satellite, instead ♪ of kind of looking down on Earth, you ♪ look up at the stars?"

♪ So we said yes and have been refurbishing it, putting new ♪ instruments on, and that is kind of what we're now using.

♪ That's the Roman Space Telescope.

♪ - Roman will take sweeping infrared pictures of ♪ the universe, seeing light and waves our ♪ eyes can't, and in those waves, it will track how that ♪ light shifts and how gravity bends it across space.

♪ - And then we take every object in that universe and we simulate ♪ all the photons that are going to go through the universe, ♪ around all the structure of the galaxies and clusters of ♪ galaxies, the stars and the Milky Way, and propagate those ♪ photons through this simulated Roman Space Telescope ♪ instrument that we built in our code to basically ♪ build a three-dimensional map of the structure ♪ in the universe.

♪ - NASA started this years ago, building a ♪ simulation of our nearest neighbor, Andromeda, based ♪ on Hubble data.

♪ When Hubble built its portrait of Andromeda, it did it piece ♪ by piece, more than 400 separate frames over three years.

♪ But Roman could cover that same galaxy in just ♪ two wide-field shots.

♪ And that sweeping view comes from Roman's wide-field ♪ camera, made up of 18 separate detectors working together ♪ like a single, giant mosaic.

♪ With that reach, Roman won't just map galaxies.

♪ Researchers hope it will also help reveal what dark matter ♪ and dark energy are doing out there.

♪ Proxler's approach, called weak gravitational lensing, uses ♪ tiny distortions in galactic shapes to trace the ♪ invisible mass in between.

♪ [splash] ♪ - If you think about a pool on a hot summer day, and you ♪ look down at the bottom of the pool, you'll notice there ♪ are all these speckles and waves of light, bright parts ♪ and dark parts.

♪ And this is really, really similar to the effect that ♪ gravity has on how large-scale structure appears to us.

♪ Where there's a lot of mass, you get photons that curve around ♪ the mass and converge, produce a brighter image.

♪ And when there's not much mass, the photons curve away ♪ from that area of space.

♪ And so those waves of light that you see on the bottom of ♪ a pool are kind of like the measurements that we're ♪ making of these faraway objects in the universe.

♪ - First they build the universe in a computer, ♪ galaxies, stars, all of it.

♪ Then they follow the photons to predict what the telescope ♪ would record when it starts its work, tracing how that light ♪ travels through the mirrors and down to the electronic sensor ♪ that captures the final image.

♪ How do you build a simulated universe?

♪ I mean, what are we looking at here?

♪ Yeah, so these are what you would see if you looked at ♪ the night sky with your eye.

♪ You just see the things that are nearby, these stars, which ♪ make up objects in our Milky Way.

♪ We can take this image and change the scaling, ♪ though, to see what the Roman Space Telescope ♪ will see.

♪ And suddenly you see all of the galaxies that are in the back.

♪ In this image, there's something like 2,000 galaxies.

♪ The Roman won't be working alone, it has a partner.

♪ Its data is complemented by the Earth-based telescope, the ♪ VIRAS-C Rubin, completed in 2025.

♪ Rubin will scan about half the sky again and again, catching ♪ change as it happens, exploding stars, moving objects, subtle ♪ shifts across the cosmos.

♪ - The Rubin Observatory and the Roman Space Telescope ♪ are highly complementary.

♪ That is, we can do a lot more with them together than we ♪ can with each individually.

♪ We can see optical wavelengths like our eyes with the Rubin ♪ Observatory, but we can see further into the infrared with ♪ the Roman Space Telescope.

♪ So we can learn more about the objects that we're observing.

♪ And the two missions are designed to overlap so that we ♪ get the same data from both for the same set of objects.

♪ - We do see diffraction spikes.

♪ Scolnic is studying non gravitational lensing, ♪ but is focusing in on another signal Roman ♪ will use to track how the universe has changed.

♪ - I will use the Roman Space Telescope to find ♪ supernovae exploding billions of light years ♪ away.

And from each supernova, we get ♪ a snapshot of what the universe looked like at that time.

♪ - Roman isn't just taking pictures.

♪ It's measuring distance across billions of light years.

♪ - So the example I like to give is, it's like if you get the ♪ same light bulbs from Home Depot and you know they're the ♪ same wattage from the same factory, and you see two light ♪ bulbs in your room and one looks brighter than the other, ♪ you could tell, oh, this one must be this much ♪ closer than the other.

♪ But you need to know that those light bulbs ♪ are exactly the same.

♪ - It's a simple comparison, but the stakes are enormous.

♪ - If on the supernova side or on the lensing side ♪ we see something weirder about the universe, ♪ we see something that doesn't fit in our model, first we would ♪ say, well, extraordinary claims require extraordinary evidence.

♪ That if you're going to say our model is broken, the universe ♪ is weird, you really want to be sure, and then you want ♪ multiple different ways of measuring it to be confident.

♪ - That's the real promise of Roman, not just sharper images, ♪ but maybe some answers as well.

♪ - And who knows what we're going to see.

♪ When you open the door and look somewhere for the first ♪ time, that's where we learn about the universe.

♪ That's where we learn about physics.

♪ And that's really the exciting potential for the Roman ♪ Space Telescope, the things that we're not even aware ♪ that we don't know yet that we're going to find.

♪