Gravity Assist: Meet A Webb Scientist Who Looks Back in Time

Jim Green: The James Webb Space Telescope just presented us with some amazing photographs. Find out all the additional things it is capable of by speaking with an expert.

John Mather: How did the cosmos come to be, from the big bang to people, starting from right here in the solar system all the way back as far as you can go in time?

The Interplanetary Chat Program.

Jim Green: I’m Jim Green and here is NASA’s interplanetary chat programme, Gravity Assist. We will investigate the inner workings of NASA and get to know the intriguing people who carry out space missions.

Jim Green: I’m here with Dr. John Mather, who is the James Webb Space Telescope’s senior project scientist. The telescope, of course, recently released its first stunning images earlier this month. John is based at the Greenbelt, Maryland-based NASA Goddard Space Flight Center. John, welcome to Gravity Assist.

John Mather: Jim, thank you.

Jim Green: Being able to host you here is truly an honor. And I am aware that you, like me, have had a lengthy career at NASA and have encountered many amazing things. I’d like to discuss a few of them now. Of which COBE is undoubtedly one. This was one of your first significant missions, and it went off without a hitch, earning you the Nobel Prize. So, could you tell me a brief history of COBE?

Discussion On Cosmic Background Explorer satellite (COBE).

John Mather: Sure, the Cosmic Background Explorer satellite (COBE) was envisioned to measure the Big Bang in 1974. What exactly does it mean to measure the Big Bang then? It means to estimate the current universe’s total amount of cosmic microwave background radiation. And is proof of whatever the conditions were at the very beginning. 

First task: is that the correct color? Is it colorless in the sense of matching a black body spectrum, a theoretical curve? And it is, too.Second, is it consistent in all directions? And almost, but not quite, is the response. And that’s crucial because, whatever the big bang actually was, we interpret the hot and cold regions on the map as coming from the great bang itself.

We are here as a result of their efforts to make the universe less than perfectly uniform and less than perfectly smooth.

John Mather: Stephen Hawking declared that the map was the most significant scientific discovery of the century, if not all time, when we revealed it to the world.

Jim Green: (laughs)

John Mather: Stephen, I see. Why is that so crucial? First off, we believe that gravity acting on those early areas was able to turn the expanding cosmos around in some places, resulting in the formation of galaxies and stars, which then led to the emergence of planets and humans. As a result, we are here. Second, the majority of those spots originate from a source that astronomers have identified but no one can see. The term for it is cosmic dark matter.

Third, the pattern is slightly influenced by cosmic dark energy, which astronomers can also detect but not see. That therefore reveals the timeline of the universe’s expansion. That is significant to our story. And finally, one of the biggest unresolved mysteries in modern physics is quantum gravity, so it would be wonderful if we could ever figure out what caused these patches.

Discussion On The Big Bang.

Jim Green: Did COBE establish that the big bang occurred? Or were there any warning signs before that?

John Mather: We can always find evidence to refute claims about the big bang. Therefore, the steady state theory, a significant alternative to the theory of the big bang and the universe’s expansion, existed. And while it made some very peculiar and intriguing predictions, it was unquestionably at odds with the observations we made after receiving them from the COBE satellite. 

The only surviving theory is the big bang, or expanding universe as I prefer to call it.What was it like in the very beginning is what’s interesting. Therefore, there is still much debate over what transpired when the temperature and density were extremely high. But in the initial few nanoseconds, there was something tremendous, and I call that the big bang.

Jim Green: What is going on in the early universe, then, that James Webb will be able to elucidate? You see, it looks infrared and also in the past!

John Mather: The Webb telescope does, in fact, look back in time by observing distant objects. Light travels from there to here slowly. So, we might reflect on events that did not completely start at the beginning. 

But if nature had created something for us to look at, we should have been able to see it 50 or 100 million years after the expansion began. 

Therefore, at this time, those primordial objects are entirely predicted. They have never been sighted. But in order to be able to see them if they exist, we created the Webb telescope.

John Mather: Regarding the extent of the cosmos, it should be noted that as the universe is likely limitless in scope, there isn’t actually a way to measure it. 

Currently, or at the time the light was given to us, the portion of the universe that we can see has a dimension of 13.7 or 13 point 8 billion light-years. Therefore, that’s another tough part, since everything has obviously been moving and changing ever since the light appeared.

Discussion On The Webbs Task To Look Far Towards The Distant Objects In Space.

John Mather: In any case, the Webb telescope’s task is to gaze as far back as possible toward that instant, into what we refer to as the Cosmic Dark Ages, to find the first bright objects that emerged from that primordial material. Before the stars formed, they might have been galaxies that gathered together, stars, or even black holes; in fact, there are theories regarding how black holes can form from the material of the early universe. 

Even the logical possibility exists that some are still around from the original Big Bang. We have never actually observed any indicators of them, even though nobody has worked that one out. What about that, though? Therefore, the main goal of cosmology is to look back in time.

Jim Green: To me, it appears that you cosmologists are completing a succession of tasks that are then built upon one another. How did you transition from working on COBE to later becoming associated with the James Webb Space Telescope personally?

John Mather: Actually, I didn’t have a plan for it. This new telescope idea was already being developed by someone else. And COBE was mostly finished. What will I do next that will be as good as that, I wonder? I also received a phone call from Ed Weiler at NASA Headquarters asking if I wanted to work on a study of a new telescope. I need a proposal from you by tomorrow if we proceed.

Jim Green: (laughs)

John Mather: He therefore understood that it was time to begin and that he had something to push. Naturally, I immediately called the folks they had instructed me to contact, emailed them the plan, and we were able to move forward. I had no concept of how challenging or how long this mission would be. But as a follow-up to the COBE satellite, I immediately knew this was the most crucial project I could be working on.

Discussion On The Use Of Telescope For Observations.

Jim Green: What were the first scientific questions you were attempting to address with this new telescope you were hypothetically developing?

John Mather: It would be doing something no one could ever conceivably do in any other way, therefore we knew there were numerous questions it could answer right away. We were aware that we required an infrared telescope. Why infrared then? First off, it is now theoretically feasible. And it has never before been conceivable.

We are able to launch a telescope into orbit that is much larger than anything we have ever attempted because we have the technology to cool things down.

And Hubble is unable to. due to Hubble’s infrared light emissions. Because they radiate infrared and the sky is either dim or brilliant or opaque, ground-based telescopes are unable to perform this task. As a result, you can’t do it from here. Therefore, unless we can send telescopes into space to conduct this task, everything will remain a mystery.

John Mather: You will therefore be able to gaze inside dust clouds, where stars are currently being created, as well as further back in time and into the past. At the time, we had no idea there would be so many planets. The first planets orbiting other stars were only just being found in 1995. Now that we are aware that most stars have planets, we have modified the mission’s design to allow for the research of these planets as well.

Discussion On The Flow Of Time From The Big Bang.

John Mather: Basically, the story of the cosmos can be told by looking at everything from the solar system to as far back in time as you can go. How did it go from the big bang to people?

Jim Green: As we fill in more of the puzzle pieces and understand what is happening, the story will be wonderful. So, did Webb have these large, divided mirrors at first? Or was it—what was the original notion, you know—you know? What differences do you see between those early ideas and what we have today?

John Mather: Early ideas are actually fairly similar to the one we have now.

Jim Green: Really? Wow!

John Mather: The segmented telescope can be folded in a variety of ways. But we were aware right away that we needed a substantial parasol because the telescope needed to be kept cool. We were aware that we couldn’t keep the telescope close to Earth. because the Earth is constantly heated and gets in the way. So you couldn’t keep the telescope cold while it was close to Earth. Where should I go when I push it far away? It’s a million miles away and known as the Lagrange point 2.

But if you can get there, it’s a great spot. If you can get there, though, it implies to utilize a rocket that you can get. And as a result, the telescope will be quite different. It will be extremely light—the telescope’s mass is only half that of the Hubble.

Jim Green: Wow.

John Mather: It’s a very difficult task. But the fundamental design we developed resembles what we actually flew quite a bit.

Jim Green: So John, when did you realize “hey, we’ve turned the corner, and this is going to work” as you were putting this telescope together? Has that ever happened?

John Mather: I believe I always knew this would succeed.

Jim Green: (laughs)

Jim Green: We have a fantastic engineering system in place to keep track of everything that might possibly go wrong, and that’s the reason behind it. And everybody who is concerned about it speaks up. We discuss it and ensure that whatever the problem was is fixed. We therefore had project managers and backing from NASA Headquarters who said, “Yeah, that’s the appropriate thing to do,” from the beginning to the end. We won’t skimp on the quality of our work; we’ll do it well.

On the other side, I was just watching it go up while I was sitting there calmly at launch. Now, when we finally reached the image release, oh my gosh, all the potential problems came rushing into my mind. This is like the 25 years I spent walking along the edge of a cliff without falling off.

Discussion On The Release Of Webb’s Images.

Jim Green: We were all anxious for July 12 to arrive, after all. I must admit that I was completely taken aback. And I’m sure you did as well. What thoughts sprang to mind when you first saw this data arrive?

John Mather: My goodness, I was almost like everyone else. Before they were polished, I had not seen them. We transitioned from asking, “Is it really going to work?” for more than twenty years to saying, “It is so fantastic.” And the images are stunning. And we are carrying out what we said we would accomplish but looked impossible.

Jim Green: Yeah, I know!

John Mather: There we are, then. Yes, as far back near the beginning of time as we claimed, the Stephan’s Quintet demonstrated. In one of them, a black hole exists. You can also research the black hole, also known as an active galactic nucleus. In the image, there is a galaxy that is closer than the rest. And since you can see individual things, we can see that everything is rather pimply.

Jim Green: I know, when I saw that, it just astounded me.

John Mather: This is because they are red, that group of stars stands out. As a result, the infrared telescope effectively detects them. Then we saw a picture of the Carina Nebula, a cloud of gas and dust where hundreds of stars are being formed right now. Therefore, in order to find all the wonderful things in that one, you need a tour guide. In any case, we are overjoyed that it not only advances science but is also attractive to look at.

Jim Green: It is the ability to zoom in and see more detail makes the images more beautiful in my opinion. I find the deep field image, where far-off galaxies are suddenly visible everywhere, to be particularly stunning. The fact that many of these early galaxies have already evolved into spiral-like or flattened, wheel-like surfaces as they rotate around their centers shocked me. How did you feel about the deep field?

Discussion On The Galaxies.

John Mather: Oh well, for starters, everything is as expected. Galaxies can be found anywhere.

Jim Green: (laughs) There are galaxies everywhere. (laughs)

John Mather: We expected that the things that are the farthest away the hardest to see would just be the tiniest tiny infrared specks when we declared that the Hubble picture, the Hubble Deep Field, was fantastic, but not far enough. The Webb telescope can now see them and tell what’s inside of them. What elements make up those tiny particles chemically? Additionally, how far back in time are they? Even the Webb telescope struggles to discern the forms of the small red spots. However, we can see that they exist and what materials they are composed of. We can count them to determine their number.

John Mather: According to the current theory, the Milky Way galaxy, which has a lovely spiral form, was likely put together over time from 1,000 or so little pieces. The Magellanic Clouds are two more that are still falling in. But figuring out the archaeology of the galaxy in which we inhabit is quite difficult. As a result, occasionally learning can come from gazing at other people’s galaxies or other people. Actually, we have no real idea if somebody is out there.

Jim Green: (laughs)

John Mather: But why wouldn’t there be?

Jim Green: (laughs) Yeah, right! Of course, of course.

Discussion On The Involvement Of John Mather.

Jim Green: Are you now a member of any teams researching specific facets of JWST’s work?

John Mather: Actually, I didn’t suggest using a telescope to observe. I mean, I’d love to think of new ways to construct machinery. What kind of equipment should I construct next, then?

Jim Green: Wow, I did not know that. (laughs)

John Mather: Yes, I do have a few ideas in mind. I first had the idea for an orbiting starshade about four years ago. Therefore, a starshade is developed to enable viewing of planets orbiting other stars. And it presents a challenge since the stars are much brighter than the planets. You can’t do it because of the intense glare. So, the choice is either to construct a perfect telescope and mount a coronagraph inside of it in space, or to erect a starshade using a less ideal telescope and cast the star’s shadow onto the telescope without obstructing the planets.

John Mather: This is an excellent, challenging problem. When I first learned about it, I reasoned, “Well, first, can we do it with the Webb telescope?” That’s too difficult at this time, was the response. But what about the ground-based telescope? Huge telescopes are approaching the earth; the largest is 39 meters broad.

Jim Green: Wow.

John Mather: It’s six times as big as the Webb.

Jim Green: Wow.

Discussion On The Starshade.

John Mather: So we need to figure out how to apply it to it. The conclusion is that if you could construct a starshade with a diameter of 100 meters and position it 170,000 kilometers from Earth, you could do this and have the star’s shadow fall onto a telescope. After that, you must arrange it in a row and maintain it there for a time. So while it is a challenging engineering task, it is not insurmountable. I’m attempting to do that. In fact, Headquarters provided me with some great support through the NIAC, the NASA Institute of Advanced Concepts.

Jim Green: Right.

John investigate the “hybrid observatory of Earth-like exoplanets,” as I’m calling them. So, GrabCAD,, now has a design challenge open. You can register and send us a sketch of a solution you believe you can come up with.

Jim Green: John, that sounds wonderful. Yes, those fresh new steps are quite essential. And I discovered that the engineering community, in collaboration with the scientific community, is developing some truly amazing ideas. That starshade does, in fact, have a very distinct shape, as you mention. And, I suppose, supercomputers or other means of computing were required to determine that shape. Did you participate in any of that back then?

John Mather: Long ago, there was that initial work. We are aware of the shape we must create, but due to its size, it is incredibly challenging to do so. The entire lot on which my house is located is larger than 100 meters.

Jim Green: (laughs)

John Mather: Therefore, it is difficult and must be relatively light, which presents a fun task. That’s really cool, then.

John Mather: So that is what I enjoy doing. I adore creating new stuff.

Jim Green: That sounds wonderful, I must say. And because we can reach tiny planets with these new telescopes, we might discover something that is more like Earth than anything we have ever seen. I’m thus quite pleased about that.

Jim Green: Of course, because it will be taking planet spectra, the James Webb Space Telescope will help us comprehend what the future generation of telescopes will be. In reality, one of those initial pictures showed a spectrum of a planet the size of Jupiter. That really made me happy.

Jim Green: This was, in fact, a fascinating chance to learn more about the chemical makeup of an atmosphere.

Discussions On The Exoplanets.

Jim Green: It is crucial to have the ability to observe these exoplanets and contrast them with the planets in our solar system. Therefore, one of the first images of the solar system to be made public was of Jupiter and its moon, Europa. There are several moons orbiting Jupiter, but Europa was the most exciting because it cast a shadow on the planet.

Jim Green: How’d you like that one, wasn’t it fantastic?

John Mather: Well, it was beautiful. We shot that photo, you know, to make sure the telescope could capture that kind of image. How are we going to know that we can see dim objects adjacent to bright things, that the guiding star system will function, and all that because Jupiter is so bright? Therefore, it was crucial to demonstrate that we were capable of making those observations. Then it becomes quite beautiful as you can see Metis, Europa, and other little satellites in space.

Discussion On The Importance Of Europa.

Europa is therefore of particular importance to humans since, as you are probably already aware, we are sending a probe there to pay closer attention because there may be life in the ocean below the ice. We will therefore be keeping an eye on that, especially from this location. It has a shape; it is not just a tiny dot, as you can even see with a telescope. Then it will be even better to fly through the plumes with a probe. So we’ll be watching the locations where the water spouts out of the cracks between the ice blocks to see if there is anything interesting in the molecules coming out. However, this is really nice.

John Mather: We’ll likely also examine Titan. To me, Titan is a fascinating concept. Because, you know, people frequently ask me if the kind of life we’re seeking is the correct one to seek out. So everything on Earth is made of carbon and a liquid water solvent? There are a variety of geological and biological features on Titan that are comparable to those seen on Earth. They have rain, clouds, weather, rivers, and lakes, but they are formed of hydrocarbons, particularly ethane and methane.

Therefore, if life can live in that environment geologically, that’s a really excellent location to start looking. So, using our infrared spectroscopy, we will be keeping an eye on that experiment to do the chemical remotely. Additionally, the chemistry of the surface may vary depending on where you are. And to our great delight, NASA will send a probe to make a helicopter landing on this gorgeous satellite.

Jim Green: Yes, in addition to that, while JWST is examining the context, all the other missions we discussed, like the Europa Clipper, which will be launched in a few years, will arrive on Europa and do these amazing close-up investigations. In addition, Dragonfly, a spacecraft that will be launched at the end of this decade and land on the Saturnian moon Titan, will be observing Titan at the same time that JWST is doing so.

The fact that these missions intersect, in my opinion, is simply excitingly significant because it makes Webb so adaptable. But are you more enthusiastic about one body of knowledge about Webb than any other?

John Mather: Two topics excite me because I believe they could really surprise us. The first is the very early universe because we have never seen anything like it. There might be something going on that just doesn’t fit the typical story. And if we don’t look, we’ll never find out. Therefore, the Webb telescope will look and is already looking. We might also be in for a big surprise when it comes to all those planets. What we have in the catalog, several dozen planets to examine using the transit technique to obtain their atmospheric parameters, could be an interesting surprise or a disappointment, depending on your perspective.

The large ones, though, will undoubtedly have atmospheres because that is what they are. The smaller rocky bodies may or may not be rocks, depending on their size and temperature. They may also or may not have an atmosphere. And that is a significant first question.

Jim Green: Yeah.

Discussion On Possibility Of Life.

John Mather: We have a chance of spotting evidence of water on some little stony planet, which tells us something about whether there might be life elsewhere in the universe. On the other hand, it can be the case that there is nothing there. To find out, we must construct a different telescope.

Jim Green: Right!

John Mather: This is because the planet Earth is a really unique location. It’s the only place we like in the solar system. Venus is an inconceivable place to dwell. Mars would always need engineering assistance from Earth.

Jim Green: (laughs)

John Mather: What else are you going to do then? Earth is unique. And the fact that no other solar system like ours has been discovered yet kind of disappoints and surprises us.

John Mather: Now, it’s challenging to locate them. However, there are four small, rocky planets close to the sun in our solar system, and one of them is a pleasant place for mankind to live. It’s possible that Venus and Mars were once livable, and it’s also possible that the other one was. However, there was a break followed by four frigid gaseous planets. So far, we haven’t discovered anything similar in the other planetary systems. How come then? So perhaps Earth is indeed more unique than we ever imagined.

Jim Green: So John, whenever I have a guest on, I want to ask them to share the person, place, or incident that really helped shape them into the scientists they are today. I refer to that occurrence as a gravity aid. What was John’s gravity help, then?

John Mather: I reflect on my trajectory and how I’ve been affected by different gravitational pulls, and I realize that ever since I can remember, my goal has been to become a scientist. I was familiar with scientists even in third grade. I was aware of Darwin and Galileo, and I believed they accomplished great things. What they stated wasn’t always well received. But that only served to highlight how crucial it was. So I had plenty of chances to explore and broaden my interests thanks to my parents and the educational system. So I grew up in the country, actually on an experimental farm owned by Rutgers University, a college in New Jersey.

My father was a scientist, so I was somewhat exposed to science, though he didn’t get the physics portion. He was researching milking cows. That was therefore quite remarkable. In any case, my family and my school provided me with numerous chances to take on challenging tasks.

John Mather: So occasionally I tried them and was successful. And that gave me just enough encouragement to think that perhaps Galileo and Darwin could do great things. Perhaps I could contribute as well. So I must have had enough inspiration to say, “Well, why not try? You might not be able to accomplish it, or you might be able to.” So from an early age, I dedicated myself to become a scientist.

Discussion On The Importance Of These Observations In Solving The Questions Of This Universe.

John Mather: We have to be very understanding of the fact that scientists spend a lot of time thinking about problems that have not yet been solved. And, gosh, perhaps someone else is ahead of me. And there are several additional intimidating things. However, it is a necessary component of structured curiosity. You therefore get to observe enormous effects in the end. Where did this all come from, you wonder when you gaze upon the potential home for yourself? Engineers and society have put these scientific principles into practice.

However, it’s still pleasant to be able to state that, for example, the components in the paint on the wall come from stars. Stars themselves formed the wall. My body’s chemical components originated in stars. And how did everything function? Let’s find out, then.


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