Building the Giant Magellan Telescope with Dr. Rebecca Bernstein and Dr. Jim Fanson

[Music] you have fallen into event horizon with john michael gaudier [Music] in today's episode john is joined by dr jim fanson and dr rebecca bernstein dr jim fanson earned his doctorate at the california institute of technology in pasadena where he joined nasa's jet propulsion laboratory he was a member of the team that fixed the hubble space telescope's blurred vision in 1993. he later served as lead engineer for the design of the spitzer space telescope and project manager for the galaxy evolution explorer he now serves as project manager for the giant magellan telescope dr rebecca bernstein has had a long history of spectrographic and imaging development she is a project scientist on the giant magellan telescope project an international consortium where she will provide technical and scientific leadership for the design and construction of the telescope she received her a b in physics from princeton university and her phd in astrophysics from caltech she was a herbal and research fellow at carnegie james fanson and rebecca bernstein welcome to the program thank you very much thank you now the giant magellan telescope is probably one of the most exciting things in astronomy that's coming down the pike this huge enormous telescope so i want to give everybody an overview of exactly what this telescope is how it's being built and where it's being built let's start with the location chile in the atacama desert in the mountains why well the placement of a telescope on the ground looks for several things you're looking for a location where you have a lot of good clear night skies for observing you want a place that's in a dry area so that the water vapor in the atmosphere above you that you have to look through doesn't absorb too much light and you'd like a place that's uh that's dark and so there are a few places on the earth that are really superior for those conditions and the atacama desert in the chilean andes is one of those locations and in fact there is an existing observatory there the carnegie institution owns a large parcel of land and they have placed their telescopes there since the 1960s or 70s and so they are one of our founder institutions and they've offered that location for the giant magellan telescope i can give you a little bit more general answer about what makes a good site jim described it perfectly and the the geographical conditions that generally lead to the kind of site jim was describing are a mountain range on the western edge of a continent because as the atmosphere moves from west to east around the planet the atmosphere has a nice long time to become smooth and more laminar poppy as it's moving over an ocean so that nice smooth air gets to the edge of a continent and it's still smooth as it's you know for a little while above the continent but then as you go further into the continent it gets more choppy so a high mountain range will get you above a lot of the atmosphere having that atmosphere be nice and smooth and laminar because it's just come off an ocean is another good thing so mountains at the western edge of a continent and the atacama the high atacama desert over the andes is exactly that so that's why the andes as generally describing are a great location now is there any sky glow light pollution present or is this place just so remote that it's not even a concern well there there is a general concern about light pollution almost anywhere that you go we're located in an area that's that's still very dark but there's an active light pollution control effort between all of the observatories in chile and the chilean government and there there are laws and regulations and so on to control lighting to minimize the impact but as metropolitan areas grow in size and as mining operations expand you know we are aware of a certain amount of light pollution so it's something that we monitor and we work with the authorities through regulation and enforcement and you know just generally education and persuasion try to minimize the impact of light pollution but we're in a very dark site in chile it's very remote it's like a two hour drive from the the nearest city of any size it's not it's not really an issue for us at the moment but we keep track of it to protect the future now this area of chile nothing's ever perfect this area of chile is a seismic zone so what steps have you taken in regards to earthquakes and the telescope well that's an excellent question so chile is a very seismically active area in fact the largest recorded earthquake in history occurred off the coast of chile in 1960 so we have incorporated into the design of the telescope measures to protect the telescope from ground motion and this is really the first time this has been built into the design of a telescope optical telescope on the ground so our strategy is to place the telescope which sits on a large concrete ring wall is which we call the pier of the telescope the telescopes typically are mounted on piers and large masses of concrete but instead of bolting the concrete to the ground we're going to place that ring wall on 24 what are called seismic bearings or seismic isolation bearings and what this will do is allow the pier wall to remain fixed if you will or allow the ground to move underneath it and what that does is at least in the lateral direction it decouples the telescope from the ground motion to a large degree there's still a vertical component you know there still is is a transmission of force through the telescope here into the telescope itself but that isolation system which is commonly used for bridges and buildings and so on in civil engineering never been applied to a telescope before so it's a it's a new application but that is the primary measure we're taking to to protect the telescope and then in addition we are building in dampers into the support system of the large glass mirror segments so that their range of motion which is amplified by the structure of the telescope during an earthquake so that range of motion remains limited how much weight are we talking about the whole telescope assembly sitting on top of this this cushioning system so the um let's see so the mass of the telescope is about 2 000 tons so that's a huge a huge amount of weight sitting on the system now rebecca i have a question for you going back to light pollution as urban areas i know the lifetime this telescope is projected to be on the order of 50 years as the urban areas in chile grow what presumably the light pollution in the area will also grow is there any way to filter this out in observation there really isn't and in the past when cities have grown up near observatories they've tended to make those observatories much less useful so for example there's mount wilson just outside los angeles in fact just outside of my window here in the angelus national forest and as los angeles has gotten brighter and brighter over the last century mount wilson's stiffness for science has been limited to the infrared where the city is not wavelength range where the city is not bright once you get a lot of light pollution in the area of the telescope it really does limit its use now what about i know there's a quite a bit of discussion lately about satellites and constellations and things like that interfering is that something that can be mitigated again that's a very tricky problem the best way to mitigate it is by reducing the brightness of the satellite themselves satellites themselves and by limiting the range you know the area of space that they might occupy so there are lots of discussions going on already with the company talking about putting those satellites up and trying to mitigate the impact they'll have that way i suppose the last of the natural concerns with the telescope is wind i'm sure it gets pretty windy up there in the mountains what do you have there to protect the telescope so we have what we call an enclosure which is a large rotating building essentially with biparting doors that open and shutters that can open to allow ventilation so it's it's a structure that works in concert with the telescope it moves as the telescope moves and during the daytime and during inclement weather it protects the telescope from the elements it's also used in the assembly and maintenance of the telescope during the during the day shift so this is um a building that's about 60 meters in diameter and about 65 meters tall so it's quite a large and sophisticated building and it's of course the thing you're going to see when you drive up to the observatory you're going to see from a distance this large enclosure structure now grinding the mirrors casting and grinding the mirrors is an interesting process because the mirror is melted and spun and then very very carefully controlled and cooling from start to finish how long does it take to make one of the segment mirrors for this telescope so if you start from when you actually start building the hearth that the telescope is cast in all the way through the completion the polishing to the final surface figure specification it takes about four and a half years or so to uh to fabricate one of these mirrors it takes about 22 months to build the mold and place the glass in the mold and heat it up and flow it into the in the into the mold and let it slowly cool down and anneal and clean you know all of the mold material out so that you're left with the glass casting that takes about 22 months and then it takes about nine months to prepare the rear surface which is where the mirror is supported on the control system all the actuators and so on that attach to the back of the mirror and then it takes a little over two years to grind and polish the front surface it takes about six months to get to about 1 micron rms surface figure and then another 14 months or so to polish to final specification you know around 20 micron i'm sorry about 20 nanometers rms so it takes a long time and there's only you know for example one polishing machine at the at the keras lab where these mirrors are made underneath interestingly underneath the football stadium out at the university of arizona so they're what we call long lead items and we've been manufacturing them now for a number of years just because it takes so long to to manufacture the full seven mirrors we need for the telescope now when is first light and when will it be fully operational well our latest schedule shows 2029 as a first light date and that would have four primary mirror segments out of the seven and then it would take another year to two years to complete the telescope and you know achieve all of the uh the various operating modes once the telescope is operational this telescope has adaptive optics so even though we have a very good location for seeing it can still sort of work with the atmosphere itself tell us about that system how does the telescope compensate for earth's atmosphere so we have um the the optics on this telescope that actually do the adaptive optics correction are our secondary mirrors so the secondary mirrors are seven mirrors that are roughly one meter in diameter each and they are matched one to one with the primary mirror segment so the light comes from one primary secondary and then down to the focal plane and these secondary mirrors are fully adapted meaning they can alter their surface shape to correct the turbulence in the atmosphere on a kilohertz time scale so very rapidly and by measuring the wavefront that we're getting through the atmosphere and by rapidly correcting the mirror to essentially form the the inverse away front of that measurement we can take out the turbulence the damage to the wavefront that's being done in the atmosphere by the atmosphere as the light travels from the top of the atmosphere down to the telescope how is the atmosphere measured to adapt to it so you basically look at one star and you take the image that forms from that star and you manipulate it so that what you're looking at is the pupil image the actual wavefront image and then by measuring that wavefront and feeding that information mirror more rapidly than the shape of the wavefront changes and actually correct that turbulence in real time it's absolutely amazing now resolution of this telescope this is an enormous telescope with much much greater technology than say hubble how much more resolution will this telescope provide versus hubble you know or any space telescope for that matter we get almost a factor of 10 better images than hubble just in round terms so the resolution that a telescope can get is just limited by the diameter of the telescope so the aperture quantum mechanics the interaction of light with the telescope aperture the primary mirror itself is what limits the image size and so by having a larger telescope diameter you get inversely better image quality so by having that very large diameter we do much better than hubble let's get to the science this telescope offers a probe into the universe that's you know much greater than the instrumentation that we have now so in trying to solve mysteries about things like dark matter and dark energy where's this telescope going to take us what what can we look at with this higher resolution that might solve some of those mysteries well gmt is being designed basically the important things about a telescope are its sensitivity and its resolution and with greater sensitivity and resolution you can basically look at anything that is fainter and smaller and that means anything nearby or anything that is intrinsically faint because it's nearby or whether it just appears to be faint and small because it's on the other side of the universe and curiously the way that we study all areas in astronomy can depend on this resolution and sensitivity whether it's planets and stars and galaxy and our own galaxy nearby or whether the actions about the formation of the universe itself studying things at the other at the very edge of our of the visible universe or trying to understand the universe from sort of the archaeological record of things that have formed throughout the history of the universe so when you ask what we'll be able to see and what it will bring us the answer is it's complicated being see things at all distances help us to study all different aspects of astronomy so i can tell you a couple of things that are very interesting but these are the things i'm gonna i can tell you about in detail are you know things that have come up as questions for us because of what we know today there are going to be an endless number of things that we don't even know to ask today but some of the things that have come up recently because of what we've been doing with the telescopes that we have so these questions that we know to ask now these include things like how do planets form do other planets host life even 25 years ago we didn't know that there were other planets we suspected that there were of course because if our planet formed other planets should be able to form but we weren't able to point to any of those planets so in the last 25 years we've been able to find definitively thousands of planets just in the neighborhood of our sun in our galaxy and hundreds of those planets we now know are potentially capable of hosting life we don't know whether they do yet but we've we're able to determine that they have the right pre-existing conditions to potentially host life so one of the things we might potentially do with gmt is study hundreds of those nearby planets to look for the biosignatures of life the combinations of molecules that can only be found if the in the atmosphere of those planets if life exists on those planets so that's one example of something that will certainly do others examples can be found in all areas of astronomy from understanding dark matter to understanding the physical phenomena that explain dark energy or the acceleration of our universe understanding black holes and how black holes co-evolve with galaxies which we already know that they somehow do but we don't understand exactly how spectroscopy in regards to exoplanet atmospheres seems to be well within the reach of this telescope for close by systems and of course as you mentioned bio so if you see something that has weird oxygen levels and a little bit of methane and things that look a lot like earth then you can begin to ask the questions maybe there's a biosphere there and this telescope should take us there what other biosignatures are within reach of this telescope i mean what um what are the the principal things you would look for in an exoplanet atmosphere you answered the question i think you got it what we're looking for is molecules in the right combinations that can only be really sustained in an atmosphere if that atmosphere is being is being impacted by life on the planet so water methane molecular oxygen are some of the key molecules now doctor the the unknown unknowns the mysteries that we do not yet know about that this telescope as with previous instruments have done will reveal even more mysteries so how does one look for a mystery that you don't yet know exists that's a great question i think what you're getting at is how do we position ourselves to be able to answer questions that we don't yet know will have and that really boils down to the history of ground-based astronomy for 400 years and that what every generation of telescopes seeks to do is judging a leap in sensitivity and resolution that will allow us to see things we haven't seen before and every generation of telescopes answers questions and shows us things that we weren't even able to conceptualize we weren't questions we weren't even able to conceptualize in the last generation so with this telescope we will reach no other level make a next leap in sensitivity and resolution and having the the instrumentation to exploit that sensitivity and that resolution is what will allow us to address new questions we haven't thought of yet now in regards to exoplanet atmospheres we have a set of planets in the solar system some of them with atmospheres or substantial atmospheres anyway but do you expect to find atmospheric makeups on exoplanets that no one expected just really strange stuff do you think that's on the table or do you think the universe is going to be more or less the same as the solar system as far as variation in atmospheres i think that we have found planets that generally fall into categories that were beyond what we would initially have expected from our own solar system and from our own theories but they do fall into categories that are not so far beyond what we have imagined so water worlds gas giants rocky planets and the atmospheres of those are generally dictated by the chemistry and physics that we that we understand so i'm sure that we will find surprises but i think that they will fall into understandable ranges so you might find odd levels of something you know some noble gas or something but nothing that's going to scream we didn't we don't understand that planet it's going to be more like we know what's going on there but that's interesting now jim i wanted to ask you you were involved with a bunch of space telescopes including fixing hubble's vision back in back when that launched what was that like i mean solving a problem of that magnitude of fixing something that was defective in space working to fix on hubble was a very interesting experience of course when we launched the telescope we expected that everything would work according to plan and it came as quite a surprise that there was a problem focusing the telescope nasa had planned a backup camera for the telescope which had been 60 complete it was basically a clone of the original camera science instrument and when the problem with the telescope was discovered everyone scrambled to figure out you know what could we do to fix the problem you know it's just it's not practical for example to carry another primary mirror up to the telescope and for astronauts to put that in so the question was you know can we can we figure out what went wrong that was causing the problem could we figure out a way in the backup camera that we could correct the problem and could it be engineered in the amount of time that we had nasa had scheduled a servicing mission for three years after the launch of hubble that you have to remember the hubble was envisioned to be visited by astronauts on a regular basis so that the science instruments could be replaced and upgraded and repairs made to the telescope systems and the servicing mission as they call them was scheduled for 1993 and nasa was determined that they were going to go back up to the telescope in three years and so the question was could we figure out how to engineer a way to correct the problem and so it was it was really a crash program it's the fast one of the fastest things i've ever been involved in and because it was such a hugely visible program a hubble was anticipated for many years before it was launched as a transformative you know we talked about it being being as big a step forward as big an advancement beyond the best telescopes on the ground since galileo first turned his telescope to the heavens so the repair was something that was scrutinized by congress and you know by the public we had there were blue ribbon panels of nobel prize winners that were reviewing what we were doing i won't say they were looking over our shoulder but it was like working in a fishbowl there was so much visibility and scrutiny on what we were doing and we had very little time compared to what you would normally do to figure out how to redesign or rebuild this backup camera so i had a role in in you know one part of the system you know building some active mirrors that we could control from the ground to make sure that the correction uh the optical correction in the instrument would exactly cancel the error in the hubble telescope itself it's like subtracting two large numbers and trying to get zero if any of those numbers is not is not exactly the same as the other you won't get zero you get you could get a big error still and so we were very conscious of the fact that if we didn't get the corrective optics properly aligned with the telescope optics that we could actually make the problem worse so it was um you know i remember sleeping on a cot in my office many nights having a great deal of anxiety about whether things would break on the vibration table as we were testing them i remember being at the launch of the space shuttle and feeling the ground shake under my feet and you know the the clothes i was wearing vibrating just from the power of the rocket being three miles away from the launch pad and thinking there's there's no way anything is going to survive that kind of a of a of an environment that kind of vibration but when it all worked out it was tremendously gratifying and was kind of like you know floating on air for a while when we saw the sharp images come back and sharp images they were they hubble did more for popularizing science with the amazing imagery that it returned than a few other things now dr bernstein with this telescope 10 times hubble can we expect that again can we expect absolutely amazing photography yeah absolutely i think we'll find that this is an eye-opening in the same way that hubble was now jim you also as i recall worked with kepler which found an unbelievable thousands of exoplanets well these exoplanets that kepler found be targets are some of them anyway be our closer ones be targets for the gmt um i would say uh probably not the average target star for the kepler mission is about a thousand parsecs distant you have to remember that at the time we were building kepler we really had no idea how many or what type of planets form in what kind of orbits around various types of stars in the galaxy so kepler was a survey mission designed to answer that question so it stared at one part of the galaxy continuously measuring light from a you know about 250 000 stars waiting for planets to pass in front of the disk of those stars and we would measure the dip in the light curve so you know what we now know based on the kepler mission is that roughly half of stars like our sun will have a planet about the size of the earth orbiting in the habitable zone and so you know that that means we now know how deep we have to look into the into space uh to find the nearest exoplanets and it's really the nearest exoplanets that telescopes like gmt are going to follow up on uh give us the ability to measure the light from the planet itself as as opposed to the star that it's orbiting proximity helps a lot you know not being too far away for that so kepler was you know really eye-opening in terms of understanding what what exists out in the galaxy and now the focus with missions like tess that nasa has has launched is looking for the nearby exoplanets and the big ground-based telescopes are the ones that are going to really be able to do the follow-up and explore what the atmospheres of those planets look like what's next for gmt where where is the the timeline at right now as far as construction and building the mirrors what's where is it at now and what's next well let me give you some uh updates on various parts of the project so at the site in chile we have leveled the mountain that was done a number of years ago we actually leveled an area that's big enough for two gmt sized telescopes and we have excavated the foundation for the enclosure and the telescope pier we've built the residence buildings to house the construction crew we have a dining facility a recreation facility we're too far from from any population centers for people to commute back and forth to the construction site so we house the the crew on site that's all completed the construction power infrastructure is completed we're finishing now the water infrastructure so basically everything is set for the major construction to follow you know and that that will progress over a period of years in terms of the optics we have completed the first two of these giant primary mirror segments each of these segments is 8.4 meters in diameter they are themselves each of them the largest mirrors that are have ever been made in the world two of them have been finished three more of them are in various stages of grinding and polishing in the mirror lab in arizona so that makes five out of the seven the sixth mirror is going to be cast early next year and that'll be followed by casting the seventh mirror so the optics are are well along you know we know how to manufacture them we've we've proved that we can do that in terms of these magical adaptive secondary mirrors that rebecca was describing these are the mirrors that have like 600 and some actuators in back of each one of them and there are seven of those up at the secondary we have i'd say we're about halfway through building a prototype of those mirrors and we're going to now very soon start the long lead procurement and fabrication for the first production year and those by the way are technology developed by a consortium in northern italy our first light science instrument which is called in a shell spectrograph and which will have a role in exoplanet detection and characterization through the radial velocity precision radial velocity method looking at the doppler shift of the reflex motion if you will of stars that planets are orbiting that instrument has completed its final design and is in the early early stages of long lead procurement and fabrication and then the telescope structure this large what we call the mount which positions and controls the optics and the instruments is under contract with a team of companies that are finishing their design and uh then they will proceed into the fabrication of of the mount so there are various pieces of the telescope that are well along there are other pieces that are are still in design and so we're progressing in in parallel in various parts of the of the world in uh you know in europe in australia in uh in chile in the united states you know if i had to give you a percentage i'd say you know we're maybe 30 finished with the work that needs to be done my last question is for dr bernstein once the telescope is finished up and running what's it going to be like for astronomers doing research with the telescope will they even need to go to chile or will the telescope remotely collect data and just send it to them how how will that work like most ground based telescopes will have a proposal process and there will probably be a fair amount of time on the telescope that goes to individual small projects individual principal investigators and small projects that can be executed in somewhere between a night and a few nights and then there will be larger projects that involve large consortia of scientists across the partnership and across between individual scientists across the partnership but after they apply for time and get granted time they they will have a choice to go to the telescope and participate in observations and to have the observations conducted remotely and that is similar actually to the way it's largely done on telescopes today some observations are not that unusual or fairly routine and the way that you collect the data is fairly predictable even if the science is very original the way you the kind of data that you need to get or the way you collect the data is is fairly traditional and it doesn't require a lot of unusual steps and so in those cases you can have either do the observations remotely or have the observations executed by experts at the telescope with you know the scientists just sort of eavesdropping on the process and i think that that it will it will be largely the same as you as we use gmt for some of the observations you know they're more exploratory or you need to make last-minute decisions as the data is being collected and for those you may decide it's really worth going to the telescope and you may decide that you can do even that and in each dropping mode with experts at the observatory so i think all different strategies will be incorporated in the in the use of the telescope all right i thank you both for joining us today and i wish you great luck with the gmt thank you very much thank you thanks for listening i am futurist and science fiction author wrong channel no it's not thanks for listening i am futurist and science fiction author john michael gautier currently hosting event horizon and wondering where anna actually came from one day i had a tablet computer the next i had a boss very disturbing be sure and that's enough of that youtuber forever like subscribe and hit the bell sell out what [Music] you

Channel: Event Horizon

Views: 61,825

Keywords: Hubble, Hubble space telescope, extremely large telescopes, elt, GMT, Giant Magellan Telescope, fixing Hubble, building, giant ground based telescopes, first light, vera Rubin, new telescopes, space, astronomy, biosignatures, Rebecca Bernstein, Jim fanson, event horizon, John Michael godlier, asmr, event horizon John Michael godlier

Id: VfII8baDnIQ

Length: 37min 22sec (2242 seconds)

Published: Thu Feb 11 2021