Chandra's Universe Transcript
This has been a golden age for astronomy and astrophysicists. It's very complex and amazingly it does exactly what it's supposed to do. Chandra has put X-ray astronomy right alongside all the other areas of astronomy firmly and forever and that's never going to change.
Seven, six, five, four, three, we have a go for engine start. Zero. We have booster ignition and liftoff of columbia reaching new heights for women and astronomy.
The real effort that led to Chandra finally be launched started up again in '76. We wrote a proposal to NASA of what we call the 1.2 meter telescope and we started working with Marshall Spaceflight Center early in '76 and '77 and it was a continuous effort with the technology focusing on the mirror in the early days and led to NASA eventually working Chandra up to the top of the list of priorities.
I used to have in the days that we use to use a plastic view glass. I had one in my files and I can probably find it. It had a curve on it and I used to add a plane to every year. At that point it was 1991 and it slipped year per year for the next seven years. That period was very, very difficult. The interesting thing is we didn't lose faith. We knew it was a great mission and it was going to happen.
Getting any big NASA project or any big physics project going is not easy. It involves a lot of political hurdles because you're ultimately asking the taxpayer and your agency to support something that is quite expensive. Chandra cost in real dollars over 20 years of development a billion and a half. Still, a lot of money. Per year, it wasn't a lot of money, but still, it's a lot of money and you're asking the taxpayer to come up for this and other missions that are scientifically interesting and have supporters that also have very prestigious backing.
Look at sustaining a development program over a 15-year mission, as well as Shuttle launch calls for 15 years, every two or three years. It was just an exorbitant amount of money.
There were a number of design changes imposed by going to, from the lower earth orbit to a Shuttle launch to this very highly-elliptical orbit that goes a third of the way to the moon and stays out of the radiation belts most of the time, another adVantage of it. The Shuttle couldn't get us through that orbit so we had to use another stage and it turned out to be Boeing's inertia outer stage that we ended up using.
We had to make it as lightweight as possible. So the redesign was the goal and to take a lot of weight off of that vehicle. We took off two mirrors that saved tremendous amount of weight and then we took out all the metal that we could and we created probably the biggest epoxy graphite observatory or structure that is in space today. By doing these types of things we got it down to the required weight for the ius to be able to lift us.
In hindsight, it was a big, difficult thing to do, very stressful for a lot of people, but at the same time if you stop and look back at it now in today's perspective in the terms of the dollars that we saved and it was free to invest in other science activities, I think we made a very wise choice.
So in late '88 Congress decided that they would approve the first lump of funding for Chandra and they directed us to use an X-ray telescope with a better resolution and there was a lot of skepticism as to whether you could build a mirror that good. They gave us a set amount of money in three years to build and test this X-ray mirror, so we had to start with the glass and the machinery to polish it and measure it and the test facility at Marshall Spaceflight Center actually tests the X-ray performance of the mirror.
So there was an insistence that we prove that we could prove the telescope that we thought we could build and that was a major achievement. To have a senior, Congressional staffer flying down at the Marshall Spaceflight Center to witness the test of a scientific instrument. That's not your typical situation. So that got a lot of scrutiny. By the way, because that was successful he became a convert. So he was one of the people in the government who helped make it happen.
After the earlier successful testing at marshall of the initial outer pair of mirrors and the redesign of the observatory that resulted in the change of orbit, the completed mirror assembly arrived in huntsville for testing at the X-ray calibration facility.
So that part of the analysis of the whole process of getting Chandra into orbit and understanding how it works involved a lot of late nights. There was a 24-hour operation at Marshall. A lot of analysis where we had to take results just coming from a detector. Go back to the computer and try and analyze them and understand what was happening and redesign a test the next day in order to verify whether what you think you saw was actually correct.
On August 19, 1999, after years of engineering, tests and a successful launch.
Look at that thing. Yeah. That's amazing.
The Chandra team members gathered in the new control center at Cambridge. It was obvious and understandable excitement as the initial or first light image of cassiopeia a emerged.
I Was in the room and the scientists were jumping up and down waving their arms. I Was saying Chandra's open for business.
We got spoiled to be with this observatory because it operates itself, the spacecraft operates so well and so smoothly and so efficiently that we don't have a lot of problems. We don't go into safe mode every few days, every few hours, every few months. In fact, we were wondering after early intermission whether perhaps we would go into safe mode because this observatory is operating so well.
The reason for the observatory's smooth operation is a dedicated team of professionals that ensure that Chandra continues to exceed upon expectations, day in, day out.
And we have, I've come to the term they have for how we run things around here, it's conservatism, but it allows for innovation. We have this philosophy to be conservative with what we do and we don't stifle innovation. If they come up with a better, brighter idea we'll go ahead and look at it and put it in place if it makes sense.
We communicate with the spacecrafts in deep space network. From this control center here when we have a prime contact with Chandra, it's connected to one of the deep space network antennas. We have three processes per day of one or two hours each. The basic concept is once a year there's a call for proposals from the funds community, international funds community.
And that is in tune with more than a hundred coming from all over the world. We have 800 proposed per year. We discuss and we decide which ones get the time and which ones are the best and the most possible.
Once we have the targets, our mission plan can use the flight mission plane team to develop long term and short-term schedule. So on a weekly basis, our detailed schedule is developed and command loads that is in orbit. Coming to the sun and the bright earth. Those command lights are uplinked about one week ahead of schedule and we get one link every couple of days. Once it's uplinked to Chandra, Chandra operates autonomously.
Not only does Chandra operate largely autonomously, it does so with a large robustness.
People designed and built it and it's a testimony a little bit to good fortune as well because there are, on almost any space mission, there are random failures. They can sometimes be something small that you have redone in a way that's failed or not essential for the ongoing performance of the observatory. I always have a couple of small things on Chandra, but nothing that's affected the primary performance.
The Chandra project was very challenging. It had, I guess, unfortunately it had a long history from the time we thought about it until we started to build things and that period of time gave us some on opportunity to go through some of the challenges together. I Think we realized that everybody brought unique expertise to the table. The world expert was Leon Van Speybroeck which was chosen to be the scientist. He's, unfortunately, passed away and he was with us and he got to see the beautiful images that Chandra returned.
In addition to Leon Van Speybroeck, many people contributed to the telescope's success-- Bruno Rossi of course and the invaluable leadership and Riccardo Giacconi.
Giacconi is an extraordinary leader, scientific leader in particular because he's an excellent scientist. He has the highest integrity and sense of what's important and he inspires people.
He had an enormous vision of where the field of astronomy was going to go and whether it was going to be useful.
What he didn't see, of course, were the answers, but he saw the questions. He saw X-ray astronomy was going to be important. He saw that, technically, you needed X-ray telescopes. He saw that some of the most important questions were how do galaxies evolve? How do clusters of galaxies evolve and he saw the ways in which you would go about answering those questions. The program was called the adVanced X-ray astrophysics facility, what a mouthful.\e or access for short, which sort of sounds pretty harsh. It was a facility so it wouldn't be a telescope because we were asking for something new and we had already asked for the hubble space telescope, so we didn't want to ask Congress for two telescopes for the facility. As we approached the launch, we held a contest. We ultimately chose the winner, the name Chandra which was short for the last name of Nobel prize-winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. It was appropriate because he did a lot of work on astrophysicists, hence the name Chandra... Very fitting.
With the observatory up and running and properly named, attention turned to the detection of X-rays. But what are the main processes that generate X-rays?
There are a number of different ways that X-rays are generated in the universe and one of those is temperatures very high. To produce X-rays you need a lot of energy and you need a lot of heat and you need temperatures in millions of degrees. The hot stars are like that. Another way is having charged particles move in magnetic fields. Very strong magnetic fields and very energetic, charged particles or both. We have that situation in the vicinity of the compact things called neutron stars where we have huge magnetic fields. Those are two very principal mechanisms. Another way to add energy, probably about the third category is gravity. Accelerate a charged particle really hard and it will radiate X-rays, and if you just let it fall to the surface of a very compact object, neutron star or in the vicinity of the black hole outside the event horizon so you still can see the X-rays. That's a way of producing X-rays.
The first images began to be that Chandra was going to be very different. The first light image of cassiopeia of just about an hour, hour and a half's exposure, we could see a faint dot which was the neutron star when the star blew up 300 years ago.
We see how clearly how beautiful the Chandra images are. They're not only beautiful, they're spectacularly, scientifically informative. When you look, for example, for the discovery of the ring around pulse ar, where for the first time you see what people would theorize that the wind particles emanating from this pulsar would become shocked and start radiating in X-rays and a distance from the object and there's my ring, just like everybody thought it should be and how you can study it in detail. For normal stars to comets to planets to active galaxies to super-massive black holes to finding out that the hot question in question in the galaxy is not distributed nice and uniformly, that there's a lot of action going on with those big, active galaxies that are in clusters of galaxies and their super massive black holes are doing all kinds of things on time scales and hundreds of millions of years, sounds like a lot certainly to me, but it's very short in the lifetime of a cluster.
We know now that in the centers of all galaxies that there's a super massive black hole that has masses of up to a few billion solar masses. Very compact and at very early stages, these were very active and they corresponded to the quasars that are seen as high depths. These super massive black holes formed at early stages of the universe didn't go away. They're still sitting there in the center of the galaxies. So when you drop a little bit of material on to them they give off an X-ray emission primarily. Sometimes a bit of radio, sometimes a bit of infrared, but a fair amount of X-ray emission comes off.
Plus, another area that's very active and again, this is a surprise we've discovered a lot of structure in clusters of galaxies which in the X-rays that we thought were pretty smooth because usually what we see is hot gas and most clusters are very, very big and they're fairly smooth, but in fact they found lots of structures, sort of like tall things that you get in the weather and Chandra is the only satellite that would be able to resolve those as well.
In the X-rays, what we actually see are regions around these black holes and these galaxies and these clusters. We see regions where the gas carved out or pushed away and we call them voids, they may not be totally empty, but the gas down by a large factor. And in those regions where the X-rays are deficient where the gas voids exist in the same regions where you see the radio lobes, for the jets and lobes that are formed by the radio. You know the particles are being shot away from the black hole by some kind of mysterious process and they're pushing the gas away and they're pushing the gas aside because they have the temperature properties that we measure in the X-rays, it's very easy to calculate the amount of work needed to clear these voids. So you can actually measure the energy that's carried out by these jets of particles and you can mish the energy release. It's almost like a fossil record.
Chandra will no doubt go down in history as a major astronomical mission. It took a rough description of how it worked and built up detailed pictures of what's really happening. It was in the 1960s originally. It was perceived by the X-ray missions that missions quit looking for such detail. Chandra can. So, Chandra is taking all those very vague ideas that we had about the way the X-ray is working and really giving us the physics behind it in vague descriptions of how they work and they're starting to know how things work with Chandra. Chandra is that link between the very vague, building up with a full understanding of what's really going on and going from there to study things in much greater detail. There's a very interesting Chandra result on a cluster of galaxies known as the bullet cluster. There's a small fragment of galaxies, a subcluster that's merging and the shock has been formed. The edge of a bullet tearing through. A fabric. We've seen that most of the mass is determined by the location of the X-ray emitting gas and separately using hubble and a very large telescope and the magellan telescope on the ground. We've used a process called lensing to map the overall distribution of material by looking at the distortion and the shapes of galaxies on the far side of the cluster. Most of the material, mainly the dark material is located slightly in front of this X-ray gas we see with Chandra.
Dark matter is important because most of the cluster mass turns out to be in the form of a dark mirror, and clusters are so big that the competition of clusters is exactly the same as that of the entire universe. So we can say in these clusters of galaxies, dark matter makes 70% of it to extrapolate this result. If the dark matter makes 70% of the mass, it makes 70% of the mass of the entire universe.
So the reason why this matter has been dubbed dark matter, you know it's there, just like you know the earth is here. We're being attracted by the center of the earth, just like you don't see the earth from this room, and you are unable to see what is the matter in a galaxy which causes this attraction. You still have to be there. The only alternative is the laws of gravitation are wrong. Most people would question that statement. So if there, you measure the gravitational attraction, you don't just have a name for this type of matter. It's dark matter.
From the obvious, but invisible influence of dark matter to dramatically visible supernova remnants, Chandra continues to astound us.
The thing about supernova remnants is that they're big objects that they're the result of massive star explosions that are blowing the insides of the stars completely out into space and there's a process that goes on that synthesis with heavy elements all of the way up, while all of the heavy elements that make up the interesting things for us that carbon and oxygen and iron and the things that allow us to be people.
You know, every kind of object that you can think of in the universe that has-- that the representative of that class of object has been seen with Chandra and even with missions before Chandra. So there's a lot to study. The whole range of questions from the service system, you know, objects are in the galaxy with normal stars, similar to our sun or the end points of the revolution like neutron stars like the black hole.
Chandra's X-ray images continue to add volumes of the human kind's understanding of some of the most fundamental processes of our universe.
The biggest and most important scientific contribution that Chandra has made is to give us an X-ray tool on a par with any other wavelength range to study the universe.
Think it's well understood at NASA headquaters and the scientist community how special Chandra is. It's really the gold standard for X-ray astronomy right now.
It may be that we're at a particularly specail point in time that these discoveries are made and once we understand them we've made certain breakthroughs in our understanding of the universe and the laws of physics that govern the universe. It's possible in 50 or a hundred years people will think back about how crude our telescopes were and how limited our ideas of the universe were. We don't know at this point. One could imagine that our imaginations are inadequate and that the discoveries still to be made are just unbelievable.