asteroid's path can be redirected in space. recently on c-span's q&a, nancy cabot -- chabot from johns hopkins discussed this recent mission. >> i heard there is a comment you do not like the look of. tell me about it. you have 20 minutes. >> is five to 10 km across.

>> that is a clip from don't look up. it is a disaster movie senator and meteors striking earth but now science is catching up with art and you are involved in a project called dart revolving around this. tell me about it.

susan: we have seen news reports of the past about meteors striking. what is the difference between an asteroid and meteor? >> when they get bright in the atmosphere, you can look up and see meteors come in. some make meteorites, which are the rocks that survive here on the planet. it really depends on the size when talking about objects.

a meteor hits the earth once every year, roughly. i got my phd studying meteors. i love them. they are like free samples from space. it's not all bad. there is quite a lot of good about it. it's just when it gets bigger that you can have devastation. so it is important to distinguish between the size and objects -- sides of objects. susan: how large would an object have to be to cause significant damage? >> that is an important question. a lot of time people are talking about kilometer size objects like in that movie. those would cause extinction. we are concerned about ones that

are a few hundred meters. 140 meters in diameter would cause regional devastation. it would wipe out a city or state. they are rare events but they could happen and this is the population. it is important we start taking steps to be ready in case. susan: how much notice would earth inhabitants have if there was a dangerous asteroid headed our way? >>: that is really important. you do not want these things sneaking up on you which is why it is so important to take the steps to find all of the

asteroids now. you have to find the asteroid decades in advance or more, and that is what we are actively working on with planetary and -- with planetary defense. susan: the dart mission launched last week of november 2021. how many years in the making was this? >> the funding was started in 2015. it will go through final data analysis. before that it was a spark in somebody's eye. my colleague came up with the idea while exercising in his basement. he has a great story. it shows how things go from being idea to reality. that was before 2015. at conferences he talks with

other experts. then nasa started investing in the mission. susan: what did he envision while exercising at home? >> i guess his exercise equipment is different than mine. it was really the binary asteroid system. this is the double asteroid system. there are two asteroids there. why that is so important for the dart mission is we are hitting the smaller asteroid that goes around the larger one every 11 hours. this would deflect the smaller one around the larger one slightly so it is within the double-asteroid system. it gives it a safe way to do the test and it is something we can then measure with telescopes that exist. that is the ingenious part. we know telescopes discovered

this in 1996. we know the smaller moon goes around every 11 hours 55 minutes. we are going to change that slightly. the job of the spacecraft is to deflect it slightly but then it will be destroyed and then the telescopes on earth would make that measurement. susan: was this the only asteroid under consideration? >> this was the ideal target. it is a binary asteroid system. the brightness of the system changes with time from earth.

the second important part is in 20, the difference between these asteroids in the earth can be minimized. sometimes they are on opposite sides of the sun. that's not great for telescopes. still about one million kilometers so nobody should be worried, as far as telescopes

are concerned, they will get the most precise data they have gotten. host: would you explain the role nasa has in this mission and the role of your organization at johns hopkins? guest: so dart is built and managed at the johns hopkins applied physics lab where i work for the nasa planetary defense coordination office. it is owned and managed and operated here at apl. along with them we have other partner institutions across the country and we actually have a large number of international team members contributing to this as well. this planetary defense is an international issue that is one of the pillars of the national planetary defense strategy, is international corporation. host: this is nasa's first defensive mission which makes it historic, was the newly formed u.s. space agency involved at all from the defense department? guest: this has been a nasa mission. nasa is the one tasked with doing planetary defense missions. there is a national plan that was developed in 2018 that involved multiple agencies of which nasa is one. it lays out that missions like this are firmly in nasa's purview and control. so this is a nasa mission. host: tell me about your particular role in this project. guest: i am the coordination lead for dart. it is sort of a new mission, -- a new position because this

mission is a little different than some of the science missions nasa traditionally runs, being the first one out of nasa's planetary defense coordination office. my role is to help organize and coordinate our very large international investigation team which will carry at the planetary defense investigation and also worked with our engineering team at apl, which is leading the mission and operations to ensure everything comes together to meet the requirements and our measurements that we want to accomplish for planetary defense for dart to be a success. but it is important because dart is just the start. it is the first planetary defense mission for nasa. but it will not be the last. we want to get information in the way that we can build on it going forward. host: tell me about the dart spacecraft itself, what is unique about it at where it was built. guest: the dart spacecraft was built at apl in laurel, maryland. it is about two meters on the

main cube. the main body of the spacecraft, where most of the mass is, it is sort of the size of a golf cart or vending machine, sometimes we say. one of the distinguishing features if you look at dart now is that it has the rollout solar arrays, rosas. they were wrapped up like roles of aluminum foil when they launched. the spacecraft looks much larger, that they are very lightweight, they don't have a lot of mass. as far as the deflecting the asteroid part goes, they don't matter very much, is the main body of the spacecraft we worry about. dart has one instrument on it, a draco camera. it was also built and developed at apl, and it has heritage from the camera that flew on the new horizon mission that captured the spectacular images of pluto that i think we all remember from a few years ago. using that design, it was modified in order to go onto the dart spacecraft.

that payload is important because it will give us images of what the asteroid looks like, dimorphos, which would have never seen before. from earth you cannot separate didymos from dimorphos. we really did not know what the asteroid looked like. the draco imagery uses the navigation at the end of the mission to ensure we hit dimorphos, which is a challenge in itself. host: is the autonomous navigation technology new technology? guest: yes. the autonomous navigation, smartnav, is one of the challenges and the new technologies for this mission. we are targeting an asteroid that is 140 meters in diameter. this will be the smallest object nasa has sent a spacecraft to. to complicate matters, it is going around didymos. that is 780 meters in diameter. and you are coming in so fast. 14,000 miles an hour. the camera images will not be

able to distinguish these two objects from each other until the last hour of the mission. before that, they just looked like a single point of light. so you can clearly see that you need to have your spacecraft smart enough to use those images , fire the thrusters and target , dimorphos and hit dimorphos as nearly head-on as possible. that is where this smart technology comes in. it is a really good technology for planetary defense, for targeting these objects. and also a main challenge because we don't know what dimorphos looks like, we don't know its shape. from other asteroids we have been to, we know they have a whole variety of shapes. there is extensive testing that has gone on in order to meet this challenge, and we are looking forward to the demonstration. host: give me a sense of all the years of development and the teams involved. once the idea was that we were

going to try and affect the trajectory of this asteroid, what kind of craft would be capable of doing that? how did the process evolve? guest: there is a lot of paths that don't work out. all ideas are on the table at the early stages. first and foremost, dart is a very focused mission. and that was very important to this whole discussion. a lot of times when you get the opportunity to fly in space, you want to be able to do all sorts of things, because there is some -- because there is still so much that remains to be done. but dart has one purpose, and that is to hit dimorphos and deflect how it goes around didymos. you have to use the best technology so you can situate on -- so you can concentrate on new challenges like the smartnav navigation in order to autonomously target the asteroid in the last hours of the mission. so in a lot of ways, it was

meant to be robust and focused. this is what you would want if you were potentially having to deflect an asteroid in the future. you want something that is as simple as possible in order to enable the mission to succeed. host: how fast will it be traveling when it hits the target? guest: it will be going at 6.1 kilometers a second, or 14,000 mile per hour. that is the basis about how this much smaller spacecraft, like i said, the size of a golf cart, can deflect something that is the size of a sports stadium or the great pyramid. it is about 100 times smaller. the spacecraft. so it is remarkable that it is able to deflect this much larger object at all. there really is only about a 1% deflection, but coming in very fast, 14,000 miles per hour is key to enabling that. host: where were you at lift-off

when the spacecraft went into space? guest: i was out in a dark field in california at vandenberg space force base looking out -- looking up along with everybody else. it was a great night. people had warned me that there might be fog and things, but we didn't have anything like that, it was a beautiful and clear night, you could see very clearly the excitement and the cheering. a lot of my colleagues were working hard on operations to watch it live. everything went flawlessly. and everybody was very pleased with the launch. host: where are the possible points of failure for this mission along the way? where will you be holding your breath? obviously, lift-off was one of them. it made lift-off. after that, where will you be watching to see that, yes, this technology performs as expected? guest: after liftoff we had a 30

day commissioning period where you turn everything on in space for the first time. and you do it one at a time. you rollout of the solar arrays , you practice using the propulsion engine, and other new technology. you opened the door for draco and take your first images of stars. those days of commissioning went fabulously. that was another big milestone to get through after launch. now the spacecraft is cruising its way to the didymos system and we are running a lot of rehearsals for executing the commands and sequences that will be done. there is a lot of testing we can do during the cruise period to ensure that we don't have any issue during the last few days. that said, it is nasa's first planetary defense mission. anytime you do something for the first time, it is because it has never been done before and part of that challenge is part of the reason you need to do this test. if we were confident this would

work, we would not need to be doing dart. dart needs to see what it is like to target a small asteroid that you have never seen before autonomously, and how much do you deflect it? this is a big unknown, because the dart spacecraft will be at this massive velocity. we know that, but what we don't know is how much eject will come out. we think this will actually increase the amount of push that you get, the amount that you deflect the asteroid. it is sort of like that little jet engine that adds to deflect an asteroid even more. it is one of the main thing scientifically we want to do. we have done models and tests, but it really depends on the structure of the asteroid, what it is made of, the boulders, how sandy, how strong it is. all of those are factors. so doing this real-world test on a real-world asteroid in space, of this size. there is a concern of

potentially hitting the earth in the future makes dart really well set up for this planetary defense demonstration. host: what price tag is nasa using for this overall project. -- project? guest: the overall price of dart narrowing over eight years is $330 million, including the launch vehicle and the operations and development. host: and when is the exact date of impact planned? guest: september 26 later this year, 2022. nominally, at 7:14 p.m. eastern daylight time. that might change by a few minutes, but it is about 7:00 p.m. on the east coast, is what we are looking at. it will be an exciting time, a spectacular time as the draco camera images are used autonomously to target the asteroid, they will also be streaming back to earth, one per second. at first it will just be a dot of light, but the last images in the last minutes and seconds where we really get to see this

asteroid for the first time, will be spectacular to be shared. host: how soon after the impact will you know that the intended goal was successful? guest: we will know pretty soon because one of the main goals is impacting the asteroid, so these images will come streaming back in the asteroid will get bigger and bigger in the field of view, and then the signal will stop and the dart spacecraft will have done its purpose. that really is the fundamental goal of the mission. now, how much do we deflect the asteroid is the most important measurement. the telescopes on the earth will have to weigh in on this. >> we will leave this program to go live to a briefing on nasa's dart program. experts are expected to give an update. this is live coverage on c-span. >> the impact of