Hi I’m Wendy Zukerman, this is Science Vs from Gimlet. This is the show facts versus fireballs. On today’s show, Asteroids.
We’re going to start our story -- on February 14th 2013… The world’s finest asteroid researchers were meeting for a conference in Vienna[1] …Alan Harris[2] was catching up with some colleagues.
We had a nice evening at a restaurant in Vienna. You know talking shop as people do
Some of that shop talk - was about an asteroid that was expected to fly by earth the next day. It had been discovered a year before and scientists had been tracking it very closely... they predicted it was going to just skim past us…
It was coming quite close to the Earth, The scientific community was ready and waiting, And so we were all geared up!, we were expecting it
The asteroid is called Duende[3]. It’s potato shaped rock about 130 feet across… and it was expected to be one[4] of the closest encounters ever recorded between us and an asteroid of its size.[5] Scientists had press releases ready and interviews scheduled[6] … It was all rather exciting. So, with a big day ahead, Alan hit the hay.
AH Yknow brushed my teeth. Had a wash and then just fell asleep
In Vienna, Alan slept peacefully. But two thousand miles away[7] ...in the city of Chelyabinsk in Russia... [8]
<<Bird chirping>
CRASH
<<Some yelling car alarms!>>
Sergey Zamozdra - an astrophysicist - remembers hearing the asteroid as it exploded over his hometown[9][10][11].
SZ: Doooooorr[12]
SZ: People were saying they were frightened.
Sergey says some people were frightened. He also told us when the asteroid exploded it caused a chemical reaction[13]…
SZ The super bright radiation caused a chemical reaction in the air, so it smelled different.
He says, the air smelled different… Some people even sensed a different taste in the mouth. They said it had some metal flavour.
Some people even sensed a different taste in the mouth. They said it had some metal flavour.[14]
Across the city, the blast damaged buildings...caving in some roofs[15]… and shattering windows. [16][17] More than a thousand people were treated for injuries, mostly cuts from broken glass.[18] … [19] The Asteroid ended up causing millions of dollars in damage[20].
Back in Vienna. Alan had no idea what had happened while he was sleeping -- he woke up brushed his teeth, and headed down to breakfast.
All I could see from where I was sitting having my breakfast was a reflection of a TV monitor uh which was just showing the news -- and the picture that kept being repeated was that of streak across the sky. And I could see the word meteor written backwards
Alan was confused... Duende, the asteroid we’d been tracking, wasn’t supposed to come by Earth until later that night…[21]. And it wasn’t meant to hit Earth… just come close. He realized… This asteroid he was seeing streak across the sky on television -- the one that had just exploded over Russia - was not Duende. It was an entirely different asteroid!
And that really when my jaw just dropped, it just dropped. And I got up I left my breakfast and to view the TV… I gaped at the screen I think when I saw this I just couldn't believe it.……AH It was just total coincidence,
Alan just stood there agape for a bit processing what had he seen --he was stunned -- but of course he had a meeting to get to so he hopped on the metro...
AH we got onto the train and there immediately sitting in front of us on the train were the colleagues from JPL and from NASA headquarters… AH so you know all the people in the world you would want to talk to about this event were right there
WZ Did any of them have any idea that this might happen?
AH None at all. nobody could have been predicted this would didn't know anything about it. The only event predicted was that of the close approach of Duende
Alan says some researchers were a tad red faced.
AH: Well i think there was a little bit of embarrassment- how are we going to explain to the world that we did not see this coming?
Yeah I mean really -- how are you going to explain it Alan…how did you and the rest of the Asteroid researchers spot one asteroid that was passing by earth BUT MISS THE ONE that slammed into us!? That answer, today on the show…
Plus, if we did spot an even bigger -- supersize asteroid heading straight for us-- is there anything we could do to stop it?[22].…
When it comes to asteroids, there’s lots of…
Doooo
But then there’s Science.
AHHHHHHH
Science Vs asteroids is coming up, just after the break.
PRE ROLL
DETECTION -- Cathy Plesko
Welcome back. Just a few years ago as scientists around the world were carefully tracking the movement of one asteroid… Duende… another one...Chelyabinsk smacked us in the face.
How did this happen? How did we have one all this information on one asteroid and nothing on the other?
Well to answer that question.. we're first going to tell you how we knew Duende was going to sail past us.
About a year before the big NASA - whoopsy! - [23] some nerds were looking up at the skies using a big telescope off the South of Spain[24]… And they saw this tiny dot moving.
CP:They got a couple of images, and saw something that moved differently relative to everything else… and were able to say oh hey, we think we just found an asteroid.
That’s Cathy Plesko, who studies how to save us from asteroids at the Los Alamos National Laboratory[25] . in New Mexico… Cathy told us that, as is protocol, the nerds in Spain reported their finding to the Minor Planet Center[26][27]. They keep track of every asteroid that’s ever been discovered[28]. So they looked at their records and asked
CP Is this something that's been seen before? And everyone went through and checked and said nope.
This was a new asteroid![29] And it looked a bit like it was headed for earth ...so … the Minor Planet Center put out a call to a network of telescopes[30] around the world saying
CP Everybody else, hey go look for it. Because this looks like it might be something coming at us… So let’s go get more images and establish its orbit.
So scientists from all around the world pointed their telescopes at Duende… trying to get a bunch of pictures how it was it moving[31]…A telescope in Spain spotted it at 1:45 AM their time; in France they caught it 3:21 AM... Arizona spotted it at 5:30AM[32] And each time someone saw it they took a picture and sent the coordinates to the Minor planet center[33]...who verified it and put it on an official map.
That’s when we know whether or not it's going to hit us, is once we learn about, enough about its orbit[34][35] [36].
When scientists crunched the numbers to pinpoint its orbit. They realised that Duende would miss us. But come close.[37]…... Remarkably. Close, as NASA put it[38]. The nerds breathed a sigh of relief. And scientists predictions about when and where Duende would be and when -- were totally on the money. It sailed past earth just as they thought it would. But any pats on the back were overshadowed by….
<EXPLOSION!!>>
Chelyabinsk.
And Cathy says just like Alan and all the other researchers[39] -- she was completely shocked
CP: What just happened? Haha. I I literally did the take a sip of coffee, and then did a little bit of a spit take on my monitor.
So how did we know about Duende but miss Chelyabinsk?
Well, what made Duende special is that it was easier to see than the average space rock… . You see… Asteroid hunting tends to be very tricky partly because most asteroids are dark[40] [41] … really dark...and in the darkness of space, that’s a problem...
CP: These things are really hard to find. They’re all fairly dark. So asteroids tend to be about as dark as black velvet or charcoal briquettes. So if you're looking for charcoal briquettes in space that’s a lot like looking for black cats in a coal mine.
Duende on the other hand, was bright-- for an asteroid[42][43] …More like spotting a grey cat in a coal mine. And Duende had another thing going for it - the direction it was coming from.
See, one of the problems with Chelyabinsk was in the weeks leading up to hitting Earth it was basically coming from the direction of the sun[44].
CP: So we weren't going to be pointing a lot of telescopes at it because if you point a telescope at the sun that’s not prepared to look at the sun, you start a fire on your mirror.
Yeah… If you’ve ever tried to burn an ant with a magnifying glass[45]…you know why… just imagine that on a very big scale. Also, shame on you. Did you even listen to our ants episode?
Ok so a couple of things came together that made Duende easier to spot… it was bright. And not coming from the direction of the sun. But it’s still kind of a miracle that we found it at all -- because here’s the thing -- Duende was small… it was only about 40 metres across, some 130 feet… [46]and in the vastness of space
CP That's tiny!! That's really hard to find …
Cheylbinsk also small-- only about 20 meters across[47][48] … So Cathy is not surprised at all that we missed it. … .[49]
So there are a lot of 20 m objects out there that we don't know about.
WZ Oh wow so we're still missing some potentially dangerous asteroids,
CP: so many, so many of them, yeah[50][51].[52]
So that's the story of Duende and Chelyabinsk; … But that’s just two pretty small rocks.. asteroids come in all different sizes. And the larger they get, the more dangerous they are. When they get up to around 1km-[53] things start getting very very very scary. That's more than 100,000 times bigger than our friends Duende[54] and Chelyabink[55]: roughly the difference between a basketball and a hot air balloon.[56] If one of these space rocks hit Earth.. It would be so much worse than Chelyabinsk…. [57]
It would hit and then boom! If you were there, say it hit Manhattan, you wouldn’t survive, you’d be vaporized
WZ: What do you mean vaporized?
CP: What happens is this chunk of rock hits-- it’s still going really really fast. It’s squishing up. And so it’s slamming in, earth is pushing back. It compresses, compresses compresses compresses. Until finally it runs out of gas. Then you’ve got this super dense, super hot piece of rock. That then decides oh it needs to be a vapor .It’s got so much energy in it It just. .. Explodes.
The power that this rock would hit the ground with would basically make anything near it turn to dust… These asteroids would hit with a force that THOUSANDS of times the power of the nuclear bomb detonated over Hiroshima[58][59].
CP There’s a reason we’re using y’know nuclear terminology to describe this. Because it’s just that huge.
WZ it is crazy to think about
CP It really is
And the effects could be felt across the entire world…
CP Right so If something like that it hit the earth it would wreck the Earth’s climate and prevent crops from growing for a year or two.
When a large enough asteroid punches into Earth it can throw up so much dust into the atmosphere… that it literally blots out the sun[60],[61] . Scientists think this dust helped do in the dinosaurs [62]...when they were struck by a super giganto asteroid. So long dinosaurs. So…could this happen to us?
Well… the good news is, that the bigger the asteroid is, the easier it is to spot. So we’d most likely see one of them coming. We’d have time to run around screaming. Actually we’d have time to do something about it. But what? That’s coming up after the break.
<<BREAK>>
DART PROJECT - ANDY CHENG
Well, people at NASA have been asking this very question. And they’ve got some plans of attack - which are different depending on how big the asteroid is. We’re going to start with the plan for a medium sized asteroid. So if Chelyabinsk was a basketball, these are like the height of Steph Curry[63]. And they’re big enough to do some real damage, like wipe out a large city and its surrounding areas[64].[65][66]
And in less than two years, NASA is going to launch a spacecraft to deal with this kind of a rock.. The mission is called DART.[67] And it’s a world first.[68][69]
Andy Cheng is one of the lead scientists on the mission[70][71]... It was his idea![72]
AC: it just came to me! AC Once I thought of it I said oh wow this is really what we gotta do
Ok. So here’s the plan. A spacecraft is going to whack into an asteroid[73] to push it out of the way… literally. That’s the plan.
AC if you have a threatening asteroid that’s going to hit the earth, you want to change it s orbit so it won't hit the earth.
And while this whole “whack an asteroid” idea seems like something your 3 year old might have come up with. There’s actually some huge technological feats involved.[74]. Hitting the asteroid will be extremely tricky because both the asteroid and our spacecraft are moving and FAST. The spacecraft for example will be zooming towards the asteroid[75] at nine times the speed of a moving bullet[76].
This is by far the smallest target[77] we've ever tried to hit with a spacecraft..hitting with a spacecraft going ..13 thousand miles/ hour,[78][79][80] it’s just like hitting a bullet with another bullet… NASA has never launched something like this before[81]…
The asteroid we’re gunning for is called Didymos B.... it’s nicknamed “Didymoon”.[82] It’s about 160 meters across[83] . It’s like SIX blue whales, long ways[84]. And Andy and his team picked it because it has a friend nearby.
AC An 800 meter guy he is spinning.
Didymoon is orbiting a space rock five times its size[85]”. And this was Andy’s big idea. To target on a pair of asteroids, and that’s because the way that Didymoon kind of dances around its mate … it’ll make it easier to detect how much Didymoon will be shoved when the spacecraft hits it. Easier than, say if we just hit a lonesome asteroid.[86] [87][88][89]
And to do this mission, we’re sending our best and brightest.
AC: The spacecraft is a refrigerator sized box[90] … Now It has big solar panels[91]— when they’re fully extended almost 19m from end to end, that’s like what more than 60ft
WZ Does it look a bit like birds wings?
AC: Uhh well haha strange looking bird
The solar wings will power of the spaceships engines and processing[92]... And so in 2021. Our brave little refrigerator-bird will be ready to fly out to Didymoon!!![93]
We’re going to fly! It’s just an awesome moment.
It’ll take about a year of flying until the spaceship will get its very first glimpse of the asteroid [94][95]. From ground control… Andy will see a tiny dot on the spacecraft’s camera… getting bigger and bigger…
Andy and his team will help guide the spaceship to its target - as it gets close to the asteroid our spaceship will become autonomous…[96] So that means our little space chicken will have to find Didymoon all on its own and smash into it.[97]
AC That’s the nail biting part. That’s when it gets really tense, because the spacecraft is on its own and this has to work or it’s not going to hit. We're of course watching from the ground. In fact, I can just see a bunch of us sitting by the TV monitors as we’re waching… Very tense.
If all goes well...this is a kamikaze mission Andy will be very well aware of this end comes close… he’ll be counting down….[98][99]
The end of its existence is 4 minutes away
As the ship gets closer and closer…
AC: 20 seconds before the end!!
Target getting Bigger and bigger as you get closer and closer
AC 5 seconds
From Ground Control, Andy will be seeing Didymoon almost fill the entire field of view… our little flying fridge greets the giant space rock and then…
[pause]
AC: Silence is what it is. Silence, darkness.
You wouldn't hear a thing. Sound can't travel in space, because there are no air molecules for it to vibrate through. [100]. But…c’mon… that’s no good for a podcast… Cue the sound effects!
EXPLOSION…
That’s more like it.
spacecraft is destroyed it’ll be pulverised
Bye bye birdie. And what will become of Didymoon?
AC: Asteroid will sort of dust itself off. keep doing its thing. Its orbit will have changed,
Telescopes from all around the World will have been fixed on this crash…[101]… so that we can measure the change in Didymoon’s orbit.
And if this all works out… and we can hit and move Didymoon… which isn’t a threat. That means that we could use this same technique on something that is actually on track to hit Earth.
Nuclear Option [Cathy Plesko]
Ok so that’s the plan for medium sized asteroid. The kind that can wipe out a city. But it couldn’t work for something bigger--- say an asteroid that would threaten the entire world[102]. They’re just too big. It could swat away our refrigerator bird like a fly… So, is there anything we can do to save ourselves from one of these monsters? Well, Cathy Plesko says we’ve got a plan for this.
So Probably that would be a nuclear issue[103]
A nuclear issue. As in bring out the nukes. Cathy says blowing up the asteroid with a nuclear device… while not totally off the table… [104][105][106]… isn’t ideal because it would just break the asteroid up into lots of little asteroids, which could come hurtling down to earth and cause trouble. I guess that 90s documentary - Armageddon got it a bit wrong. Still, Cathy reckons that we could use nukes. Just a little differently....[107]
So the idea there isn't to necessarily shatter it and blow it up. the idea is to push on it
Push on an asteroid? With a nuke? Here’s how it would work: We would explode a nuclear bomb near an asteroid[108]… so the explosion itself would push the asteroid out of the way. And basically what we’re trying to do is to make the surface of the asteroid become so hot from the explosion that it’ll start to vaporize...[109]. Because that vapour… ?
CP: It wants to expand really, really fast and really, really hard. And so that vapor expands off the surface, and as it's moving away, it’s pushing a little bit on the surface of the asteroid that’s solid. And I know this is a hard core science podcast so I'm going to get a little mathy. A lot of people will have seen the ideal gas law, PV= nrt.
CP: Uh oh, oh no, too nerdy, too nerdy, back up!
WZ: Hard core science? What kind of show do you think we’re running here...
CP: Oh dear, I'm sorry I just nerded all over your podcast.
<<so let me back up. Alright>>
Yep… let’s back up… ideal gas law basically tells us that the Nuclear bomb would heat up the surface of the asteroid so much, that'd it start to vaporize and create a ton of pressure. That could ultimately push the asteroid it off course. And it’s not just about nudging the asteroid a little to the left so it would miss us. Both Andy’s refrigerator bird and the nuke-near-it option would also change the speed that the asteroid is moving… which means it might slip past us.
CP The asteroid is delayed a little bit or hustled up a little bit, so that when it does cross Earth's orbit, Earth is not at that point in its orbit. So it would-- instead of hitting the Earth, it would do a zipper merge on the highway, it would wait its turn, it would pass through, and no one gets hit
Through computer simulations Cathy has found that if you have a massive asteroid hurtling towards earth… and you did the nuke-near trick… it should work. As long as we had plenty of time.[110]
CP: One cm per sec change in velocity, ten years ahead of time- would make the object miss the earth by one earth diameter. WZ Wow. CP Which is really close!
WZ: Basically a bee’s dick away
CP YES, that’s a skin of the teeth miss.
CP This is a very slow, very big ballet. This is not something you can do really fast. This isn’t Star Trek where we are going to fly out there with our photon torpedoes and just shove it out of the way and then in half an hour everyone is having cake and fireworks.
So now that we know what we would do about big asteroids heading towards earth -- what's the chance that we’re actually going to need any of these plans? Like how likely is it that an asteroid will be headed our way?
Well to figure this out, scientists count how many asteroids we’re tracking in a given part of space[111] …and they calculate the likelihood that we’ve missed some… they feed that information into statistical models. According to these models, they expect that a Chelyabinsk- sized asteroid would hit us - on average - every 100 years or so[112]… One in every 100 years.
The city killers - the Didymoons - they hit waaaay less often. One in every 20,000 years or so[113]
And for the really, really big rocks? The ones that could change the world’s climate?… Well, looking through our telescopes, we don’t see many of these in the skies. So to get more information, count craters - literally, they count the scars of when asteroids have hit in the past. [114][115][116].
So we know from the moon and the Earth and other planets that we’ve looked at[117] what the impact record is, so we do have a pretty good handle about how often asteroids of different sizes hit.
And from this scientists have found that these really, really big asteroids---
CP: Those objects that size hit maybe every 100 to 500 thousands years[118][119].. Casino odds. And so they do happen but it would be like winning the worst lottery ever it happened to us tomorrow…
WZ: And then, so why do you study this option that would only be used for the big ones?
CP It is a very low probability thing, but you know I don’t expect to find a fire, but have a fire extinguisher in my kitchen, Ideally.. Like the best possible outcome for this work that I'm spending years of my life honestly on is that it will become a dusty little PDF file on somebody's computer … and we won’t ever need it. But in case we do. … It’s better to think through it, when no one’s shouting about it, when nothing is aimed at us, so let's do the models now.
And Cathy reckons that the ideas that scientists are cooking up here -- like nuking near it and whacking into it - they will work. Which makes asteroids kind of special when you compare them to other natural disasters.
CP we know how to do this. We.. can't right now deflect a hurricane and tell it to go somewhere else, we can’t cork a volcano. We can’t superglue san andreas fault shut and stop it from making more earthquakes. We can potentially push an asteroid off course and stop it from hitting the earth with technology that we have right now.
So when it comes to the asteroid apocalypse… should you be worried?
Well, probably not… we’ve got some ideas to get them out of the way if one was coming for us… plus the odds of a big scary asteroid hitting us in our lifetime… are just so small… it’s just really really sm-
<<BOOM>>
<<silence>>
That’s Science Vs Asteroids
CITATIONS
And this is the last episode of the season!! It flew past! We’ll be back with a new season in March! MARCH. Thank you so much for listening! And here’s a little montage to remember the good times by..
RF What’s that stuff you shove down the lavatory umm WZ poo? RF No no laugh (Sleep)
I wanna be on this TV… I wanna be in the NFL. This is what I love to do so
RR It makes you smile really broad
IS Yes it does. (football)
CS In the middle of the street, not only did they burn the garbage, but they burned a pile mountain of garbage! It was amazing! (young lords)
LB Neuroscientists said ohhh it’s too messy, too much emotion… you can’t study it scientifically! it seems magical! We said ohhh we think maybe we can (Heartbreak)
GS Are you kidding me? Like this is all related to those dumb mango favoured pods I would find. What the hell is going on? (Vaping)
Mum 1: What do you mean you don’t have a ventilator for her?
Nurse 1: I’m sorry, ma’am, but all our ventilators are in use at the moment.
Mum 1:. So take one from someone else! (Pandemic)
5, 6, 7, 8 the bigger the correlation doesn’t mean the better the causation, yah!! (Exercise)
DB they convince the cells around them that you should become stalks. (Ants)
MH like whisper in their ear? “Stalks are doing great work out there”
DB so they whisper in the ear to become a stalk “be a stalk” “be a stalk”
RR two to go WZ let’s do this RR you actually have to shotgun them, it’s in the protocol laugh WZ it is not, that’s a lie (sleep)
A big thanks to Carl Smith at The Australian Broadcasting Corporation for suggesting this topic - Carl did a podcast series on a bunch of the Apocalypse scenarios. Including the likelihood of a supercharged sun storm doing us in! And a supervolcano getting us! You can find it at the podcast Science Friction and search for the Apocalypse series.
This episode was produced by Wendy Zukerman along with Lexi Krupp with help from Michelle Dang, Meryl Horn and Rose Rimler. We’re edited by Caitlin Kenney. Fact checking by Michelle Harris. Mix and sound design by Peter Leonard. Music written by Peter Leonard, Bobby Lord and Emma Munger. Recording assistance from Verónica Zaragovia, Sofi LaLonde, Lawrence Lanahan, and Kevin Caners. Translation help from Andrew Urodov and Dmitriy Tuchin. A big thanks to all the scientists we spoke to-- Dr. Carrie Nugent, Dr. Mark Boslough, Dr. David Kring, Dr. Daniel Durda, Dr. Kelly Fast and the other Dr. Alan Harris And thanks to the Zukerman Family and Joseph Lavelle Wilson.
I’m Wendy Zukerman, fact you next year.
[4] This would be the 8th closest encounter ever recorded between an asteroid and the Earth, and the first time such an event was known about more than a few days in advance." https://www.sciencedirect.com/science/article/abs/pii/S0019103519304038?via%3Dihub
[5] The flyby of asteroid 2012 DA14 is the closest ever predicted Earth approach for an object this large...Scientists at NASA's Near-Earth Object Program Office in Pasadena, Calif. estimate that an asteroid the size of 2012 DA14 flies this close every 40 years on average
[6] Ironically, many were prepared for what was expected to be the big news event of the day, the close passage of asteroid (367943) Duende. With interviews and press conferences scheduled.. https://core.ac.uk/download/pdf/31021006.pdf
[7] 2,325.0 mi Vienna to Chelyabinsk by driving or 1951 miles from point to point https://www.mapdevelopers.com/distance_from_to.php
[8] DUENDE: Asteroid 2012 DA14 will be closest to Earth on February 15, 2013 at about 19:24 GMT (2:24 p.m. EST or 11:24 a.m. PST), when it will be at a distance of about 27,700 kilometers (17,200 miles) above the Earth’s surface.
CHELYABINSK On 15 February 2013, a piece of asteroid entered Earth's atmosphere over Russia at about 09:20 YEKT (03:20 UTC) [1] with an estimated speed of 20 km/s (42,500 mph);
[9] Email with SZ
[12] Objects approximately 25-30 meters in diameter can cause a fireball, airburst, shockwave, and minor damage. [Chelyabinsk]
[13] Shock radiation contributed to surface heating and ablation, but did not completely evaporate all fragments of Chelyabinsk .... 76% of the meteoroid evaporated, with most of the remaining mass converted into dust... Witnesses reported smelling “sulfur” and burning odors over a wide region concentrated near the fireball trajectory
[14] Out on the streets, startled residents screamed and shouted expletives as the concussion hit them and set off car alarms. https://core.ac.uk/download/pdf/31021006.pdf
[15] Structural damage included the collapse of a zinc factory roof … suspended ceilings were sucked down
[16] In Chelyabinsk itself, 3,613 apartment buildings (about 44%) had shattered and
broken glass…. In Yemanzhelinsk, window frames facing the trajectory were pushed inwards
[17] “Suddenly, just under a minute and a half after the brightness of the fireball peaked, an unexpected blast wave ripped through the city, blowing out windows and showering spectators with high-speed shards of glass… ” https://core.ac.uk/download/pdf/31021006.pdf
[18] It damaged thousands of buildings and injured over a thousand people, mostly due to glass broken by the shock wave
[19] “Fifteen hundred people would have to be treated for their injuries. Out on the streets, startled residents screamed and shouted expletives as the concussion hit them and set off car alarms.” https://core.ac.uk/download/pdf/31021006.pdf
[20]http://www.amostech.com/TechnicalPapers/2013/POSTER/RYAN.pdf “... caused millions of dollars in damage from a shock wave that impacted structures and injured ~1500 people”
[21] The Chelyabinsk asteroid came from the direction of the Sun in the northern hemisphere, and Duende was arriving from the southern nightside. https://core.ac.uk/download/pdf/31021006.pdf
[22]The DART project established its cost and schedule baselines in August 2018 with an estimated cost of $313.9 million and a launch date of February 2022, which is a $22.9 million cost increase and 9-month delay from the preliminary range set in June 2017. https://www.gao.gov/assets/700/699373.pdf
[23] Discovered 2012 Feb. 23 at OAM Observatory, La Sagra.
[24] It was discovered on 2012 February 23 in the Spanish observatory La Sagra Sky Survey (J75).
[27] All of the MPC's operating funds come from a NASA Near-Earth Object Observations program grant. Much of the computer equipment that the MPC uses was provided by the Tamkin Foundation. https://minorplanetcenter.net/
[28] “The Minor Planet Center (MPC) is the internationally agreed-to public archive of small-body orbit data submitted by observers from around the world. The MPC notifies observers worldwide about NEO discoveries so that timely follow-up observations can be collected for identification, and orbit computation. The MPC is sanctioned by the International Astronomical Union and functions as a subnode of NASA’s Planetary Data System Small Bodies Node.” https://www.nasa.gov/planetarydefense/neoo; https://minorplanetcenter.net: The MPC is responsible for the identification, designation and orbit computation for all of these objects. This involves maintaining the master files of observations and orbits, keeping track of the discoverer of each object, and announcing discoveries to the rest of the world via electronic circulars and an extensive website.
[29] Described in here: https://academic.oup.com/mnras/article/459/4/3986/2623970
[30] Blog from La Sagra, the group that first discovered Duende: As soon as we had confirmed it, we reported it to the Minor Planet Center, where it was listed on their near-Earth object confirmation page. This page lists newly discovered near-Earth objects so that astronomers around the world can obtain follow-up images to confirm that it is truly an asteroid, and to help determine its orbit.
[31]https://www.nap.edu/read/25476/chapter/4#15
Astrometric observations measure the course of an asteroid across the sky in order to refine its orbit. Without astrometric observations, the positional uncertainties from insufficiently constrained orbits will quickly grow, impeding future targeted observations and the accurate assessment of impact probabilities.
[32] La Sagra, Spain discovered Feb 23 at 0:40UTC or their time: 1:45 AM; France telescope observed Feb 23 at 2.21 UTC or 3:21 AM their time; Sabino Tuscon, AZ observed Feb 23 at 7.18 UTC or 12:15AM their time; Kitt Peak, Tuscon AZ observed Feb 23 at 12:33UTC or 5:30AM their time; THEN the Minor planet center posted these observations on Feb 24 1:59 UTC
[33] The Minor Planet Center (MPC) is the single worldwide location for receipt and distribution of positional measurements of minor planets, comets and outer irregular natural satellites of the major planets. The MPC is responsible for the identification, designation and orbit computation for all of these objects. Submissions info
[34] There's even a schools program dedicated to getting kids to do this stuff. http://iasc.cosmosearch.org/index.html
[36] Many professional and amateur observatories made observations of Duende light curve (see for example Birtwhistle 2013; Elenin, Molotov 2013; Terai et al. 2013).
[37] On 15 February 2013, the asteroid 367943 Duende (2012 DA14) experienced a near-Earth encounter at an altitude of 27,700 km or 4.2 Earth radii.
[38] 2012 DA14 is coming remarkably close
[39] His point was driven home in February 2013, when the world was primed for the close approach of asteroid Duende. While everyone watched the sky in one direction, a second asteroid shot towards the Earth and exploded above Russia. This was the Chelyabinsk meteorite whose collisional path had not been anticipated.
[40] Asteroids emit no visible light of their own; their visible brightness depends on the amount of sunlight reflected/scattered from their surfaces...in visible wavelengths, the brightness depends on the asteroid’s size as well as on the intrinsic reflecting ability (albedo) of its surface (most asteroids are very dark, reflecting only 10 percent or less of the sunlight that falls on them), and the phase at which it is observed.
[41] In comparison to the planets, asteroids are small and dim.
[42] Source 1: https://nssdc.gsfc.nasa.gov/planetary/text/asteroids.txt Albedo refers to an object's measure of reflectivity, or intrinsic brightness. A white, perfectly reflecting surface has an albedo of 1.0; a black, perfectly absorbing surface has an albedo of 0.0…. C-type (carbonaceous): Includes more than 75 percent of known asteroids. Very dark with an albedo of 0.03-0.09. https://www.aanda.org/articles/aa/pdf/2013/07/aa21373-13.pdf Paper on 2012 DA14 (Duende) From the absolute photometry, together with some constraints on size and shape, we compute a geometric albedo of pV = 0.44 ± 0.20, which is slightly above the range of albedos known for L-type asteroids (0.082−0.405).
[43] Near-Earth Objects: Finding them before they find us (page xi)
https://books.google.com/books?hl=en&lr=&id=PDMeDAAAQBAJ&oi=fnd&pg=PP1&dq=duende+Chelyabinsk&ots=SQbBxzrCi0&sig=m33SgSMh3Lxu8sfhUiWyLr3oSJQ#v=snippet&q=duende&f=false “Observations made near the time of closest approach indicated that this asteroid rotates with a period of nine hours and has a relatively high reflectivity, reflecting about 44 percent of the incident sunlight.”
[44] The asteroid spent the six weeks before impact within an elongation of 45 degrees from the Sun, a region of the sky inaccessible to ground-based telescopes.
[45] Both focus light, which makes it possible to ignite fires. See Chapter 9 “Sunbeam explodes” on magnifying glasses starting fires. And safety methods for using telescopes.
[46] the calculated sizes of the asteroid turned out to be (40 × 12 × 12)
[47] https://www.nature.com/articles/nature12671 “corresponding to a diameter of 19 m”
[48] Combined with the best kinetic energy estimate, an entry mass of 1.3 × 107 kg (with a factor of two uncertainty) and a diameter of 19.8 ± 4.6 m is derived, assuming a spherical shape and the meteorited erived density of 3.3 g/cm3 based on x-ray computed tomography (SM Sect. 4.2, table S16).
[49] We note that telescopic surveys have only discovered about 500 near-Earth asteroids that are 10–20 m in diameter (comparable to the Chelyabinsk asteroid) of an estimated near-Earth asteroid population (http://ssd.jpl.nasa.gov) of around 2 x 10^7 , implying that a nonequilibrium impactor population at these sizes could be present but not yet apparent in the discovered near-Earth asteroid population.
[50]NAS report estimates there are over 500,000 objects larger than 40 meters that could pose an impact hazard and would be very challenging to detect more than a few days in advance. https://www.nap.edu/read/25476/chapter/3#8
[51] after almost two decades of search, NASA and its partners have catalogued about one-third of the estimated 25,000 NEOs that are at least 140 meters in diameter. [1/3rds of 25000 = 8,333]
[52] According to current estimates, there are almost 10 million NEOs larger than 20 meters, but they are extremely difficult to detect prior to entering Earth’s atmosphere.
[53]Estimated damage from 1 km object: “Global effects, many millions dead“ https://www.nap.edu/read/25476/chapter/3?term=%22once+every%22#8
[54] Duende: the calculated sizes of the asteroid turned out to be (40 × 12 × 12) = volume 5760 m^3 = 11.12m radius = 22 diameter
[55] Chelyabinsk This implies a pre-entry diameter of ~20 m; corresponding to a diameter of 19 m
[56] Basketball = circumference = 75cm so .12m radius = .24 diameter; Hot Air Balloon diameters start at 41 feet = 12.5 m diameter Ratio of Hot Air Balloon/Basketball = 12.5/.24 =52. Ratio of 1000m/20m (1km to Duende/Chelyabinsk) = 50.
[57] See Table 1 https://core.ac.uk/download/pdf/31021006.pdf
[58]15 kiloton Hiroshima bomb. AND NEOs larger than 140 meters... would strike Earth with a minimum energy of over 60 megatons of TNT 60 megatons = 60,000 kilotons; 60,000/15 = 4000.
[59] Models suggest that airbursts are more damaging than nuclear explosions of the same yield (traditionally used to estimate impact risk, although nuclear radiation is not produced by the impact of a NEO).
[60] Every once in a while large volcanic eruptions produce temporary cooling for a year or two. The largest of the past 500 years, the 1815 Tambora eruption in Indonesia, produced global cooling of about 0.5◦ C for a year. Year 1816 became known as the ‘Year Without a Summer’ or ‘18 hundred and froze to death’
[61] Among the most notable effects were global weather anomalies the following year, which has come to be referred to as ‘the year without summer’.
[62] For example, during the Cretaceous-Paleogene (K-Pg formerly K-T) event 66 million years ago, an asteroid with a diameter currently estimated as 12-14 kilometers impacted what is now the Yucatan Peninsula and resulted in long-duration global climate change that famously caused, or contributed to, the extinction not only of the dinosaurs but also of more than 75 percent of all nonavian life on Earth
[63] Diameter of Duende 20m, Diameter of diddymoon 160m = 1:8 ratio. Diameter of Basketball .24m; .24*8=1.92m=6.3 ft, 6’4’’. Steph Curry is 6’3’’
[64] “Larger NEOs greater than 140 meters have the potential to inflict severe damage to entire regions or continents. Such objects would strike Earth with a minimum energy of over 60 megatons of TNT, which is more than the most powerful nuclear device ever tested.”
[65] If an NEO of this size were to impact Earth, it would release an impact energy of ~400 MT TNT and would cause regional devastation (over more than a metropolitan area). https://www.sciencedirect.com/science/article/abs/pii/S0032063317304579?via%3Dihub
[66] ~140m object would cause “destruction on a regional/ national scale”
[67] Launch window opens July 22, 2021
[68] As the first demonstration of asteroid deflection by a kinetic impactor, DART will provide important validation of the technique before it is considered viable for implementation in the event of an impact emergency.
[69] DART will be the first high-speed impact experiment at an asteroid and at a realistic scale for planetary defense, where the impact conditions and the physical properties of the projectile are fully known
[70] Bio: https://www.jhuapl.edu/PressRelease/080530; Dr. Cheng is the DART Investigation Team co-lead;
[71] According to interview (& our interview), he conceptualized the initial DART idea to target a binary asteroid for testing. “The answer came to Andy Cheng, of the Johns Hopkins Applied Physics Laboratory in Howard County, in his basement during his morning calisthenics routine. Cheng realized the simplest approach was to crash a spacecraft into the smaller of a twin pair of asteroids—whose orbits are linked—and then measure the change in the orbit of the smaller asteroid against its larger twin.”
[72] Email w/ AC: [AC] proposed the mission that became DART in 2011 (it did not have the name DART at the time). NASA funded DART studies starting in 2013. NASA approved DART in 2018.
[73] The DART spacecraft will achieve the kinetic impact deflection by deliberately crashing itself into the moonlet at a speed of approximately 6.6 km/s
[74] Because we consider two-body dynamics, and in the absence of capturing effects, the terminal constraints change from case to case (there’s a lot to account for in orbital dynamics)
Also, we’re not quite certain the exact shape of Didymos as well as shape deformations that will occur; might affect orbit dynamics of both bodies
[75] The DART spacecraft will achieve the kinetic impact deflection by deliberately crashing itself into the moonlet at a speed of approximately 6.6 km/s
[76] a speed about nine times faster than a bullet
[77] smallest asteroid ever visited (source: ESA on Hera, follow-up mission of DART)
[78] The impact of the >300 kg DART spacecraft at 6.67–7.38 km/s (depending on launch date) will produce a speed change on the order of 0.4 mm/s (assuming β=1, i.e. no contribution of impact ejecta) … [But models show that ejecta will multiply that effect (exact extent unknown)]: It is expected that the momentum transfer efficiency to the target will be β>1, because of crater ejecta released backwards in the incident direction. The momentum carried off by crater ejecta can lead to β>3
6.67 km/s*60s.min*60min/1hr*.621mi/km = 14,911 mph ~ 13,000 mph
[79]“DART will be the first high-speed impact experiment at an asteroid and at a realistic scale for planetary defense:
[80] According to this paper, the asteroid’s material (which is not certain) will not make a big difference, but simulations show porosity of the asteroid (also uncertain) has significant effects in simulations of DART
[81] As the first demonstration of asteroid deflection by a kinetic impactor, DART will provide important validation of the technique before it is considered viable for implementation in the event of an impact emergency. DART will be the first high-speed impact experiment at an asteroid and at a realistic scale for planetary defense, where the impact conditions and the physical properties of the projectile are fully known
[82] The DART impact on the Didymos secondary (Didymos B) at ~6 km/s will alter the binary orbit period. Didymos is a binary asteroid
[83] While the Didymos primary body is approximately 780 meters across, its secondary body (or “moonlet”) is about 160-meters in size, which is more typical of the size of asteroids that could pose the most likely significant threat to Earth.
[84] https://www.nationalgeographic.com/animals/mammals/b/blue-whale/ (82-105 feet which is 25 to 32 meters); https://animaldiversity.org/accounts/Balaenoptera_musculus/: Average length: 25-27 m
[85]https://www.researchgate.net/figure/65803-Didymos-binary-system-Didymain-on-the-left-is-modeled-as-a-polyhedral-object_fig1_317400553 “The binary near-Earth asteroid (65803) Didymos is the target for the DART demonstration. While the Didymos primary body is approximately 780 meters across, its secondary body (or “moonlet”) is about 160-meters in size”- NASA
780/160 = 4.875
[86] Interview w/AC: targeting a binary asteroid allows us to use one large spacecraft instead of two. For a regular asteroid, we’d have to send up a second ship that would track and observe the orbit of the asteroid before and after the impact. Instead, with a binary asteroid, we can track its light reflections from earth and do calculations.
[87] Andy’s 2014 paper on why to target binary asteroids: 1) The sizes, mass and orbit pole direction of the system can be determined from distant observations (and, indeed, can already be estimated from Earth-based observations). 2) Precise measures of the mutual orbit and rotation state of the binary components …. 5) The presence of a secondary may allow areas on the primary to be observed in “moonlight”
[88] Didymos is an eclipsing binary, which enables accurate determination of small
period changes by ground-based optical light curve measurements (Pravec et al., 2006). In an eclipsing binary, the two objects pass in front of each other (occultations), or one object creates solar eclipses seen by the other, so there are sharp features in the lightcurves that can be timed accurately.
[89] Beginning at roughly 4 hrs prior to impact, DRACO can separate Didymos A and B ….Starting at 4 hrs before impact, DRACO is targeted on Didymos B
[90] https://www.sciencedirect.com/science/article/abs/pii/S0032063317304579?via%3Dihub Dimensions of the spacecraft box are 1.14 m x 1.24 m x 1.32m (3.74ft x 4.07ft x 4.33ft) DART has 22 m2 rollout solar arrays
[91] Roll out solar arrays: ROSA provides a compact form and light mass for launch that then deploys into two large arrays once DART is in space, each extending 8.6 meters in length. (~19m accounts for box)
[92] The ROSA solar array for the DART mission will provide more than 6.6 kilowatts of power at beginning-of-life… The ROSA solar arrays will provide reliable and continuous power for NASA's Evolutionary Xenon Thruster-Commercial (NEXT-C) ion drive system.
[93] DART Impact date: September 27 – October 2, 2022 (launch window opens July 2021)
[94] https://www.nasa.gov/planetarydefense/dart The DART spacecraft launch window begins in late July 2021. DART will launch aboard a SpaceX Falcon 9 rocket from Vandenberg Air Force Base, California. After separation from the launch vehicle and over a year of cruise it will intercept Didymos’ moonlet in late September 2022 when the Didymos system is within 11 million kilometers of Earth,enabling observations by ground-based telescopes and planetary radar to measure the change in momentum imparted to the moonlet.
[95] Long-range imaging observations will begin approximately 30 days before impact to provide ground based optical navigation images which include Didymos and at least 3 stars.
[96] DRACO imager pg 10: Provides images and centroids for close, autonomous guidance to Didymos (SMARTNav)
[97] Beginning at roughly 4 hrs prior to impact, DRACO can separate Didymos A and B ….Starting at 4 hrs before impact, DRACO is targeted on Didymos B
[98] Email w/AC on why autonomous navigation is turned off at 2 min: “It is to benefit imaging of the target”
[99] The final transmission prior to impact will provide better than 40-cm resolution imaging of the impact site. This data will provide additional context to support the reconstruction of the event in the impact models.
[100]For sound to travel, there has to be something with molecules for it to travel through. On Earth, sound travels to your ears by vibrating air molecules. In deep space, the large empty areas between stars and planets, there are no molecules to vibrate. There is no sound there." http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-is-there-sound-in-space.html
[101] http://www.lcpm12.org/wp-content/uploads/2017/08/1355-1415-Reed.pdf see pg 18 for list of telescope agencies that will be involved
[102] Global effects happen with asteroids 1 km or bigger. DART-style mission (with a few years to a decade of warning time) is “effective for NEOs with diameters up to about half a kilometer”
[103] See Table 5.2 https://www.nap.edu/read/12842/chapter/7#68
[104] If we detect a [potentially hazardous object] that is likely to hit us, we have several options besides doing nothing. The options fall into two broad categories. The first category is disruption and dispersal of the PHO into harmless fragments. While this scenario makes for entertaining Hollywood movies, in practice it would be extremely difficult to confirm that we did indeed disrupt the asteroid and disperse the fragments enough to be harmless…..We feel that disrupting an asteroid should be considered a method of last resort. -2010 paper
[105] Disruption has been widely proposed as a mitigation option, but disruption could make the situation worse. Specifically, if the hazardous object breaks into a small number of large fragments with only a very small spread in velocity, the multiple impacts on Earth might cause far more damage than a single, larger impact. Thus, disruption or fragmentation is a sensible strategy only if it can be shown that the hazard is truly diminished. https://www.nap.edu/read/12842/chapter/7#76
[106] A subsurface nuclear explosion is the most efficient use of nuclear explosives [10, 11]. The nuclear subsurface explosion, even with shallow burial to a depth of 3 to 5 m, can deliver a large amount of energy into the target asteroid, so that there is a likelihood of totally disrupting the target asteroid. Such subsurface nuclear explosions are known to be at least 20 times more effective than a nuclear contact burst (a nuclear explosion very close to the surface)
[108] See Figure 1 https://aip.scitation.org/doi/abs/10.1063/1.3326272
[109] https://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-11-03133 “Part of this thin surface layer is vaporized and heated to temperatures as high as 10,000 K.”
[110] “The ultimate goal of our project is to create a catalog of deflection simulations where we vary the distance, magnitude, and targeting of the burst from PHOs of different sizes, shapes, internal structure, and compositions” https://aip.scitation.org/doi/abs/10.1063/1.3326272 “In contrast with other natural disasters, it is likely that an asteroid or comet nucleus on a collision course with Earth will be detected with enough warning time to possibly deflect it away”
[111] Fig. 2. And Table 1 (likely where the next source, NAP, got its data) “The continuous curve represents discoveries as of August 2014; the curve traced by the circles represents the estimated total number of objects in the NEA population, derived from computer modeling of discovery and redetection rates by optical telescope surveys over the two-year period to August 2014.” This paper describes more clearly how computer modeling taking sky observations is used to estimate the number of near-Earth asteroids
[114] Page 360 “This is done in a novel way by rigorously comparing the crater size distributions on the different planetary objects in an analytical way… the resulting data are related to the lunar data which are our best data base for studying the cratering record of the Earth-Moon system. In this way, the characteristics of the inner solar system impactor family are assessed and impact probabilities on Earth are derived to a high degree of accuracy.”
[115] Bottom right pg 33: https://www.nature.com/articles/367033a0
[116] The evidence is clear from the impact craters on the Moon, Mars, Mercury, other planets and moons in our solar system, as well as from over 160 identified impact craters on Earth.
[117]See pg 378: https://books.google.com/books?hl=en&lr=&id=xXWZolI9NkUC&oi=fnd&pg=PA359&dq=impact+interval+asteroids+craters&ots=12Q3y9eF0r&sig=-n0ETd6GWzBQta0bAaDfB1e9r1Y#v=onepage&q=impact%20interval%20asteroids%20craters&f=false
[118] For the Kilometer size https://www.nap.edu/read/25476/chapter/3#8
[119] A probability of 1 in 100,000 cannot be viewed as an impact every 100,000 years. In other words, just because there has not been a 300- to 500-meter impact in 100,000 years does not mean that Earth is “due for one.” Neither is it the case that it is not.