Astrum Space - The Image NASA Didn't Want to Receive from the Deep Impact Probe

Episode Date: March 18, 2025

How NASA crashed into Tempel-1 and visited Wild-2 with the Deep Impact and Stardust probes. Discover our full back catalogue of hundreds of videos on YouTube: https://www.youtube.com/@astrumspaceFor early access videos, bonus content, and to support the channel, join us on Patreon: https://astrumspace.info/4ayJJuZ

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Tickets on sale now at Yamava Theater.com, only at Yamava Resort and Casino, celebrating its 40th anniversary. You in? Must be 21 to enter. If you've ever looked up at the night sky and watched a comet streak by, you will know of the wonder of watching one of these celestial visitors. Often seen with awe or fear throughout humanity's history, these bright-tailed objects in our skies were known as harbingers of change. And yet, in the last 50 years, the tables turned on these icy wanderers,

and it went from them coming to visit us to us being able to visit them. Scientists had long wondered about the nature and origin of comets. Where had they come from? How were they formed? In 1986, the first probe was launched to Image Halley's comet, and scientists began to find answers. But to truly understand comets, it would take more than photographs. A more physical approach would be needed. Between 1999 and 2005, two probes were launched. Their mission was to interact with comets in ways that had never been attempted before.

One would bring collection equipment that would allow it to scoop star dust right from the comet's icy tail to help scientists analyze the chemical makeup of these frosty harbingers. The second would take a more forceful approach. Rather than quietly collecting a smattering of space dust, the second probe would crash, head first into the surface of the comet itself, exploding with the force of 5 tons of TNT, to see what could be learned from the resulting crater and debris. And yet, although these two missions were two different comets, through chance there was one comet that unexpectedly brought them both together, Temple One.

I'm Alex McColgan and you're watching Astrum. Join with me today in today's Supercut as we explore the explosive story of Temple One and how the stardust and deep impact probes both were needed to help discover what lay at the heart of this space-born nomad. In the early 90s, comets were still a bit of an enigma. By 1999, eight different spacecraft had been launched to investigate comets in our solar system, with five of them having flown by Halley's comet in 1986. But beyond that, only two other comets had been visited, Comet Gia Gobini Sina in 1985, and

Comet Griggs Skellerup in 1992. And while some fascinating photos and dust samples had been taken as close as 200 kilometers from some of these incredible celestial bodies, comers and tails, comets still had many mysteries. What was their internal structure like? What were they made from? And how had they formed in the first place? In 1999, NASA scientists proposed the plan to hopefully answer some of these questions.

It would be difficult to understand the internal structure of comets by simply looking at their surface. To know what was going on, scientists would need to dig a little deeper. Their plan was to create a crater in a comet using an impactor spacecraft, which would collide with the comet at high speeds. As they would know the mass of the impactor and the speed it was traveling at, they could calculate from the size of the impact crater valuable information about the comet, whether its surface was a loose aggregate of dust and ice, or whether it had a hard, frozen shell,

for instance. The comet they wanted to target was a short period comet called Temple One, which had a nucleus of 8 kilometers long and 5 kilometers wide. Scientists weren't exactly certain what would happen when the impactor hit. Perhaps the impactor would punch straight through, like hitting a snowdrift and not really create a crater at all. There were many theories, but scientists were eager to find out which was correct. NASA approved the project, giving it a budget of $330 million and named it Deep Impact.

You might have thought that this was a reference to the 1998 Hollywood film of the same name. but apparently the names for both the project and the film had been come up with independently around the same time. Quite a remarkable coincidence, if so, as Deep Impact, the film, was about scientists trying to blow up a meteor that was on a collision course with the Earth by flying a spacecraft to it carrying nuclear warheads. There certainly seemed to be some similarities to the NASA mission, especially as NASA scientists worked on the film.

I don't entirely buy NASA's claim of a coincidence. Although, fortunately for the Earth, there were some differences between the film and the mission too. Temple 1's orbit was nowhere near the Earth's, and given the size of the impactor compared to the comet, there was no chance of knocking it off its current trajectory by more than a centimeter or so. It would be more like a fly hitting the front windscreen of a large vehicle. Additionally, nukes would not be necessary to create a crater on Temple 1, or any kind

of explosives for that matter. The sheer speed and kinetic force the impactor would have when it collided with the comet's surface would be enough to create the crater, which some predicted would be roughly 100 meters across and 30 meters deep. With the mission going ahead, scientists began work on the deep impact spacecraft. The spacecraft was actually made with two parts, the payload and another larger mother ship to carry it and record the result of the impact. The second section was called the flyby.

It weighed 601 kilograms, was 3 meters long, and housed scientific devices, solar panels, a debris shield, and two powerful cameras, the high-resolution imager and the medium-resolution imager. These would take photos of the comet after the impact, as well as help with navigation. The impactor itself was smaller, only 372 kilograms, but it was still smart and housed the camera of its own. This camera, the Impactor targeting sensor, would take photos of Temple One right up until the moment of impact, streaming back the images it collected to its parent, flyby, which would then relay the images to Earth.

There was considerable public interest in the mission, which NASA encouraged in 2003 by getting members of the public to submit their names to be recorded on a CD, which was placed on the Impactor. Roughly 625,000 names were collected in this way to be carried directly to Temple One's surface. On top of that, NASA timed the impact to take place on the 4th of July, American Independence Day. While this may have been because it was one day before Temple One's perihelion, and its proximity to the sun may have produced clearer images, I suspect that the more likely reason for this

date was that American scientists like the idea of a large cosmic firework. Deep Impact launched on the 12th of January 2005 on a Delta 2 rocket. But then a problem hit. Within a day of leaving the Earth's orbit, Deep Impact's onboard computers switched itself to safe mode, which it would only do if there was a fault. Something on board was apparently overheating. This gave scientists a bit of a scare, but fortunately the cause of the problem was quickly found to be a minor programming issue.

heat tolerances had been set too low, so Deep Impact thought its thrusters were overheating, when in reality they were just fine. Engineers corrected the issue, and Deep Impact was able to properly begin its mission. The spacecraft spent the next six months traveling to its rendezvous point with Temple One. In that time, it traveled 429 million kilometers. It had to course correct twice on the journey, but this was actually impressive, as it had originally been planned for there to be three course corrections. One was just so precise that the other was deemed unnecessary.

On the 25th of April 2005, Deep Impact caught its first glimpse of Comet Temple One. Of course, NASA scientists couldn't manually guide Deep Impact as there was a several-minute signal lag. Deep Impact and Temple One were now roughly 130 million kilometers away from Earth, more than twice the closest distance between Earth and Mars. Deep Impact smart on-board programming would have to guide it in for. for the final leg of the journey. On the 29th of June, the impact was successfully released from the flyby, and positioned itself into the comet's flight path to crash into it head on.

This was done for a few reasons. First, the front of the comet was in sunlight, which would allow for better pictures to be taken. Second, it would allow a greater accumulated speed to be reached, resulting in greater kinetic force. And on the 4th of July 2005, just one second out from the second out from the flight to be reached, resulting in the Fourth of July 2005, just one second out from the anticipated arrival time, the impactor hit. And what a magnificent spectacle it produced.

Scientists were thrilled that they had struck so accurately. Deep impacts payload had been travelling at 37,000 kilometers per hour, and had struck with a force of 19 billion joules of kinetic energy. This produced the bright flash you see here, the energy of which is roughly equivalent to 5 tons of T&T. This flash was much brighter than scientists expected. It lit up the surface of Temple 1. However, ironically, the success of the first part of the mission caused an unexpected negative side effect. A large dust cloud was kicked up by the impact, which obscured the flyby's view of the impact crater. Dust outgassed from the comet for the next 13 days,

peaking five days in, which made it hard to see the results of this interstate. stellar bullseye. Although, it did offer some interesting insights into the internal pressures going on inside the comet, around 5 million kilograms of water, and between 10 and 25 million kilograms of dust were ejected from Temple 1 in that time. Fortunately, scientists were able to rely on other eyes, at least to capture images of the explosion. The collision had been observed through numerous other telescopes on or around Earth, including

Hubble, Swift, and even many amateur astronomer telescopes. Still, this was a serious problem. Although this outgassing was fascinating to record, the primary purpose of the Deep Impact mission was to take photographs of the crater caused by Deep Impact. Without images of the result, many of the questions about Temple One would remain unanswered, like about its structure and composition. Like a partially unwrapped gift, Temple One had been opened, but it had not yet been seen what lay inside. Some other craft would be needed to complete Deep Impact's unfinished mission.

Fortunately, another craft capable of doing so had already been launched, and, having completed its own previous mission, was now drifting serenely through space. It was about to receive another task. It's time to talk about Stardust. Let's go back to the late 1990s, when Cometry Scyst. science was even more patchy. Although by this point we had sent six probes up to visit these enigmatic celestial bodies, not very much was known about their origins. It was believed at the time that comets were foreign visitors to our solar system, older than the sun, having been

informed from the loose pre-solar grains of dust that orbit other stars, before drifting through space towards us, only to be caught up in the sun's gravitational pull. It was believed that this theory could be confirmed by travelling to one of these comets and picking up some of this loose dust, or star dust, that surrounds them in space. By examining the isotopic composition, scientists would be able to tell if it was unusual when compared to the dust given off by our own star. However, this was a challenging mission. As is often the case, it came down to a question of speed and energy.

Comets travel through the inner solar system at speeds reaching 160,000 kilometres per kilometers per hour. While it was possible for a probe to try and match that speed and come up alongside it, this had to be done without needing too much fuel, or the weight of the craft would be too heavy and thus too expensive to get into space in the first place. Initially, Stardust had nothing to do with Temple 1. For this mission, scientists selected a comic known as VIL-2. They believed that they would be able to get Stardust alongside Ville 2 at a relatively low velocity.

However, this velocity would still be around 6.5 kilometers per second, or 23,400 kilometers per hour. As you can imagine, catching even particles at that speed would be extremely challenging. Although particles would likely not do too much damage to stardust, being too small to really impact it, it would do irreparable damage to the particles themselves. When an object crashes at 23,400 km per hour into a surface, the odds of it keeping its original shape and structure are incredibly small. Scientists would not learn much about the structure of these particles if they smash those

particles into pieces, not to mention the warping effect, all that kinetic energy being suddenly converted into thermal would have on the molecular bonds involved. So what was their solution? What was their mechanism for catching objects travelling at those speeds? Well, much like how an airbag softens the blow for you if you are involved in a car crash, scientists realized that they would need an airbag of their own, something that would not halt the particle all at once, but would reduce its speed over a longer distance,

thus reducing the amount of crushing deceleration involved. For this, they found an incredible material that was basically air, solid air. They decided to use aerogel. Aerogel is a fascinating substance that was discovered in 1931 by Samuel Kistler, when he made a bet with fellow scientist Charles Lernard about jelly. As you've probably seen, if you've ever made it yourself, jelly is formed of two parts. Firstly, a relatively solid structure that acts like a kind of sponge, and secondly, water. When you add water to solid cubes of dense jelly, it absorbs the water and expands into the wobbly

substance we are familiar with. If you were to extract the water, the solid part of the jelly would normally contract again. Kisler's bet with Lernard was to be the first one to remove all of the liquid from the jelly without making it shrink. In short, to make a jelly that was entirely filled with air, an air jelly. Without going into all the details, Kisler won his bet, and at the same time invented the first aerogel. Eurogel is a fascinating substance, as it is usually over 99% air, and yet has the structural

strength to support bricks. Nowadays it tends to be made from silica composites rather than jelly, but can be made from a wide range of materials. It is incredibly light, and is, strangely enough, an even better insulator than regular air. And most importantly for Stardust, when particles hit it, it would offer just the right amount of resistance to slow down the particle with it. without denaturing or destroying it. The trails left behind in the aerogel would also be useful for scientists to spot where a particle

had been captured. Stardust was fitted with a tennis racket-sized aerogel collector tray made up of 90 blocks of aerogel 3 cm thick, with over 1,000 square centimeters of surface area, which would be deployed from inside the main body whenever sampling was to take place. Stardustardust would also capture from the interstellar medium to allow comparisons and to learn more about the dust in our own solar system. Once it had collected these samples, it would store them on a sample return capsule, which would be fired back towards the Earth for re-entry and collection. This SRC was 80 cm by 50 cm, weighed 45 kilograms, and came fitted with an aerosheel

shield, navigation recovery aids, and a parachute. Also on board Star Dust was a navigation camera, a cometry and interstellar dust analyzer, and a dust flux monitoring system, among other scientific devices. The probe launched on the 7th of February 1999 and spent the next five years travelling through space, passing the asteroid 5535 Anne Frank along the way, which it took some photos of. But on the 2nd of January 2004, It finally arrived at its target, comet Vild2. And what it found was immediately extraordinary. Scientists had not expected much from Vild2.

Some NASA scientists described their expectation of it to be a rather bland object looking somewhat like a black potato. However, this is not what they found. Instead, the surface of Vild 2 was covered with spiky pinnacles hundreds of meters tall, cliffs, massive holes, jetting dust and gas out into space. even on parts of the comet that were pointed away from the sun, and thus were expected to be less reactive. In short, the surface of the comet was unexpectedly alive and self-renewing. Something else was just as notable for its absence. Craters.

Unlike almost every other body in our solar system with surfaces exposed to space, there were no craters on the surface of Ville, too. This puts it in stark contrast to places like Mars, or our own moon. Given the period of time Ville 2 is thought to have existed, it surely must have encountered other objects which impacted with it. So where had these craters gone? It shows that the comet's surface can either be self-renewing or active, reducing signs of visible craters over short timeframes, astronomically speaking. And of course, during this flyby, Stardust had its aerogel collector exposed, and was rapidly collecting dust samples.

Just listen to the frequency in which dust struck the spacecraft. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals, because we're built for what you're building. Fit for your ambition for Citizens Bank. Peak pollination season, and my business is scaling fast. To keep the nectar flowing, I need a phone plan with top priority data speeds. That's why I chose GoogleFi Wireless.

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The angle of approach had to be just right as it was just right. traveling at tremendous speed. If the approach angle was too low, it would just skim off the atmosphere and fly back into space. If the angle was too high, the heat would disintegrate the capsule. So it was with great relief that the DC-8 NASA airplane monitoring the sky saw it approaching at just the right second and just the right angle. The SRC landed in the Utah desert where it was recovered, everything having worked and deployed just as it was designed to. And take it to the same, Taking the samples back to the lab, scientists learned another completely unexpected fact about Cometvill 2.

It was not a visitor to our solar system at all. Unlike what had previously been believed, Cometville 2 had not originated from another star, it had been born from our own. By comparing the isotopic composition of the particles star dust collected with the samples from our own solar system, it was proven that Cometville 2 originated from the solar system. And contrary to what all the ice on its surface might lead you to believe, the rock at its center was formed under white hot conditions. Chondrules and calcium-aluminium inclusions were both found among the samples stardust collected.

These are structures that only form under incredibly hot conditions, and can be found in other asteroids between Mars and Jupiter. So scientists had to rethink their theory that comets formed in cold conditions at the edge of solar systems, even if they do spend some time there. fire and ice go into making comets. And thanks to the careful, delicate way that the particles had been collected, scientists were able to find out one last surprising thing, the amino acid glycine. Amino acids are the building blocks that make up proteins that are vital for all living

things. Although this does not mean that there was anything alive on Cometville too, this does lend weight to the idea that it was from Comets such as this, crashing into our Earth. Earth millions of years ago that life's first building blocks found their way to our planet, which I'm sure you all agree offers a tantalizing glimpse into our own origins. Given all these discoveries, you might have been forgiven for thinking that Star Dust's work was done. But NASA is always reluctant to waste perfectly good spacecraft if they have more to give, and Star Dust still had fuel in the tank. And so, when the question arose in 2006 of

how NASA could capture that close-up image of Temple 1, Stardust name was put forward. This would prove to be an interesting opportunity. Stardust was calculated to have enough fuel to make a six-year journey around the solar system to arrive at Temple 1. This would represent the first time a comet was visited and then revisited years later, providing an intriguing chance to see how Temple 1 had evolved over the intervening years. Deep impact only imaged about one-third of Temple One's surface as it flew past. But even that was enough to identify fascinating geological features. Layered terrains, smooth flows that contrasted sharply with the rougher terrain around them,

crater-like vents and cliff faces. It would be incredibly insightful to see how these had changed in the time Temple One had orbited around the sun. Stardust would be able to take images of things previously unseen, giving even greater coverage of the rich geological history of the comet. There were other advantages to using Stardust. It would be significantly cheaper to use equipment that had already been launched than to develop and launch something new.

Stardust shielding was even designed specifically with cometry exploration in mind, which certainly came in use for reasons I'll go into later. It had all the camera equipment it needed to take precise images. And so, Stardust was approved and was given a new name to match its new assignment. The Stardust New Exploration of Temple One Mission, or Stardust Next. Of course, achieving this goal wouldn't be easy. Course corrections had to be made years in advance to conserve fuel and make sure Stardust arrived when it was supposed to.

This made things complicated, given that Temple 1 didn't just remain static as it traveled. spins once every 40 hours. So it wasn't just a case of figuring out how to get star dust to meet up with Temple One. NASA had to make sure it happened when Temple One's impacted side was facing the sun and facing star dust once Star Dust flew past. In effect, even though Temple One was not easy to see clearly, they had to calculate all the spins that Temple One would make a full year ahead to ensure the arrival time matched up. With stardust diminished fuel reserves, there would be little room for error. Incredible

precision and excellent models would be required. As such, NASA enlisted the help of dozens of observatories around the globe. Temple 1 was little more than a tiny dot in the night sky, thus it was impossible to track through its surface features, which were indistinguishable at that distance. However, its asymmetric shape meant that its brightness fluctuated as it traveled, dimming as a narrower profile was pointed our way, then brightening as the wider profile rotated into view, in regular intervals that allowed a detailed model to be created with a high degree of certainty. Scientists counted the spins as Stardust traveled. One, two, three, knowing that if they missed a single count, it would potentially mean the failure of the primary mission objective, their model needed to be perfect.

Stardust travelled for years through space, engaging in one Earth gravity assist and multiple laps around the Sun before timing its final maneuver, a full year before it would arrive at Temple 1. The burn would alter its arrival time by a small yet significant eight hours. Stardust was now locked in. A year later, as it closed in on the comet, Stardust shields began to detect sounds, as tiny particles began clattering off it. Temple 1 was still ejecting dust and small rocks into space. Stardust was hit dozens of times. Although these rocks were tiny, only a millimeter at most, some of these hits had enough force

to go through the front of Stardust, cutting through a graphite cyanide honeycomb sheet as thick as your finger. Still, Stardust survived the barrage, and on the 14th of February 2011, Stardust made its flyby. It passed at the distance of 181 kilometres and took 122 images. I find it amusing that scientists waited for another holiday for a Temple One visit. They chose an Independence Day for their initial impact. Here, on a less violent visit, they chose Valentine's Day. Scientists had to wait for hours for the images from Stardust to arrive back, but when they did, NASA saw that they'd managed another bullseye. They'd correctly predicted the rotation of

Temple 1 to an accuracy of a single degree. Right on Temple 1's surface was the crater that had been left by Deep Impacts payload. The mission was a success. From the images Stardust took, Scientists were able to calculate that it was approximately 150 meters across, so 50% larger than they were predicting. From this, they learned that the surface of Temple 1 was a very fluffy material, made from more dust than was expected, and finer in substance than a powdered snowbank. The surface was incredibly porous. In fact, they were able to estimate that 75% of the comet was actually empty space.

the whole thing held loosely together by gravitational forces. From analysis of the plume that had been ejected from Temple 1 after the impact, scientists were able to identify several interesting material components, including clays, silicates, sodium, and even organic material. While not life itself, these heavily rich carbon materials may have been carried to Earth by comets in the past, providing the vital materials that make up life here. Not only that, but they were able to see other changes that had taken place on Temple One's surface.

Three pits that had formerly existed had merged to become one. A cliff face had eroded back around 20 to 30 meters. This indicated that Temple One's surface was a dynamically changing place, leading to interesting questions about how these formations had formed in the first place the scientists could now puzzle over. So, Deep Impact's mission finally had closure, and had been a resounding success. But this was not the end for Deep Impact. Following in Star Dust's footsteps, Deep Impact's flyby was later given a new mission

entitled Epoxy, or the Extra Solar Planet Observation and Deep Impact extended investigation, which in 2007 saw it heading off to investigate other comets, and taking hundreds of thousands of photos, before ultimately dropping out of contact. in 2013, but by then, Deep Impact had already done significant amounts to advance our understanding of comets and our solar system. What about Stardust? After its extended mission, scientists saw that there was still a little fuel left in its tank, so it ran with it.

Firing it for as long as it could, scientists checked to see if their models of how much fuel Stardust held matched up with the reality. To its last breath, Stardust could be able to be. kept doing signs until the end. When at last all its fuel was used up, it sent one last transmission to Earth to acknowledge that it was being turned off for good. Now it finally rests among the stars. Comets are truly fascinating things, and it was thanks to the incredible work of the Stardust

probe and the Deep Impact mission that we were able to learn a great deal about their inner composition and workings. While still retaining their beauty, we have pierced through their layers of We understand that they are not some foreign visitors, but originate here, from our own solar system, and may have even led to the blossoming of life itself on this planet. And it was human ingenuity and precision that allowed these discoveries to be made. So the next time you see a comet, with its beautiful tail flaring out across space away from it, it will no longer be quite so mysterious or foreboding.

They may even be the reason you are here today. And all it took to learn this was to catch the dust from one and to punch another really, really hard. Thanks for watching! If you enjoyed this Supercut, be sure to check out my others in this playlist here. And a big thanks to my patrons and members. If you want your name added to this list too, plus a bunch of other perks, you can support the channel using the links in the description. All the best and see you next time.