Contact has been lost with Opportunity since
the 12th June 2018. This pioneering rover survived an incredible
15 years on Marsâ harsh surface, when finally, a global dust storm blocked the sunlight from
hitting its solar panels for several months. This video is a recap of Opportunityâs entire
mission, from its first landing to the final dust storm, with all the challenges it overcame
and discoveries it made along the way. By the end of this video, I think youâll
agree with me that it was a remarkable mission and that it has contributed a huge amount
to our knowledge of the red planet, and itâs this knowledge that has paved the way for
the missions we are seeing today, like Perseverance. It answered question like: did Mars once have
a more substantial atmosphere? Did it have huge bodies of liquid water on
its surface? And, was it once more like Earth, and if so,
what changed? Iâm Alex McColgan, and youâre watching
Astrum, and together we follow the record-breaking journey Opportunity took on Mars. Letâs start right at the beginning. Having launched on a Delta II Heavy spacecraft,
Opportunity landed on the other side of Mars from its sister rover, Spirit, about three
weeks after Spirit had already landed. Opportunity used a parachute to slow itself
on its descent and fired some rockets just before it landed. The effects of the rocket firing are evident
from this lighter patch of ground, as seen by the Mars Global Surveyor. Opportunity first bounced, and then came to
land inside a tiny 22m crater, now known as Eagle crater, with the heatshield and parachute
ending up a few hundred meters away. NASA scientists were so excited by this that
they called the landing a âhole-in-oneâ, although they werenât actually aiming for
this crater. They didnât even know it existed until they
got there, as Opportunity actually landed about 25 kms away from its intended target. As Opportunity emerged from its protective
shell, the first thing it did was have a look around. Opportunity is equipped with a panoramic camera,
which it can use to survey the area. It saw some outcrops only a few centimetres
tall, made up of extremely fine dust, each grain far smaller than the grains typically
found in Earthâs sandstone. Opportunity and Spirit were primarily on Mars
for its geology, the end goal being to see if Mars was ever a place that was conducive
to life. The way they did that was by looking at rocks
for evidence of water, thus giving scientists an idea of what Mars might have been like
millions of years ago, as rocks contain clues about their history. Opportunity explored the outcrop closely over
the course of the next few weeks, already discovering evidence that in the past some
kind of moving current had made the bedrock dip, although it wasnât clear if it was
water that had done this, or volcanic flow or wind. You can see this in this image as the thin
rock layers are not parallel to each other. On Sol 30, or Opportunityâs 30th Martian
day on its surface, it got close to the outcrop and used its Rock Abrasion Tool to drill into
a section of the rock face. As it did so, it found something known to
geologists as âvugsâ or voids in the rock, the result of crystals having been eroded
away. The rock also contained hydroxide ions, meaning
water was likely present when the rock formed. Next up for Opportunity was to dig a trench
in the soil for further analysis. It did this by digging its front wheels into
the soil while the back four wheels held it in place. After some shuffling about for 22 minutes,
it had made a trench 50 cm long and 10 cm deep. Under the top layer of soil were some things
it had not seen before, including shiny little pebbles and grains so small this microscopic
image canât distinguish between them. Over the course of the next few Martian weeks,
having discovered everything it needed to, Opportunity powered out of the crater at an
average speed of 1cm per second, and headed towards the next biggest crater in the vicinity,
Endurance Crater, which is about 200m wide. On its way, it passed by this little tiny
crater called Fram. It took a photo, but didnât stop for long. On Sol 84, it reached the edge, and had a
look inside. Mission planners already knew that Endurance
had many layers of rocks to be investigated, and wanted to have a closer look at them. Opportunity circled around the crater, looking
for a good entry point, as getting in wouldnât be a problem, but getting out might. By Sol 127, mission planners decided to drive
Opportunity into the crater even if it couldnât get out, as the value of the science that
could be garnered was too promising to pass up. So on Sol 131, it carefully edged its way
over the ridge of the crater, and tried to reverse back to see if it could. Luckily, the angle of the rim was only 18
degrees, well within Opportunityâs known safety margin, so the excursion into the crater
began in earnest. Opportunity went on to spend 180 Sols in the
crater. It explored an area called Karatepe where
it saw various layers in the bedrock. It went near to, but not into some sand dunes
as mission planners didnât want it to get stuck. It saw some wispy clouds similar to Earthâs
cirrus clouds. And lastly, it went to a cliff face called
Burns cliff, an impressive looking cliff face with various layers separated by broken up
rocks and dust. It finally left Endurance on Sol 315. During the time there, the data collected
by Opportunity meant that scientists were able to confirm that water didnât just cover
this area once, but it was in fact episodic in nature, with floods that would have washed
across this landscape before drying up again. At any rate, the water here would have never
been that deep. After that substantial discovery, the next
stop on its adventure was to investigate its own heat shield. On the way, it came across a rock that was
later confirmed to be a meteorite, named Heat Shield Rock. It was the first meteorite to be identified
on another planet. Opportunity then set a course for Erebus crater. It pressed ahead through a region called the
âetched terrainâ to search for more bedrock. While traversing this area, on Sol 445, Opportunity
got stuck in a 30cm sand dune. Things did not look good for the rover; all
four of its corner wheels were dug in to the dune by more than a wheel radius. This dune came to be known as âPurgatory
Duneâ. It stayed motionless for just short of 20
Martian days as mission planners frantically tried to figure out how to get it out. They simulated the scenario on Earth and tried
various methods before they ordered Opportunity to try anything. On Sol 461, the rover advanced a few centimetres
to see if it was doing what their tests had predicted. Over the course of the next 20 Martian days,
Opportunity moved a few centimetres, took a photo of the progress, and sent the results
back to mission control. By Sol 483, Opportunity had successfully escaped
the dune and all six wheels were on firmer ground. It would have been disappointing if it had
travelled for a year on Mars, just to get stuck by a 30cm dune. Opportunity studied Purgatory dune for another
12 Martian days, before setting off again on its way to Erebus crater. During its journey, mission controllers uploaded
updated software to Opportunity to prevent it from getting stuck again, with software
designed by learning what happened from the experience at Purgatory. With this new software update, it was ready
to carry on its adventure at Erebus crater. As Opportunity approached Erebus, it came
to sections of ground where the bedrock was exposed. Mission controllers named this section the
âErebus Highwayâ. As we know, Opportunityâs main mission was
to search for signs of water on Mars, clues of which can often be found in the planetâs
rocks. It used its rock abrasion tool to carve circles
into the bedrock, and with its microscopic camera, it compared the different structures
of the rocks to search for evidence of water. Youâll notice by here that Opportunityâs
tracks are in front of the rover, this is still the front camera, but sometimes mission
controllers drive Opportunity backwards to even out the wear and tear on the equipment. Erebus is a very old and eroded crater, filled
with sand with only a few outcrops showing. You may not have been able to tell itâs
a crater from the ground perspective because it is so shallow and eroded, it only really
becomes visible from the satellite photos. It is about twice as big as Endurance crater,
at 350 meters in diameter. Opportunity never actually went inside the
crater as there was only more dunes in it. Instead, it stuck to the rim, avoiding larger
dunes as it went. Even while carefully manoeuvring around these
dunes, it hit some soft sand and its wheels sunk in. Luckily, the software that was installed only
a few weeks previously noticed the wheels were slipping, and it stopped its drive command. You see, Opportunity is not controlled in
real time by a person on Earth with a joystick. There is too much of a latency for this, between
6 minutes to 40 minutes, depending on the proximity of Earth and Mars. So instead, Opportunity is given drive commands. Using these same navigational images you are
seeing here, and comparing it with satellite based imagery, mission controllers command
Opportunity to drive forward a certain distance, where it will then take a new photo to show
its progress. The software that prevented Opportunity from
getting stuck meant that mission controllers could get the rover to reverse out without
another several week delay. During Opportunityâs time there, it collaborated
with the ESAâs Mars Express Orbiter. The Mars Express images the surface of Mars
from orbit to search for different types of materials. Without actually sampling the surface, the
data it collects can be hard to interpret. Opportunity, however, can physically interact
with the surface material, confirming whether what the Mars Express data showed was correct
or not, helping them to refine their future observations. While Opportunity was near Erebus crater,
it was also able to see an incredible transit of the Sun from Marsâ closest and biggest
moon Phobos! As it was still making its way around Erebus
crater, a big dust storm hit, and Opportunity went dark for a few days. Very interestingly, you can see the difference
the dust storm made to the rover, as the camera goes from having a clear image to having some
dust particles visible. Also, dust settles on the solar panels, meaning
it canât generate as much electricity. Very fortunately though, Mars has occasional
âcleaning eventsâ, where wind, or even a dust devil will pass over the rover, blowing
the dust off the solar panels and camera. Because Mars is so dry, this dust is not at
all adhesive, and the dust so fine, almost as fine as cigarette smoke, that it doesnât
take much at all to shift it off. You can notice this cleaning happen over time
too if I speed up the footage. Look at this fleck of dirt here, and how it
disappears over time. Opportunity doesnât have means of clearing
this dust off by itself, so it has always relied on these cleaning events happening,
which thankfully over the course of the 15 year mission, they did. Sadly however, during the time at Erebus,
Opportunity encountered its first mechanical fault; its arm was getting stuck all the time
as you can see here. There was a broken wire, although the motor
still worked if it was given more power. After careful deliberation, engineers decided
the best thing to do would be to only stow the arm away while travelling long distances. Over short distances, it would be kept in
a âhover-stowâ. This replica is being used to test how it
can travel with the arm out in this âhover-stowâ position, where the arm is out but it bends
back at the elbow towards the rover. They thought it would be better to have the
arm stuck while it was out rather than to try and stow it away, to find it could never
be used again, at least it would still be somewhat functional like this. Over the course of the mission up until this
point, it was also encountering a problem with a heater for a motor in the arm that
wouldnât turn off. Engineers managed to get away with switching
it off with a T-stat switch, meaning a thermometer switch would cut power to the heater if the
motor got too hot. But as Martian winter drew near where there
would be less sunlight, there wasnât enough power to have the heater on all night. They fixed this by completely disconnecting
the batteries at night. This led to another problem, where there would
be very big swings in temperature between the day and night, meaning the motor would
likely wear out faster. At this point in the mission, this motor stalled
altogether. Engineers temporarily fixed it by applying
more current through the motor, although as a precautionary measure, they stowed the arm
outside the rover at night in case the motor permanently stalled. Youâll start to notice this in the camera
view from now on. By February 2006, or sol 744, Opportunity
visited its last site around the Erebus crater, called the Payson outcrop. This outcrop of fine layers shows a diverse
range of primary and secondary sedimentary textures formed billions of years ago. The structures that were observed here were
likely caused between a mix of wind and water processes. By Sol 766, Opportunity had left the rim of
Erebus and was on its way to the biggest and most impressive crater yet, Victoria. It journeyed through large ripple sand dunes,
a type of dune we donât have on Earth! However, Opportunity tried to stick to paths
of exposed bedrock, as these are much easier to traverse, and it can stop and investigate
along the way. These cobble fields are a bit of a mystery,
as we are unsure how they formed like this. On Sol 833, Opportunity almost got stuck again. Previously, mission controllers were thrilled
by the meters of progress per day Opportunity had been making towards Victoria, but in this
sequence, it took 4 days to get out of this dune, which they named Jammerbugt, a Danish
term for the âbay of wailingâ! Nearly 200 Martian days after it left Erebus,
it arrived at Victoria, and what it saw was amazing. High ridge walls, a steep slope in and beautiful
sand dunes in the centre. It had already overcome so many obstacles,
and this sight was the reward at the end. So, what was so interesting about Victoria
crater? Was it able to provide any valuable information
about Mars that Opportunity hadnât picked up anywhere else? Victoria was always going to be an important
landmark for Opportunity to reach, although few thought Opportunity would last the 7 km
journey from its initial landing site. At this point, Opportunity had lasted more
than 10 times longer than its original designed lifespan. Victoria is the biggest crater Opportunity
had visited yet, being 730 meters wide. It was also the deepest, meaning ancient bedrock
outcrops along the walls of the crater were exposed to the surface. Exposed bedrock contains the clues to Marsâ
past that Opportunity was looking for. Also, as you can see, Victoria made for an
impressive sight, especially in contrast to this otherwise flat plain that Opportunity
had landed in. In preparation for this new exploration site,
mission controllers uploaded new software to the rover, which would enable it to decide
whether to send back an image, or to extend its arm in preparation to sample an interesting
rock outcrop, and even improved the intelligence of the rover to detect obstacles it should
avoid, and to make its own path around them. These features save a lot of time for mission
controllers, who would have had to have gone through hundreds of images and wait through
painful latency delay for commands to be sent to the rover. At its furthest point, the latency between
Earth and Mars can be upwards of 40 minutes. This is one of the reasons why it took three
years to only travel 7 kms up until this point. To test this new software update, mission
controllers had Opportunity drive towards a patch of rubble, and settings were adjusted
to make Opportunity think that this rubble was a no-go zone. In reality, the biggest of these rocks is
only 10cm tall, meaning Opportunity could have easily driven over it, but they didnât
want to test the systems on something that could actually damage the rover if it went
wrong, so they chose these rocks instead! As you can see, the rover adjusted its course
around the dangerous area, and took this panorama so mission controllers could see how the rover
responded to the new program. Opportunity began to circle to outskirts of
the crater, imaging it as it went. It came across a few cliffs, or âCapesâ
along the way, imaging them with a very clever technique called a âsuper-resolution mosaicâ. These images have a much higher resolution
than the camera onboard Opportunity is capable of, and the way they did this was by taking
lots of photos of the same thing, and then in post processing on Earth they combined
the images to provide the resolution you see here. On a side note, this technique is used in
many different fields, including microscopy and astronomy. Scientists say that the layers you see in
the rocks found in all these cliff faces are due to a geological process called cross-bedding. They believe these layers are ancient sand
dune deposits, which is why the lines are inclined upwards and not just horizontally. From these lines, they predict that this used
to be a sand dune field not unlike the Sahara Desert on Earth. While this science data was very useful, mission
controllers were primarily looking for a passage down to the crater floor, and they thought
they found one by here at the âValley Without Perilâ. On closer examination though, it was decided
that the slope was too steep. Opportunity investigated a couple of cliffs
while it was there, and even came across another meteorite called Santa Caterina, before mission
controllers decided to drive the whole way back to the original arrival point at the
crater to try and get down by there. This site was chosen because the slope was
within the safety limits of the rover, plus the ground was made of flat, exposed bedrock,
which meant it wouldnât have much wheel slippage. On the 28th June 2007, or 1,200 sols into
the mission, Opportunity prepared itself for its descent. But just as it perched itself on the top of
the slope, the biggest dust storm Opportunity had seen yet rolled in, decreasing the brightness
of the Sun by 96%. Thatâs not quite as bad as it sounds, as
the dust also scatters some of the sunlight towards the rover too, meaning it was generating
roughly 128 watts on the darkest day compared to its usual 700 watts on a clear day. But this is bad news for a solar powered rover,
that kind of power level isnât enough to keep the rover going, in fact anything under
150 watts means the batteries begin to run flat. So, operations were cut back substantially
until the storm was over, and Opportunity was only commanded to communicate back to
Earth once every 3 days. If the batteries did run flat, the components
on board Opportunity could be damaged due to the intense cold on the planet during the
night. Typically, the motors have heaters powered
by the batteries during the night to keep the motors warm, if the batteries run flat,
there would be nothing to stop there being extreme temperature differences between night
and day, at the equator anywhere up to 20°c during the day and -75°c at its coldest at
night, which would damage the sensitive components. The reason for this temperature variability
is because although Mars does have an atmosphere, it is 100 times thinner than Earthâs meaning
it is not anywhere near as good at retaining the heat it absorbs during the day. Going back to the batteries, if they reached
a critical level, Opportunity was also designed to trip a low-power fault. This basically disconnects the roverâs batteries
from all but the most essential systems of the rover, putting it to sleep as it tries
to charge its batteries with whatever available sunlight there is. Every sol the rover would check the battery
level to see if it could reconnect the other systems, and if so, it would then re-establish
communications with Earth. This low-power mode could mean the rover stays
asleep for only a few days, but also it could go on for weeks or even months. Chances are that at that point, even if it
did switch back on, too many of its components would be broken and it wouldnât be able
to function anyway. Back to the dust storm at the start of July,
2007, mission controllers initially thought it would only last a week, but by the 15th
July the storm had reached its peak. These are true colours images showing a time
lapse of the storm, and as you can see it does get very dark. Thankfully, the severity of the dust storm
was not quite enough to trigger the low-power fault this time, although it did get worryingly
close for a while. Eventually, by 21st August, or sol 1271, the
storm had cleared enough so that Opportunity could start to move forward again. Sol 1291 saw Opportunity finally enter the
inner slope of the crater, but like it did before with the previous crater, just after
it entered, it backed out again to assess the amount of wheel slippage from the slope. As it happened, wheel slippage did exceed
the mission controllerâs threshold of 40%, so the rover stopped with two of its wheels
still over the lip of the crater. After two days of decision making, mission
controllers decided to press ahead regardless, and an extended exploration into the crater
began. As Opportunity descended, it took some time
to investigate any interesting looking parts of the exposed bedrock. It also took some images of the cliffs on
either side of it. I think these images showcase just how steep
the slope is that Opportunity is sitting on, roughly 20 degrees. Opportunity didnât venture too far into
the crater, as only sand dunes were found towards the base. It spent its time examining this light patch
of bedrock, taking various pictures and using its rock abrasion tool to investigate the
rockâs structure. It was determined from the data Opportunity
collected that this area was likely not ever so hospitable to life, so mission controllers
picked the next waypoint on their journey, Endeavour crater. If you thought Victoria was big, look at this
mammoth. Endeavour was thought to contain some clays,
meaning water was once there, so Opportunity started its journey out of Victoria. At this point, on sol 1502, Opportunity encountered
another fault with its arm. No matter how much power they put into the
joint, the arm wouldnât move from its stowed position under the rover. Sol after sol passed, and the joint refused
to move, until they determined the time of day the joint had the least electrical resistance,
which was just at dawn before the heater for the motor switched off during the day. When that time came again, they put as much
power as possible into the motor and⌠it worked. Not risking ever stowing it away again, engineers
had to determine how to manoeuvre the rover safely without risking damage to the arm. Opportunity then began its 2-year trek towards
the Endeavour crater. This is Endeavour crater, a huge but shallow
crater at 22km across and 300m deep. But why Endeavour crater? Due to the distances involved, it would take
a long time for Opportunity to get there, so, whatâs special about this place compared
to anything Opportunity had seen before? The most compelling reason, and indeed one
of the science goals of Opportunity, was to find evidence of past oceans on Mars. At this point in 2008, the theory that Mars
once held an ocean on its surface was only just starting to get solid evidence thanks
to the Spirit and Opportunity rovers. Opportunity at this point had discovered that
water once existed on the places it had visited, but these places were no more than shallow
flood plains which dried up periodically, not a true ocean. On the other hand, the Mars Reconnaissance
Orbiter had spotted what was believed to be clays around Endeavour crater, clays being
hydrated minerals which could have only formed from water being on the surface for extended
periods there. Could Endeavour have been part of a more permanent
ocean? And if there really was a surface ocean, are
there clues to indicate that could it have harboured life? Mission controllers had to find out. And so Opportunity left Victoria crater and
began its arduous journey south. The mission team were determined to reach
their destination as quickly as possible, while also keeping a look out for anything
of interest along the way. Opportunity made good time across the Meridiani
plains, and by sol 1818 it had travelled more than 3km. Nothing noteworthy really happened until sol
1947, where a large rock was spotted. The mission team decided to investigate, discovering
that it was a meteorite which they named âBlock Islandâ. In fact, large rocks seemed to be the only
thing to keep Opportunity busy, later spotting another one named âShelter Islandâ, and
a third called âMarquette Islandâ. Marquette Island was of particular interest
to scientists though, as they believed this rock was part of the ejecta from a large meteor
impact, meaning this rock would have come from deep in Marsâ crust. Scientists could tell because the grains within
the rock are coarse with a basalt composition. The coarseness indicates it cooled slowly
from molten rock, allowing crystals time to grow. Had it formed near the surface, the crystals
within it would have been a lot smaller as it would have cooled a lot quicker. Opportunity was never alone on Mars. It had a sister rover named Spirit, which
was exploring the other side of the planet at the same time. They both landed on Mars at roughly the same
time, and had both far exceeded their original expected life span of 90 sols, at this point
they were 1900 sols into the mission. Although, just like Opportunity up until this
point, Spirit had encountered some mechanical failures too. Most notably, one of its front wheels jammed
only 700 sols into its mission, meaning it dragged this wheel along as it travelled. In a way, I almost think Spirit was NASAâs
darling between the two rovers, Spirit often got more media attention for the things it
was discovering on the planet. However, it was around the time Opportunity
explored those rocks that Spirit, on the other side of the planet, attempted to drive over
a sand dune and got its wheels stuck deeply in the sand. Spiritâs operators began the long process
of attempting to get it unstuck through simulations and testing on Earth based replicas. Meanwhile, Opportunity carried on its long
journey to Endeavour. By Sol 2138, Opportunity finally reached a
landmark of note, ConcepciĂłn crater. It is only 10m wide, but probably the youngest
crater visited yet, evidenced by the exposed rubble and ejecta. Nothing particularly new was found there compared
to any of the bedrock Opportunity has examined in the past, which was simply sulphate rich
sandstone containing peppercorn size spheres, known as blueberries. At least the crater provided a contrast to
the vast expanse of rolling sand dunes. Eight months had passed since Spirit got stuck
in the dune. The sand that enveloped its wheels was particularly
fine, and the process of excavating Spirit was exasperated by its jammed wheel. During this recovery process, another of Spiritâs
wheels jammed, meaning only 4 of the 6 now worked. The Martian winter approached for Spirit,
and it was getting less and less sunlight to power its batteries, until finally, a low
power fault occurred on the rover, and its systems disconnected from the battery. Spirit went silent. Mission controllers attempted for months afterwards
to regain contact with the rover, but NASA eventually called an end to Spiritâs mission. For the first time since it landed, Opportunity
was now alone on Mars. Opportunityâs long slog over kilometres
of sand dunes to reach Endeavour was becoming taxing for the rover. Perhaps overly anxious not to have a repeat
of what happened to Spirit, mission controllers decided to reroute Opportunityâs course,
a longer route but hopefully a less arduous one. This route would also take it by what was
named Santa Maria crater. By sol 2244, Opportunity set a new record
for the longest lasting mission on Mars, finally beating Viking Iâs mission duration. Opportunity could begin to see the rim of
Endeavour, spotting the landmarks of Cape Tribulation, Cape Byron and Cape Dromedary. However, even 100 sols later, it was only
halfway to Endeavour from Victoria. It had made good time, considering it has
a top speed of 5cm per second, and often went half of that to be safe, with frequent stops
to look out for potentially problematic sand dunes. Youâll notice the roverâs tracks are ahead
of the rover in this time lapse. This is because there is also a navigational
camera on the back of Opportunity, allowing it to drive forwards or in reverse to evenly
distribute wear and tear on the motors. Although, another reason right now was to
protect Opportunityâs extended arm, which as I mentioned in the last episode, got stuck
in this position. On sol 2449, Opportunity finally arrived at
Santa Maria crater. Itâs a 90-meter-wide crater, and was important
to mission controllers as there was already evidence here of hydrated sulphate minerals. As I mentioned, hydrated minerals can only
form under bodies of water over extended periods of time, so this was an exciting precursor
to what they wanted to really investigate around Endeavour, which was still a tantalising
two-year journey away. Opportunity also stopped here to take a spectacular
time lapse of a Martian sunset or two, with one of the time lapses showing a transit of
Mars biggest moon Phobos across the Sun. Over two Earth years had passed in just this
one episode. Opportunity had soldiered on well beyond its
expected mission lifetime of 90 sols, and even outlived its sister rover Spirit. It and the mission team had earned a rest
at Santa Maria, and they all spent three months happily examining rocks and unlocking secrets
about the history of Mars. After that, it was onward and upwards for
Opportunity towards Spirit Point, a point around the rim of Endeavour, an inspiring
commemoration of the missionâs loss on the other side of the planet. After spending 3 fairly uneventful months
at Santa Maria Crater, Opportunity headed towards the closest hill on the crater rim,
known as Cape York. Along the way, it came across a few small
craters, some of which were very young, with ejecta from the impact strewn across the place. But Opportunity didnât stay for long. Approaching Endeavour, Opportunity was finally
able to see some variation in the landscape after years of simply crossing flat plains
of sand dunes. Peaks and capes started to rise up on the
horizon as Opportunity approached the crater rim. On sol 2709, Opportunity finally arrived at
Cape York, and specifically a place known as Spirit Point, named after Opportunityâs
sister rover, that had come to the end of its mission on the other side of the planet
only a few months previously. Opportunity had travelled over 30km up until
this point, 50 times further than the original planned mission distance. Mission planners decided not to go into the
crater, as points of interest were again found around the rim of the crater. Bedrock is exposed to the surface there, which
allowed Opportunity to study the oldest rocks it had seen so far on this journey. It was also around these peaks and capes along
the rim where the hydrated minerals, or clays, were detected by the MRO. Perched on top of Spirit Point, Opportunity
looked over Endeavour crater, providing a perspective about just how big this crater
is. From the onset, Opportunity began discovering
phenomena never before seen on Mars. You may remember from previous episodes that
the soil found around the areas Opportunity had thus far explored contained countless
smooth, tiny, round rocks nicknamed blueberries. Around Endeavour, no blueberries were to be
found. Instead the soil looks much coarser, the rocks
sharper and not as rounded. Mission controllers were so impressed by the
variation of this area compared to the initial landing site that they said that this section
of the mission provided the equivalent of a second landing site for the price of one. The first point of interest Opportunity examined
was a large ejecta rock called Tisdale 2. It was unlike any other rock so far examined
on Mars. It had volcanic characteristics, but contained
more zinc and bromine than previous seen. It was determined to be a type of breccia;
old rock fragments having been fused together. This was further evidence for water. The impact that threw this bit of ejecta likely
released hot, underground water that deposited zinc in the rock. Just a short distance from Tisdale 2, Opportunity
discovered perhaps the most conclusive evidence that water existed on Mars thus far. Can you guess what it is from this picture? Look closely at the bottom of the image, and
youâll see a thin white line exposed in this outcrop. A close-up examination of the vein revealed
it to be gypsum, the Alpha Particle X-ray Spectrometer on the roverâs arm detecting
the minerals calcium and sulphur, together making calcium sulphate. They named this vein the Homestake deposit,
and it likely formed from water dissolving calcium out of volcanic rocks which combined
with sulphur, and then was deposited as calcium sulphate into an underground fracture that
later became exposed at the surface. The impact that threw Tisdale 2 likely had
something to do with this vein as well. If this is the case, it shows that water once
flowed through underground fractures on Mars. Later analysis of the data Opportunity collected
showed that not only was this likely to be gypsum, but also that the water here was much
less acidic than it would have been around other locations on the planet, meaning it
could have been more conducive to life. Martian winter was soon setting in, meaning
shorter days and a lower Sun in the sky. For a solar powered rover that canât adjust
the angle of its solar panels, this is not the ideal situation. But, for the first time since the mission
began, opportunity had the opportunity to spend the winter on a slope aimed towards
the Sun, meaning that for this winter, it would be confined to an area named Greeley
Haven. This area was not only aimed towards the Sun,
but was also rocky, meaning Opportunity had a lot it could examine during these few months. This 360-degree panorama shows the tracks
of Opportunity as it carefully navigated its way to its winter lodgings. The fact Opportunity had to wait a few months
in one spot was actually handy, as the MĂśssbauer spectrometer in the roverâs arm uses radiation
from cobolt-57 to determine the composition of a sample. However, cobalt-57 has a half-life of only
nine months, which wouldnât have been a problem for a 3-month mission. However, Opportunity was now 8 years in, and
examining the composition of a rock now took weeks compared to the half hour it would have
taken at the beginning of the mission. When it was not examining rocks, it could
also use the time to study tiny wobbles in the rotation of Mars to gain insight about
the planet's core. It requires many weeks of radio-tracking the
motion of a point on the surface of Mars to measure changes in the spin axis of the planet,
something which couldnât be done before as Opportunity was always on the move. The wobbles they were looking for would indicate
whether the interior of Mars is still molten or not. Opportunityâs wait also meant it could examine
the effects of wind on the dunes of Mars from a ground perspective, even at a microscopic
level using the microscopic camera on the roverâs arm, checking for slight changes
over the months it was stationary. Months had passed, and winter was turning
again to summer. On sol 2947, Opportunity moved again for the
first time since it set up camp in Greeley Haven. Luckily, everything that was functioning from
before seemed to still be functioning, and Opportunity headed out to the next point of
interest. MRO data suggested clays where present in
this area, and the mission team were determined to find it. A beckoning outcrop was spotted around sol
3057, and the microscopic camera revealed something about it that no-one was expecting. Much like Opportunityâs landing site, these
smooth polished âblueberryâ rocks were observed, however, this time they were very
much a part of the rock. They were also smaller than what Opportunity
had seen before, only a few millimetres in diameter, and not rich in iron like the landing
site blueberries. A few of the exposed blueberries observed
had been eroded away, revealing their internal structure. Scientists described these blueberries as
âcrunchy on the outside, and softer in the middle. They are different in concentration. They are different in structure. They are different in composition. They are different in distribution.â It was quite the mystery. Opportunity had just one more place to visit
on its trip around Cape York, and that was the clay patch dubbed âWhitewater Lakeâ. On its way there, the Earth and Mars was just
going through a phase called solar conjunction, where Mars is behind the Sun, which blocks
communications between mission controllers and the rover. This has happened a few times during the course
of the mission already, but this time Opportunity gave mission controllers a bit of a scare,
as during the communication blackout, Opportunityâs onboard computer reset into a standby mode. Thankfully, communications were restored,
Opportunity booted back up properly, and it carried on to Whitewater Lake. And it was there Opportunity discovered "Esperance",
the pale rock in the upper centre of this image, which is about the size of a human
forearm. This was it; the treasure scientists had been
looking for. Esperance's composition was found to be higher
in aluminium and silica, and lower in calcium and iron, more so than any other rock Opportunity
had examined in more than nine years on Mars. Testing found that this rock had a clay mineral
content due to intensive alteration by water. Opportunity spent weeks here, making sure
the measurements were correct, getting everything it could get done before Martian winter came
around again. Sights were set on a place called Solander
Point, a sun facing slope on the next hill 1.5 km further south. Opportunity left Cape York on sol 3344, having
spent 9 Earth years, or 5 Martian years on Marsâ surface. It had found the best evidence out of any
Mars mission that neutral ph water once existed on Mars. Even though this huge discovery had been made,
Opportunity still had a lot ahead of it. Mission controllers wanted more evidence of
water, and they had their sights set on Solander Point, about 1.5km further south from Esperance. Martian winter was starting to come around
again, which brings with it a reduction in sunlight, from the length of the day, to the
angle of the Sun in the sky. To maximise the generation of power for the
little rover, Solander point was chosen as itâs a north facing slope, meaning as Opportunity
explores the area, its solar panels would be angled towards the Sun too. It was also believed to contain more evidence
of hydrated minerals and exposed layering in the rocks, as spotted by the Mars Reconnaissance
Orbiter. 1.5 km doesnât seem so far away, but Opportunity
was a slow rover, with a top speed of only 2cm/s, and it often travelled half that to
be safe. Scientists didnât want it to crash into
rocks, or get stuck in sand dunes, so Opportunity would move forward a bit, look around for
hazards, and repeat the process. Along the way, the floor underneath Opportunity
looked very peculiar. It was primarily large chunks of rocks, smoothed
off at the top, with sand and dust filling the gaps, almost like a random mosaic. Flat rocky ground is the ideal terrain for
Opportunity, so it made good progress on the way to Solander Point. Much like the rest of the mission blueberries
were spotted again, rounded rocks a cm or two across. By Sol 3390, Opportunity made it to its winter
lodgings, and began work on the slope. Even while working here, energy production
was very low, hitting only 270 watt-hours per day. Any lower than that, and the rover would have
gone into a type of hibernation mode. This was due to the Martian winter, but also
because dust had been settling on the roverâs solar panels, and there hadnât been a cleaning
event for a while. This low power mode meant that work around
Solander Point was slow, and it wasnât until Sol 3530 that a cleaning event finally pushed
energy production up to 370 watt-hours per day. Cleaning events occur when wind blows extremely
fine dust off the panels. Because Mars is so arid, thereâs nothing
adhesive about the dust, so even though Marsâ atmosphere is so thin, these dust particles
can easily be blown off. A bit like blowing dust off the cover of a
book. Dust settles on the rover over time, especially
during the massive dust storms that are so big, they can be seen from space. Around Sol 3519, Opportunity spent the day
examining a surface target. However, embarrassingly, the mesh they use
to calculate the distances of objects to the rover was wrong, meaning the instruments on
the arm were off by about 5cm, so the images taken were blurry and the Alpha Particle X-ray
Spectrometer couldnât properly detect what it was looking at. This was quickly rectified, and the usual
crisp images started coming back to mission control again. A bizarre discovery that was noticed just
a few Sols later was something known as Pinnacle Island. Opportunity often took days to examine certain
patches of ground, but scientists noticed some variation between one photo, and another
taken a few days later. This rock seems to have appeared out of nowhere. Mission controllers werenât so impressed
though, putting it down to a nearby meteorite impact, or even Opportunity bumping the rock
into place with one of its wheels. A flyby of the Mars Reconnaissance Orbiter
revealed no fresh impact, so that discounted that theory. But mission controllers sent Opportunity on
its merry way without investigating the rock further. This caused outrage online, with people suspecting
aliens left the rock there as a means of communicating with us on Earth, or that is was a type of
fungus that had grown over the 12 days between photos. Some people even went to the lengths of suing
NASA over their reluctance to investigate Pinnacle Island further by imaging it with
the microscopic camera onboard Opportunityâs arm. However, before that really got going, as
Opportunity looked back on Pinnacle Island, the mystery was solved. Opportunity had indeed cracked a rock in half,
as can be seen by the tracks left in the sand. As far as we are aware, this was the first
time something like this has happened on its whole mission. But the chances of it occurring were likely
increased as Opportunityâs arm was getting less and less mobile through wear and tear. This means that the rover itself now had to
turn in order for the arm to reach specific objects, instead of the arm simply reaching
across. Another problem that was becoming more and
more persistent for Opportunity was the onboard computer randomly resetting. Although Opportunity was always able to turn
back on, each reset wasted about a dayâs worth of science activities. By Sol 3749, these resets caused about half
the month to be missed. Mission controllers narrowed the problem down
to the onboard flash memory. Flash memory can get temperamental after repeated
use, heightening the risk of losing new photos before they can be sent back to Earth, and
so the decision was made to reformat the entire drive. This would not only clear the storage, but
also identify any bad cells within the drive itself, so those cells can then be avoided
in the future. By Sol 3773, the reformatting was completed
successfully. Soon thereafter, Opportunity reached Wdowiak
Ridge, south of Solander Point. As this was going on, a visitor from the outer
edges of the solar system was hurtling towards Mars. Its trajectory would take it just 130,000km
above the planetâs surface, before it continued on towards the Sun. This visitor was again not an alien, but Comet
Siding Spring, a visitor from the Oort Cloud. The Oort Cloud is found well beyond Pluto
and the Kuiper Belt, millions of icy rocks in orbits that take millions of years to complete. Because it had such a long time to accelerate
towards the Sun from the furthest point in its orbit, the trip from Mars to the closest
approach to the Sun only took 6 days. Thatâs 56km per second. However, because of the close flyby of Mars,
it meant that the spacecraft on and around Mars where actually in a better spot to witness
Comet Siding Spring than we were on Earth. Mission controllers of the various missions
were also a bit nervous about the dust particles that are ejected from the comet travelling
that speed, potentially impacting and damaging spacecraft in orbit around Mars. As such, Hubble, as well as spacecraft around
Mars, all began observations of this visitor. Fortunately, mission controllers had already
had some practice at this with Comet ISON, another comet that passed by Mars only the
year previously. Comet ISON, however, was 80 times further
away than Siding Spring would be, too far and too dim for Opportunity to spot. Unfortunately, it was day just as Siding Spring
made its closest approach to Mars, but Opportunity was able to snap a couple of photos of it
just before dawn. Can you spot it? Hereâs the annotated version of the same
image. As it passed by, none of the spacecraft were
damaged by ejected dust particles, but what they did observe from this flyby was completely
unexpected. As it passed by, it plunged Marsâ weak magnetic
field into chaos, albeit temporarily. Unlike Earth, Mars doesnât have a magnetic
field generated from within its core. Its magnetic field comes from plasma high
up in its atmosphere, which generates a very weak charge. This is enough to deflect solar wind coming
from the Sun, but solar storms from CMEs and solar flares push past this induced magnetic
field, stripping away atoms from the atmosphere. Comet Siding Spring had a very similar effect
on Mars. Comets are also surrounded by a magnetic field,
again induced from interactions with the solar wind, this time with the cometâs atmosphere,
or coma. A cometâs coma can reach out for a million
kilometres from the comet, meaning that as Siding Spring passed Mars, Mars was enveloped
in its coma for a good few hours. This merged both magnetic fields for the duration
of the event, with charged particles from both objects interacting strongly with each
other, and the atmosphere of Mars lost some particles to space as a result. However, apart from the image Opportunity
was able to take from the surface, all this went largely unnoticed by the rover. 2015 was quickly approaching, and Opportunity
was heading for Marathon Valley, which would take the odometer reading of Opportunity to
the distance of a typical marathon. Completing a marathon in 11 years? Thatâs a pretty impressive finishing time. In celebration of this milestone, mission
controllers took part in a relay marathon with a replica of Opportunity as they crossed
the 42km, or the 26.2 mile mark. But there was more to Marathon Valley than
just a waypoint, there were interesting rocks here that mission controllers wanted to investigate. To get down into Marathon Valley, Opportunity
had to go down the steepest slope it had faced yet, 32 degrees. Such was the steepness of this slope, that
dust that had built up on the solar panels began to flow off. After successfully descending down the slope,
Opportunity first investigated a region known as the Spirit of St. Louis. Itâs actually a small crater, yet it has
some outcrops exposed. Unfortunately, it was around here that the
flash memory caused the onboard computer to reset again. Although mission controllers had narrowed
down the problem to a specific cell bank on the flash drive, quarantining this section
apparently hadnât completely solved the problem. The solution had helped somewhat though, a
reset once a month is a lot better than the few times a day they were getting before the
reformatting and quarantining. Eventually though, engineers decided to bypass
the flash memory altogether, and operate the rover in RAM-only mode. The danger there though was that RAM gets
wiped if the computer switches off, meaning any scientific data not transmitted back to
Earth is at risk of being lost forever should the onboard computer turn off. The northern edge of Marathon Valley was a
ridge named Hinners Point, to the south was a ridge named Knudsen Ridge. In these regions, Opportunity was again looking
for clays, evidence of past liquid water oceans on Mars. Mission controllers detected clays on these
ridges from orbit with the MRO, which correspond to these reddish areas seen in the enhanced
colour versions of these photos. Opportunity found these rocks to be brittle
and to disintegrate a lot easier than other rocks it had previously observed, as well
as having unusual compositions. They were unlike a lot of other rocks in the
area. Although data collection was constant here,
it was also extremely slow going. The alpha spectrometer on Opportunityâs
arm was losing its potency, meaning sample anaylsis that would have taken minutes at
the beginning of the mission were now taking days or weeks. This was also combined with Opportunityâs
temperamental onboard computer, which was really starting to struggle. As a result, it took Opportunity well over
a year to get through Marathon valley. It began to head deeper into Endeavour, and
it was greeted with quite a spectacular sight. A dust devil was spotted on the crater floor. Spirit, Opportunityâs sister rover, had
seen dust devils in the past, but they were a lot rarer for Opportunity. It is believed that dust devils passing over
the rovers had been responsible for the occasional cleaning events that removed dust off the
roversâ solar panels. Opportunityâs next goal was again found
further south, a gully that scientists believe might have been carved out by water. A gully had never been closely examined by
any Mars mission in the past, so scientists were excited by what they might find. But getting there was tricky. On its way down the crater rim, it passed
through a gap in this ridge named the Lewis and Clark Gap, down Bitterroot Valley, to
Spirit Mound. On its way down, it took some spectacular
panoramas of various ridges overlooking the sand dunes stretching across the crater floor. Upon reaching Spirit Mound, Opportunity had
been on Mars for well over 4500 sols, roughly 12 Earth years. All things considered, Opportunity was in
reasonable health, and generating a very comfortable 450 watts of power from its solar panels. On its way to the gully, it would stop periodically
to perform some science operations, like imaging select rocks and measuring argon in the atmosphere. Opportunity finally reached the gully in September
2017. The gully was named Perseverance Valley. Scientists wanted to know whether it was water,
ice or wind that had carved this gully. From the shape of the gully, it certainly
looks to have had something flowed down it. Opportunity also spotted rocks lining the
channels. Could these have been deposited by water currents? As it turned out, Opportunity wasnât able
to find anything conclusive. After several months of examining the area,
Opportunity passed through 5000 sols on Mars. And what better way to celebrate than by taking
its first full selfie. Youâll notice this image is very blurry,
thatâs because it was taken with the fixed focus microscopic imager on its arm. It was only designed for very close targets. In June of 2018, the MRO detected the formation
of a dust storm. This isnât unusual, Mars has seen its fair
share of dust storms coming and going on a fairly regular basis. Opportunity had even lived through some itself. However, within days of its first formation,
it was clear that this was going to be a big one. It very quickly spread across the entire planet,
and mission controllers began preparations for a period of low power. On the 3rd June, Opportunity was producing
468 watts of power, by the next day, this had dropped to 345 watts. By the 6th June, it had plummeted to 133 watts. Dust caught up by this storm filled the atmosphere,
obscuring the precious light from the Sun to the point where it would have barely even
been visible. The worst storm Opportunity had experienced
up until this point was in 2007, where the atmospheric opacity, known as a tau value,
was at 5.5. This is almost enough for Opportunity to not
make it through. This storm, on the other hand, had a tau value
of 10.8, almost twice as bad as the previous storm. Although operations were kept very basic,
only sending back health reports every morning and evening, by the 12th June, Opportunity
fell into a continuous hibernation mode. The storm dragged on for months, and with
each passing day mission controllers lost more hope that Opportunity would wake up on
the other side. Three months later, the storm finally subsided
enough for Opportunity to wake up from its hibernation mode, and efforts were made to
re-establish contact with Opportunity. By October, the storm had cleared completely,
but no contact had been made with the rover, even after 350 attempts. From November on, mission controllers hoped
that if the rover simply had a lot of dust on its panels, that wind would blow a lot
of it off, however 1000 communication attempts later all the way through to February, mission
controllers gave up hope and declared the mission dead. The 15-year, or 5352-sol Mars mission had
finally ended. And what a mission it was. Opportunity measured temperatures, atmospheric
readings, the rotation of Mars and more, however the real prize was the definitive proof that
Mars was once a world similar to our own in that it held stable bodies of liquid water
oceans on its surface in the distant past. While we may take that for granted now, when
it was first confirmed it was truly ground-breaking. Shortly before communication was cut off,
Opportunity was in the process of sending back one last panorama of its final resting
place. Its famous last communication was poetically
translated to be âMy battery is low and it's getting darkâ, and its final image
was of the Sun obscured by the dust. And there we have it! A recap of the entire Opportunity mission. Thanks for watching! And a big thanks to my patrons and members
for continuing to make videos like these possible. If you want to support Astrum too, find the
link in the description. Subscribing and liking also goes a long way
if you want to support in other ways. All the best! And see you next time.
Damn, you beat me to it! I love Astrum's channel.
This is such a great documentary! Wasn't familiar with this channel before now, this guy really does his research.
Amazing content. Thank you
What an amazing watch đ