March 16, 2022
Season 4 – Episode 4: A Lifetime on Mars: The Adventures of Spirit and Alternative
On A Mission
Born collectively, the Spirit and Alternative twin rovers adopted divergent paths after they landed on reverse sides of Mars. Alternative’s journey was marked by luck, whereas Spirit’s was troubled from the beginning.
TRANSCRIPT
(music)
Narrator: From Earth, the planet Mars seems to be like a crimson star within the night time sky, a beacon that alerts one of the accessible alien worlds. Not solely is Mars comparatively near us within the photo voltaic system, but it surely has a panorama the place we will discover a footing. Mars appears virtually benign in comparison with the metal-melting warmth of Venus, or fuel big planets like Jupiter that vaporize any craft that dares enter its intense environment.
And but, Mars is named “the dying planet” as a result of so many missions trying to succeed in it have failed. When NASA launched twin rovers to Mars in the summertime of 2003 – Spirit in June and Alternative in July – solely a 3rd of the missions to Mars had survived the lengthy journey.
The European Area Company had combined outcomes when it despatched an orbiter and lander to Mars that very same yr. Their Mars Categorical satellite tv for pc efficiently orbited Mars, however the Beagle 2 lander that was supposed to succeed in the floor on Christmas Day disappeared with no hint.
[1:09] The perpetrator was unknown, however some suspected {that a} months-long mud storm was guilty. The storm winds wouldn’t have been a problem: they’re light in comparison with storm winds on our planet, as a result of the Martian environment could be very skinny – lower than one % as dense as Earth’s. However tiny mud particles, lofted excessive by swirling winds, take in daylight, heating the air round them and making the environment develop. This puffed-up environment might have an effect on a parachute throughout a touchdown on Mars.
NASA engineers fine-tuned the touchdown directions for the Spirit and Alternative rovers as they approached Mars in January 2004, utilizing climate observations of the Mars World Surveyor and Mars Odyssey satellites. Right here’s JPL scientist John Callas.
[2:00] John Callas: The environment had ballooned, and we truly made changes between Spirit’s touchdown and Alternative’s touchdown three weeks later since you wish to have the parachute open on the optimum altitude. If it opens too excessive, you then drift too lengthy and also you’re farther off track and your retro-rocket firing might not put you the place you wish to be. And naturally, when you launch a parachute too late, it’s possible you’ll not decelerate sufficient and it’s possible you’ll impression the bottom quicker than you are planning. In order that was a really essential parameter to remain throughout the candy spot of the parachute opening.
Narrator: Opening a parachute too excessive additionally might imply there’s not sufficient air to replenish the parachute, inflicting it to “squid” – or flap round with out absolutely opening.
Spirit entered the hazy Martian air house on January 3rd, 2004.
[2:55] Mission Management: Spacecraft reporting lander is separated. We anticipate that we are going to lock, radar will lock on the bottom in roughly 5 seconds from now. Present altitude 8,000 toes, transferring at a pace of 173 miles per hour. We’re close to our terminal velocity…
Narrator: As anticipated, the sign from the spacecraft was uneven because it rushed towards the planet’s floor, after which let go of the parachute after inflating the airbags that will let it bounce on touchdown.
Mission Management 1: We don’t see a sign in the mean time; no sign in the mean time.
Mission Management 2: We noticed an intermittent sign that indicated we had been bouncing. Nonetheless, nevertheless, we at the moment would not have sign from the spacecraft.
Mission Management 1: Please stand by.
Mission Management 2: Stand by.
Narrator: The seconds ticked away into minutes. Ten excruciating minutes later: no sign. quarter-hour: nothing. Had we misplaced the rover? Had Mars claimed yet one more mission?
[3:51] Mission Management: We see it – there it’s!
(cheers)
Mission Management: Yeah, lastly!
Narrator: Spirit was reporting that it had survived its touchdown. Three weeks later, the Alternative rover additionally arrived safely on the opposite aspect of Mars. The plan was for every rover to discover Mars for 90 days. However they lasted longer than that. A lot, MUCH longer.
John Callas: We labored on Mars for 14-and-a-half years, and so it turned acquainted to us. We turned Martians as a result of we went to work on Mars on daily basis and we noticed the sights – these mountains and these valleys and these craters – and so Mars turned our world. So, once we say, “our world,” we now not imply simply the Earth. It additionally has to incorporate the floor of Mars. And that is one of many features of the legacy, the wealthy legacy that these rovers gave us.
[4:53] (Intro music)
Narrator: Welcome to “On a Mission,” a podcast of NASA’s Jet Propulsion Laboratory. I’m Leslie Mullen, and on this fourth season of the podcast, we’re following within the tracks of rovers on Mars. That is episode 4: A Lifetime on Mars: The Adventures of Spirit and Alternative.
(music)
Narrator: The dual golf-cart-sized Spirit and Alternative rovers had been robotic subject geologists, in a position to scramble round with a toolkit to check the crimson rocks and soil of Mars. The rovers had been in search of indicators that lakes of liquid water had been on what right now is a barren panorama, drier than any desert on Earth. Discovering proof of previous water on Mars would enhance the chances that life as soon as might have survived there.
[6:16] Spirit landed in Gusev Crater, an space the scale of the state of Connecticut that’s positioned simply south of the Martian equator. Alternative landed within the wide-open plain of Meridiani Planum. In regards to the measurement of South Carolina, Meridiani lies nearer to the Martian equator than Gusev.
John Callas was glad when NASA determined to ship two rovers to totally different locations on Mars.
John Callas: This is a vital resolution, as a result of the rover’s design is what we name, “single string.” There is not any redundancy. So if one essential half fails, then that is it. The mission is over. You recognize, there is not any spare tire, if you’ll. So how do you guard in opposition to a essential failure in a system that’s single string? A technique you do that’s with two rovers, so you have got two probabilities of success on Mars, not only one.
[7:13] However there’s additionally a special form of danger, which is scientific danger. What if we land in a spot that’s completely boring from a scientific perspective? So we had two totally different touchdown websites, and so they truly explored two totally different scientific hypotheses.
So Spirit was headed to Gusev crater, which is that this 100-mile-diameter crater that reveals visible proof of historic flooding: we see an influx channel; we see an historic river delta; we will see areas the place the crater was breached to the north, the place water flowed out of it. And so we mentioned, “Aha! That is visible proof – morphological proof, as we are saying – of water being current for a time frame.”
[7:58] Alternative was going virtually utterly on the opposite aspect of the planet, , 12 Martian time zones away, a spot referred to as Meridiani Planum. From orbit, we noticed chemical proof of the mineral hematite. Some individuals is likely to be aware of it as a mineral that is utilized in jewellery, but it surely’s an iron-bearing mineral that kinds in a watery surroundings. And the one place that Mars World Surveyor noticed hematite was at Meridiani.
So the 2 hypotheses: Gusev – visible proof; Meridiani – chemical proof of water.
Narrator: After Spirit landed in Gusev crater, it took over two weeks to run by way of the exams to verify the rover was working correctly, after which have it drive off its touchdown platform and onto Mars. An airbag that hadn’t absolutely deflated partially blocked Spirit’s path, however after navigating fastidiously down the ramp, Spirit lastly was set to discover.
However then, only a few days later, the rover was in sudden peril.
[9:01] (music)
John Callas: That was a really intense second as a result of for no cause we might perceive on the time, the rover simply stopped speaking, , radio silence. And this was simply 18 days after we landed and it is like, “Wow, what occurred? Oh my God.”
Narrator: The flash file system on Spirit’s pc stored crashing and rebooting in an countless loop. This not solely prevented Spirit from speaking to us, it prevented the rover from turning off.
John Callas: The rover was on a path to dying. Identical to human beings, these rovers have to sleep at night time, and that is primarily to preserve vitality. And if they do not sleep, then they don’t seem to be saving vitality, the batteries are depleted, and with out vitality, they cannot function. They’re basically useless.
And we had Alternative on the way in which. You recognize, it is such as you’re birthing twins, and all of the sudden the primary little one has a medical emergency, however the second little one is about to be born too. And, , what do you do?
[9:58] Narrator: Engineers labored across the clock to determine what was unsuitable with Spirit, and tips on how to repair it. Lastly, simply hours earlier than Alternative was attributable to arrive, they discovered an answer.
John Callas: It was as a result of in floor testing, we had left some further information recordsdata, which we thought on the time was innocuous. We’re all taught to assume, “I’ve a 32-gig drive, I ought to be capable to get 32 gigs of knowledge on there.” Properly, there’s one other limitation, and that is the variety of recordsdata.
Narrator: Deleting the additional recordsdata helped the engineers get better Spirit, and so they additionally made positive Alternative wouldn’t endure the identical downside earlier than it landed.
Mission Management 1: “We have now constructive affirmation of a secure touchdown.”
Mission Management 2: “We’re seeing it on the LTP …”
(cheers)
Narrator: Alternative’s airbag touchdown had bounced it proper right into a small impression crater – a cosmic “gap in a single” that delighted the scientists, as a result of it put the rover within the good place to analyze the kind of rocks they’d hoped to seek out.
[10:54] John Callas: The rim of that crater was revealed uncovered bedrock. And this was an “Aha!” second, as a result of we had been on the lookout for floor proof of liquid water on Mars. And people rocks contained that proof, and all we needed to do is simply drive a couple of toes as much as them, and there it was for us to see. In order that was like getting an “A” on the primary query on the check. I imply, we simply nailed that one. And it made it look really easy, if you actually have to recollect how exhausting it’s not solely to get to Mars, however to discover Mars when you’re there.
(music)
John Callas: So I discussed that we noticed from orbit the presence of hematite on the floor the place Alternative landed. So now that we’re down on the floor, the place’s the hematite? And it wasn’t clear at first.
We had a spectrometer on board, a miniature thermal emission spectrometer, that will enable us to detect minerals like hematite. One of many fascinating issues is that once we used it to scan the floor, we noticed a hematite signature, however we seen wherever the airbags from the rover bounced through the preliminary touchdown, the hematite sign went away. And it is like, “Properly, what’s it concerning the bounce that will make hematite disappear?”
[12:09] However as we began to rise up near the rocks and discover, we noticed all these tiny little granule issues, these little spherules. They had been concerning the measurement of tiny blueberries, and so they had been very spherical and darkish in shade, so that they regarded like blueberries. It is like, “What is that this?” And it was to the purpose the place if you’re an astronaut on Mars at this location, you’d should watch out about the place you step, as a result of it might be like strolling on ball bearings and also you’d slip and fall!
And it seems the hematite is in these “blueberries.” And it took a short time to sleuth that out as a result of we did not have the flexibility to resolve that hematite signature to as small a measurement as a blueberry. We might simply see in a subject of view that there’s a sign for hematite, however was it coming from the rock? Was it coming from the mud? Was it coming from the blueberries?
[12:59] So it wasn’t till we bought to a degree the place we discovered what we name the “berry bowl,” which was a melancholy within the rock the place a bunch of those spherules had collected, so it regarded like blueberries in a bowl. We used the spectrometer to take a look at an space adjoining to that, after which proper on high of the blueberries, and you may clearly see that the sign was coming from the blueberries.
Narrator: The mysterious disappearance of hematite at every airbag bounce mark – a footprint so sharply outlined you may see the airbag’s stitching – was as a result of hematite blueberries had been pushed down into the soil with every airbag hit.
Scientists wished to make use of the rover’s Rock Abrasion Device to chew on the blueberries scattered round Eagle crater, the place Alternative was sitting. However the group was nervous about utilizing the grinder on such an uncommon goal.
John Callas: Yeah, as a result of hematite, it is probably a tough mineral. When you have ever used your electrical noticed at house and also you’re chopping by way of a chunk of wooden, you do not wish to lower by way of a chunk of wooden that has nails in it, proper? And so, we had been utilizing the Rock Abrasion Device to grind into rocks, we do not need these little disparate items of exhausting materials that will catch the blade and probably shatter the grinding ideas.
[14:14] Narrator: Regardless of this concern, the Rock Abrasion Device made a meal of the blueberries, permitting scientists to see that the hematite wasn’t only a coating on the floor.
Alternative’s preliminary good luck set the tone for the dual rovers’ totally different experiences on Mars. Whereas Alternative discovered proof for previous water straight away, Spirit solely discovered volcanic rocks that confirmed no indicators they ever had been touched by water.
John Callas: Spirit appeared to should wrestle for every little thing, and issues appeared to come back a lot extra simply for Alternative. And this truly had an impact on the group, as a result of there have been folks that had a robust private attachment to Spirit as a result of it was the rover that needed to wrestle probably the most. It’s extremely comprehensible – we naturally have compassion for people who wrestle more durable than people who do not wrestle as a lot.
[15:08] Narrator: Within the hopes of discovering extra promising rocks within the distant Columbia Hills, Spirit started an extended dusty slog throughout the desert.
John Callas: Throughout that drive, we noticed elevated wheel currents in the appropriate entrance wheel, and it is like, “Oh my gosh, is that this an indicator that the wheel may fail?”
And in order that was a tricky push. We had this system: for 90 % of a drive, we would not energy the appropriate entrance wheel, however we’d drive with the opposite wheels as a method to kind of favor it – identical to if you’re strolling and one knee begins to hassle you just a little bit, you stroll just a little bit in a different way so you do not put all of the stress on that one knee.
Narrator: As Spirit limped on a sprained foot, Alternative nursed a trick shoulder.
[15:49] John Callas: The thermostatic heater for the shoulder azimuth joint on the robotic arm was caught on. In order that meant that heater was on on a regular basis. And so, we developed this system referred to as “Deep Sleep,” which is, the one approach you may flip off that heater is you turned off every little thing. I imply, that is foolish as a result of that is form of like you have got a light-weight swap in your own home that is caught on, so to be able to flip off the sunshine, you go outdoors each night time and also you flip off the breaker for your entire home.
Now, if you shut off the grasp breaker for the rover, if you shut every little thing down for Deep Sleep, the one factor that continues to be powered is the alarm clock: the grasp clock for the rover. And in order that may very well be set to wake you up. But when it is sleeping, and the Solar powers up the photo voltaic panels, it might get up as properly. This is rather like in case your alarm clock fails to go off within the morning, however the Solar comes beaming by way of the home windows, you may ultimately get up as a result of it is daylight out.
Narrator: Whereas the rovers woke and slept with the rising and setting of the Solar, the rover operators in Mission Management needed to disconnect from this pure cycle.
[16:59] (music)
John Callas: A Martian day is nearly 40 minutes longer than an Earth Day, so 24 hours, 40 minutes. Due to that 40-minute distinction, the phasing between daytime on Earth and daytime on Mars will shift by 40 minutes on daily basis. Properly, we wished to maximise the utilization of those rovers, and so as an alternative of constructing the rovers modify to Earth time, we made the Earthlings modify to Mars time. So our workday would shift by 40 minutes on daily basis. And also you may assume, “Oh, that is nice since you get to sleep in an additional 40 minutes each single day.” No, it would not work that approach. What it means is that you simply’re completely jet-lagged as a result of your physique by no means will get sufficient time to regulate to the shift in time, as a result of it is a continually transferring goal.
[17:49] And so, we had a number of workshops with sleep specialists to grasp concerning the human sleep cycle, and tips on how to modify to a shifting work-sleep schedule, and tips on how to mitigate the results that come from shifting that schedule. There have been issues like, when you’re working through the night time and attempting to sleep through the day, if you get off your night time shift, put on darkish sun shades to attenuate the quantity of Solar that your eyes understand. Have blackout shades – 100% opaque blackout shades – in your sleeping room. Be certain it is quiet to be able to sleep through the day. Whenever you shift your schedule, shift every little thing, which incorporates if you eat, if you bathe, if you train. And that is actually, actually exhausting when the remainder of the world is on regular time. Children would rise up within the morning and go to high school and also you’re attempting to sleep, and the landscaper’s outdoors with the leaf blower. It simply would not work.
[18:45] One of many issues we did do, which was very profitable, is we had a science group that was primarily from distant establishments that had been visiting throughout this time. And so as an alternative of placing them in inns, we organized with a number of Pasadena builders to hire condominiums. So at one time, the MER (Mars Exploration Rover) mission was the biggest landlord in Pasadena as a result of we had 75 condominiums rented for supporting the science group. And the condominium suppliers not solely gave us a really engaging price on fully-furnished flats, however they accommodated our requests for placing blackout shades, after which they organized for the maid service to be on Mars time, and they also made positive they would not disturb the science groups throughout their sleep cycles.
However ultimately, it’s robust. We had two separate operations groups for every rover, and I used to be supporting each groups. Early on, I believed I may very well be a superhuman and truly put a sleeping bag in my workplace and I believed, “Oh, I will be awake for when Spirit is lively.” After which when Spirit goes to sleep, Alternative turns into lively – as a result of bear in mind they’re twelve time zones aside, so every is half a day aside – and I believed, “I will sleep a short time, then I will go on to Alternative after which sleep a short time once more and are available again to Spirit.” (laughs) That lasted possibly two days. And I mentioned, “That is inconceivable for a human to do.” So for me, the perfect factor that I might do was to decouple from Mars time altogether.
[20:11] Narrator: Dwelling on Mars time with two robotic explorers wasn’t one thing John had ever anticipated to do.
John Callas: Yeah, I am a fish out of water. I’ve by no means taken a geology class and I’ve by no means taken an astronomy class, so what am I doing exploring the floor of Mars?
However I am a physicist. I at all times puzzled what was smaller than an atom or what’s out past the celebs. And I knew from a really younger age I wished to do engineering or science, and so, I truly studied engineering as an undergraduate – I’ve a bachelor’s of science basically engineering. However physics turned my real love as a result of physics was understanding what all of it means. You recognize, in engineering, in these days, you’d have these tables behind the textbook that you’d reference to resolve a specific downside. Properly, I wished to know the place these tables got here from! (laughs) And that is what physics means that you can do, is to know the elemental constituents of our universe, elementary forces, the way it all works, why it really works, why it’s the approach it’s.
[21:17] Narrator: John first fell in love with physics in highschool. He additionally had a flair for electronics, which he used in the summertime job that helped him save for school.
John Callas: I labored in a boatyard in South Boston, in Massachusetts. And it was a uncooked, exhausting form of job.
(sound of shipyard)
John Callas: These had been industrial pleasure crafts, however we had been altering engines and rebuilding buildings and lifting boats out of the water and repairing propellers. And my job was putting in electronics on these boats. So it was very soiled, it was very laborious, and I used to be paid $2 an hour.
(sound of pub crowd, music)
[22:00] John Callas: At lunch time, the crew would go to a neighborhood bar referred to as the Erie Pub, as a result of they’d cheap sandwiches there. And it was very a lot a working man’s bar in a working-class neighborhood. And it was July of 1976, and so they had a TV on behind the bar and we had been having lunch. And I bear in mind wanting up on the display screen and there was a narrative concerning the Viking landers.
ABC information reporter: For the primary time, Earth has obtained photos – good photos – of Mars taken from floor stage, if “floor” is the phrase up there. An extremely advanced unmanned American mission, 11 months and 240 million miles outdated has accomplished simply what it was deliberate to do. ABC’s Jules Bergman experiences from the Jet Propulsion Laboratory in Pasadena…
John Callas:
And one of many Viking landers had an issue that the meteorological mast would not deploy as a result of the pin within the hinge had come out partially and jammed the mechanism. And so, the engineers at JPL reprogramed the soil pattern arm of the lander to come back over and faucet the meteorological arm to get it to deploy efficiently.
[23:11] And I bear in mind pondering, “Wow, that is exceptional that there is this downside thousands and thousands of miles out in deep house, and scientists and engineers right here on Earth clear up it.” I mentioned, “Wow, JPL should be like the best place to work within the photo voltaic system!”
Narrator: Whereas engaged on these Boston ships, the attract of spaceships exploring distant worlds was so robust it stayed with him, and years later, he jumped when a possibility got here to attach with an engineer at JPL.
John Callas: I knew a pal who knew somebody at JPL, and I picked up the cellphone, as a result of this was earlier than the web, and I cold-called this individual at JPL, Chad Edwards, who I do know to today and I nonetheless admire him taking my name. And out of the blue, we chatted for like 45 minutes about what he does at JPL, and JPL basically.
[24:07] And I believed, “Properly, why do not I fly to California, see if I might go go to JPL, and if nothing occurs, not less than I could make a trip out of it.” So I purchased an affordable airline ticket. I might by no means been to California, however I had a distant relative that lived within the space that I might stick with. And I introduced a enterprise swimsuit with me, and I used to be in a position to name Chad Edwards and go to JPL, and it changed into an interview, so I wore my swimsuit that day. And right here I’m.
Narrator: John labored on many Mars missions: Mars Observer, Mars Polar Lander, and Mars Local weather Orbiter didn’t survive the journey, however the Mars World Surveyor and Mars Odyssey satellites went on to nice success on the Pink Planet. By the point he was requested to hitch the Mars Exploration Rover mission, he was a Mars veteran.
[24:57] John Callas: I used to be the science supervisor, and the way in which I describe it’s I am answerable for managing the science group, however I am not a scientist on the science group. And my analogy is I am like the final supervisor of a sports activities group. I recruit the gamers. I see that they are educated and so they’re outfitted, and so they have a fantastic stadium to play in. However I am not out on the sector, I do not name the performs, however I get to take a seat within the air-conditioned skybox with a full catering through the recreation to observe.
Narrator: The stadium he put collectively for the science group had loads of followers – the massive, state-of-the-art video convention room earned the nickname, “The Callas Palace.” The performs labored on the market steadily led to extra discoveries because the rovers navigated inside their totally different Mars zones.
Alternative’s investigation of the Meridiani plain constructed up an image of the traditional Martian previous, when shallow water flooded the realm periodically, just like salt flats or playas on Earth. In the meantime, with its sore foot rising worse, Spirit was like an injured participant on the sector who was so centered on the objective that giving up wasn’t an possibility.
[26:09] John Callas: As we had been up over the Columbia Hills, close to a spot referred to as Dwelling Plate, the appropriate entrance wheel on Spirit failed.
(wheel failure sound impact)
John Callas: So to drive can be to both push or drag that wheel. This being the appropriate entrance, we made the choice to drive the rover backwards, predominantly, and we might drag that wheel.
That is form of like a type of annoying grocery retailer carts that has a jammed wheel and also you’re attempting to go down the aisle approach and keep straight and it tends to yaw, twist in a single course. That is the issue we had with Spirit, so we needed to continually compensate for the truth that the rover would twist as we’d drive it backwards. However we had been ready to try this successfully, and so we had been in a position to preserve exploring with the rover. We simply could not go as far every day as we would accomplished beforehand.
[27:00] However truly, I’d say that this failure of the wheel turned out to be the best scientific discovery on Mars for Spirit and Alternative. As a result of proper beneath the floor, coated by the veneer of mud, might probably be all types of discoveries, and we’re simply driving by them. However as a result of we had been dragging this wheel, we had been chopping a furrow in Mars and revealing what’s simply beneath the floor.
(sound of wheel scraping grime)
John Callas: And at this one location, we revealed this very shiny white materials. And we checked out it and mentioned, “Whoa, what’s that?” And it turned out to be opaline silica. It kinds not solely in water, however in sizzling water. So what we’re speaking about right here is an historic hydrothermal system that produced this opaline silica.
[27:54] It is a large discovery as a result of, , we had already established that there was liquid water on Mars for a sustained time frame. And in reality, massive, kilometer-scale our bodies of water on Mars. And with that, as a result of it was liquid, there should have been hotter temperatures and thicker environment, so we established that Mars needed to have been extra Earth-like. However now we discovered proof of a hydrothermal system, so we add another necessary important ingredient to the habitability of Mars, and that could be a supply of vitality.
As a result of right here on Earth, wherever we discover liquid water and a supply of vitality, we discover a thriving ecosystem. Simply consider these deep ocean volcanic vents the place you have got all of the fish and all of the biota, or consider the geysers in Yellowstone Nationwide Park, this sizzling, steaming water comes capturing out of the bottom, however round these geysers are these thick stromatolites – mats of wealthy organic creatures – thriving on the vitality that comes not from daylight, however from the new water. So now we now have yet one more essential contribution to the bodily habitability of Mars that took place as a result of the wheel failed.
[29:07] Narrator: Many discoveries had been made lengthy after the rovers had pushed previous their 90-day guarantee, generally known as the prime mission. By then, the groups had shifted off Mars time, in a position to function on a extra Earth-based schedule by sending the rovers directions a day or two forward. This shift within the work day was accompanied by a shift in perspective.
John Callas: We needed to make the psychological swap from the concept that these had been only a 90-day mission, to at least one that would presumably prolong for an extended time frame, as a result of we had been working these rovers as if tomorrow was our final day. And it was a gradual evolution to make that transition that possibly these items are going to last more. Possibly we’ll get by way of the Martian winter! On touchdown day, nobody would have wager that we’d have survived the Martian winter.
[30:01] Narrator: The shorter days of winter would make it more durable to cost the rovers’ photo voltaic panels. The colder temperatures additionally might threaten their electronics and mechanical elements. Once more, Spirit was dealt a harder hand than Alternative – this time due to its extra southern location.
John Callas: Being additional south made it rather more difficult to outlive the winter. Since you’re additional away from the equator, your Solar angles are steeper, so you aren’t getting as a lot photo voltaic vitality on common over a yr. Identical to right here on Earth, the farther away from the equator, the deeper the seasonal cycle. So the summers are hotter, however the winters are colder.
Narrator: The crimson, talcum-powder-like mud accumulating on the rovers’ photo voltaic panels was one other risk to the mission. Engineers had identified this is able to be an issue – the Pathfinder lander and Sojourner rover in 1997 had collected an more and more thick layer of mud on their photo voltaic panels that had steadily decreased their energy. For the Mars Exploration Rovers, proposed dust-busters had included windshield wipers, compressed fuel blowers, and a transparent plastic cowl that will roll to disclose a clear new sheet – however ultimately these had been all deemed too difficult and heavy for an area mission.
[31:22] However then, Mars got here up with an answer.
(sound of wind)
John Callas: Mud devils, or wind occasions, or wind gusts, or no matter you wish to name them, will come alongside at periodic instances. For Alternative, they’d are likely to utterly or practically utterly clear the photo voltaic arrays.
In Spirit’s case, it might get a cleansing, but it surely by no means would restore it again to the place it was earlier than. So there was this secular downward development of general efficiency for Spirit. And issues had been dustier than they had been for Alternative, so there was extra mud accumulation on Spirit. So that is, once more, a part of that very same narrative – every little thing was more durable for Spirit.
[32:03] Narrator: The mud devils might have been unpredictable, however they helped breathe new life into the mission. Each rovers survived their first winter, though Spirit needed to keep parked on a slope, its photo voltaic panels angled to higher seize the sparse daylight. When spring rolled round, for as soon as it was Alternative that bumped into hassle.
John Callas: So with lengthy length, you have got better alternative to seek out the challenges on the floor of Mars. And one in all them was Purgatory Dune.
(music)
John Callas: So there’s numerous windblown mud on Mars, and it kinds these sculpted dunes. And we had been driving over these dunes, and we did not absolutely admire the hazards that these dunes might signify.
One of many modes we now have known as blind driving, which is, you shut your eyes and also you spin the wheels a sure variety of revolutions, and if you’re accomplished spinning the wheels, you see the place you might be.
[33:01] Narrator: Rover operators didn’t blind drive as a result of they had been thrill-seekers. As an alternative, by not ready for the rover to cease and take photos with each step, they might drive farther.
John Callas: On Mars, we do not have to fret about site visitors lights or pedestrians, so we will do this. Besides when you’ll be able to’t, and that is if you encounter a hazard. And what occurred with Purgatory is the rover was driving into one in all these dunes, however as an alternative of driving over the dune, the wheels dug into it. And since we had been blind driving, it stored spinning and spinning and digging itself deeper into this dune, and so it turned embedded.
(sound of wheels digging into sand, with robotic beeps)
John Callas: And so, it was buried as much as its hubcaps on this dune. And it is like, “Oh boy, this can be a significant issue, as a result of we’re caught.” And , you’ll be able to’t name AAA on Mars. So what can we do? Properly, we will not go to Mars to repair the issue, however possibly we will have Mars come to Earth to assist us perceive what the issue is.
[34:04] So we now have a testbed, and it is full of gravel to be a proxy for the soil on Mars. And we tried to grasp what the bodily properties of this dune the place Alternative was embedded had been like, and recreate these on Earth. And that is actually exhausting to do. You may’t simulate Mars on Earth as a lot as you strive – and we had the world’s finest consultants attempting – at finest, it is a poor consultant, as a result of the gravity is totally different, the environment is totally different. And although we labored out all types of various simulants to strive, they had been only a actually poor illustration of what was occurring on Mars. Nevertheless it was the perfect we might do.
And we spent a number of weeks testing our third sibling – , Spirit and Alternative are an identical siblings; there’s a lesser-known third sibling, which was their check rover. So we’d intentionally bury it prefer it was on Mars, after which we’d see, might it drive out? And after a number of weeks of testing, the perfect factor we got here up with was to place it in reverse and gun it.
[35:12] However the actuality is the rovers do not drive very quick. They transfer about as quick as a tortoise on the floor of Mars. So you do not actually gun it, however what we did is we reversed the wheels, and we needed to spin them 100 instances greater than you usually would to go one meter on Mars. Every day we’d do some bit and we would see, is it making progress or is it getting worse? Ultimately we began to see indications that sure, the rover was slowly popping out, and after numerous wheel spinning, the rover did again out and we bought it out of the dune.
So then we made adjustments. We’re not going to drive throughout dunes anymore like that. (laughs)
Narrator: It took six weeks to get Alternative out of Purgatory. Two years later, Alternative confronted one other trial by sand when one other storm billowed within the skies above the rover. The dust-choked air would filter out daylight wanted to cost the photo voltaic panels, and since there’s nearly no moisture on Mars to trigger the tiny particles to clump collectively, that tremendous mud can keep suspended for a very long time.
[36:15] John Callas: So we had the orbiting spacecraft, Mars Odyssey and Mars Reconnaissance Orbiter, that had been monitoring the climate on Mars. And they might be capable to give us warnings or heads up as to coming dangers. And so, we realized that the skies are going to darken, so we cease and we save vitality. And one of many large vitality consumptions is for the rover to speak to us, and so we instructed the rover, “Do not discuss to us for a number of days.”
And this was robust. I imply, that is like your little one. And also you’re sending your little one right into a harmful scenario and you are not going to listen to from them for 4 days. I imply, , as a guardian, you would be climbing the partitions.
And I bear in mind being within the operations room ready and staring on the screens, hoping to see telemetry from the rover. And proper in the mean time we anticipated, the telemetry got here in and the rover mentioned, “I am OK.” That was a extremely thrilling, dramatic second for all of us.
[37:14] Narrator: One other dramatic second, in 2009, got here from Earth reasonably than Mars: an infinite wildfire that sprang to life within the mountains simply outdoors of JPL.
(sound of crackling flames)
John Callas: The hearth got here proper as much as the Lab’s property line.
(music)
John Callas: The rovers depend upon the Earthlings to maintain them going, however what occurs if the Earthlings cannot be there? And so we, from the very starting, had contingency plans, , within the case of an emergency and we could not occupy our operations services to function the rovers.
Properly, to start with, the rovers are sensible sufficient to deal with themselves if they do not hear from the bottom. So their first obligation is at all times to be secure. However with the onset of the Station Hearth and the evacuation of JPL, we took measures to verify the rovers may very well be secure for an prolonged time frame.
[38:07] Narrator: A extra predictable seasonal occasion additionally would trigger us to lose contact with the rovers.
John Callas: With each orbital sequence between Earth and Mars, we undergo a interval referred to as photo voltaic conjunction. That is when, as seen from the Earth, Mars is both very near and even behind the Solar, and we will not talk to the rovers for a interval of a few weeks. And so we put together for that forward of time and provides the rovers directions to be well-behaved throughout that couple-of-week interval. That is form of like the primary time you belief your teenage youngsters to be house alone whilst you and your partner exit of city for a brief trip.
Narrator: The rovers had been rising up, their growing older accelerated by tough travels on an alien world. When their fourth Martian winter was approaching, the mission group regarded for a slope to park Spirit in order that it might sit out the season whereas sunning itself, simply because it had the earlier winters.
[39:04] John Callas: However now the issue is we now have this failed wheel, which limits the rover’s skill to climb any form of slope. We mentioned to ourselves, “Can we discover one thing we will go down?” As a result of we will not go up, we now have to go down. However we nonetheless wished to scientifically discover.
So, we regarded on the map and there have been these options that had been to the south of us of the order of 100 or so meters. We thought, “Properly, possibly we might get to these,” as a result of they had been scientifically fascinating as a result of one had kind of this uncommon cap rock, and the opposite one appeared extra like a crater. And we thought, “As soon as we get there, we will toe-dip down into that factor, and get a pleasant north-facing slope.” So we thought, “We’ll take probably the most direct path to get there.” And as we began out, we began to turn into embedded within the terrain. And we go, “Oh, this is not going to work.” And so, we wrestle to get again out of it, return, after which strive a special course.
[40:01] And we’re burning up time simply attempting to go down one in all these instructions, getting embedded, spending, , weeks attempting to get again out once more, after which one other month backtracking once more. And so, the clock is ticking on us.
So we tried the second route, and there we bumped into issues. So it is like, “OK, this is not going to work.” We have got to return out after which do our third possibility, which was our least most popular possibility as a result of it was the longest route, and the least surveyed method to go. So we began heading that approach. And every little thing was going nice, after which unexpectedly, BAM!
(sound of crust cracking)
John Callas: We broke by way of into what I’d name a camouflaged tiger entice. I imply, the floor terrain regarded tremendous, however there’s this duracrust, and we broke by way of that crust.
This isn’t not like when you’ve gone snowshoeing and also you’re stepping on the highest of the snow and it is supporting your weight and also you’re in a position to make progress. After which all of the sudden you break by way of that crust of snow and also you go down deep into the gentle, fluffy snow.
(sound of footsteps in snow, after which ice crust crack)
[41:04] John Callas: After which every step you are breaking down into the gentle, fluffy snow, after which your progress simply bogs down. That is form of like what occurred for Spirit. It broke by way of the crust into this unfastened, fine-grained materials, and with solely 5 working wheels and the sixth wheel appearing like an anchor, we had been caught. And we tried every little thing to attempt to get out. After which, a second wheel failed.
(wheel failure sound impact and robotic beep)
John Callas: However we continued to strive, and we began to make just a little little bit of progress at extricating ourselves, however we ran out of time. And winter fell upon us, and dusty photo voltaic panels, and a really unfavorable orientation of the rover relative to the Solar in wintertime – all these conspired to have the rover go silent through the winter after which by no means get up once more.
(music)
[42:04] John Callas: We at all times knew these rovers had been mortal and that they’d finish sometime. However what we wished to do was to verify the rovers’ finish was not as a result of we made a mistake. The rovers would finish as a result of Mars would resolve it was time to take the rovers from us, and that is what occurred. And although we had been on borrowed time, it was unhappy for all of us that we needed to say goodbye to a pal, a beloved one, and an intrepid explorer.
However even on this unlucky goodbye for Spirit, it offered one of many different nice discoveries: that this fine-grained materials that trapped the rover had been indicators of current water motion on Mars. And after I say current, I imply like 1,000,000 years, versus a billion years.
[43:01] Narrator: Contemplating how Spirit struggled at the start of its journey to seek out any proof of previous water on Mars, how unbelievable that it met its finish swamped in a sea of sand that testified to a once-saturated panorama. Spirit had explored Mars for over 6 Earth-years, or 2,210 Martian days, generally known as “sols.”
To honor its fallen twin, the placement the place Alternative was exploring was named “Spirit Level.” Alternative then continued on, racking up the mileage.
John Callas: We had been the primary human enterprise to do a marathon on one other world. And we truly held a Mars marathon here at JPL to have a good time that.
JPL Mars Marathon announcer, John Callas: “Welcome to the Mars marathon right here on the Jet Propulsion Laboratory.” (cheers)
[43:51] John Callas: And the factor that simply was exceptional is, when was this rover going to cease? As a result of we had exceeded the design testing of the motors by many, many elements. It was bordering on being absurd. It is form of such as you’re driving your automotive, you are in the course of nowhere, and the fuel gauge is on empty. And also you assume, “I will run out of fuel any second now,” and you retain driving for six or eight or extra hours (laughs) and you continue to have not run out of fuel. And also you’re saying, “What is going on on right here?”
And that is what we had been saying, “These motors have tens of thousands and thousands of revolutions on them. They failed on the producer properly earlier than that. And but, they’re nonetheless going – why is that this?” In fact, we’re delighting on this as a result of it means we will proceed to discover Mars.
One other actually great factor concerning the prolonged mission is we had been in a position to convey on new individuals to have the expertise of working a rover on Mars. And so, we turned a coaching pipeline to offer house flight operations expertise to individuals recent out of college, simply starting their careers.
[45:03] Narrator: JPL scientist Abigail Fraeman’s profession was launched by the Alternative rover.
Abigail Fraeman: I used to be a highschool pupil, and I truly bought to come back out to JPL to be within the room when Alternative landed as a part of an outreach program. And it was wonderful to see the primary photographs from the rover come again and to be within the room with the science group who had been leaping off the partitions and already attempting to interpret the primary picture of Martian bedrock that we might ever seen. And so, that actually impressed me to enter planetary science.
I believe I at all times knew I wished to be a scientist. It wasn’t till Alternative landed that I noticed I wished to be a planetary scientist. There are nonetheless so many new locations that have not been visited, that have not been seen, and by being part of planetary science and planetary exploration, you not solely get to see these locations for the primary time, be the primary human to ever uncover a location, however then you’ll be able to have a look at what you are discovering, and use it to grasp one thing actually necessary about how planets work, how issues evolve; reply a number of the greatest questions – are we alone within the universe? And that, to me, was so thrilling and so compelling, I could not consider the rest I wished to do.
[46:23] So I turned concerned within the mission in quite a lot of methods all year long after I was a highschool pupil, after which I did a summer season internship as an undergrad after my freshman yr, engaged on information from Alternative. After which I joined the science group after I was in graduate faculty in 2010, after which rejoined the mission after I began at JPL and have become the deputy mission scientist. In order that’s a really particular mission to me.
Narrator: Whereas Abigail was exploring Mars with Alternative, she additionally joined the group for the subsequent Mars rover, Curiosity. Curiosity is greater, heavier, with extra superior devices and skills than the Mars Exploration Rovers. And Curiosity is a mountain climber – after it landed in Gale crater in 2012, it headed up Mount Sharp, a peak rising 18,000 toes, or 5.5 kilometers, above the crater ground.
[47:20] Curiosity is ready to take selfies through the use of a digital camera on the top of its lengthy arm. Seeing Curiosity staring again on the digital camera, a lone determine surrounded by the huge Martian panorama, impressed the Alternative group.
Abigail Fraeman: After seeing the success of Curiosity’s selfie, individuals on the Alternative group had the concept that, we do have a digital camera on the top of our arm. And, sure, its focus is not going to permit us to get as crisp of an image as Curiosity. And it is not going to be in shade; it will be in black and white. However we will attempt to take a selfie of ourselves, too. There is not any cause we will not. And so, we labored exhausting to determine that out.
[47:59] And truly, on sol 5,000 of the mission, Opportunity took its first selfie, and it is one in all my favourite photos from that mission. To see Alternative with our personal eyes, , it is the primary time we would seen the rover since 2003. And we bought this image in 2018. That was actually cool.
Narrator: When Alternative took its selfie, all these years on Mars had clearly taken a toll.
Abigail Fraeman: A number of of the actuators on Alternative had failed, , the steering actuator on one of many wheels wasn’t turning. The arm joints had damaged, so it might form of solely go up and down, it could not go aspect to aspect anymore. Its reminiscence had began to fail, so we needed to do new methods of working the car the place we’d downlink the entire information earlier than we went to sleep at night time, or we’d overlook what we had accomplished through the day.
Narrator: Regardless of these afflictions of age, Alternative managed to maintain going, and the mission group was on the lookout for factors of curiosity on the horizon.
[48:56] John Callas: We have gone 45 kilometers (28 miles) on Mars, and the subsequent large crater function is like 50 kilometers (31 miles) away. And we’re pondering, “Is that within the realm of chance?” However that by no means got here to be, as a result of Mars determined it was time. A worldwide mud storm descended upon the planet, and it was historic in magnitude.
(sound of wind and robotic beeps)
John Callas: The final data we bought from the rover was, “Batteries had been low. It is getting darkish, and it is chilly.”
And the skies simply darkened so shortly and so deeply over the rover, that the rover shut down. There was zero gentle on the floor of Mars and the rover was in full darkness.
And we needed to wait, and we waited for eight months, continually listening on daily basis, sending a command. “Are you there? When you’re there, say hi there.” However we by no means heard from Alternative once more.
(sound of wind)
[50:01] Narrator: After practically 15 Earth-years exploring Mars, or 5,111 sols, Alternative’s mission was declared over on February 12, 2019.
Mission Management/John Callas: I wished to say with the completion of tonight’s commanding, this concludes operations for MER-1, spacecraft ID 253….
Abigail Fraeman: You recognize, the mission had been such part of my life. And so, on the one hand, it was fairly unhappy to have that gone, and now not realizing that, it doesn’t matter what was happening, Alternative was nonetheless exploring Mars. However, after all, however, like, “Oh my goodness, the mission was purported to final for 3 months, and it had lasted from the time after I was a highschool pupil all over getting my Ph.D. and getting employed at NASA after which attending to work on it. That is unbelievable.
Narrator: Because the group mentioned goodbye to Alternative, the track, “I’ll be seeing you,” performed in Mission Management.
“I’ll be seeing you,” sung by Billie Vacation
I will discover you within the morning Solar
And when the night time is new
I will be wanting on the Moon
However I will be seeing you….
[51:10] Deep Area Community: Thanks to your feedback, and it’s a tragic day for all of us.
Mission Management/John Callas: 14, you might be launched.
Deep Area Community: 14 copy, launched.
Mission Management/John Callas: MER mission off the online.
Narrator: Alternative’s closing resting spot was in Perseverance Valley. Coincidentally, Perseverance was the identify of the subsequent rover to launch to Mars. With the arrival of Perseverance in 2021, NASA as soon as once more has two rovers exploring Mars – Curiosity remains to be climbing up Mount Sharp, whereas Perseverance landed down in Jezero Crater. The legacy of Spirit and Alternative could be seen in these rovers – from their altered wheel designs to cope with sand, to new sorts of capabilities impressed by the lifetime travels of the dual Mars Exploration Rovers.
(music)
[52:13] John Callas: These days, rovers on Mars looks like, , individuals have grown up with that. However in 2003, 2004, the thought of a sustained floor robotic mission was a completely new idea.
The story of Spirit and Alternative is an epic human journey, as a result of people created these machines to be our proxies, our representatives, our ambassador to a distant alien world. And so they did it past expectations, beneath the harshest doable form of situations. And that’s simply actually a exceptional story.
Narrator: We’re “On a Mission,” a podcast of NASA’s Jet Propulsion Laboratory. When you loved this episode, please comply with and price us in your favourite podcast platform. You should definitely take a look at our different episodes, and NASA’s different podcasts – they’ll all be discovered at NASA-dot-gov, ahead slash, podcasts.
[run time = 53:17]
