I mean, they were launching Titan IIs in 2003 OTL, so it's not without precedent
Small Steps, Giant Leaps: An Alternate History of the Space Age
- Thread starter ThatCallisto
- Start date
ISTR a proposal from like 2001 to launch an ISS cargo capsule on a Titan II.I mean, they were launching Titan IIs in 2003 OTL, so it's not without precedent
You’re right it was a crewed thing. I only mention it because it might fly in a TL I’m planning to do someday which features the ISS as it was meant to be (Russian solar power tower,CRV,that wonky lab module on the Harmony zenith port,etc)
Great stuff as usual just one little quibble:
Unless there's a VERY significant design change in the Orbiter it was actually configured and prepared for ground controlled/computer guided flight with out crew input both up and down. Yes it's part of the 'test' but NASA wanted the Orbiter back if something happened to the crew so they could figure out a fix.
This was achieved during the 'test' phase with a specialty cable that had to be attached between the flight computers and the flight control system, needless to say the Astronaut Corps HATED it because it made uncrewed flights possible so it was only installed for the designated "test" flights and was only carried a few times after that before being removed completely.
(In context this was only brought up a couple times in OTL so it's kind of not common knowledge. The first time was when Buran flew a totally automated mission and the Soviet's bragged about it with NASA responding essentially "Well we COULD have flown unmanned... but we actually trust our design"
The second time was during the Columbia investigation where it was brought up in the context of a 'rescue mission' and then trying to get the Columbia back under automatic control)Randy
I believe (according to Jenkins, at least) that the cable was only built after the Columbia disaster? There were limited autopilot systems before that, but they were tested and performed poorly on STS-3 to my knowledge. I believe the cable system would have instead allowed the Shuttle to be remotely piloted from the ground instead of a true autopilot.Great stuff as usual just one little quibble:
Unless there's a VERY significant design change in the Orbiter it was actually configured and prepared for ground controlled/computer guided flight with out crew input both up and down. Yes it's part of the 'test' but NASA wanted the Orbiter back if something happened to the crew so they could figure out a fix.
This was achieved during the 'test' phase with a specialty cable that had to be attached between the flight computers and the flight control system, needless to say the Astronaut Corps HATED it because it made uncrewed flights possible so it was only installed for the designated "test" flights and was only carried a few times after that before being removed completely.
(In context this was only brought up a couple times in OTL so it's kind of not common knowledge. The first time was when Buran flew a totally automated mission and the Soviet's bragged about it with NASA responding essentially "Well we COULD have flown unmanned... but we actually trust our design"
Randy
I'd have sworn Jenkins was where I first saw about the cable being needed and it being installed for the test flights because I know it was stated that it was removed from even being carried once the test flights were over. Yes is was more in the nature of 'ground controlled' flight and landing as they found out early on they lost control (and as you note the autopilot was not so good early on) during reentry but the idea remained that they could fly totally unmanned since there was always the chance of a loss of crew during a test flight and they wanted the orbiter to be able to come back or at least have that chance.
Randy
Excellent chapter, can't wait to see how the lessons of the past inform the future. Fly high, Kitty Hawk!
(insert eerie background music here)
Next time on Small Steps, Giant Leaps, we return to an old friend...
(Credit to beanhowitzer for the art!)
PIONEER MARS
Tomorrow (hopefully), SSGL returns! What might this be...
(Art credit to beanhowitzer once again)
Chapter 2, Interlude 2A: Огонь (Fire)
Small Steps, Giant Leaps - Chapter 2, Interlude 2A: Огонь (Fire)
Almost from the moment Navigator arrived at Mars, NASA had been interested in returning. A variety of discoveries from the mission pointed strongly towards evidence of Mars being far more dynamic than previous findings from Mariner had indicated. Higher-resolution terrain mapping revealed an abundance of features, such as meandering riverbeds, water-carved canyons, and fluvial deposits, that pointed towards vast quantities of liquid water being present on the Martian surface at some point in the distant past.
The strategy for post-Navigator Mars exploration could be summed up in three words: Find the Water. Evidence was needed to determine if the strikingly Earthlike terrain features had been formed by water, and if so, where that water had gone; if water had been present in large quantities on the Martian surface, it was entirely possible that life had arisen there. In addition, discovery of surviving water deposits beyond the polar caps, either in subsurface aquifers or as ice, would no doubt be of great benefit to future human explorers.
In pursuit of this water-finding goal, JPL began studies as early as late 1977 into two complimentary spacecraft, both benefiting from the rapid advancement of small-scale electronics throughout the latter part of the 1970s:
- Mars Mapping Mission, an orbiting probe capable of mapping Mars’ surface in fine-detailed resolution and (hopefully) detect the chemical signatures of any subsurface water, as well as providing an orbital relay for surface craft
- Mars Rover, a wheeled “robotic geologist” which would be landed at a promising site to study surface features with cameras, microscopes, spectrometers, and an onboard “lab” to analyze samples
Although robotic exploration vehicles had previously been employed to great success in exploring hostile regions such as Earth’s seafloor and - in the case of the Soviets - the surface of the Moon, Mars' great distance from Earth and the resulting signal delay meant that the Mars Rover would have to be autonomous, "thinking for itself" to a much greater extent than previous missions. Unsurprisingly, the cost estimates for such an ambitious and advanced vehicle rapidly ballooned. The entire mission came close to cancellation at the hands of a budget-conscious Congress under the Dole administration, but ultimately what happened was a significant retooling instead of outright cancellation. The more technically complex Mars Rover would be split into two smaller vehicles for redundancy and delayed to a future Mars window (likely 1986) to allow time for the concept to mature, while a simplified mission would fly in 1981, demonstrating key technologies before risking what was quickly becoming a billion-dollar national asset.
This “risk reduction” mission would utilize a lander vehicle built essentially out of Navigator spare parts and fitted with new instrumentation and upgraded electronics; as it turned out, the amount of test and flight spare equipment produced by the earlier program was sufficient to assemble a third lander on the cheap. To avoid the need for expensive plutonium nuclear fuel, the lander's radioisotope thermoelectric generators were replaced with a pair of unfolding solar panels, which would deploy after landing. The use of solar panels, though cheaper than plutonium RTGs, did pose a number of headaches; they were heavier overall than the SNAP-19 units used on Navigator, which meant a smaller scientific payload could be carried, and dust accumulation on the Martian surface meant that surface operations could not be guaranteed for more than perhaps 30 sols. The weight in particular resulted in the deletion of the heavy Navigator Life Detection Package, which had at any rate previously produced inconclusive results. Much of the lander’s science payload was dedicated to a small passenger, the Small Rover Experiment. A four-wheeled, shoebox-sized assembly with only a camera and a single scientific instrument, SRE would demonstrate key technologies like autonomous navigation for the larger rovers to come.
Rebranded as “Pioneer Mars Lander” both as a nod to the similarly-inexpensive Pioneer Venus mission and for its job of “pioneering” technology to be used on the eventual Mars Rover, the lander would piggyback on the Mars Mapping Mission (itself soon renamed “Pioneer Mars Orbiter”) for the journey to the Red Planet. Unlike Navigator, since the Martian surface was now mapped well enough to avoid the need to wait in orbit, the lander would separate from the orbiter before orbital insertion and make a direct entry into the atmosphere from an interplanetary trajectory.
Initially planned to launch on the Space Shuttle, delays to the new launch system meant that Pioneer Mars instead left Earth in the 1981 transfer window atop the final launch of Titan IIIE. It was a bittersweet launch for the Titan crews; with the Shuttle beginning operations, the future of expendable vehicles like Titan was unclear.
[Pioneer Mars releases its lander en-route to Mars (artist’s impression). Image credit: beanhowitzer.]
On the other side of the Iron Curtain, the Soviets would make another attempt at Mars in 1981 as well. In contrast to their belated success at Venus in the latter part of the 1970s, no single Soviet mission had successfully made it to the surface of the Red Planet. The most successful by far had been Mars 3, which successfully soft-landed but failed only minutes after with half of a grainy image transmitted. The previous three probes of the 1975 launch window (Mars 5, 6, and 7) had all failed to successfully put a lander on the surface, despite successful flybys by Mars 5 and 7.
Every attempt at a Mars landing by the Soviet Union had failed, one way or another. For the upcoming 1981 transfer window, with budgets less starved by Rodina and with the Adventure probes finally launched, the USSR was determined to finally find success at Mars.
The twin Mars 8 and Mars 9 spacecraft would be the first missions to fly with the new 5MV probe bus, an incremental improvement on the 4MV that incorporated weight-saving measures and improved electronics from the Adventure program. Riding atop the 5MV would be a lander of an entirely new design, the space program's attempt to break the "Mars curse".
All previous landers except Mars 3 had failed during descent, largely due to the complex nature of a Mars landing operation coupled with the notoriously poor quality of Soviet electronic equipment in the early 1970s. Mars' atmosphere essentially presents the worst of both worlds to a lander; unlike the Moon, its atmosphere is thick enough that a heat shield and parachute are necessities, but unlike Earth and Venus, it is too thin to land on parachutes alone. Both the previous missions of the Mars program and the American Navigator probes had solved the problem with a multi-phase descent, where a lander was encased in a heat shield which it would release after entry, followed by a parachute, and finally by terminal descent with retrorockets similarly to a lunar landing.
In order to simplify the descent and reduce the chances of failure, the complex retrorocket pack which had placed Mars 3 gently on the surface would be replaced with a set of small solid rocket motors, which would fire at a preprogrammed altitude and velocity to bring the lander to a stop a few dozen meters above the ground, at which point the rocket pack would be released and the lander would fall to a rough landing. To protect the Mars 8 and 9 landers from the force of such an impact, each lander would be surrounded by a set of airbags that would inflate during descent; these would cushion the crash landing and allow the lander to bounce to a stop. Once safely stopped, the airbags could be deflated and the lander deployed. A set of four "petals" would unfold from the sides of the lander after touchdown, pushing it upright in case it had landed on its side during the bouncing. Three of the petals would contain a set of solar panels to unfold after deployment, in another major upgrade over previous missions to allow for longer-term surface operation. The fourth petal would carry a small tethered “rover” on skis, an upgraded version of the Prop-M design first flown on Mars 2 and 3. The tiny rover contained only a seismometer, and its mission was simple: to "waddle" as far from the lander as its tether could take it, and lower the seismometer down, in order to obtain sensitive seismic readings of Mars’ surface without interference from the lander's main body.
Unlike previous landers, whose main body was a spherical pressure vessel containing the electronics, the Soviet space program now had access to electronic equipment capable of operating in a vacuum. This would enable the lander to function in Mars' thin atmosphere without resorting to a pressure vessel, so the spherical body was dropped, enabling a flat "instrument deck" to be installed on top of an octagonal bus, carrying much more scientific equipment than Mars 3 thanks to the greater internal volume and smaller electronics. Instruments included a drill and scoop to collect surface samples for chemical analysis, a weather and atmospheric properties station mounted on an extending mast, the seismometer on Prop-M, and the usual array of cameras and spectrometers.
[A modern diagram of Mars 8/9's landing sequence, as illustrated by a user on a web discussion forum focusing on Soviet spaceflight. Image credit: KAL_9000]
Both Mars 8 and Mars 9 launched successfully for the 1981 Mars transfer window, lofted by twin N11 Gorizont rockets with Blok-D upper stages. After a thankfully uneventful cruise to the Red Planet, both orbiters successfully released their landers and entered Mars orbit, with Mars 9 trailing behind by approximately 5 days.
In order to maximize the chances of a successful landing, both landers were aimed for Hellas Planitia, the lowest-elevation region of the entire planet and consequently the region with the thickest atmosphere. It initially seemed that the Soviets would finally have a fully successful Mars mission on their hands, but these initial hopes were dashed when contact was lost with Mars 8's lander upon its touchdown. Telemetry analysis quickly determined that the airbags had failed to deploy due to a software glitch, causing the lander to break apart on impact. This would not necessarily prove fatal for Mars 9, however, as the probe’s upgraded electronics allowed for a hasty in-flight reprogramming to patch the issue.
[Mars 8 listens in vain for any signal from its failed lander (artist’s impression). Image credit: beanhowitzer]
As Mars 9’s lander approached its target, all those in Moscow could do was sit and wait. Following those few terrifying, fiery minutes of entry interface came indications of a successful retrorocket firing, airbag inflation, and finally, after several small bounces across the surface, a signal confirming the lander was safe, upright, and stable on Mars in Hellas Planitia.
Unlike the short-lived success of Mars 3, Mars 9 remained in contact with its orbiter until it slipped below the horizon, uploading its initial set of data and telemetry indicating that solar panel deployment was proceeding as expected. Upon the orbiter's return, Mars 9 resumed contact, reporting that all three solar panels had deployed successfully and that the batteries were charging.
Over the following several Martian sols, Mars 9 deployed its Prop-M rover (affectionately nicknamed Бобик, “Bobik”, a common Russian name for a small pet dog). After an initial scare where the rover became stuck in a small pile of sand, it eventually traveled its full 12 meters of cable length and activated the seismometer, enabling real-time detection of “Marsquakes”, and seismic mapping to determine the planet's inner structure in fine detail surpassing even that of the American Navigator landers.
Mars 9’s lander would remain in contact with Earth for four months following its landing, before finally succumbing to the dust covering its solar panels. The mission’s unmitigated success did its part to boost Soviet pride in a new era of planetary exploration, but more importantly for the future, it gave the Politburo further motivation to approve ambitious follow-up proposals, such as larger landers or even an independent “Marsokhod” rover.
[Mars 9 in Hellas Planitia, early 1982 (artist’s impression). Image credit: beanhowitzer]
While the Soviets found their first great success at Mars, NASA’s own mission trailed behind by two months.
Unlike the earlier Navigator probes, which had entered orbit first before releasing their landers, Pioneer Mars’ landing element detached from its orbiter well before orbital insertion, still well over a million kilometers from the planet. After lander separation, Pioneer Mars Orbiter adjusted its own trajectory to avoid impacting Mars while the lander within its aeroshell carried on. Despite its faster entry, the Pioneer Mars Lander fared just as well as its two predecessors, the first Mars landing in history to use a flight-proven design like this. Following the searing heat and shocking deceleration of the initial entry phase, the lander deployed its parachute, separated from its aeroshell, and ignited its retrorockets. At the end of this “7 minutes of terror”, the Pioneer Mars Lander safely touched down in the eastern edge of Isidis Planitia.
Following safe confirmation of touchdown and initial surface activation, the first images were transmitted home to Earth. The lander was found to be sitting on a light slope amongst a diffuse rubble field of suspected crater ejecta. This site would prove to be an incredible gain in NASA’s search for signs of past Martian water, with deposits of iron hematite and magnesium carbonate salt pointing strongly towards the Isidis region having been significantly affected by water, perhaps as the edge of a theorized vast Martian sea spanning the northern hemisphere.
[Pioneer Mars Lander on the surface of Mars, early 1982 (artist’s impression). Image credit: beanhowitzer]
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Pioneer Mars Lander would deploy its passenger, the Small Rover Experiment - now dubbed Marie Curie after a nationwide essay competition from American schoolchildren - on the third sol of the mission. Despite minor difficulties encountered in navigating some of the rougher patches of rubble, Marie Curie made its way across the surface of Mars and investigated several large rocks around the site, corroborating with its X-ray spectrometer the findings of the lander’s on-board instruments.
In orbit, Pioneer Mars Orbiter’s results would be just as incredible as those found on the ground, if not more. The spacecraft would, in time, produce readings which indicated widespread subsurface ice deposits across much of Mars’ northern and southern hemispheres, far more accessible than previously thought. Combined with the lander’s discovery of hematite and magnesium salts, Pioneer Mars essentially closed the case on whether or not Mars ever had widespread seas of liquid water in its distant past. The key questions for missions future, be they the upcoming Mars Rovers or otherwise, were clear:
1. What happened to Mars to turn it from a relatively wet, warm world like Earth to the cold, arid wasteland of today?
2. Were Mars’ ancient seas stable and long-lasting enough to be habitable for life?
[Marie Curie investigates hematite and magnesium-rich rocks in Isidis Planitia, as captured by Pioneer Mars Lander’s television camera. Image credit: beanhowitzer]
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KAL's notes for Chapter 2, Interlude 2A:
-I know my earlier image teaser showed Skylab for "up next". Rest assured, we'll be covering that in the next proper Part.
-Pioneer Mars' extremely short development time is mainly due to it being built from at least 70% leftover Navigator (ITTL Viking) hardware.
-Interlude 2B will be covering Grand Tour and Adventure's encounters with Saturn, and should be coming up later in the week.
-I know my earlier image teaser showed Skylab for "up next". Rest assured, we'll be covering that in the next proper Part.
-Pioneer Mars' extremely short development time is mainly due to it being built from at least 70% leftover Navigator (ITTL Viking) hardware.
-Interlude 2B will be covering Grand Tour and Adventure's encounters with Saturn, and should be coming up later in the week.
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Thank you all for reading, and thank you to KAL for an incredible Interlude covering Mars in the early 80s! Coming Soon(ish), we'll be seeing Interlude 2B cover some probe operations further out in the solar system. Also, MASSIVE thank you to beanhowitzer for the stunning probe imagery. Building a Viking-alike without proper Viking parts in KSP is one heck of a feat.
(Sneaky ninja edit, I also wanted to apologize for the long gaps between updates - 5-day-work week and extended summer hours not to mention chronic illness on my end has slowed my contribution to the TL significantly, but we're still chugging along!)
(Sneaky ninja edit, I also wanted to apologize for the long gaps between updates - 5-day-work week and extended summer hours not to mention chronic illness on my end has slowed my contribution to the TL significantly, but we're still chugging along!)
Chapter 2, Interlude 2B: Лед (Ice)
Small Steps, Giant Leaps - Chapter 2, Interlude 2B: Лед (Ice)
In January of 1980, the Soviet Academy of Sciences came to their American counterparts at NASA/JPL with grim news. Приключение-1 - Adventure 1, one half of the USSR’s entire Outer Solar System program, was in trouble. Though the heroic efforts of Soviet mission controllers had kept the spacecraft limping along following the unexplained radiation damage encountered at Jupiter, several of Adventure 1’s systems came out of the ordeal permanently damaged. Most importantly, a series of short circuits in its communications system significantly reduced the probe’s transmission power and bandwidth; even with the extensive upgrades made by both the Americans and the Soviets to their respective deep space communication networks, Adventure 1 would be unable to communicate with Earth very far beyond Saturn.
With one spacecraft hobbled and its planned mission to the Ice Giants precluded, the Soviets turned to its healthier twin - Adventure 2, originally destined for Pluto, would instead be redirected towards Uranus and Neptune, judged to be more scientifically-valuable targets. This would leave NASA’s Grand Tour 2 to travel the journey to Pluto alone, encountering the lonely little planet (and its suspected moon, first detected in 1978 and provisionally-designated “S/1978 P1”) in 1986.[1]
By July of 1980, both NASA and the Soviets had worked out their respective flyby plans for Saturn. Leading the pack once again would be Grand Tour 1, aimed for a close flyby of Saturn’s enigmatic largest moon Titan, after which it would be flung out of the ecliptic and its planetary mission would end - this particular element of the mission being planned from the start, with Titan - and specifically the moon’s thick atmosphere - being one of the highest-priority targets of the entire project in the first place.
Following behind Grand Tour 1 would be the USSR’s Adventure 2; originally launched on a trajectory similar to that of Grand Tour 1 & 2 in service of its original Pluto target, the new path to the Ice Giants would result in one of the more interesting trajectories in spaceflight history. In order to completely switch “tracks” from Pluto to Uranus without prohibitive fuel expenditures, Adventure 2 would come as close to Saturn’s atmosphere as Soviet mission planners dared, passing between the planet itself and the rings in an extreme gravity assist maneuver nicknamed the “handbrake turn”.[2]
Next would come Grand Tour 2, flying a slightly more “normal” trajectory than its two predecessors. Unfortunately, in service of a Pluto flyby, Grand Tour 2 would not make any significantly close approach to any of Saturn’s 7 largest moons, and would mostly perform distant imaging as opportunities arose.
Limping in at 4th place, Adventure 1 would be redirected for a close Titan flyby similar to that of Grand Tour 1, to maximize science gain in the Saturn system.
Finally, rounding out the international fleet was Grand Tour 3, making the closest approach to Saturn and its rings of the three American probes on its way to the Ice Giants. The probe would, therefore, focus on the planet’s atmosphere and the inner moons and rings, attempting to expand on the fleeting glimpses caught by Pioneer 11.
In November 1980, Grand Tour 1 closed in on Saturn. With a comparatively-modern suite of cameras and instruments, the probe quickly exceeded the fuzzy snapshots and radiation-fried science results gathered by Pioneer 11, revealing an intricate, complex, and beautiful system of worlds dancing around the Solar System’s second-largest planet. The first notable discoveries concerned Saturn’s magnetic field, found to be relatively more sedate when compared with the raging intensity of Jupiter and comparable in strength to that of the Earth; should any astronauts venture to the Gas Giants in the distant future, they would no doubt find the radiation environment around Saturn far more tolerable than that of its larger sibling. Like Jupiter, Saturn was found to - as expected - be composed primarily of hydrogen and helium, the two primordial gasses making up most of the universe. Unlike Jupiter or the Sun, however, Saturn was found to have a comparative scarcity of helium; fascinating, but ultimately something which could only be speculated on in the limited time afforded by the flybys.
[Saturn with its moons Tethys and Dione as imaged by Grand Tour 1. Image credit: NASA/JPL]
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Saturn’s most famous feature, without any doubt, is its large and complex ring system. Although both Jupiter and Uranus were discovered to have faint rings in 1977, Saturn’s rings are by far the largest and brightest of any body in the Solar System, easily visible from Earth in even the smallest of telescopes. Up close, Grand Tour 1 was able to observe complex structures in the rings such as “spokes” of particles, complex ‘braiding’ in the twisted F ring, and innumerable gaps between the rings seemingly empty of debris due to gravitational resonances with the planet’s moons. Grand Tour 1 was even responsible for the discovery of a ring of its own, the faint G ring.[3] Careful analysis of the spacecraft’s trajectory also allowed the total mass of Saturn’s rings to be determined by measuring slight gravitational perturbations; the result, approximately the same mass as that of an icy moon like Mimas or Enceladus, pointed towards the rings’ likely origin and the most commonly-accepted theory today, that Saturn’s rings were formed by the gravitational breakup of a moon which strayed too close to the planet.
Saturn’s moons revealed themselves to be as equally mysterious as their Jovian counterparts. Although none of the moons Grand Tour 1 imaged would provide the same stunning surprise as Io, they once again upended the traditional view of outer Solar System moons as geologically dead worlds. Unlike Io or Europa, the icy moons were covered in significant amounts of craters, but crater counting and features like rift valleys and strange “wispy” terrain on Tethys and Dione pointed to geologically young surfaces, refreshed perhaps as recently as a few hundred million years ago.
[Rhea, Dione, and Tethys, the three "sister" moons of Saturn, all similar in size and with similar cratered surfaces, pictured by Grand Tour 1 in color (image not to scale). Image credit: NASA/JPL]
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For all that Saturn’s inner moons were fascinatingly varied little worlds warranting further study, Grand Tour 1’s mission at Saturn was utterly dominated by the probe’s final flyby, the mysterious and mighty largest of Saturn’s family of moons: Titan.
The second-largest moon in the Solar System and the only moon in the Solar System possessing a substantial atmosphere, Titan is - befitting of its name - a truly colossal world, making up over 96% of the mass in Saturn’s extensive system of moons and rings. Grand Tour 1’s priority target proved something of an enigma, and to some extent a disappointment; frustratingly, the first images received from the flyby revealed the moon to be entirely shrouded in a thick, opaque orange haze, determined by the probe’s spectrometers to be composed mainly of hydrocarbon molecules called tholins, formed when sunlight reacts with carbon-containing molecules. This haze meant that the surface of Titan was completely obscured, appearing merely as a uniform dark orange sphere and obscuring any potential surface views.
While visual imaging at Titan was a bust, Grand Tour 1 was still able to determine the moon’s atmospheric composition and pressure (mostly nitrogen with traces of hydrogen and methane, slightly denser than Earth’s at sea level) as well as temperature, an environment found capable of supporting stable bodies of liquid methane on the surface; the resulting theories about methane lakes or an entire methane cycle analogous to Earth’s own water cycle would, of course, have to remain theories for the time being given the available instruments aboard the five probes encountering Saturn.
[Titan's all-obscuring haze from afar (left) and close up (right) by Grand Tour 1. Image credit: NASA/JPL]
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Following hot on Grand Tour 1’s heels, Grand Tour 2 sped through the Saturn system hardly a week later on a trajectory which, from there, would fling the spacecraft onwards towards far lonely Pluto in mid-1986. In order to achieve this Pluto encounter, Grand Tour 2 unfortunately was unable to fly near any major moons and collected only distant imagery; it was, however, able to image several moons Grand Tour 1 could not - most notably Iapetus, found to bear a strange two-tone dark and light surface. It also gathered data on Saturn’s rings using its photopolarimeter (a light-sensing device which had failed on Grand Tour 1 following the Jupiter encounter) which, combined with data from its Soviet counterpart, gave significant amounts of high-quality imagery of the structure of Saturn’s rings and its small ‘shepherd’ moons.
[“spoke” structures in Saturn’s rings imaged by Grand Tour 2. Image credit: NASA/JPL]
Following more distantly behind the first two of its American counterparts in the early months of 1981, Adventure 2 would be next. Similar to Grand Tour 2, Adventure 2’s trajectory disallowed any close encounters of Saturn’s moons, and the probe spent its initial approach to Saturn primarily imaging the planet and its rings. By far the most nerve-wracking part of the spacecraft’s encounter would be the dive between the planet and those rings, the so-called “handbrake turn” maneuver to divert Adventure 2 towards the Ice Giants. Although the American Pioneer 11, true to its name, had proven that crossing the ring plane was safe, no spacecraft had ever attempted to pass between rings and planet in such a daring maneuver before. Even more stressfully, this maneuver would also briefly put Adventure 2 behind Saturn, and thus completely out of contact with Earth for a period of several hours.
After much wringing of hands in Moscow and Pasadena alike throughout the momentary radio blackout, Adventure 2 reported back from its passage behind Saturn with nothing concerning save for an (expected) spike in its micrometeoroid detectors during the ring plane crossing, having made the jump safely onto its new track towards Uranus, set to reach its next target in 1986.
[Saturn with several of its moons, imaged by Adventure 2. Image credit: Soviet Academy of Sciences]
[Adventure 2 images Saturn’s rings while crossing into the planet’s night side during the “handbrake turn” maneuver. Image credit: Soviet Academy of Sciences]
Slotted between the two Soviet probes, Grand Tour 3 followed in August of 1981. The data it was set to gather would, it was hoped, complement that of its two sisters and round out NASA’s comprehensive analysis of the Saturn system. This was the case for the duration of its inbound trajectory, but the same could not be said for the latter outbound half; shortly following closest approach to Saturn, Grand Tour 3’s imaging platform locked up, and remained stuck, staring off into the black of space, for several agonizing hours before a temporary workaround was implemented. This was later found to be caused by a (thankfully temporary) lack of lubricant on the actuators moving the platform due to the many repeated fast movements programmed for Saturn flyby imaging; a “speed limit” would be set on the imaging platform’s slew rate for the remainder of its life to prevent future issues.[4]
[Saturn’s other three spheroid moons (left to right, not to scale): Enceladus, notable for its smooth surface; Mimas, notable for its resemblance to “Star Killer Station” from 1977’s blockbuster film The Star Wars; and Iapetus, notable for its strange two-tone appearance. Image credit: NASA/JPL]
Limping in at last place, Adventure 1 finally reached Saturn in late September of 1981. The probe, with instruments irreparably damaged and its communications bandwidth reduced, would return a limited amount of data when compared with its twin and American peers. Soviet scientists, nonetheless, endeavored to make the most of Adventure 1’s flyby of Saturn. The probe was able to capture additional imagery of several of the major moons, and in one final “grand finale”, flew by Titan at close range, even capturing atmospheric occultation data as it passed behind the moon relative to the Sun.
[Adventure 1 images of (clockwise from top left) Dione, Rhea, Titan, and Tethys. Image credit: Soviet Academy of Sciences]
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Following a successful flyby of Saturn, mission controllers in Moscow spent several months coaxing Adventure 1’s battered communications system to downlink its Saturn encounter data, the communications link becoming progressively weaker as time went on. By early 1982, with all the Saturn data downloaded and bandwidth degraded to a mere 8 bits per second, one final command was sent to the probe: to power off all of its systems. With this command was bundled one final, brief message from Earth to the dying spacecraft: a pair of phrases translating to “Farewell” and “Thank you”.[5]
With Saturn in the proverbial rear-view mirror, planetary scientists back on Earth were left with a wealth of data to sift through, a task which would take not just years, but decades; a career-defining wealth of information. From here, the paths would diverge; two spacecraft on towards Uranus and Neptune by the decade’s end, one off to cold, lonely little Pluto on the edge of the Solar System; and two out of the ecliptic entirely, one awake and one derelict, hurtling through the infinite void as eternal emissaries of humanity.[6]
[Adventure 2 prepares to dive between Saturn and its rings (artist’s impression). Image credit: Talv/Jess]
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Thank you for reading! MASSIVE shout-out to @Exo for making all of our Soviet probe imagery, Jess as always for the spacecraft renders, and @KAL_9000 for doing the heavy lifting getting this one to the finish line.
Apologies, again, for the persistent delays - I’m going to be posting a proper “State of the Timeline” update about where everything sits right now with regards to SSGL, probably in a few days or so when I’ve got the time to sit down and write it.
Callisto’s notes for Chapter 2, Interlude 2B:
- Yes, Star Wars is slightly different in this timeline just for the hell of it. We might have a post about it at some point just for fun.
[1]: Pluto’s largest moon and binary partner was not officially named until 1985 IOTL, so as of the early 80s it still doesn’t really have a proper name.
[2]: Don’t ask how this works. It just does. Our source is KSP.
[3]: This is as OTL with Voyager 1.
[4]: This happened OTL with Voyager 2, and was probably one of the biggest scares of the mission to that point.
[5]: Mission controllers do this kind of thing all the time it seems, so I don’t think this is out of character or weird to include. No, I do not know the Russian words for these. Yes, I am absolutely crying about a fictional space probe.
[6]: Based on rough trajectory, Adventure 1 would likely have crossed the heliopause some time in the late 2010s.