With the return of the first images from Mars and the discovery of the closer location of FRA-1, NASA as well as the Soviet Union moved to find out what exactly FRA-1 was.
In the Soviet Union the program of Mars explorations continued as it was, as the missions of the Mars M-73 program had already been planned in early 1969. Four probes were launched, two of them designed as pure orbiters, while the other two would carry landers to Mars.
Sadly the Mars M-73 was plagued by failures that would later be attributed to the use of helium in pre flight tests, resulting in the degradation of the failed probes computers. For Mars 4 the retro rockets failed, resulting in just a flyby of Mars with a swath of images from the surface. Mars 5 was able to enter an orbit, but after a few days of operation, failed. Mars 6, carrying one of the landers, reached the planet without problems, but the lander itself was lost during descent, as the retro rockets meant to slow it down failed. The lander of Mars 7 detached prematurely, missing the planet.
Mishin was able to find the people responsible for the failure of the entire Mars M-73 program in the workers and engineers of the microchip factory that had produced the faulty chips of the probes computers. With the new economic policies in place, they were replaced by more competent people, while the original 423 workers of the factory got a second chance by working in a siberian gulag for the remainder of their lives.
Mishin also stopped planning on further Mars probes with the goal to develop a new, more advanced probe and lander for Mars.
Meanwhile NASA was working on the Voyager Program and while the Jet Propulsion Laboratories were ready to build another set of Mariner probes with better cameras, NASA decided that they’d rather wait until the Voyager probes and landers were ready.
Originally the Voyager program had called for the use of a Saturn V as carrier vehicle to send two of the probes to Mars, but most of the planning was done before Congress enacted the Space Finance Act. During the time the remaining three Saturn V had been reserved for launching Skylab and any following space station and as such the JPL and the Langley Research Center, developing the final version of the Voyager probes and landers, was stuck will less capable launch vehicles.
Finally settling on the Titan III-E launcher, the Voyager probes were more limited in weight and as such in capability.
To finalize the plans for the orbiters relatively fast, it was decided to use the preliminary designs for the potential Mariner 10 and 11 Mars probes as a base for the Voyager Orbiters.
The landers themselves were developed on top of the Surveyor series of Lunar landers, adapted for the atmospheric situation on Mars and would be housed in an aeroshell with heatshield for the first part of the journey through the Mars atmosphere, before they would use parachutes to decelerate and finally land with rocket propulsion. A radioisotope thermoelectric generator was used as power supply, while two TV cameras with variable optics would take images of the surroundings. An experiment to search for life on Mars was also integrated, but some of the engineers hoped that it would be possible to see any possible life.
The greatest challenge for the JPL however was to design an autonomous control system that would allow the Voyager landers to touch down relatively close to the source of the radio and radar signals. For the development of that system, IBM was selected as external contractor, as they were also responsible for the Instrumentation Unit of the Saturn V.
Both designs were finalized in early 1973 and production of two orbiters and landers began, a month before the Space Finance Act was enacted and NASA kept the Voyager program going, while the JPL began work on a more capable lander and orbiter for the newly created Viking program.
Voyager 1 and Voyager 2 were launched on August 20 and September 9 1975, reaching the Red Planet on June 19 and August 7 1976. The arrival of both probes triggered the same radio and radar activity as before, though the duration was reduced.
Both probes sent much more detailed images back to Earth, discovering a feature that looked very much like a human face as well as confirming the unnatural lines of FRA-1.
Voyager 1 detached its lander on July 20th, and it was the second man made object that managed to softly land on Mars. The Radio Beacon Assisted Descent System of IBM worked as planned and Voyager touched down within visual distance of the radio source of FRA-1.
Voyager 1 remained active and first took a panorama image with its two TV cameras, showing a quarter of the horizon with something that might be called a ‘skyline’. Over the next few days the probe used the zoom feature of the cameras to take detailed images of the ‘skyline’. The structures visible were too far away for the cameras however, but it was possible to identify them as being artificial in origin.
Voyager 2 landed on Mars on September 3, managing a soft landing. The first panorama image showed half of the horizon taken up by strange structures. More detailed information was delivered by the cameras, they were clearly constructions, all formed in a way to try and blend in with the environment they were built in and by that, difficult to spot. That they were detected from orbit by Mariner 6 was attributed to the bad damage due to extensive wear and tear of Mars’ unstoppable geological forces.
A radio subsystem of the probe was able to connect to Voyager 1 and with the help of the Voyager orbiters it was possible to triangulate the position of both probes, which had landed within a distance of ten kilometers of each other.
Once the position of both probes was known, the same radio subsystems were used to triangulate the position of the FRA-1 radio source, finding that Voyager 2 had landed only two kilometers away from it. The cameras of the Voyager 2 lander photographed the FRA-1 radio source. It was clearly artificial, with gleaming metal visible that had been polished to a silver shine by the collaboration of dust and on Mars.
With the success of the NASA Voyager program, the Soviet Union needed a success themselves.
Ever since the failure of Mars M-73, NPO Energia had developed a new series of probes for Mars, the Mars 5M series. Heavier than the previous Mars 4MV series, the probes needed the N-1F with an SR upper stage to be boosted into a transfer orbit to Mars. Each of the two probes of the Mars M-77 project contained an orbiter with powerful sensors and a single lander, which had been designed and built from the ground up.
Mars 8 and 9 launched on October 10, 1977, and following an eventless transfer, entered Mars orbit June 23, 1978. Having learned from the failure of the Mars landers of Mars M-71, the orbiters first mapped much of the surface of Mars, with a better image quality than the Voyager probes two years earlier.
Both landers detached from the orbiters on August 1. The lander of Mars 8, which was nicknamed Misha, encountered no problems during descent and manages to use a similar radio beacon following system to land near FRA-1, ten kilometers distant to Voyager 1 and twelve from Voyager 2. Over the next four years Misha took a large amount of high quality images during its active period, allowing the Soviet Union to make their own theories about Honore City.
The Mars 9 lander did not have as much luck as Misha. During the last part of the descent with rocket power, just after detaching from the parachute, contact was lost.
The descent of Mars 8 was also captured on an image by Voyager 1.
The success of the Voyager probes was motivation for the teams at JPL and Langley during the development of the more capable Viking probes. The closeness of the structures tempted the engineers and scientists at Langley, responsible for the Viking landers, just as they had been for the Voyager landers, and built a robotic vehicle to traverse the martian surface and take a closer look at the ruins of Honore City.
This time around, NASA had the last of the original Saturn V available for the launch of the two Viking probes on November 28, 1979 to send out both planned probes, Viking 1 and 2. The launch itself happened without any problems, as did the injection into a Mars transfer orbit. Both probes separated from the transfer stage with Viking 1 poised to arrive before Viking 2.
On January 30, 1980 however Viking 1 ceased its transmissions and the JPL was unable to reestablish contact forcing the team to write off the probe as lost. Viking 2 continued on its way, and did its injection burn for a martian orbit on August 13, 1980.
The more powerful cameras of the Viking 2 orbiter took images of an even higher resolution than those of the Voyager orbiter and even showed that the Mars Face was simply a trick of light and shadows. The better images also showed a distinct structure of roads and open areas in the area of FRA-1, reinforcing the general consensus of it being a city or perhaps just a large base of some sort.
On September 2, Viking 2 detached its lander and it softly touched down three kilometer away from Voyager 2 and a little further out from FRA-1. Langley took control of the rover on the Viking 2 lander on September 15, giving it the name Pathfinder. The construction of Pathfinder made the rover extremely slow, to avoid running into obstacles and making it necessary to plan the traverse of the rover well in advance, using the images of the rovers camera.
The rover was not only designed to drive to FRA-1 and take images, but also to do sampling on the way, using a simple robot arm with an attached camera to make closer images of rocks and the ground.
Its first job was to drive up to Voyager 2, reaching it three months later, after starting out from Viking 2. The images of both manmade probes taking images of each other became as iconic as the Apollo 8 image ‘Earthrise’.
January 12, 1981 was the date when Pathfinder reached FRA-1, having taken images of the structure over the entire trip from Voyager 2, showing the strong erosion from the Martian environment in detail.
The following four weeks were used to drive the rover around the structure, taking images all the way, and discovering the wreckage of the Soviet Mars 9 lander laying next to FRA-1. Apparently the Soviet probe had impacted into the FRA-1 structure during descent.
Early March, Pathfinder was finally directed towards Honore City, four kilometers away. Regrettably Pathfinder would never reach the outskirts of Honore City as two of its four wheels failed within the first week of April, stranding the rover just one kilometer away.