48 years ago, the Viking 1 spacecraft landed on Mars
There are now several devices on the surface and orbit of Mars that have studied it quite well. But half a century ago, the Red Planet was full of mysteries. Before the start of flights to Mars, NASA even continued to believe that there were canals on the surface of the planet! (I don’t have proof at hand, so I’ll refer those interested to the articles of the historian of cosmonautics Pavel Shubin). The planet’s mystery was added by the frequent failures of the first missions launched by the USSR and the USA. And if the Soviet device “Mars-3” was the first to land on Mars, then the probe “Viking-1” Instead of the planned 90 days, he worked on the Red Planet for six whole years!
What did the hardy American Viking learn in the inhospitable conditions of cold Mars? Today I, Alexander Baulin, leading manager of MTS Digital and a fan of science and technology, will tell you. Welcome under the cut!
Soft landing on Mars
Preamble. I know very well about the Soviet apparatus “Mars-3”, which managed to make a soft landing and transmit from the surface of Mars for 12 seconds. Unfortunately, it was not possible to extract useful data from that transmission. The orbiter of the same mission helped in studying Mars, but the laurels for transmitting from the surface of Mars fairly went to the probe from the USA.
Viking 1 was launched from Earth in 1975 and entered orbit around Mars on June 19, 1976. The mission had an orbiter and a lander, plus a backup, Viking 2. With a history of failed missions in mind, NASA sent two spacecraft to Mars to increase the odds of success.
The following were installed on the orbital vehicle:
long-focus television camera for taking pictures (resolution 40 m when shooting from an altitude of 1,500 km);
wide-angle television camera for taking pictures;
an infrared spectrometer to map water vapor in the Martian atmosphere;
infrared radiometer for creating a heat map of the planet.
The relay transmitted data from the surface of Mars to Earth. The throughput was only 10 Kbps – think about that the next time you have a slow 4K video.
On July 20, 1976, the descent module separated from the orbiter and a few hours later successfully landed on the surface of Mars. The design protected the station from dust, radiation and temperature fluctuations. Scientists made sure that terrestrial microorganisms did not get to Mars. However, the processing methods of those years are now being questioned. Perhaps some extremophile bacteria could have survived and are now populating Mars.
After landing, Earth scientists received the first images of the surface of Mars – one can only imagine what an impression it made on everyone. Even now, panoramas of the Red Planet from Curiosity and Perseverance cause admiration, but back then these were the first photos of a new world.
IMHO, without preparation it can be confused with the first photos of Venus, although the conditions on Mars are not so destructive for the devices.
How the Mars station was equipped
Scientific equipment automatic Martian station on the surface:
two television cameras with all-round visibility;
instruments for meteorological research that measure pressure, temperature, wind speed and direction at the surface;
seismometer;
a combined gas chromatograph with a mass spectrometer for identifying organic substances contained in soil samples by molecular weight, as well as for analyzing atmospheric gas samples;
X-ray fluorescence spectrometer for identification of inorganic substances contained in soil samples;
an installation for searching for life in soil samples based on such signs as photosynthesis, metabolism and gas exchange.
The module was controlled by the Guidance Control and Sequencing Computer (GCSC), which used two Honeywell HDC 402 processors. The memory was a whopping 36 KB, which was quite good for that time. Another feature was the lack of an assembler for the landing module computer. The developers had to write patches in eight-bit code, taking into account changes in the configuration and changing addressing (faulty memory cells were constantly excluded from operation).
The entire system was powered by two RTGs with a total power of 70 W. Each weighed 13.6 kilograms. Several more nickel-cadmium batteries ensured power stability during peak loads.
What happened next?
The second station also reached its destination without problems and began work. According to the plan, both Vikings were supposed to collect research data, send images of the surface of Mars to Earth, and conduct research.
The project's engineers managed to develop devices with a large margin of safety – after all, they are from the same school as the designers who made the Voyagers that are still working. The following rovers also set records – the most striking of them was Opportunity. It have worked 15 years and traveled 45 kilometers. This is a lot for the rover: each time it travels only a small section of the path, then takes a picture of the picture in front of it, sends it to Earth and waits for a return signal. Information can travel up to 48 minutes there and back. During periods when the Earth hides behind the Sun, the rover stands still, waiting for the next signal.
The first few years of Viking-1 functioned without failures. But then the capacity of three of the four batteries dropped sharply. Engineers began to think about how to solve the problem. In 1982, they managed to deeply discharge the batteries, and their capacity was restored (just don’t do this with your smartphones — modern batteries are lithium, and deep discharge is contraindicated for them). Unfortunately, four months later, the failure occurred again.
Then the scientists decided that they needed to reduce the number of charge-discharge cycles and repeat the deep discharge of the batteries. The developers wrote a code to control the battery and divided it into fragments – the Viking-1 computer simply did not have room for the entire program.
But the constantly changing addressing made itself felt. An error occurred: the code was written to the area responsible for the communication system, in particular for the positioning of the antennas. After that, the device stopped responding to commands, and the connection with it was lost. Most likely, the program redirected the antennas to the wrong position, and Viking-1 continued to work, sending data to nowhere. It is also possible that the automatic station's computer simply switched off due to erroneous commands.
Engineers continued to try to bring Viking 1 back to life, but to no avail.
Results
As a result, Viking 1 became the first long-lived Mars rover — it worked for 2,245 sols, or six Earth years. Its brother, Viking 2, failed a couple of years earlier, in 1980, also due to a problem with its batteries. The devices produced the first high-resolution color photos of the surface of Mars. The composition of the soil was determined: silicon, iron, calcium, aluminum, and even titanium were found in it. Experiments were conducted to search for life.
Incidentally, life on Mars is not so clear-cut. At first there were signs of life, then there were none. The results of the first experiments were considered an artifact, although Dirk Schulze-Makuch, an astrobiologist from the Technical University of Berlin, suggests that during the experiments, the Vikings simply killed local bacteria with too much water. Unfortunately, life on Mars was not discovered by subsequent missions, which Viking 1 paved the way for.
And here's what I talked about in previous posts:
