Back in the 1990s, there was a veritable flood of new information about the once secretive Soviet space program including details of their early failed planetary probes whose missions turned out to be far more ambitious than anything the United States actually flew at the time. The earliest of those failed missions was a pair of Mars probes the Soviet Union attempted to launch toward Mars in October 1960 (see “The First Mars Mission Attempts“). Had they been successful instead, they would have been the first probes to reach another planet. Aside from giving the Soviet Union the propaganda value of yet another space first, what if these probes successfully completed their mission to Mars? What would they have potentially discovered? In 1997 I created a simulated image (which I have since used as an illustration in presentations and articles for years) to start answering that very question.
Development work on the Soviet Union’s first Mars probe, designated Object 1M, began in 1959 at OKB-1 which, under the direction of Chief Designer Sergei Korolev, had been responsible for all the Soviet Union’s early satellites, Moon probes as well as the development of the Vostok manned spacecraft up to that point in time. Korolev’s Mars project received official government approval on December 10, 1959 for the launch of a pair of 1M probes using the new 8K78 rocket (later known by the common name “Molniya” which was also developed at OKB-1) in September 1960. The encounters with Mars were scheduled for May 13 and 15, 1961 or about a month after the successful flight of Vostok 1 – the first time a human reached space.
By early 1960 the design of the 1M probe was completed and its instruments selected. The 1M probe was a cylinder 105 centimeters in diameter with a roughly hemispherical cap giving it a height of around two meters and a mass in excess of 650 kilograms. The interior was pressurized and the temperature controlled to provide a laboratory-like environment for the internal equipment. A pair of fixed solar panels with a total area of two square meters was used to recharge batteries that supplied power to the probe’s equipment. It was also fitted with a KDU-414 engine generating two kilonewtons of thrust. The engine and its propellant tanks were mounted beneath the hemispherical cap at the top of the probe and were to be used for midcourse maneuvers to ensure the 1M flew between 5,000 and 30,000 kilometers from Mars. The probe’s Mars encounter data would be transmitted back to Earth via an umbrella-like directional antenna with a diameter of 2.33 meters while other data gathered during the long cruise to Mars were to be transmitted via a omnidirectional antenna.
The 1M carried instruments to characterize magnetic fields, cosmic rays, radiation, the solar wind, and micrometeorites. It also carried an infrared spectrometer designed to study what were called “Sinton bands” named after American astronomer William M. Sinton of the Lowell Observatory. He had found a trio of absorption features near a wavelength of 3.5 microns in the infrared during the late 1950s that were thought by some to be potential evidence of plant life on Mars (see “A Cautionary Tale of Extraterrestrial Chlorophyll“). Rounding out the original 1M instrument suite was a camera similar to the one carried by Luna 3, which photographed the far side of the Moon in October 1959. This imaging system used photographic film that was developed and scanned electronically on board after the photographs were taken during the flyby. The camera employed a 750 mm focal length lens to create an image 50 by 150 mm in size. Ideally the acquired image would include a view of a Martian polar cap and it was expected to reveal features as small as 3 to 6 kilometers.
Unfortunately the camera package never had a chance to fly. Electrical interference with other systems discovered during the integration of the camera with 1M caused major issues. In the end, delays in the delivery of the 1M probes and the certification of the new 8K78 rocket pushed the launch beyond its ideal late September launch date. Needing to lighten the pair of 1M probes so they could reach Mars so late in the launch window, the infrared spectrometer and the troublesome camera were stripped from the 1M and only ten kilograms of instruments were carried. Unfortunately, both Mars probes were lost due to launch vehicle failures on October 10 and 14, 1960. The opportunity not only to reach Mars first but acquire the first close up images of its surface had been lost. The next chance to do so would have to wait for the improved 2MV series of probes to be launched in the fall of 1962.
Simulated 1M Mars Image
Despite the loss of the pair of 1M probes, I had wondered what they might have found if they had survived launch and successfully made it to Mars to execute their missions. Part of what I do for a living involves simulating what proposed instruments will observe given information about the instrument’s performance and the properties of the intended target of observation so I had the tools and knowledge needed to simulate a 1M image of Mars. In an idle moment in the spring of 1997, I finally had the raw material at my disposal to attempt a simulation.
On March 20, 1997, NASA released the latest images of Mars acquired by the Hubble Space Telescope (HST) just ten days earlier. With a pixel footprint of 22 km, these were the best images of Mars yet acquired by HST. The resolution of these images (which would be in the 44 to 66+ km range, depending on how you wish to define “resolution”) was too coarse to simulate the hoped for 3 to 6 km resolution of the 1M which would presumably be acquired at the lower end of the expected 5,000 to 30,000 km range of flyby distances. But the resolution of the HST image was within a factor of two or three of what a more distant flyby might see – maybe in the 15 to 30 km range. Given the crude nature of interplanetary navigation this early in the Space Age, I figured a more distant flyby was more probable than the hoped for closer flyby. In addition, the HST images of Mars were acquired when the solar longitude was about 88° corresponding to the end of spring in the Martian northern hemisphere. The pair of 1M probes were to encounter Mars on May 13 and 15, 1961 when the solar longitude was about 75° corresponding to late spring or about a month earlier in the season than the HST image. I figured that this was close enough for a reasonable simulation of what 1M might have seen.
I took one of the published HST 24-bit color images, namely STScI-PRC1997-09a, and separated out its red channel. It had been known for decades that red-filtered images of Mars helped suppress atmospheric scattering (which is strongest in the blue end of the spectrum) and improve the contrast of surface features. It would be reasonable to assume that the 1M camera package had been fitted with a red filter to do the same. I then resampled the HST image to a scale of 6 km/pixel and added some white noise amounting to an average of 10% of the image pixel brightness values. Any real image from 1M would contain noise and this seemed like a good value to use. It was certainly better than the noise level in individual images of the Moon acquired by Luna 3. Next I cropped the image to a size of 1000 by 333 pixels to simulate the 150 by 50 mm image acquired at a range of 30,000 km using a 750 mm lens. This yielded an image that covered about 6,000 by 2,000 km and included the north polar cap as seen in the top panel of the illustration below.
To get a better feel for the improvement of a 1M image over contemporary Earth-based observations of Mars, I then created a simulated telescopic image of Mars. Again, I took the red-channel HST image and convolved it with a Gaussian filter whose size was chosen to simulate arc-second quality seeing of Mars when it was at its closest distance of 56 million km from the Earth. I then cropped the resulting image to match the simulated 1M view as shown in the bottom panel of the illustration above.
Judged by today’s standards, the quality of this simulated 1M image is relatively poor. The high Sun conditions (resulting in subdued shadows) and coarse resolution combine so that the Martian craters we now know exist are not unambiguously evident. Only the albedo patterns on the surface are clearly visible in the image. Higher resolution images acquired at closer range under more oblique light conditions would be needed to reveal craters.
Judged by the standards of the day as typified by the simulated Earth-based telescopic view, however, the improvement in image quality would have been significant. While craters might not have been clearly visible, the quality was sufficient to resolve more clearly the albedo patterns on the Martian surface. This image would have definitively shown no evidence for the canals of Mars that had been reported by visual observers for at least 84 years by that point in time bolstering the case that they were merely illusions. That alone would have been a major scientific finding back in 1961.
Had the infrared spectrometers on the 1M probes had their chance to take data, they also would have made a significant contribution to the study of Mars. They would have failed to detect the purported Sinton bands or indeed any spectral feature associated with organic compounds. It would be years before it was finally discovered that these bands had nothing to do with life on Mars and were in fact due to deuterated water vapor (i.e. water with one of its pair of normal hydrogen atoms replaced with a heavier isotope of deuterium) in Earth’s atmosphere.
The lack of canals visible in the 1M images and the absence of Sinton bands would have quashed hopes of there being life on Mars early on. And if by chance Moon-like craters had been unambiguously observed in the 1M images, the discovery would have further dimmed the prospects of there being life on Mars. However, history ended up unfolding differently and it would be four years before the American Mariner 4 was able to make the first close up observations of the Red Planet beginning the process of understanding the planet as we do today (see “Mariner 4 to Mars“).
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“The First Mars Mission Attempts”, Drew Ex Machina, October 10, 1015, [Post]
“A Cautionary Tale of Extraterrestrial Chlorophyll”, Drew Ex Machina, October 5, 2014 [Post]
“Mariner 4 to Mars”, Drew Ex Machina, July 14, 2015 [Post]
Wesley T. Huntress, Jr. and Mikhail Ya. Marov, Soviet Robots in the Solar System: Mission Technologies and Discoveries, Springer-Praxis, 2011
Timothy Varfolomeyev, “The Soviet Mars Programme”, Spaceflight, Vol. 35, No. 7, pp. 230-231, July 1993
“Hubble’s Sharpest Views of Mars”, News Release Number STSci-1997-09, March 20, 1997 [Press Release]