While first mapped in the 1970’s within a series of 1:5,000,000 Quadrangle maps of Mars, the map is a great example of just how far planetary imaging, especially on Mars, has advanced within the last 50 years.

Mars Makes a Mark on Many Minds

When planetary mappers think of Mars today, we think of a planet with a deeply varied geologic history, much like our own, with complex volcanic, fluvial, and tectonic systems. Mars has even become prominent enough in popular culture (thanks, Matt Damon) that most people know that Mars has large dust storms, is home to the largest known volcano in the solar system, and has ice on its’ surface.

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With this familiarity, it can be difficult to remember that only a few generations back, knowledge of Mars was much more limited. The first recorded observation of Mars from Earth was by the ancient Egyptians around 2000 BCE, and Mars was first telescopically observed by Galileo in 1610. More recently, the 20^th century brought about many fictitious accounts of Mars and its’ inhabitants. Despite their scientific inaccuracies, H.G. Wells' War of the Worlds, and the Looney Toons' Marvin the Martian helped popularize the idea of little green men, making Mars a household name.

Until the 1970’s, information from those stories tended to be the general public’s perception of Mars, due to the lack of evidence to convince anyone of the contrary. Seeing the red planet up close and personal, however, and the confirmation that we don’t have emerald-hued alien neighbors, only occurred within the last 60 years.

When the Mariner 9 spacecraft took the first orbital images of Mars in the 1970’s, scientists were in awe. Although Mariner 9 arrived at Mars during a global dust storm, the dust soon began to settle, and for the first time, planetary scientists were able to look at the red planet up close. They expected to see something that looked like the Moon – full of craters and (seemingly) not much else. To their amazement, river beds, volcanoes, erosional features, and varying surface conditions- the very things we expect to see in 2023- were observed as well. These first images from Mariner 9 began the effort to comprehensively map Mars, starting with a series of 1:5,000,000 quadrangle maps.

Martian Imagery: Then and Now

Planetary exploration has evolved over the decades, and our imaging capabilities have significantly improved. With all the advancements in imaging since the days of Mariner 9, it is impressive to compare the maps of the Shalbatana Vallis area from the 1970s and today. Considering the limitations on 1970s imagery and general lack of knowledge about martian processes (compared to how much we know today), the two maps still have many similar observed features and geologic units.

The new Shalbatana Vallis map is an example of the large scale, small area maps that are becoming more common now, as opposed to the 1:5,000,000 quadrangle maps that dominated many decades of mapping. This may be because in the 1970s, the entire surface of Mars needed to be mapped, and now after years of small scale mapping, there are few Martian quads remaining to map. Mapping focus has subsequently shifted to larger scale, smaller area mapping. Learn more about the trend towards large scale planetary mapping here.

The first USGS Geologic map of the Shalbatana Vallis region was actually a collection of four separate maps. The series of 1:5,000,000 quadrangle maps listed below were the first time this region had its geology studied by humankind, all released within the range of 1974-1979.

• USGS IMAP 894: Geologic Map of the Lunae Palus Quadrangle of Mars, 1:5M. Wilhelms, D.E. (1974)
• USGS IMAP 895: Geologic Map of the Oxia Palus Quadrangle of Mars, 1:5M. Milton, D.J. (1976)
• USGS IMAP 897: Geologic Map of the Coprates Quadrangle of Mars, 1:5M. McCauley, J.F. (1978)
• USGS IMAP 1144: Geologic Map of the Margaritifer Sinus Quadrangle of Mars, 1:5M. Saunders, R.S. (1979)

These maps all used basemap imagery from Mariner 9, which launched in 1971. Mariner 9 was the first craft to orbit another planet, and used the most advanced imaging technology available. Mariner 9’s onboard cameras (a wide and narrow angle set of television cameras which took analog data and conveniently transmitted it into film) achieved a resolution of 98 m/pixel. This was a vast improvement over the 790 m/pixel resolution captured by the previous Mariner 6 and 7 flyby imagery. The spacecraft was able to transmit over 7,000 of these images back to Earth, giving planetary scientists their first look at the red planet as more than a blurry disk in a telescope.

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Thankfully, that wasn’t the last time Mars had its picture taken. The THEMIS IR Daytime Mosaic used as the primary basemap for the new Shalbatana Vallis map has a resolution of 100 m/pixel (similar to the 98 m/pixel of Mariner 9). However, THEMIS is just one set of data that collects infrared data, which can be used to interpret geologic characteristics about the surface. Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) images are commonly used as supplemental data today and have an average resolution of 6 m/pixel. The highest resolution photos that we have are from the MRO High Resolution Imaging Science Experiment (HiRISE) camera, which has a resolution so high (up to 10 cm/pixel), you can view objects that are about the size of the table that you might be sitting at right now. The Perseverance and Curiosity rovers are also constantly sending back high resolution digital photos and video from the surface of Mars. This high resolution imagery and widespread access to the internet allows for the creation of highly detailed geologic maps that any planetary enthusiast can view from the comfort of their own home.

What’s next?

Earlier this year, the Perseverance rover finished collecting samples from the Three Forks region of Jezero Crater. These samples are now cached on the surface of Mars, waiting to be picked up and returned to Earth. When the samples are analyzed on Earth, the geochemical and astrobiological insights garnered may make our current knowledge look like the Mariner 9 data does today. For mappers, this could support more detailed mapping and geological study of Mars than ever thought imaginable.

Looking beyond sample return missions, NASA’s Artemis missions are underway to help humankind learn how to explore further into space as part of NASA's push to further explore the Moon and Mars. Undoubtedly, Artemis will bring back invaluable information about the process of sustaining long-term, anthropocentric space exploration. If science and technology continue to advance at the same rate as they have within the last 50 years, within a few generations, we may have hand-drawn maps of Mars come home.

View the interactive map of the Shalbatana Vallis Source Region (USGS SIM 3492)

The mission of the USGS Astrogeology Science Center is to serve the Nation, the international planetary science community, and the general public’s pursuit of new knowledge of our Solar System. The Team’s vision is to be a national resource for the integration of planetary geosciences, cartography, and remote sensing. As explorers and surveyors, with a unique heritage of proven expertise and international leadership, USGS astrogeologists enable the ongoing successful investigation of the Solar System for humankind. For more information, visit http://astrogeology.usgs.gov