In 1976, NASA’s Viking Project sent the first images from a Mars lander back to Earth; its landing-site lessons influenced later U.S. Mars missions

On July 20, 1976, Viking 1 grew to become the primary American spacecraft to land safely on Mars and return an image from the floor, an achievement marking its fiftieth anniversary this 12 months. It was not simple to get there safely. Two scientists concerned in deciding on that landing web site, Harold Masursky and Norman Crabill, later defined in a paper titled ‘The Viking Touchdown Websites: Choice and Certification’ revealed in Science that the unique touchdown zone was deserted simply days earlier than touchdown, over security considerations. The last-minute scramble helped set up a course of that NASA nonetheless makes use of as we speak at any time when it selects a touchdown web site on Mars.

A photograph that modified how we noticed Mars

About 40 minutes after landing, a single black-and-white picture of rocks and dusty soil, relayed to NASA’s Jet Propulsion Laboratory, confirmed the bottom in an space known as Chryse Planitia, or ‘Golden Plain.’ It was the primary image ever taken from the floor of Mars, although not the primary from one other planet altogether; the Soviet Venera 9 lander had already returned the primary picture from the floor of Venus, in October 1975. Viking 1 didn’t work alone for for much longer. Viking 2, its sister ship, landed on September 3, 1976, at a spot known as Utopia Planitia. Each landers operated past their deliberate lifetimes. Viking 1 was constructed to final for 90 days, however returned knowledge for greater than six years, and the landing-site course of refined below strain in 1976 outlived the {hardware} itself, shaping how NASA has picked each Mars web site since. Neither lander discovered definitive proof of life, however they did discover one thing virtually as tantalizing: sturdy proof of historic riverbeds and flooding, on a planet that used to look very completely different from the chilly, dry one we see as we speak.

The location no person anticipated to reject

Mission planners had already chosen and analyzed the proposed location for Viking 1’s touchdown primarily based on pictures obtained by Mariner 9 throughout its reconnaissance flyby. Nonetheless, the extra detailed examination made by Viking 1’s orbiter and by ground-based radar throughout June and July 1976 revealed that the preliminary web site was not appropriate for a protected touchdown. The workforce needed to search the close by terrain virtually from scratch. They settled a compromise spot about 900 kilometers away, one which struck a stability between what cameras might see and what radar steered in regards to the floor beneath, in accordance with the examine. It wasn’t the most suitable choice on paper, however it was protected sufficient. Viking 1 efficiently landed there on July 20, 1976.

Viking’s playbook turns into NASA’s rulebook
That scramble wasn’t for nothing. It was a case examine for future missions. As NASA equipped for the Mars Pathfinder mission, almost twenty years later, engineers had been nonetheless utilizing Viking orbital pictures and radar knowledge to mannequin what the brand new touchdown web site would appear like on the floor, says a NASA technical report on the Mars Pathfinder touchdown web site choice course of. Pathfinder’s workforce used a two-step method: first, they mapped engineering dangers and scientific worth individually, after which they held an open workshop for scientists worldwide to weigh in on the ultimate determination. That very same NASA technical report traces the open-workshop mannequin again to classes Viking’s workforce realized through the 1976 web site scramble.

From Chryse Planitia to Gale Crater

NASA’s later Mars missions adopted an identical sample: acquire orbital knowledge, invite the science group to debate candidate websites, and let security considerations have the final phrase. Analysis from the Smithsonian Nationwide Air and Area Museum says the method used to pick touchdown websites for the Spirit and Alternative rovers was later used to pick Gale Crater for Curiosity and Jezero Crater for Perseverance. Every spherical used newer instruments, together with sharper pictures from the Mars Reconnaissance Orbiter, however the notion of holding open group workshops earlier than locking in a web site is paying homage to what Viking’s workforce cobbled collectively below strain a long time in the past.

Why this nonetheless issues

NASA has used some model of this orbit-map-then-workshop course of for each Mars rover and lander web site chosen since Viking, and mission planners have stated it’ll seemingly information the seek for a crewed touchdown web site as properly. Fifty years after that first grainy picture, rovers now drive themselves and orbiters map the planet in far higher element, however the first query any Mars mission should reply stays the one Viking’s workforce confronted in 1976: is a given patch of Martian floor protected sufficient to threat a whole mission on?