ARRIVAL
A FIELD GUIDE TO VIKING & MARS
Ten chapters on the twin spacecraft that were the first to survive a landing on Mars and search its soil for something alive — and on everything sent after them, still asking the same question. Scroll to begin the mission.
BEGIN — CHAPTER 01 →A window that opens every 26 months
Earth and Mars only line up for an efficient transfer once every 26 months. Launch outside that window and the fuel cost climbs fast; launch inside it, and a spacecraft can coast along a long, curving ellipse — a Hohmann transfer — from Earth's orbit out to meet Mars roughly seven months later.
Adjust the departure burn and see the same spacecraft either fall short, meet Mars, or overshoot into a wider orbit.
Two identical spacecraft, two questions
Each Viking spacecraft paired an orbiter, which mapped the planet from above, with a lander that carried its own biology lab to the surface. Designed for 90 days, both missions ran for years. Scrub through the program.
Three experiments, no clear answer
A chemistry lab on three legs
Each Viking lander carried a robot arm, a miniature biology and chemistry lab, a weather station, and a seismometer — all built to run for three months with no possibility of repair. Select a component.
Thin air, no second chance
Mars' atmosphere is thick enough to superheat a spacecraft on entry but far too thin to slow one down on parachute alone — a problem every Mars lander since Viking has had to solve in its own way. Step through Viking's sequence.
A planet, not just a target
Whatever the biology experiments did or didn't prove, Viking returned the first real, sustained picture of Mars as a place.
From two fixed labs to a fleet of rovers
Viking never moved an inch. Everything landed on Mars since has been able to go somewhere — illustrative landed mass by mission, growing by orders of magnitude.
Ninety days, six years
Both landers massively outlived their design lifetime, and the debate their soil data started has never fully closed.
Still asking Viking's question
Figures below reflect the state of active programs as of mid-2026 and are illustrative — mission plans and budgets for sample return shift often.
From two landers to a return trip
Fifty years after Viking scooped the first Martian soil into a lab it couldn't leave, the next step is bringing that soil to labs on Earth.