Voyager 1 launched in 1977 with 3.5 seconds of fuel to spare

NASA launched Voyager 1 on September 5, 1977, at 12:56 UT aboard a Titan IIIE-Centaur rocket from Cape Canaveral, Florida, and the launch came within about 3.5 seconds of failing. Had the Centaur upper stage run dry a moment sooner, the probe that is now the farthest from Earth might never have left the vicinity of home.

How close it came

The trouble started in the Titan’s liquid-fuelled upper stage, which burned with an incorrect ratio of fuel to oxidiser and fell short. The Centaur had to make up the difference, spending about 1,200 pounds of extra propellant just to reach its parking orbit. Mission planners then waited to learn whether enough remained for the burn that would send the craft toward Jupiter.

“It did, finally, but there were only three and a half seconds of propellant left in the Centaur tanks.” — Charley Kohlhase, former manager of Voyager’s mission planning office, 2012

The numbering puzzles many readers: Voyager 1 lifted off 16 days after Voyager 2. NASA numbered the twins by arrival, not departure. Voyager 1 flew a faster, shorter route, overtook its sibling on December 15, 1977, and reached Jupiter first, in March 1979. Until March 1977 neither was a Voyager at all: built on Mariner designs, they were known as Mariner 11 and Mariner 12.

The narrow escape paid off. After Saturn in 1980, Voyager 1 left the plane of the planets, became the most distant human-made object in 1998, and in 2012 became the first spacecraft to cross into interstellar space.