Watch the scene in the control room at NASA's Jet Propulsion Laboratory during the landing of Curiosity.
The uneventful nine-month, 150,000,000-mile journey of the Mars Science Laboratory Rover, which also goes by the whimsical name Curiosity, ended with a harrowing 7-minute landing in Gale Crater. Getting the fourth Mars Rover into space was a piece of cake compared with setting it back down. Curiosity will explore Gale Crater for one Martian year (687 Earth days) to 1) look for evidence of extraterrestrial life and to 2) evaluate the habitability of the planet.
Sputnik gave birth to the Space Age on Oct. 4, 1957.* Barely six months later, seeking to reassure an anxious nation, President Dwight Eisenhower shared “An Introduction to Outer Space,” a remarkable statement from his Science Advisory Committee, with the American public. A brief section titled “A Message From Mars,” notes that much of what we wish to learn in space can be gathered by instruments and transmitted back to Earth at a small fraction of the cost required to send scientists to other planets.
The Apollo 11 moon landing was hailed as the opening of a new era of human exploration. The stars, it seemed, must be just around the corner. Since the Apollo program, however, no human has ventured beyond low-Earth orbit.* What led to the quiet shelving of the dream of interplanetary travel?
There seemed to be two NASAs in 1969: the NASA that would build Hubble and explore the solar system and the NASA that put together the Space Shuttle but found itself trapped in low-Earth orbit. It was human astronauts vs. virtual astronauts.
NASA was initially conceived as a civilian agency. The science side has given us space telescopes and missions that are still going strong to Mercury, Jupiter, Saturn, and beyond. The Cold War side has its remnants in plans to send people to Mars, despite physiological, psychological, genetic, engineering, and other obstacles.
Beginning with the Viking 1 lander in 1976, we’ve been looking for life on Mars for 36 years—and we’ve found zip. Carl Sagan’s disappointment showed on his face in 1976 when the Viking 1 camera panned the horizon of Chryse Planitia (the Golden Plain), revealing a barren, boulder-strewn surface. Chryse Planitia is only a small region of the surface of Mars, but so far, nothing has softened the first impression that Mars is not a living planet.
If we sent astronauts to Mars, they would travel for nine months and then have to sit on their hands for another 18 months, awaiting the next conjunction with Earth permitting departure. It's not a pretty picture; countless millions of Earth organisms would hitch a ride to Mars in every human gut and multiply in their excrement while there. We would find life on Mars, but it would look familiar. Mars should be quarantined.
The term rover refers to a self-contained mobile robot that functions as an electromechanical extension of a remote human operator. The first Mars rover was Sojourner, used in the 1997 Pathfinder mission. An operator, comfortably seated in Mission Control, sees Mars through the eyes of the rover, which are far better than human eyes; they can focus on a grain at the foot of the rover or a distant mountain. Sojourner never broke for coffee or complained about the cold nights. Spirit and Opportunity, twin rovers, followed. For a time they seemed almost immortal, but with rovers, as with people, they finally just wore out.
Curiosity is bigger, faster, and handier with tools, and it gets its power from plutonium-238. That’s not the bomb stuff; the 238 isotope is not fissile. It just gets hot from alpha decay and generates electricity. Humans have changed little in 200,000 years, but our rovers get better with each mission.
It's been 36 years since Viking 1 and 2 searched for life to understand whether Mars was, is, or can be an abode of life. What is missing, and has been missing for three decades, is a sample-return mission. But that’s a job for a rover. (And what NASA doesn't say when it comes to searching for life on Mars is that the most exciting discovery of the new millennium is the abundance of extra-solar planets.)
“Will people ever visit Mars?” I am frequently asked. “They already have,” I reply. “The great adventure of our time is to explore where no human can ever set foot.” Having become virtual astronauts, we will all be able to see Mars through Curiosity’s eyes.
Correction, Aug. 6, 2012: This article originally stated that humans had not ventured into low-Earth orbit since Apollo 11. Humans have not ventured into low-Earth orbit since the end of the Apollo program. (Return to the corrected sentence.)
Correction, Aug. 7, 2012: This article originally stated that Sputnik was launched on Nov. 4, 1957. It was launched on Oct. 4, 1957. (Return to the corrected sentence.)