The views are nice out there. Cassini has taken fabulous images of Saturn's rings and the huge moon Titan. In approaching Saturn, Cassini managed to pass within 8,000 miles of an eccentric moon named Phoebe. It's a heavily cratered ball of ice that in all probability is an exotic thing known as a Kuiper Belt object, a planetoid of a type normally found on the fringe of the solar system, this one somehow captured by Saturn. Cassini's camera obtained an image of Phoebe of stunning clarity, offering planetary scientists an instant treasure that they will interpret for years to come.
In such a moment, humans are seeing something entirely new. This is the essence of exploration. Does it matter that astronauts weren't along for the ride? Maybe only in the degree of drama.
"It's different from walking on the moon," says Mitchell. "You just can't compete with that."
I, Human
Elachi, JPL's director, works in an office filled with a little boy's fantasy collection of model spaceships: Cassini, Magellan, Ulysses, the Spitzer telescope, the rovers, Odyssey, Mars Global Surveyor.
"This is good ol' Voyager, still flying," he says, pointing to a probe that visited the gas giants in the late 1970s and 1980s and is still beeping away as it heads toward interstellar space.
One might guess that Elachi, as head of JPL, would heavily favor robotic rather than human spaceflight. But he'd love to see humans operating a drilling rig on Mars, searching for microbes deep beneath the surface.
"There are certain things that robotics cannot do. We can make them more sophisticated, we can make them sing and dance, but you're still going to need human judgment in the end," he says.
Robots vs. humans is an old argument at NASA. The best feature of robotic craft is that you don't have to keep them alive. They aren't going to be fried by solar radiation during their interplanetary trek. They don't need oxygen and water and food. They travel light, compared with humans.
But advocates of human spaceflight argue that machines only do what they're told to do. No machine has anything like the dexterity of a human hand or the analytical power of a human brain. The speed of light creates an inevitable delay between Pasadena and Mars, so someone like Brian Cooper can't actually drive a rover in real time. It takes 12 minutes right now for a radio signal to make the one-way journey from our planet to the red one. As Elachi puts it, "You can't joystick things."
And there's one other thing a machine can't do. It can't feel anything. No joy, no wonder, no inspiration.
Going the Distance
There are lots of cosmic questions that NASA would like to answer. Are there oceans under the surface of Jupiter's icy moons? Are there Earthlike planets orbiting distant stars? Where might we find life in the universe?
The robotic program and a new generation of space telescopes will grapple with these mysteries. Space science has a bright future even if human spaceflight has a cloudy one. NASA recently launched a spacecraft toward Mercury. There are programs underway to send robotic probes to comets, to the moon, to Mars again, past Pluto to the outer edge of the solar system, and to the tantalizing moons of Jupiter. In roughly a decade, a planned telescope known as the Terrestrial Planet Finder may be able to obtain a direct image of an Earthlike planet in a different solar system.
The NASA road map for the future would have human and robotic spaceflight functioning in tandem. In some situations, rather than the machines supporting the humans, the humans would be supporting the machines, deploying and fixing telescopes and scientific instruments in space. It's not lost on NASA that one of its best moments in recent years came when shuttle astronauts managed to repair the Hubble Space Telescope.
NASA anticipates retiring the shuttle as soon as the space station is completed. Though the shuttle and station have powerful political allies, they are much derided among space buffs. In returning again and again to Low Earth Orbit -- just a couple of hundred miles above the surface -- NASA is hardly venturing into deep space. It's like a champion swimmer who only treads water.
