On September 15, a meteor will burst through the cloud tops of Saturn’s atmosphere, burning bright and breaking apart into hundreds of pieces. From Saturn’s surface, this would appear as a beautiful cosmic event, like shooting stars that arc across the Earth’s night sky. But this meteor won’t be a piece of rock jostled loose from an asteroid. It will be the Cassini spacecraft in its final moments of life.
Jupiter saw a similar tail of fire streak through its atmosphere back in 2003, when the Galileo probe turned to face the planet, fired its thrusters, and sped into Jupiter at 108,000 miles per hour. More than a year earlier, a team of people at NASA’s Jet Propulsion Laboratory had decided they would kill the spacecraft by throwing it into into the giant planet. It’s a decision not to be taken lightly, especially when these missions cost billions of dollars and can take decades of planning. Every mission has a team that plans the deaths of these spacecraft; some have planned both the demise of Galileo and Cassini, and they likely won’t stop there. They have good reason to kill these robotic explorers.
When Galileo was sent to investigate the inner workings of the Jovian System, it was meant to be a major flagship mission. But then the probe made a monumental discovery: The thick crust of ice that blankets Jupiter’s lacerated moon Europa hides a vast ocean of salt water, more than what covers Earth.
“The discovery of water on Europa was really what sealed Galileo’s fate,” says Rosaly Lopes, a team scientist on Galileo and member of the Cassini Flight Project. NASA’s Office of Planetary Protection prohibits the contamination of potentially habitable bodies in the solar system with microbes from Earth, so with Europa now in that category, Galileo had to disappear to avoid ever crashing into the watery moon. The probe “de-orbited” into Jupiter on September 21, 2003, never to be heard from again.
The kind of skill set required for creating and managing deep-space planetary missions is hard to come by, so many of the people at NASA work together again and again over the course of their careers. Many current team leaders got their start on the Voyager probe fresh out of graduate school, moving to higher positions over time. But Voyager is still roaming the skies, en route for another solar system. For some team members, Cassini will …read more
Source:: The Atlantic – Science