In June 2018, Arvidson was deeply worried about his own cherished companion on Mars. A dust storm had swept across Opportunity’s location in a gravelly valley near the equator. A common occurrence in Martian summer, but this tempest clogged the atmosphere with more dust than Arvidson had ever seen since he began working on Mars missions in the 1970s. In the resulting darkness, Opportunity, a solar-powered being, slipped into a deep sleep.
Engineers dispatched daily commands to the rover, asking Opportunity to beep if it could hear them. After a couple of months with no response, NASA leaders decided that the recovery attempt should wind down in the fall, but engineers at the agency’s Jet Propulsion Laboratory (JPL) passionately lobbied for more time, Arvidson says. They kept listening until February 2019, relaying all sorts of transmissions to the 14-year-old spacecraft. “We went as far as we could to try to wake her up,” Arvidson says.
(Here’s what the Opportunity rover gave to humankind.)
NASA mounted a similar campaign a decade earlier for the Spirit rover, on an impact crater on the opposite side of Mars. The spacecraft spent most of its time on the planet driving in reverse after one of its front wheels failed, like a wonky shopping cart, says Arvidson, who worked on the Spirit mission too. In 2009, while dragging the faulty wheel along, the robot’s remaining wheels broke through a crust and into a sandy pit.
Engineers executed a variety of wriggly maneuvers, but the rover only sank deeper. Spirit could no longer prepare for winter by moseying to a sunny slope, where its solar panels could bask in battery-sustaining light. But “it was in a beautiful place scientifically,” Arvidson says. For a few months before the decisive season arrived, Spirit, trapped but alert, used its rock-grinding tool to study the surrounding soil, making the most of its final months as a Martian geologist.
Cosmic murder isn’t out of the question—despite efforts to extend robot lives and make the most of their deaths. Take the Cassini probe, which departed Earth for Saturn in 1997. At the time, mission managers were thinking about all the wonderful things the spacecraft might discover about the ringed planet—not about the possibility that, someday, they would deliberately kill their beloved robot.
This animation, created by NASA, shows how Cassini’s last moments played out.
Yet the team had a mandate from the beginning to prevent Cassini from colliding with two Saturnian moons, Titan and Enceladusif it ran out of fuel in orbit. Scientists think these worlds could harbor their own forms of lifeand if Cassini crashed into either, it could contaminate the icy moons with Earthly microbes.
Source: www.nationalgeographic.com
