NASA’s Mars Exploration Rovers, named Spirit and Alternative, launched for the Pink Planet in summer time 2003. Credit score: NASA/JPL-Caltech
When people go to Mars later this century, they’ll alight on its ochre-hued sands with the identical spirit of journey and thirst for alternative as a younger woman whose essay was chosen from amongst 10,000 on-line submissions to call a pair of Mars-trekking rovers.
In 2002, nine-year-old Sofi Collis, then residing in Scottsdale, Arizona, entered the competition run by NASA, the Planetary Society, and toymaker Lego, which challenged college students aged 5 to 18 to conceive names for the golf-cart-sized Mars Exploration Rovers. A Siberian orphan who had been adopted within the U.S. on the age of two, Collis wrote that she used to search for on the “sparkly” night time sky to elevate her spirits. “In America, I could make all my goals come true. Thanks for the ‘Spirit’ and the ‘Alternative.’”
Twin explorers
The robotic Spirit and Alternative rose from Earth and fixed their gaze on Mars 20 summers in the past. Meant to outlive on the planet’s frigid, wind-whipped floor for simply 90 Earth days and drive solely about 0.4 mile (600 meters) atop a chassis of six cleated wheels, the twins vastly outperformed all expectations: Spirit 20 instances over, Alternative by a staggering 60.
Spirit lasted six years, roving throughout 4.8 miles (7.7 kilometers) of Martian terrain. However Alternative endured some 15 years, snaring a report in 2014 for the farthest-driven automobile on one other world. By the point she fell silent, she had over 28 miles (45 km) on her odometer. And between them, this intrepid duo snapped greater than 341,000 images.
Focusing on reverse hemispheres of the Pink Planet, Spirit headed for the 103-mile-wide (166 km) Gusev Crater, doubtless shaped by an asteroid influence 3.5 billion years in the past and presumably the positioning of an historical lake. Alternative took purpose at Meridiani Planum, a broad plain with sturdy chemical signatures of a moist, watery previous. Collectively, they sought clues to Mars’ previous setting and whether or not this modern-day chilly, dry desert had ever been conducive to life. Laden with cameras, spectrometers, a rock abrasion device for direct sampling, and their very own wheels to assist dig exploratory trenches within the martian filth, the solar-powered twins have been tasked with searching minerals left behind by water-driven processes. They might additionally hint the geological mechanisms that formed Mars’ now-arid panorama. Every rover weighed 408 kilos (185 kilograms), stood 5.1 ft (1.5 m) tall, and was 7.5 ft (2.3 m) broad and 5.2 ft (1.6 m) lengthy. They inched their method throughout the ever-present crimson regolith at a snail’s tempo, averaging simply 0.02 mph (0.03 km/h).
An extended journey
Launched by two Delta II Heavy rockets from adjoining Launch Complexes 17A and 17B at Florida’s Cape Canaveral Air Power Station, Spirit flew first on June 10, 2003, adopted by Alternative on July 7 (native time). Thus started a 302-million-mile (486 million km) trek to make clear Mars’ aqueous previous.
They sat snugly for his or her voyages inside solar-powered cruise phases, guarded in opposition to the temperature and radiation extremes of deep house. However their actual close-quarters safety got here from an ablative aeroshell, parachute, retrorockets and airbags that slowed them from 11,800 mph (18,900 km/h) on the level of entry into Mars’ skinny environment to an virtually dead-stop a number of tens of ft above the floor. The descent from the highest of the carbon-dioxide-rich environment to the bottom took six minutes. Mission controllers referred to as it their “six minutes of terror”.
Spirit reached the planet on Jan. 3, 2004, a cocoon of 4 six-lobed airbags cushioning the rover because it bounced as much as 5 tales excessive and so far as 0.6 mile (0.96 km) throughout stony terrain, lastly coming to a halt contained in the Connecticut-sized Gusev basin. The airbags deflated, the lander’s sides opened like nice mechanized petals, and, after unfurling her two photo voltaic panel “wings,” Spirit drove onto a barren, featureless plain, framed by a horizon of low hills and backlit by a decreasing boring crimson sky.
Three weeks later, on Jan. 25, Alternative duplicated Spirit’s feat at Meridiani Planum, which straddles Mars’ equator and may need held sufficient water 3.7 billion years in the past to harbor river channels and even a salty sea. Alternative’s arrival, by pure happenstance, noticed her roll right into a 72-foot-wide (22 m) crater, later named Eagle: an apt golfer’s time period for a hole-in-one.
Choosing Gusev and Meridiani required each websites to exhibit sturdy proof of historical water, however in addition they needed to lack too many rocks which may hinder the rovers and their airbags. Mission planners wanted to account for wind speeds, sloping terrain, and the prevalence of mud, in addition to guarantee each locales hugged the equator, receiving sufficient daylight to energy the twins on their travels.
A legacy of science
Quickly after touching down, their respective touchdown websites have been named for 2 misplaced house shuttle crews: Gusev turned the Columbia Memorial Station and Meridiani the Challenger Memorial Station. The ridge of low hills on Spirit’s horizon was styled the Columbia Hills, its highest peak, the 269-foot (82 m) Husband Hill — which the rover summited in August 2005 — honoring Columbia’s late commander, Rick Husband.
Spirit discovered six distinct rock sorts within the hills, all displaying alteration by aqueous (water-based) liquids. Some have been enriched in phosphorus, sulfur, chlorine, and bromine, which are sometimes carried in watery options. The invention of goethite (a mineral that varieties solely in water’s presence) proved particularly notable. Coatings and cracks inside rocks additionally hinted at water’s actions, whereas traces of clays, near-pure silica, and presumably an space of evaporate added to a corpus in favor of a wetter Gusev, way back.
At Meridiani, Alternative found deposits of gray hematite, an iron-oxide mineral normally produced in water-rich environments. It discovered curious spherules of the stuff (nicknamed martian blueberries), some sitting loosely on the bottom, others embedded in rocks, and most measuring lower than 0.2 inch (6 millimeters) throughout. Stratified patterns in outcrops pointed to water exercise and irregular distributions of chlorine and bromine hinted on the shoreline of a long-gone salty sea.
In March 2004, Spirit acquired the primary picture of Earth from one other planet’s floor. And in January 2005, Alternative discovered the primary meteorite recognized on one other world: the basketball-sized Warmth Defend Rock. It was the primary of eight iron-nickel meteorites discovered by the roving twins.
Trials and tribulations
Regardless of their successes, the duo struggled with mechanical and martian maladies: lack of wheel steering, flash reminiscence glitches, and savage mud storms. Though one fortunate encounter with a mud satan in March 2005 cleaned Spirit’s photo voltaic arrays and aided her longevity, extra typically, Mars’ magnetic mud — which Alternative discovered incorporates titanomagnetite — conspired in opposition to them, forcing the rovers to hunker down into low-power hibernation.
Spirit acquired caught in mushy sand in Might 2009, inflicting her wheels to lose traction. (On the time, solely 5 of the six have been working, one having given out three years earlier.) Regardless of efforts to free her, she was repurposed as a stationary science lab. One in every of her new duties was to know wobbles in Mars’ rotation which may point out whether or not the core is stable or liquid. However on March 22, 2010, Spirit fell silent for the ultimate time as temperatures plummeted and battery energy ebbed away. In Might 2011, NASA introduced a transmission to the rover on the twenty fifth could be their final try to awaken it; with no reply, the mission formally ended.
Her sister carried on for eight extra years. However lastly, she, too, succumbed. A raging planetwide storm in June 2018 blanketed Alternative’s location and early the next yr, after fruitless makes an attempt at contact, its mission additionally ended. NASA’s final transmission to the previous rover have been the strains of “I’ll Be Seeing You” by Billie Vacation.
However maybe at some future date, residing explorers will set foot on Mars and human eyes will see these hardworking twins as soon as once more.
