If you send a rover to Mars,Germany you need to figure out what you want to study once it gets there.
Do you want an up-close look at former hot springs? Are you interested in learning more about the planet's past volcanic activity? How about checking out a crater that was once filled with water?
These are the questions NASA is asking right now as it prepares to send a rover designed to hunt for signs of past life on Mars by 2020.
SEE ALSO: 6 scientists are living like they're on Mars for the next 8 monthsScientists working with the space agency have narrowed down a list of possible landing sites to the final three. Now, NASA just needs to figure out which one to choose.
One possible landing site -- the Jezero crater -- is thought to have a wet past.
About 3.5 billion years ago, rivers on Mars sloshed water into the crater, making it a lake.
"Scientists see evidence that water carried clay minerals from the surrounding area into the crater after the lake dried up," NASA said in a statement.
"Conceivably, microbial life could have lived in Jezero during one or more of these wet times. If so, signs of their remains might be found in lakebed sediments."
If the 2020 rover -- which is also expected to cache rock samples for a future mission that will return them to Earth -- does land in the crater, it won't be the first time a NASA spacecraft has explored a previously wet crater on Mars.
At the moment, the space agency's Curiosity rover is roaming around Mars' Gale crater, and has found that at least part of the planet could have once been habitable for microbes.
While the 2020 rover won't have the chance to visit Curiosity's part of Mars, it may land on a part of the red planet already explored by NASA's Spirit rover.
Spirit found that springs of water may have once sprouted from Columbia Hills in the Gusev crater, so it's possible that the 2020 rover will land there to more fully investigate what Spirit found.
"After the rover stopped working in 2010, studies of its older data records showed evidence that past floods that may have formed a shallow lake in Gusev," NASA said.
That watery crater could have also preserved signs of past life in its ancient past.
The third possible landing site, in the northeast part of Syrtis Major, is thought to have been volcanically active in the ancient past.
"Microbes could have flourished here in liquid water that was in contact with minerals," NASA said. "The layered terrain of NE Syrtis holds a rich record of the interactions that occurred between water and minerals over successive periods of early Mars history."
The 2020 rover -- which will carry seven science instruments to Mars -- will be a car-sized spacecraft modeled somewhat on Curiosity.
The rover is expected to launch to the red planet in July 2020 from Cape Canaveral Air Force Station in Florida, and NASA should pick its final landing site for the rover about a year or more before that launch date.
Between now and then, NASA will continue to evaluate the three candidate landing sites to see which ones are safest and most rich for exploration.
Saudi officials order arrest of rapper over 'Girl from Mecca' YouTube videoKatherine Johnson, NASA mathematician and subject of 'Hidden Figures,' dead at 101Minions are invading the world of LEGOHere's NASA's new idea to get its stubborn Martian drill to workYour next Android smartphone will probably have more RAM than your PCHow to voice message, from sexting to avoiding mom's callsFacebook to ban coronavirus 'cure' adsThis new bill would legalize weed in CanadaThis new bill would legalize weed in CanadaFather decks truck out in rainbows to support of marriage equality for his sonA Japanese company has invented sliced mayo and I want to try it'Kidding' showrunner on Ariana Grande and the power of healingAmazon removes fake products promising to 'kill' coronavirusTrain ticket officer's savage shut down of a racist passenger is pure goldiOS 14 might have an extremely useful iPad featureWhy the warming oceans will get louder.Phoebe WallerYou're definitely not the only person googling 'World War III''The Office' children's book is here to inspire a whole new generation of fansThis new bill would legalize weed in Canada The Effusions and Offenses of Kaiser Wilhelm II Adrift: Remembering Yoshihiro Tatsumi by Chris Oliveros Staff Picks: Grim Reaper Hex, Ouija Board Sex by The Paris Review Steve DiBenedetto’s Cave Paintings for the Future When Did Table Settings Become So Lavish? Staff Picks: Grimonprez, Malcolm, Barry, Kushner Farewell to Meat: At Masopust, the Czech Festival of Spring Remembering St. Nicholas Magazine for Children Better Call Caravaggio: “Saul” Borrows from Baroque Painting Photos from Dhallywood, Bangladesh’s Film Capital Listen: An Archival Interview with Reynolds Price Strand's Last Interview, Joyce's Favorite Escape, and More Botero’s “Adam,” the Sculpture New Yorkers Love to Touch Judas: No One’s Favorite Apostle When Eudora Welty Went Sailing with Faulkner Manet to Monet: Don’t Let Renoir Paint Leavening Agent—Or Ticking Time Photos from Our 2015 Spring Revel Macaroon vs. Macaron: Cookie Summit 2015 “On the Ship,” a Poem by Constantine P. Cavafy