Mars exploration will get a big boost next summer.
Earth and the Red Planet align favorably for interplanetary travel just once every 26 months, for a few weeks at a time. The next such window opens in mid-July 2020, and four big-ticket missions aim to take full advantage.
These newcomers will push Mars’ robotic population into the double digits. There are currently two operational craft on the Martian surface (NASA’s Curiosity rover and InSight lander) and six orbiters circling the planet (NASA’s MAVEN, Mars Odyssey and Mars Reconnaissance Orbiter; Europe’s Mars Express and the European-Russian ExoMars Trace Gas Orbiter; and India’s Mars Orbiter Mission).