Rovers are incredible tools for exploring Mars, and looking ahead, it won’t be too much longer before the next Mars rover is on its way to the Red Planet. For years, Mars has been one of the most fascinating worlds in outer space. It’s close to Earth, has evidence of ancient lakes, and may have once had life. Besides Earth, it’s the planet humans know the most about — and the one scientists and astronomers are most eager to keep learning about.

One of the reasons for our vast understanding of Mars is thanks to advanced rovers on the planet. Along with satellites, probes, and orbiters, rovers are responsible for some of the biggest Mars discoveries. The Perseverance rover, for example, is actively collecting Martian rocks that’ll eventually be returned to Earth for further examination. The Curiosity rover has also detected multiple traces of carbon on Mars — a considerable puzzle piece in finding evidence of life there.

Related: The Wheels On NASA’s Mars Rover Look Awful In These New Photos

As impressive as existing Mars rovers are, it’s difficult to not look forward and get excited about what’s next. So — when is the next rover going to Mars? At the time of publication, the next Mars rover will be the ESA’s ExoMars Rosalind Franklin rover. ExoMars was originally supposed to launch in 2020 but was delayed due to technical issues. The ESA then hoped to launch it in September 2022, but that’s also been delayed because of Russia’s attack on Ukraine. The ESA says it’s “very unlikely” ExoMars will launch in 2022 and hasn’t offered a more specific update beyond that. The ExoMars rover may launch in 2023, 2024, or even later. As of right now, all we know is that it almost certainly isn’t happening in 2022.

New Mars Rovers Cost A Lot Of Time And Money

While humans have launched thousands of satellites in space over the years (and keep doing so more frequently), Mars rovers are few and far between. Sojourner, NASA’s first Mars rover, landed on Mars in July 1997 after three years of development. Sojourner was succeeded by Spirit & Opportunity, both landing on Mars in January 2004. It then wasn’t until August 2012 before NASA’s next Mars rover — Curiosity — arrived on the Red Planet. Almost nine years later, Perseverance became the fifth rover on Mars when it landed there in February 2021. Along with NASA’s five rovers, the only other rover on Mars is the CNSA’s Tianwen-1 rover (which landed on Mars in May 2021).

Along with requiring a tremendous amount of time and planning, Mars rovers are also very expensive. NASA spent $2.5 billion just on the Curiosity rover. It also spent around $2.7 billion on Perseverance. Whether NASA, ESA, CNSA, or another organization wants to launch a Mars rover, doing so means needing a heap of money. When you add all of that together, it’s easy to see why there have only been a handful of Mars rovers. We’ll keep following ExoMars as the next Mars rover when it (hopefully) launches in the next year or so, and after that, we’ll keep an eye out for what comes next.