2020 has been called the year of Mars, as there are three missions poised to launch toward the red planet, including NASA's Perseverance, the United Arab Emirates' first ever interplanetary Hope Mars mission, and China's first Mars exploration mission – Tianwen 1. But have you ever considered why all of the launch windows for these three missions are at the same time – from mid-July to mid-August? Why can't they launch their spacecrafts in other months?