Free Astronomy Magazine March-April 2021

MARCH-APRIL 2021 E fficient interplanetary travel is all about timing. Within a span of just nine days, three travelers from Earth, all launched in July 2020, have found them- selves either inserted into Mar- tian orbit or, most recently, present on its surface. This clus- tering of missions is, of course, not by coincidence – the nearby and near-circular orbits of Earth and Mars result in periodic win- dows for relatively short and fuel-efficient travels. This partic- ular path for Earth and Mars, their Hohmann transfer orbit, greatly reduces overall fuel re- quirements and transit times, Perseverance T he launch on a ULA Atlas V rocket of Mars 2020 from Cape Canaveral on July 30, 2020. [NASA] by Damian G. Allis ❖ NASA Solar System Ambassador