Three missions on the way taking advantage of a window which opens up about every 26 months.
It has been 60 years since the first exploited launch window, in 1960, saw a pair of Soviet spacecraft sent on their way. Around 50 missions have used the 27 subsequent launch windows until the present one. Only in the last two decades have successes overtaken failures: more than half of attempts to reach Mars to date have failed.
Of the three missions on their way (a fourth European mission which was to have joined them has been deferred until the next launch window in 2022), the first launched is a relatively modest mission jointly undertaken by the United Arab Emirates in collaboration with three American universities, the University of California, Berkeley, the University of Colorado, Boulder and Arizona State University.
The “Hope” orbiter, launched from a Japanese H-IIA rocket in Tanegashima, Japan, has been described as Mars’ “first true weather satellite,” though it is adapted toward the very different variations displayed by the Martian atmosphere as compared to Earth’s. In particular, it carries scientific instruments which can study the process by which Mars loses atmosphere to space, a process which, thanks to Mars’ lower gravity and lack of a substantial magnetic field, is much more rapid than Earth’s loss, and also thought to be more complex.
The second mission launched, China’s Tianwen-1 (“heavenly questions”), is China’s first independent interplanetary mission. It will both build an independent Chinese orbital capability to study the surface and relay radio communications from it, as well as land a rover modeled to some extent on, but with more contemporary technology than, the twin US Mars Exploration Rovers (MER) Spirit and Opportunity of 2003.
Unlike those missions, which did not include an orbiter component, Tianwen-1 will not proceed directly to a landing, but rather enter orbit and begin studies to select from several preliminary sites, and only then will the lander separate and make its way to the surface.
Perseverance will carry two other novelties: first, a small solar-powered helicopter, that can travel up to 2,000 feet per flight and image the possible driving route, and secondly, a ground-penetrating radar (a first also shared by the Tianwen-1 rover), to study what no lander yet has in detail, the depths beneath the Martian surface. Perseverance will also test from the Martian surface a technology to manufacture oxygen from the largely carbon dioxide atmosphere, a necessity for future hopes at human exploration or even for more efficient fueling of Mars return rockets from supplies generated locally, rather than brought from Earth. https://www.wsws.org/en/articles/2020/07/31/mars-j31.html
