Why Three Spacecraft Must Leave For The Red Planet Within Weeks Or Miss Their Chance
2020 is a big year for the solar system. July will see three spacecraft launch to Mars. First the Emirates Mars Mission, then China’s Huoxing-1, and finally NASA’s Mars 2020. They will all take turns to launch their respective missions to the “Red Planet.”
However, if they miss their tight two-week launch windows they’ll have to wait until September 2022 for another go.
Why can we only go to Mars every two years or so?
It’s all about celestial mechanics.
What missions are launching to Mars this month?
There are three missions going to Mars in July 2020:
UAE’s Emirates Mars Mission
Launch window: July 15 through August 3, 2020
The first planetary science mission from the United Arab Emirates (UAE)—and also the first by an Arab-Islamic country—will blast-off from Tanegashima Space Center, Japan. The first chance comes on July 15, 2020. Its probe called “Hope” will go into orbit in February 2021 and study how the upper atmosphere of Mars is affected by its lower atmosphere.
China National Space Administration (CNSA)’s Huoxing-1 (HX-1)
Launch window: July 23 through early August, 2020
China’s Huoxing-1 mission (which translates as Mars-1) is scheduled to launch from Hainan, China on the top of a Long March 5 rocket. It will be China’s first Mars orbiter, lander and rover. An ambitious mission, it will deploy an orbiter around Mars between February 11-24, 2021, and put a rover on the surface on April 23, 2021 to explore for 90 days.
NASA’s Mars 2020
Launch window: July 30 through August 11, 2020
Scheduled to launch from Cape Canaveral Air Force Station Space Launch Complex 41 on July 30, 2020 (it was supposed to launch 10 days earlier, but was delayed by NASA), Mars 2020 will land NASA’s rover Perseverance in Jezero crater on Mars on February 18, 2021. It will seek signs of ancient life and collect rock and soil samples for a possible return to Earth.
What about Europe and Russia’s ExoMars mission?
There would have been four missions heading for Mars this month, but COVID-19 put paid to preparations for the ExoMars mission from the European Space Agency (ESA) and Russian Space Agency (Roscosmos). It had been scheduled to launch from Baikonur, Kazakhstan on July 26, 2020, but will now be departing around September 2022 to land on Mars around May 2023.
Why is everyone going to Mars at the same time?
Celestial mechanics means that every 2.2 years a launch window opens for efficient, cost-effective rides between Earth and Mars, and vice versa. Earth takes 365 days to orbit the Sun and Mars takes a slower 687 days. That’s 1.88 Earth years, which puts Mars and Earth reasonably close to an orbital resonance of 2:1.
So just over every two years Earth catches-up on Mars and the planets briefly line-up. At that point they’re closest together. So just before that point the journey between the two planets takes the least amount of time.
What is the Hohmann transfer orbit?
Mars missions take a Hohmann transfer orbit, which sees them launch from Earth just before the planet catches-up on Mars.
Can’t spacecraft just fly further or faster?
It’s largely about fuel-to-weight ratios. “You can launch every two years or so when Earth’s and Mars’ orbit are starting to get together because that means the least distance to travel, and therefore you require less fuel in your spacecraft,” said Sarah Al Amiri, the UAE Minister of State for Advanced Sciences and Deputy Project Manager of the Emirates Mars Mission, to Forbes.
“Typically spacecraft that are leaving Earth have more than 50% of their weight comprised of fuel, which drives costs up and adds a layer of complexity—which is why you would always launch during this window every two years.”
Why does each mission have a slightly different launch window?
The launch windows for the three different Mars missions in 2020 differ by a few days here and there. For example, NASA’s Mars 2020 is departing a few days after the Emirates Mars Mission. Why? Rocket choice. “The launch window differs depending on your launch vehicle, which typically gives you maybe a day or two on either end of that launch window,” said Al Amiri.
What happens if either of the three spacecraft can’t launch in the window?
Practically speaking, all three should be fine—the launch window is reasonably long, certainly enough to cope with short periods of bad weather.
However, if for any reason it doesn’t happen, the whole thing will need to be postponed until the next biannual launch window opens in 2022.
That’s the next “year of Mars.”
Mars at ‘opposition’
While you wait for the rockets to launch, here’s a date for your diary—October 13, 2020, when Mars will reach opposition. At that point it will be closest to Earth, so it’s the ideal time to already be halfway through your journey to Mars; that’s how the Hohmann transfer orbit works.
During this opposition Mars will shine at its brightest in our night sky. It will also rise at dusk and set at dawn, making it the ideal time to put a telescope on our near neighbor as it will look its brightest and best for all of 2020—and, technically speaking, its best since 2003.
It all goes to show that whether you’re planning a mission to Mars or just planet-gazing, it always pays to know exactly what’s going on right now in the Solar System.
Wishing you clear skies and wide eyes.
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