Europe’s planned Venus exploration mission will rely on a challenging aerobraking procedure to lower its orbit, which will test the thermal resilience of spacecraft materials to their limits.
The Vision Missionexpected to launch in the early 2030s, will study the geology and atmosphere of Venusthe infernal planet that once could have it looked a lot like Earth but became a scorched hostile world due to a fugitive greenhouse effect.
To get EnVision into its target orbit, 500 kilometers (310 miles) above the surface of Venus (which is so hot it would melt lead), it will take thousands of passes through the planet’s thick atmosphere over a period of two years, the European Space Agency (ESA) said in a statement (opens in a new tab).
“EnVision, as currently conceived, cannot be carried out without this long aerobraking phase,” ESA’s EnVision study manager Thomas Voirin said in the statement.
Related: How Venus became Hell and how Earth is next
The spacecraft the size of a van, which will launch over the future of Europe Ariane 6 rocket, it will not be able to carry enough fuel to slow it in orbit around Venus using onboard propulsion. Instead, it will use aerobraking and follow a highly elliptical orbit that periodically takes it within 80 miles (130 km) of the surface of Venus at its closest and about 155,000 miles (250,000 km) from the planet at its closest. furthest point.
ESA previously used aerobraking to reduce the speed of the exorcise you Trace Gas Orbiter before entering its scientific orbit around Mars. But the atmosphere of Mars is much thinner than that of Venus, and its gravity is much less, which affects the speed of the spacecraft in orbit.
“Aerobraking around Venus will be much more challenging than for Trace Gas Orbiter,” Voirin said. “The gravity of Venus is about 10 times that of Mars. This means that the spacecraft will experience speeds about twice that for TGO when passing through the atmosphere, and heat will be generated as a speed cube.”
ESA briefly tested aerobraking around Venus during the last months of the venus express mission, which eventually spiraled toward the planet and burned up in the atmosphere in 2014. As Venus Express was already at the end of its mission, spacecraft controllers were not concerned about damage to the spacecraft caused by the heat. EnVision, on the other hand, is expected to explore Venus for at least four years.
Engineers are already busy working on the right materials that would allow EnVision to withstand extreme conditions. In addition to the heat experienced during the aerobraking procedure, the spacecraft will also be exposed to very high concentrations of highly reactive atomic oxygen. Atomic oxygen is a form of oxygen present in the upper layers of earth’s atmosphere, consisting of a single oxygen atom. Atomic oxygen, a nemesis of all lowland spacecraft in orbit, thermal blankets burned in several NASA space shuttle Missions in the 1980s.
Observations from previous Venus missions showed that atomic oxygen is present in the upper layers of Venus’s atmosphere in concentrations similar to those on Earth.
“The concentration is quite high. With one pass it doesn’t matter as much, but with thousands of times it starts to accumulate and ends up with a level of atomic oxygen fluence that we have to take into account, equivalent to what we experience in low Earth orbit, but at higher temperatures,” Voirin said.
ESA is currently testing the materials’ ability to withstand both the heat and atomic oxygen concentration expected during EnVision’s aerobraking and hopes to have some candidate materials selected by the end of this year.
“We want to verify that these parts are resistant to erosion and that they also maintain their optical properties , which means they don’t degrade or darken, which could have collateral effects in terms of their thermal behavior, because we have delicate scientific instruments … which must maintain a set temperature,” Voirin said. “We also need to avoid flaking or outgassing, which leads to contamination.”
Venus, sometimes considered Earth’s twin due to their similar sizes, has lately been somewhat sidelined by Solar system explorers like the potentially more habitable Mars (which is more likely to harbor traces of life) has become a favorite. But a 2020 study that found molecules that could be remains of living organisms in the planet’s sulfur-rich clouds sparked a new wave of interest in Venus.
In addition to Europa, NASA has plans to send orbiters to the scorching planet: the DAVINCI+ and VERITAS missionswhose launch is expected between 2028 and 2030. Currently, a lonely spacecraft, the Japanese akatsukiis orbiting Venus, studying its thick atmosphere in an attempt to unravel the mysteries of its harsh climate.
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