17.04.2024
Venus is leaking carbon and oxygen, a fleeting visit by BepiColombo reveals
"These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play."
An abundance of gases, including carbon and oxygen, are being stripped away from Venus' atmosphere, according to flyby data from Europe's BepiColombo space probe. This data was obtained as the Mercury-bound spacecraft flew past Venus, and could shed new light on the leaky atmosphere of our planetary neighbor. Down the line, the findings could help scientists catalog the makeup of Venus' fragile magnetic environment as well.
Unlike Earth, a planet with an intrinsic magnetic field that protects its atmosphere from escaping into the depths of space, Venus does not possess its own, stable magnetic field. That is because its cooler interior cannot slosh around molten material, a swirling necessary to create and sustain a magnetic field. Rather, sunlight battering on the amber-hued orb charges up its atmospheric atoms, which then create electric currents that produce an unstable, sunlight-dependent magnetosphere.
In August 2021, BepiColombo flew through this weak, comet-shaped magnetosphere for 90 minutes to slow down and adjust its course while heading toward its ultimate target, Mercury. Scientists analyzing data from the spacecraft's fleeting visit, however, found some valuable Venusian information. Charged particles, or ions, appeared to be escaping the planet due to sunlight accelerating molecules in the atmosphere to extremely high speeds. Those speeds were high enough, in fact, that the ions even escaped the planet's gravityand flowed out into space.
"These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play," Lina Hadid, a researcher at the Plasma Physics Laboratory in France who led the new analysis, said in a statement.
Venus' thick, hellish atmosphere is dominated by carbon dioxide, but also holds fewer amounts of nitrogen and other trace gases. Scientists previously knew tiny amounts of oxygen lofted in Venus' night-side and, last November, a different team of researchers detected the molecule on the planet's day-side too. The latter team further concluded that Venus' oxygen concentration drops in tandem with decreasing solar radiation.
Investigating the loss of these molecules and their escape mechanisms "is crucial to understand how the planet's atmosphere has evolved and how it has lost all its water," study co-author Dominique Delcourt, who is also a researcher at the Plasma Physics Laboratory, said in the same statement.
BepiColombo is nearing the end of its seven-year journey and is expected to reach Mercury in late 2025. Meanwhile, a fleet of robotic visitors are scheduled to visit Venus in the coming decade. Europe's Envision spacecraft aims to launch in 2031 while NASA's DAVINCI, originally slated for a 2029 launch, was delayed to 2031.
The resurrected VERITAS mission is now scheduled to launch no earlier than 2031 as well, although team members are still advocating for an earlier launch in November 2029.
This research is described in a paper published Friday (April 12) in the journal Nature Astronomy.
Quelle: SC
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Update: 16.05.2024
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Glitch on BepiColombo: work ongoing to restore spacecraft to full thrust
BepiColombo, the joint ESA/JAXA mission to Mercury, has experienced an issue that is preventing the spacecraft’s thrusters from operating at full power.
BepiColombo is a three-part spacecraft consisting of two scientific probes and the Mercury Transfer Module, which are designed to separate from one another as part of the mission’s Mercury orbit insertion operations.
The solar arrays and electric propulsion system on the Mercury Transfer Module are used to generate thrust during the spacecraft’s complex journey from Earth to Mercury.
However, on 26 April, as BepiColombo was scheduled to begin its next manoeuvre, the Transfer Module failed to deliver enough electrical power to the spacecraft’s thrusters.
A combined team from ESA and the mission’s industrial partners set to work the moment the issue was identified. By 7 May, they had restored BepiColombo’s thrust to approximately 90% of its previous level. However, the Transfer Module’s available power is still lower than it should be, and so full thrust cannot yet be restored.
The team’s current priorities are to maintain stable spacecraft propulsion at the current power level and to estimate how this will affect upcoming manoeuvres. Work continues in parallel to identify the root cause of the issue and to maximise the power available to the thrusters.
The BepiColombo Flight Control Team working at ESA’s ESOC mission control centre in Darmstadt, Germany, has arranged additional ground station passes in order to closely monitor the spacecraft and react rapidly if needed.
If the current power level is maintained, BepiColombo should arrive at Mercury in time for its fourth gravity assist at the planet in September this year. Final orbit insertion at Mercury is scheduled for December 2025 and the start of routine science operations for Spring 2026.
Updates will be shared as new information becomes available.
BepiColombo is a joint mission between ESA and the Japan Aerospace Exploration Agency (JAXA) to Mercury, the least explored planet of the inner Solar System.
The mission features two scientific spacecraft, which will be inserted into different orbits around Mercury: ESA’s Mercury Planetary Orbiter and JAXA’s Mercury Magnetospheric Orbiter. Both continue to perform excellently. Packed with scientific instruments, they are designed to study Mercury’s composition, atmosphere, magnetosphere and history, and to address long-standing questions on the formation and evolution of our Solar System.
Quelle: ESA