Astronomy Picture Of The Day: Japan's Akatsuki spacecraft embarked on an epic journey to unravel the secrets of Venus!!!

 

#NASA, #Space, #astronomy, #διάστημα

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Japan's Akatsuki spacecraft—named for the Japanese word meaning "dawn"—embarked on an epic journey to unravel the secrets of Venus, Earth's scorching, cloud-shrouded twin. Launched by JAXA on May 20, 2010, the Venus Climate Orbiter faced immediate heartbreak: a main engine failure during its first attempt at orbital insertion in December 2010 sent it hurtling past the planet into a lonely solar orbit.Undeterred, mission engineers executed a masterful recovery using the spacecraft's smaller reaction control thrusters for a low-energy orbital maneuver. On December 7, 2015—five years later—Akatsuki finally slipped into a highly elliptical orbit around Venus, poised to begin its groundbreaking science campaign.From its vantage point, Akatsuki peers through Venus's thick sulfuric acid clouds with a suite of sophisticated instruments: ultraviolet, visible, and infrared cameras (UVI, IR1, IR2, and LIR) that capture the planet in multiple wavelengths. These tools track super-rotating winds (where the atmosphere circles the planet in just four Earth days, far faster than Venus's 243-day retrograde rotation), atmospheric waves, lightning flashes, and colossal storm systems churning in the hellish greenhouse environment.Among Akatsuki's most stunning revelations is the discovery of immense, planet-spanning wave structures. Just hours after entering orbit in 2015, the spacecraft imaged a colossal bow-shaped stationary gravity wave—a massive, curved feature stretching nearly 10,000 kilometers (over 6,000 miles) from near the north pole to the south, hovering motionless above the highlands of Aphrodite Terra despite screaming 100 m/s winds. This "sideways smile" in the clouds, caused by airflow rippling over mountainous terrain and propagating upward as gravity waves, appeared repeatedly over elevated regions and persisted for weeks or a month at a time.Other breakthroughs include a powerful equatorial jet stream racing through the lower cloud layers, planetary-scale streak patterns slicing across both hemispheres (revealed in 2019 infrared images and confirmed by climate simulations), and a deep, propagating cloud discontinuity—a giant atmospheric disruption unseen elsewhere in the solar system—that lashes the equator periodically at about 50 km altitude, undetected for at least 35 years until Akatsuki spotted it.These phenomena illuminate the bizarre super-rotation and circulation of Venus's atmosphere, offering clues to why such extreme greenhouse conditions trap heat so efficiently and how planetary climates can evolve into runaway states. Akatsuki's data continues to reshape our understanding of Venus as a cautionary tale for Earth's own climate future.After a decade of extraordinary observations, the mission concluded in 2025: contact was lost in April 2024, and JAXA formally ended operations on September 18, 2025, deeming the spacecraft beyond its design life yet having far exceeded expectations.This mosaic of infrared views from Akatsuki's IR2 camera showcases swirling lower-cloud patterns, chaotic vortices, and dramatic wave-like features piercing Venus's veiled atmosphere. Image credits: JAXA / ISAS / Akatsuki team (various releases, including IR2 observations and processed composites.