Where Did The Air Go? Bruce Jakosky on the MAVEN Mars Mission

Episode Summary

Executive Summary: Planetary Radio covers major AGU conference updates: Curiosity’s first solid methane detection on Mars and Rosetta’s striking comet images, then interviews MAVEN PI Bruce Jakosky about early results showing unexpected solar-wind penetration, atmospheric variability, and the Siding Spring comet encounter. The episode closes with a sky update, space history, a trivia winner, and a new contest.

Main Topics: Curiosity detects methane on Mars: Emily Lakdawalla reports that Curiosity definitively measured background methane plus a two-month spike, raising questions about source, localization, and whether it is Martian or rover-related contamination. Rosetta’s early comet imagery and dust results: The AGU briefing revealed highly detailed OSIRIS close-ups and dust-aggregate images that suggest fluffy, primitive comet structure and offer clues to solar system formation. MAVEN’s early mission results: Bruce Jakoski explains that MAVEN is functioning well and has already observed unexpected solar-wind penetration into the ionosphere, opening new questions about atmospheric escape. Comet Siding Spring’s effect on Mars and MAVEN: MAVEN safely shielded itself during the comet flyby, then measured metal ions and a new ionospheric layer created by comet dust, implying a dramatic meteor storm on Mars. Mars as an integrated system: Jakoski emphasizes that atmosphere, upper atmosphere, surface magnetism, and solar input must be studied together to understand Mars climate evolution and atmospheric loss. Weekly skywatch, trivia, and community updates: Bruce Betts provides a night-sky preview, a Saturn ring fact, contest details, and the show announces a new iTelescope winner and another quiz question.

Key Arguments: Curiosity’s methane detection is strong observationally, but the source remains uncertain; investigators ruled out many rover-related explanations yet cannot fully prove Martian origin. The methane spike appears to be localized in space and time, likely near Gale Crater, because it rose and disappeared quickly. Rosetta’s imagery suggests comets may be made of very primitive, fluffy aggregates, supporting theories about early solar system building blocks. MAVEN is already beyond basic checkout and producing scientifically meaningful early data despite being only about a month into primary operations. Solar wind can penetrate deeper into Mars’ ionosphere than expected by becoming neutral through charge exchange, then re-ionizing. Surface conditions such as crustal magnetism and dust storms can influence upper-atmospheric structure, showing Mars’ atmosphere is dynamically coupled from bottom to top. The Siding Spring flyby provided a natural experiment, letting MAVEN detect metal ions and estimate a dramatic meteor storm at Mars. MAVEN complements Curiosity by focusing on atmospheric escape and solar interactions rather than methane or surface geology.

Data Points: Methane background level on Mars: 0.7 parts per billion - Curiosity detected low background methane in Gale Crater using its tunable laser spectrometer enrichment method. Methane spike level: 7 parts per billion - A two-month spike was measured at roughly 10 times the background methane level. Spike duration: about 2 months - Observed methane enhancement reported by Curiosity. AGU conference attendance: more than 20,000 geologists - Emily describes the American Geophysical Union conference as overwhelming in size. OSIRIS cliff-feature size: 2–3 meters across - Rosetta close-up images showed gumball-like/dinosaur-egg structures in a comet cliff face. Comet/spacecraft relative speed: 56 kilometers per second - MAVEN described the velocity of dust from Comet Siding Spring relative to Mars and the spacecraft. Mission primary duration: 1 Earth year - MAVEN’s nominal approved primary mission length. Possible extended mission duration: up to 10 years - MAVEN had excess fuel that could support a long extended mission. Meteor rate on Mars during comet encounter: thousands to tens of thousands per hour - Estimated surface-visible meteor storm from Siding Spring debris. Ariane rocket first launch anniversary: 35 years - Bruce Betts’ space history segment notes the first ESA Ariane launch. Saturn ring thickness analogy: DVD thick over 33 kilometers in diameter - Used to illustrate how extraordinarily thin Saturn’s rings are relative to their width.

Pivotal Quotes: "we've detected the very low background levels at about 0.7 parts per billion, which is very low, but detectable" — Emily Lakdawalla: Explaining Curiosity’s methane result and the method used to measure it. "what we're seeing on Mars, though, is exactly that kind of penetration where stuff very deep in the ionosphere has the same energy, the same speed as the solar wind" — Bruce Jakoski: Describing MAVEN’s surprising observation of deep solar-wind penetration. "If you were there and seeing this at night, you would see thousands to tens of thousands of meteors streaking through the sky per hour" — Bruce Jakoski: Estimating the visual impact of Comet Siding Spring debris hitting Mars’ atmosphere.

Implications: The episode underscores Mars as a connected system: methane, atmospheric loss, surface magnetism, and solar forcing must be studied together. MAVEN and Curiosity provide complementary clues, while Rosetta is revealing primitive cometary building blocks.