Carnival of Space 609

The Carnival of Space 609 is up at Universe Today.

Universe Today – Methane-Filled Lakes on Titan are “Surprisingly Deep”.

During Cassini’s final flyby of Titan, it aimed its radar at some of the moon’s liquid lakes. The data shows that those lakes are up to 100 meters (300 ft) deep. The data from those final days also sheds new light on Titan’s hydrocarbon cycle. Hydrocarbon rains feed the lakes, which then are subject to evaporation. Some of the liquid seeps into the subsurface, which would leave reservoirs of liquid hydrocarbons below the surface.

Universe Today – TESS Just Found its First Earth-Sized World.

NASA’s new exoplanet-hunting telescope, TESS (Transiting Exoplanet Survey Satellite), just found its first Earth-sized world. Mission planners expect TESS should find about 300 Earth-sized or Super-Earth-sized exoplanets in its two-year mission. The mission was designed to find the smaller Earth-size ones. The Kepler space telescope found more planets but they were larger planets.

Nextbigfuture – SpaceX Crew Dragon Had a Problem

Nextbigfuture – Turbo Rocket – A Single-Stage to Orbit Air-Breathing Rocket

Nextbigfuture – Breakthrough Starshot Update #SpaceAccess2019

Nextbigfuture – Antimatter Catalyzed Fusion Propulsion Update

3 thoughts on “Carnival of Space 609”

  1. I thought the greater mass could compress an earthlike composition to greater density, so *maybe* a thicker atmosphere than earth’s would be needed to give the observed density.
    Thanks for checking that out.

  2. You got me interested so I went to the original paper.

    The reasoning seems to be that the other rocky planets of similar size have a calculated density of about 7.8 g/mL, while this HD 21749b works out at 7.0 g/mL.

    They appear to assume that rocks will compress to the same density on a planet of the same size, so if one planet is less dense this should indicate that there is a thick atmosphere to bulk out the radius without adding much mass.

    I think there are assumptions there about a consistent chemical makeup and gravity resulting in consistent density that are probably common knowledge in the exoplanet researcher community and so are unstated.

    It was the summary by Universe today that turned “mostly solid rock but with a significant atmosphere” into “not rocky”.

  3. From the Universe Today article about the planets found by TESS
    “The sub-Neptune, HD 21749b, has about 23 times the Earth’s mass and its radius is about 2.7 times that of Earth. The measured density suggests that the planet is not rocky,”

    Calculating from the given Mass & Radius, I get a density a bit greater that that of earth, which indicates it is mostly rock & iron.

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