¶GOES-T and Weather Sats. GOES-T, NOAA’s latest generation geosynchronous satellite, recently completed vibration, vacuum, and acoustic testing ahead of its December launch. GOES-T packs upgraded traditional weather observation instruments (video intro), including the 16 channel ABI imager (up from 5 channels on the previous generation) with 0.5km - 2km resolution (4x the previous gen). This generation also includes GLM, the first lightning mapping system flown in geostationary orbit, which should increase lead time for severe storm warnings and decrease false positives—lightning mappers, aka optical transient detectors, function by detecting the momentary changes in a single near-infrared band. Here’s a near real-time lightning data visualization from GOES-T’s sister satellite, GOES-16. While NOAA moves toward launching this third of four massive GEO satellites that make up the $10.8 billion GOES-R program, smallsat startups at the other end of the spectrum are filling gaps in weather data, bringing commercial forecasting data availability up to the level of optical and SAR Earth observation data. Care Weather recently launched their first test sat with Rocket Lab (developed in just 3 months), with two more planned soon. Care Weather is focused on fast iteration on its way to bringing measurements of radar-derived ocean winds from twice a day to every hour. In November, NOAA issued its first purchase contracts for radio occultation (RO) data from GeoOptics and Spire. RO measures the Doppler shift of a received signal (usually from a GNSS source like GPS satellites) due to bending in a planet’s atmosphere and uses it to produce high-quality temperature, pressure, and moisture data—RO was used by Mariner to measure the existence of an atmosphere on Mars. NOAA wants these providers to generate 20,000 measurements per day and seems to be particularly interested in the application of this data to hurricane forecasting—a previous RO mission, COSMIC, was able to improve typhoon path prediction by 24%. (Related: A couple of weeks back, NOAA’s decommissioned polar-orbiting NOAA-17 weather satellite broke up into 16 trackable fragments—there is no evidence of a collision, which is consistent with this chart explaining the origins of extant space debris.) |
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¶Papers. - Instead of escaping into space, a new study in Science suggests that Mars’ water went underground 3 billion years ago, with 30-99% of Mars’s water still locked up in its crust in hydrated minerals. If the planet’s water was absorbed instead of lost to space, it would help explain both oddly high water readings in the crust and an oddly low ratio of deuterium in the Martian atmosphere, which should have been concentrated as normal hydrogen and oxygen escaped over billions of years. Perseverance is now in a 3.8 billion years old former lake bed, so we will hopefully gather more clues soon. Related: Earth’s mantle may also contain a surprising amount of water—enough that Earth might have been a waterworld (sans Kevin Costner 😢) when it formed.
- The spectral signatures of old white dwarf stars can show evidence of the long-dead planets that they consumed (paper). Stars like our Sun expand and absorb their inner planets when they die, becoming red giants and eventually white dwarfs. Absorbed planetary elements would glow when heated, but not enough to be seen through the brightness of most stars. However, very old and cool white dwarfs are faint enough that Gaia was able to map dozens of them, finding elemental signatures much like those of planets found in our solar system. This suggests that planets have existed in the Universe for a very, very long time.
- Additional tests of the EmDrive unsurprisingly (but disappointingly) show no anomalous thrust, attributing previous readings to thermal effects (1, 2, 3). Kudos, though, to the scientific process through which these accurate negative results were published and that pushed forward measurement technology along the way. “With both the EmDrive and the LemDrive, we have achieved a measurement accuracy that is below the photon pressure. That is, even if one of these concepts worked, it would be more effective simply to use a laser beam as a drive.”
- The zodiacal light, visible at dusk and dawn as a faint column of light at the horizon, is created by sunlight reflected by dust particles in the inner solar system. These particles, previously thought to be from comets and asteroids, may actually be from Mars (paper). The incidental finding comes from dust particles slamming into the (luckily well-protected) backside of Juno’s solar panels at about 4.4 km/s as the probe passed through the inner solar system. This detection was only possible due to Juno’s massive solar panels having 1,000 times the collection area of most dust detectors, and now raises the question of how the dust is escaping Mars. We appreciate the light show, though!
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 | The zodiacal light (aka false dawn) is now thought to be caused by Martian dust. |
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¶Etc. - Seraphim and AWS are launching the AWS Space Accelerator. Applications are due in 13 days.
- The eventual goal of Ian Webster’s spacereference.org is to “catalog and showcase every known object in space.” It’s built on the open source spacekit.js, which also powers Asterank and a number of other sites.
- More about the characterization of Apophis’s orbit: the latest issue of the ESA NEO Coordination Centre’s newsletter talks about a successful recent stellar occultation of Apophis—stellar occultation is when a distant object briefly eclipses a star, determining the object's orbit (and sometimes shape). “Successfully detecting an occultation event is always a challenge, but it becomes much harder when the occulting body is a small NEO, only ~350 m in diameter. This is because the ground track of the event is only as wide as the asteroid itself, and therefore the exact location of the event must be predicted to that level of accuracy.” Based on accurate radar ranging data and Gaia’s fantastic stellar position measurements, three observers were able to detect the disappearance of the target star for about 0.2 s as Apophis moved in front of it, providing sub-milliarcsecond astrometric measurements.
- Mars InSight has detected over 500 Marsquakes so far, including two recently of magnitude 3.3 and 3.1 from the Cerberus Fossae region, an area with very young (geologically speaking) surface features. While Mars doesn’t have active tectonic plates, it has had volcanic activity in the recent past, and may still today.
- Images from the ground of MEV-2 (the second Northrop-Grumman satellite servicing mission) carefully approaching Intelsat 10-02.
- Inside the digital clock from a Soyuz spacecraft.
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