Issue No. 75

The Orbital Index

Issue No. 75 | Jul 29, 2020

🚀 🌍 🛰

Our Questions to Heaven are one step closer to being answered. Following on the heels of UAE's Hope, China’s Tianwen-1 mission (translated 'Questions to Heaven') launched on a Long March 5 booster carrying an orbiter, retropropulsive lander, and 240 kg solar-powered rover (we featured China’s ambitious first planetary lander mission in Issue No. 64). Tianwen reported successful trans-Mars injection and was caught on security cam by the ATLAS-MLO planetary defense telescope (which has a lovely dashboard). After its 7-month journey, the orbiter will enter a highly elliptic orbit. After several additional months surveying the landing area, the lander and rover will descend using a combination of blunt body aeroshell, supersonic parachute, and finally, a retropropulsion system similar to the ones used for Chang'e 3 & 4. The duo should land south of Viking 2 in the Utopia Planitia (map of Mars landing sites). The orbiter will both relay signals and continue to conduct science with its 2 cameras and 5 other instruments for 1 Martian year, similar to UAE's orbiter (covered last issue). Meanwhile, the rover will survey the Martian surface for a 90-day primary mission. It's similar to NASA's Spirit and Opportunity rovers, but with different science goals, including subsurface radar (China's Yutu-2 rover found regolith layers that suggested a violent Lunar history using a similar instrument). Related: NASA’s Perseverance launch is targeted for 7:50 a.m. EDT this Thursday, July 30, and you could attend a (very early morning) virtual launch party.

Venus has active volcanic geology. Scientists have identified 37 active or recently-active volcanic structures on Venus (paper). Evidence for a volcanically-active Venus has been building for a while: the surface appears to generally be just 300–700 million years old (indicating some sort of resurfacing, possibly massive lava flows) and we found a volcanic peak that is hotter than its surroundings (which have a modest surface temperature of 450°C). It’s generally thought that Venus doesn’t have global plate tectonics because it lacks oceans, but even without tectonic plates, these and other findings support it still being quite volcanically active. An active Venus may help the proposed NASA VERITAS mission win approval—VERITAS’s powerful radar, near-infrared spectrometer, and gravimeter and would map the planet’s surface and geological history, possibly providing hints of a watery (and less face melty) past. VERITAS’s spectrometer would also determine which surface rocks were recently formed from magma flows. Here are a few recent favorites about the hottest planet in the solar system:

Akatsuki, the only craft currently operating at Venus, studies the planet’s atmosphere in infrared and ultraviolet. This image was taken with the IR2 camera of nightside heat from the lower atmosphere.

Russia appears to have fired a space-based weapon. The US Space Command and the UK condemned a space-based anti-satellite weapons test performed by Russia’s Kosmos-2543 that appears to have launched a fast-moving, anti-satellite projectile while in orbit—possibly an unfortunate first. Kosmos-2543 itself is a sub-satellite that was deployed from Kosmos-2542, an “inspection” satellite which maneuvered near the NRO’s USA 245 Keyhole 11 spy satellite. Jonathan McDowell said an analysis suggests that “Kosmos 2543 released the mysterious object July 15 at a relative velocity of more than 400 mph, or about 700 kilometers per hour.”

News in brief. Dawn Aerospace announced their Dawn Mk-II Aurora reusable space plane, capable of hosting a 3U payload on suborbital flights multiple times per day from commercial runways (intro video); a Russian Progress MS-15 cargo vehicle launched from Baikonur on Thursday to resupply the ISS, despite Baikonur’s growing COVID-19 outbreak; Virgin Orbit’s failed first launch of LauncherOne was due to a propellant line break; and, Demo-1 is scheduled to leave the ISS on Sunday and splash down somewhere off the coast of Florida.

An image, captured by the SPHERE instrument on ESO’s Very Large Telescope, shows a star 300 light-years away with two giant exoplanets—the first ever of 2+ planets orbiting a star similar to our own. (The star is being blocked by SPHERE’s coronagraph so that the planets can be seen.)

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