Spacecraft have explored Venus with radar and other techniques, uncovering evidence of its poisonous atmosphere of carbon dioxide and sulfuric acid.
Magellan was among the first ships to map Venus’ surface using its radar altimeter to measure topographic changes on its surface.
Parker Solar Probe’s WISPR camera captured nightside photos of Venus that can be seen by humans, showing darker regions at higher elevations – similar to Earth.
Magellan
The Magellan spacecraft was named in honor of Ferdinand Magellan, who in 1520 became the first European to navigate through the Straits of Magellan in southern Patagonia and open a new route to Asia. Launched on May 4, 1989 from its payload bay aboard Atlantis shuttle ship and entered Venus orbit eight months later on August 10, 1990 by using its Synthetic Aperture Radar it mapped Venus surface with resolutions as fine as 120 meters.
Researchers using Magellan radar images discovered changes to Sif Mons, an active Venusian volcano. Robert Herrick from University of Alaska Fairbanks and Scott Hensley from NASA’s Johnson Space Center used eight month difference radar images taken eight months apart to examine this volcano, noting it grew larger and altered its shape, suggesting it remains active. Their discovery will aid researchers as they try to better understand how Venus has developed into such an inhospitable place with volcanic plains covered by volcanic plains and an unwelcoming atmosphere.
Venera
Soviet Venera probes were heavy-duty spacecraft venus designed to collect data about both its surface and atmosphere of Venus. Each probe consisted of a cruise “bus” and atmospheric entry probe – with the former relaying data back to a lander while the latter made direct measurements of Venus’ atmosphere.
These instruments included UV absorption spectrometers and aerosol particle-size analyzers which demonstrated that clouds contain sulfuric acid droplets. Other instruments measured atmospheric hydrogen and nitrogen concentrations as well as surface K, U and Th measurements as well as gamma ray spectra.
Venera missions began with an impactor designed to collate atmospheric data. Later missions managed to land successfully on Venus; one, named Venera 13, only lasted 127 minutes, though all other landings, including Venera 9 and 10, sent back surface images of another planet.
Mariner
NASA’s Mariner 2 passed close to Venus in 1962, altering how scientists view Earth’s nearest neighbor. They now saw it as an earth-heating global hothouse whose dynamics may provide clues to protecting Earth from future such events.
Magellan launched its radar system into Venus’ clouds for the first time in 1989 to map this strange world with few craters and many volcanoes, and uncover a multitude of volcanoes – but also raised questions of why Venus has changed into such an uninhabitable place?
Now, with DAVINCI+ and Rocket Lab-MIT missions set to take place simultaneously, an army of spacecraft are ready to penetrate our planet in search of trace gases, water vapor and pressure data and transmitting that back up to orbiters above. Free-fall probes will descend towards Earth’s surface to collect information such as trace gases, moisture content and pressure analysis before relaying data back up into orbiters for analysis.
Pioneer
Venus researchers lamented for decades the lack of missions dedicated to studying their nearest neighbor; but suddenly in June 2021 their wish was granted: NASA agreed to two new missions called VERITAS and DAVINCI while Europe approved EnVision, all three scheduled to conduct observations beginning in 2030s.
Pioneer Venus probes used radar to produce an in-depth map of their home planet, discovering evidence of vast lakes and rivers on Venus as well as “tesserae,” or rock layers with distinct edges that could either have preserved remnants of ancient water bodies or indicated global volcanism.
Venera and Mariner probes failed to thrive due to extreme heat and atmospheric pressure; only Venera 7 managed 50 minutes on the surface, but NASA is launching DAVINCI with an expected descent probe that should send data for about an hour after landing.