Just next door, cosmologically speaking, is a planetalmost exactly like Earth.
Thats a question that preoccupies an ever-growing number of planetary scientists, and motivatesnumerous proposed Venus exploration efforts.
Im a planetary scientist, and Im fascinated by how other worlds came to be.
The surface of Venus as seen in these reprocessed perspective image panoramas from the Soviet Venera 13 lander.
Don P. Mitchell, CC BY-SA
A once-blue Venus?
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With ever more water vapor in the atmosphere, the planet entered arunaway greenhousecondition from which it couldnt recover.
An artists impression of what a formerly water-rich Venus may have looked like.
For example,radaris needed to pierce the opaque, sulfuric acid clouds and see the surface.
Thats a lot trickier thanthe readily visible surfaces of the Moon or Mercury.
Thats a far cry from Mars,where rovers can operate for more than a decade.
Visible-wavelength light is unable to penetrate the thick cloud layer on Venus.
Instead, radar is required to view the surface from space.
This is a global radar image mosaic of the planet, compiled with data returned by the Magellan mission.
Humans havent always ignored Venus.
And theVenera 13 landerwas the first spacecraft to return sounds from the surface of another world.
But the last mission NASA launched to Venus wasMagellanin 1989.
That spacecraft imaged almost the entire surface with radar before its planned demise in the planets atmosphere in 1994.
The Magellan mission was launched from Atlantis cargo bay on May 4, 1982.
The spacecrafts high gain antenna is visible at the top of the image.
NASA
In the last few years, several NASA Venus missions have been proposed.
The most recent planetary mission that NASA chose is a nuclear-powered craft calledDragonfly, destined for Saturns moon Titan.
However, one proposal to measure the composition of the Venus surfacewas selected for further technology development.
Some 30 years after NASA set course for our hellish neighbor, the future of Venus exploration looks promising.
But a single mission a radar orbiter oreven a long-lived lander wont solve all the outstanding mysteries.
That will take time and money, but I believe its worth it.
And, under an ever-brightening Sun, Venus may even help us understand the fate of Earth itself.
