What space exploratios have there been to Venus?

Answer 1

That depends on whether you mean surface probes, orbital probes, or fly-bys. Many probes have flown by Venus on their ways to other planets like Jupiter and Saturn, without being actual missions to Venus. It is a popular planet to use for gravitational slingshots to the outer solar system. Most recently, MESSENGER flew by Venus on its way to Mercury, missing Venus' upper atmosphere by only 300 kilometers the second time.

In general, Venus is the most-probed planet in the solar system, after Earth.

The United States' Mariner program and the USSR's Венера (Venera) program were the first to send probes to Venus.

Венера-1 was the first probe of any sort ever launched at Venus, but it failed to transmit data upon arrival. Венера-2followed after and also failed to transmit data.

Mariner 2 was the first functioning probe to reach Venus.

Венера-3 was the first man-made object to ever reach the surface of another world, crash landing on Venus.

Венера-4 was the first probe to enter the atmosphere of Venus and send data back about it.

Mariner 5 flew by Venus the day after Венера-4 entered the atmosphere, and measured the planet's electromagnetic fields and emissions.

Венера-5 and 6 both had the same mission as Венера-4, but had additional experimental apparati.

Венера-7 was the first to land on Venus intact and transmit data back.

Венера-8 had the same mission as Венера-7, but had additional experimental apparati.

Mariner 10 probed Venus on its way to Mercury. It was the last Mariner probe to reach Venus.

Венера-9 was the first man-made object to ever return a photograph of the surface of another world. The orbiter was also the first probe to actually orbit Venus, rather than either fly by or land.

Венера-10 had the same mission as Венера-9, but had additional experimental apparati.

Pioneer Venus 1 and 2 were orbital and atmospheric probes.

Венера-11 and 12 were fly-by and surface probes, which failed to return any images, due to the lens caps of the cameras not coming off. They also analyzed soil samples (GC-MS and X-ray).

Венера-13 was the first man-made object to ever return a color photograph of the surface of another world, and also analyzed soil samples.

Венера-14 had the same mission as Венера-13, but had additional experimental apparati, including a seismometer.

Венера-15 and 16 were orbital radar mapping probes, providing the first detailed radar maps of the surface of Venus. They were the last Venera probes sent by the USSR.

At this point, the Soviets launched ВеГа-1 and 2 (VeGa, for Венера-Галлей, Venus-Halley), probes with the goal of simultaneously studying Venus and Halley's comet. They used Venus as a slingshot to reach the comet, and dropped landers and helium balloons on Venus as they passed.

Next comes the Magellan probe, the first space probe launched on the Space Shuttle. Its mission was to take high-resolution orbital images of Venus, which are still the best-quality images we have of the planet.

Finally, Venus Express, a project of the European Space Agency, is orbiting Venus right now, and is transmitting data back.

There are many more planned missions to Venus, including Japan's Venus Climate Orbiter planned for 2010, the ESA's Venus Entry Probe planned for 2013, and Russia's Венера-Д (Venera-D) planned for 2016.

That's a grand total of 25 missions to Venus so far, with one still ongoing.