4th February 2019

February 5th this week will mark the date when Mariner 10 became the first spacecraft ever to test out and execute a technique known as a planetary gravity assisted flyby used to alter its speed and trajectory- in order to reach another celestial body.

Mariner 10 flew by Venus 45 years ago to enable the probe to gain enough speed and alter its flight path to eventually become humanity’s first spacecraft to reach the planet Mercury, closest to our sun.

It was the first spacecraft to visit two planets.

From that moment on, gravity assisted slingshot maneuvers became an extremely important technique used numerous times by NASA to carry out planetary exploration missions that would not otherwise have been possible.

The Mariner 10 probe used an ultraviolet filter in its imaging system to bring out details in the Venusian clouds which are otherwise featureless to the human eye – as you’ll notice when viewing it through a telescope.

Venus’s surface is completely obscured by a thick layer of carbon dioxide clouds.

The hellish planet’s surface temperature is 460 degrees Celsius or 900 degrees Fahrenheit.

Following the completely successful Venus flyby, Mariner 10 eventually went on to conduct a trio of flyby’s of Mercury in 1974 and 1975.

It imaged nearly half of the planet’s moon-like surface, found surprising evidence of a magnetic field, discovered that a metallic core comprised nearly 80 percent of the planet’s mass, and measured temperatures ranging from 187°C on the dayside to minus 183°C on the nightside.

Mercury was not visited again for over three decades until NASA’s MESSENGER flew by and eventually orbited the planet.

Mariner 10 was launched on Nov. 3, 1973 from the Kennedy Space Center atop an Atlas-Centaur rocket.

Shortly after blastoff if also took photos of the Earth and the Moon.

Ultimately it was the last of NASA’s venerable Mariner planetary missions hailing from the dawn of the Space Age.

Mariner 11 and 12 were descoped due to congressional budget cuts and eventually renamed as Voyager 1 and 2.

Source: https://www.universetoday.com/109035/mariner-10-best-venus-image-and-1st-ever-planetary-gravity-assist-40-years-ago-today/