Idaho Skies Transcript for February 4th and 5th

PAUL
Welcome to Idaho Skies for February 4th and 5th. We’re your hosts, Paul…

RACHEL
…and Rachel.

PAUL
Forty-five years ago this Tuesday, Mariner 10 became the first spacecraft to use gravity assist to reach a second planet.

RACHEL
The Mariner 10 spacecraft was built by the Jet Propulsion Laboratory and designed to explore the inner solar system. Specifically, its mission was to visit the planets Venus and Mercury. It was the last of the Mariner spacecraft, a series of spacecraft famous for being the first ones to visit the inner planets. 

PAUL
The Mariner series began in 1962 and ended with the launch of Mariner 10 in 1973. Not all the Mariners completed their missions. Three of them failed because of problems with their booster rockets. The first successful Mariner was number 2, which flew past Venus to become the first interplanetary space mission. Another one, Mariner 9, was the first spacecraft to enter orbit around another planet – Mars in this case.

RACHEL
Mariner 10 is famous because it was the first spacecraft to visit two planets, Venus and Mercury. Since Mariner 10 was launched from Earth, it had to lose a lot of potential energy to reach Mercury. Earth orbits the sun at a speed of 19 miles per second while Mercury orbits the sun at 29 miles per second. So losing enough potential energy to fall to Mercury’s distance from the sun meant Mariner 10 also increased speed by 50%. 

PAUL
To reach Mercury, Mariner 10 had to slow down in order to fall closer to the sun. However, its rocket couldn’t provide enough thrust to both reach Earth orbit and then slow the spacecraft down to reach Mercury. Mariner 10 instead used the gravity of Venus to rob enough of its potential energy to fall even closer to the sun. And this was the first time that a spacecraft had used a gravity assist to change its orbit like this. 

RACHEL
That’s Idaho Skies for the 4th and 5th of February.

PAUL
Be sure to follow us on Twitter @IdahoSkies for this week’s event reminders and sky maps.

For Idaho Skies this is Paul…

RACHEL
…and Rachel.

PAUL
Dark skies and bright stars.