Juno in Jupiter’s orbit →

Last night was an exciting one for space fans. Five years after launch, NASA’s Juno spacecraft entered orbit around Jupiter.

That isn’t a simple thing to accomplish. The spacecraft had to slow down enough to be captured by the planet’s gravity to swing around the gas giant. Slow down too much and the orbit would be too wide; miss the mark and the spacecraft could have met an early demise.

Here’s Phil Plat describing that process:

The engine burn was tense. 35 minutes is a long time for a spacecraft burn; after 20 minutes it had slowed Juno enough to be in orbit, but not the correct one. It had to continue for another 15 minutes to put the spacecraft on the correct orbit. It worked essentially perfectly. The burn time was off by just one second. That will have no real effect on the orbit.

Science isn’t starting today, though. Juno is currently in a highly elliptical orbit that will take 53 days to complete. On it’s return pass, the instruments will come on and readings will begin. After it’s second elliptical trip, (named a Perijove pass) there will be a second burn that will allow Juno to circle the gas giant from its north pole to its south every 14 days.

During these orbits, scientists hope to learn about Jupiter’s origins and much more.

This is an exciting time. Jupiter is a very hostile place, and Juno is only the second spacecraft dedicated to studying it. (Galileo was the first.) Knowing how Jupiter formed and more about it will help unlock the mysteries of not only our solar system, but of the whole universe.

Should be fun.