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  • [♪ INTRO]

  • Even though we've spent decades exploring the solar system,

  • we've really only done it in two dimensions, generally speaking.

  • But that makes sense.

  • Since the planets are all on the same plane, called the ecliptic,

  • we haven't needed to go way above or below the solar system.

  • Everything we need to study is sitting nice and cozy in that plane.

  • Well, almost everything.

  • From the ecliptic, it's almost impossible to study the area around the poles of the Sun,

  • which, like the rest of our star, we're super interested in learning about.

  • That is where the Ulysses mission came in.

  • In 1990, NASA and the European Space Agency launched the first real orbiter to go

  • out of the ecliptic, and it gathered tons of solar data for about eighteen years.

  • It revolutionized our understanding of our star,

  • but there's a reason we haven't sent another one yet.

  • Out-of-ecliptic missionsare kind of a pain.

  • All the planets orbit in the same plane because they formed from the same

  • big, spinning disk of stuff.

  • And getting out of that plane is really difficult.

  • When you launch something from a moving body inside the ecliptic, like the Earth,

  • your probe will automatically start traveling in a direction that keeps it inside that plane.

  • To get out, you have to cancel all that motion and move

  • basically perpendicular to where you started.

  • It's hard, and none of our rockets can pull it off right from launch.

  • But Ulysses made it happen, thanks to some cool engineering.

  • Usually, when we launch something that's gotta go

  • pretty far, pretty fast, we use a gravity assist.

  • Basically, you get close to a large body, like a planet,

  • then use its gravity to slingshot yourself along a new path with a higher speed.

  • And that's true for out-of-ecliptic missions like Ulysses, too.

  • You just have to get creative with it.

  • After leaving Earth, Ulysses went to Jupiter, which, as the most massive planet, can impart

  • a huge amount of acceleration to anything that gets close enough.

  • It flew up over Jupiter's poles, then let the planet's

  • gravity sweep it over and back under itself.

  • That got Ulysses going perpendicular to the ecliptic,

  • and flying back toward the point where it started, essentially going backward!

  • Then, it started its big loop around the Sun.

  • Getting Ulysses out of that plane allowed it to study the Sun from a different angle,

  • including its magnetosphere, composition, and solar winds.

  • But that's not all the mission did.

  • It also carried instruments to study dust in the solar system and ones to look beyond

  • the Sun at cosmic rays that come from really energetic sources, like black holes.

  • And it was all totally worth it!

  • Over almost two decades, Ulysses made nearly

  • three full passes over the Sun, and it taught us a lot.

  • Like, more than a thousand articles worth of stuff!

  • For one, Ulysses's unique perspective allowed us to make the first

  • 3D survey of our star's magnetosphere and composition.

  • It also took the first direct measurements of interstellar dust and showed that

  • tons of it is flooding into the solar system; up to thirty times more than we thought.

  • And because Ulysses was active for so long, it managed to gather data over about one and

  • a half solar cycles, which meant it could even see how the Sun changed over time.

  • Every six-ish years, the Sun is either super active,

  • with lots of flares and sunspots, or pretty quiet.

  • And Ulysses showed that things like the solar wind, the flow of charged particles from the star,

  • actually change depending on its activity level.

  • It found that the solar winds are getting weaker in general, too!

  • We think that coincides with a natural reduction in the Sun's magnetic activity,

  • but we don't know just how, or if and when that trend will stop.

  • Either way, understanding these changes is super important to us on Earth,

  • because the solar winds can damage electronics on the

  • International Space Station and in satellites.

  • Like, telecommunications satellites.

  • Which we need to tweet! And, you know, call 911 sometimes.

  • Because of Ulysses's discovery, we're better able to predict the behavior of the

  • solar winds, so we're better able to protect astronauts in space

  • and our precious, precious internet.

  • And looking much farther from home, Ulysses was also a

  • player in confirming the existence of magnetars.

  • These are a type of neutron star with super strong magnetic fields, which emit

  • big doses of gamma radiation... kinda whenever they feel like it.

  • At least, based on what we know now.

  • Along with a few other satellites, Ulysses snagged observations of only the fourth confirmed

  • magnetar in 1998, one that was even brighter than the others.

  • The magnetar hypothesis had just started to become accepted,

  • so these measurements were really valuable to researchers.

  • And the list of Ulysses's discoveries goes on from there.

  • The mission ended in 2008, and there are now mountains of papers and books

  • all using its data.

  • So even though getting out of the ecliptic was tricky, it was definitely worth it.

  • So worth it that we're gonna launch another one!

  • Today, the ESA and NASA are working on another out-of-ecliptic mission called Solar Orbiter.

  • It'll launch in 2020 and orbit at an inclination of 25 to 34°,

  • which isn't as dramatic as Ulysses but will still give us more exciting, 3D data about the Sun!

  • For now, though, scientists are still pouring over that data from the first mission.

  • So we'll have plenty to keep us busy until then.

  • Thanks for watching this episode of SciShow Space!

  • If you want to keep up with the latest space news, including future missions like Solar Orbiter,

  • you can go to youtube.com/scishowspace and subscribe.

  • We release brand-new news episodes every Friday!

  • [♪ OUTRO]

[♪ INTRO]

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