Nov 12: Philae Lands on a Comet, Voyager 1 Reaches Saturn and Titan

Host 1 Welcome to this day in space and astronomy on this day November 12th well we are looking at two incredible moments where humanity basically threw a dart across the solar system

Host 2 yeah once to skim the hazy skies of a moon and you know once to try and harpoon a bouncing comet

Host 1 right today's deep dive explores these historic milestones and we're keeping the focus on the people the risks involved and just the plain spoken discoveries we got from our search for the solar system's origins

Host 2 So, let's start back in 1980.

Host 1 Uh-huh.

Host 2 At 2346 UTC, so just before midnight, Voyager 1 made its closest approach to Saturn.

Host 1 Right.

Host 2 And there's this funny quirk in the records. NASA says the flyby distance was about 126,000 kilometers, but the Planetary Data System records it as 184,300 kilometers from Saturn's center.

Host 1 Wait, really? That's a pretty big gap.

Host 2 It is, yeah. But regardless of which tape measure you use, the discoveries just well they reshaped how we understand the rings, the probe found five new moons, the G ring, and what we call shepherd moons.

Host 1 I love the whole concept of shepherd moons. Like instead of just orbiting, their gravity is actively herding the ice and dust.

Host 2 Exactly yeah.

Host 1 Keeping the edges of the rings sharp sort of like cosmic sheepdogs.

Host 2 That's a great way to put it. But the real jaw dropper of this particular flyby was Titan. Voyager 1 passed just 6,490 kilometers from Saturn's largest moon

Host 1 So close.

Host 2 Right? And the atmosphere was so thick that it entirely hid the surface. But the sensors picked up that it was 90% nitrogen, just packed with complex hydrocarbons.

Host 1 Which is, you know, a huge deal for us now, right?

Host 2 Oh, absolutely. Titan's chemistry acts like a primordial freezer. It shows us that reactions leading toward life might actually be possible out there in the deep cold.

Host 1 But getting that close look, I mean, that was a huge sacrifice for the mission. For those listening, think of it like taking a highway exit at 100 miles an hour to get that close to Titan, Voyager 1 had to dive under Saturn's rings.

Host 2 Yeah, it did.

Host 1 And the gravity just slingshotted upward, right? Throwing it entirely off the orbital plane of all the other planets. We traded a grand tour of Uranus and Neptune just for a close-up of Titan. So why make that trade?

Host 2 Well, because it came with an extraordinary payoff. By flinging Voyager 1 north, you know, out of the planet's plane, we inadvertently sent it on a direct path to the stars.

Host 1 Wow.

Host 2 Yeah. It crossed into interstellar space in August 2012. And today, it's nearly one light day from Earth. And remarkably, that 1970s technology is still transmitting data.

Host 3 back to us right now.

Host 4 That is just amazing. So Voyager showed us what those life building blocks look like in an atmosphere. But our next milestone lets us chase down the delivery vehicles that might have brought those ingredients to Earth.

Host 3 Ah, you mean comets.

Host 4 Exactly. Comets.

Host 3 Right. So fast forward to 2014, the European Space Agency's Rosetta mission dropped the Philae lander right onto a comet. Now Philae was about the size of a washing machine, weighed 100 kilograms, and it had to endure this very tense seven hour descent.

Host 4 Seven hours of just waiting.

Host 3 Yeah. And it gets worse. Upon contact, the harpoons that were supposed to anchor it, well, they failed to fire. So Philae bounced three times across the comet surface.

Host 4 And just think about the reality for the engineers or for you if you were watching the live feed, there's a 28 minute signal delay because of the vast distance.

Host 3 Right, the speed of light bottleneck.

Host 4 Exactly. You're staring at screens knowing the probe's fate was decided nearly a half hour ago. You're just waiting for the ghost of that signal to finally reach Earth.

Host 3 The tension in that room was heavy, but manager Stefan Ulamec eventually confirmed the soft touchdown, at 1603 GMT.

Host 4 I bet they were relieved.

Host 3 Oh, very. Flight director Andrea Accomazzo even declared the probe to be in great shape, even though it came to rest in deep shadow with one foot potentially dangling in open space.

Host 4 Okay, wait. I have to push back on that a bit. If the harpoons failed, And it ended up resting sideways in a shadow. With a foot hanging in space, wasn't that landing basically a failure?

Host 3 I mean, it's a fair question.

Host 4 Like, how did we get any useful data out of a probe in that position?

Host 3 Well, the fact that it survived at all was a huge triumph. Even sideways, the instruments were still in contact with the surface. it was the first time humanity orbited and landed on a comet. By touching that ancient ice we unlocked objects frozen in time that hold the basic ingredients for life.

Host 4 We proved we could actually catch a comet.

Host 3 We really did.

Host 4 Also on this day, just briefly, in 1981, space shuttle Columbia launched STS-2, which was the first crewed spacecraft to return to space for a second mission.

Host 3 Oh, nice.

Host 4 And overnight in 1833, the great Leonid meteor storm sparked the birth of meteor astronomy.

Host 3 So much history today.

Host 4 So much.

Host 3 I guess I'll leave you with this thought. If a spacecraft built in the 1970s is still talking to us from interstellar space, what dormant secrets might a hibernating comet lander still hold?

Host 4 Thanks for tuning in. See you back here tomorrow.