Bits and Paradoxes #29

New Horizon, Pluto and Space Travel

Hey,

Nothing much this week except a few "Space Stuff" [0]. Just had a cold shower, bored AF.

I haven’t edited this iteration of the newsletter much because of boredom. I am only laying out my rough ideas. Hope that works!

Also do let me know if you are starting to get bored of these letters. Or how I can improve it…

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This week during Tihar, a few relatives came over to our house. I felt uncomfortable because of the rising COVID-19 cases in Kathmandu. But that’s that. I was in my room most of the time, staring at the void…

I feel so indifferent to these festivals. It’s not about my “adult life”. I’ve always been like this as far as I can remember…

Anyway, while I was "trying to have" a conversation with my uncle, it weirdly went into the domain of technology. He is from the village and doesn't know much about technology (he doesn't even use a "smartphone").

Not sure how the conversation took a 180 degree turn to space, but it has to do with his frequent “glances” at planes in the sky and his curiosity: How a piece of metal flies in the sky and such.

I told him about rockets; how we humans have gone far beyond that sky and have sent rockets to the moon, Mars, and other planets.

With his rising curiosity, he wanted to know if we have sent humans to which I acknowledged. But suddenly he asked if humans sent in the rockets return to Earth or not. His imagination was running wild. He thought that we send humans out “there”, never to return.

I told him that we are able to send humans only to a certain height (I didn't want to talk about International Space Station). Beyond that, it's all robots.

Although, I told him that humans have indeed landed on the moon.

One question suddenly took me by surprise:

"How do they return to earth then?"

This was the question I didn't even think about my whole life. I had only taken it for granted that people returning from the [[International Space Station]] (ISS) “just happen to return”.

Surely, my uncle doesn't know much about the growing tech-driven world! Surely, knowing about tech doesn't help him either to get his job done on daily basis!

But, curiosity is certainly a good base for thinking real hard.

I have realized how “information overload” can make a person (me) so ignorant, and reduces curiosity. That’s also the reason why “Bits and Paradoxes” exists in the first place; it’s about connecting the dots and re-inforcing my mental models I guess…

Uncle’s question triggered me to “reinforce” my knowledge of space travel. The whole week was "spacious". Haha.

So, let's dive (more like hurling into the void) into a few things I found fascinating, especially the disaster related to [[New Horizon]] spacecraft.

NASA's New Horizons spacecraft is the first spacecraft to explore Pluto up close, flying by the dwarf planet and its moons on July 14, 2015. In early 2019, New Horizons flew past its second major science target—2014 MU69, the most distant object ever explored up close.

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I) How do people move back and forth between the Earth and the ISS?

Send a spacecraft towards ISS and dock into ISS.

• This module is sent with the help of rockets. (These rockets hadn’t been reusable until recently. SpaceX has surely changed that.)

• Astronauts will latch the spacecraft carefully onto the docking section.

• Once everything is fine, they move into the ISS.

The process is reversed while returning. They get themselves into the module, undock, and get prepared for a bumpy ride. Since it's literally “falling”, the module has to withstand a high re-entry velocity, plus a very high temperature.

(I like to think of the ISS as one giant blob of lego pieces. :D)

Of course, there are orbital mechanics and a lot of physics going on in both.

• Like the crew, 1 week before the undocking, has to conduct training sessions with the ground team with all precise instructions. They have to go over the simulation to be prepared.

• Like the ground team should precisely figure out the landing zone.

• Like how these things depend on the orientation of ISS itself. Sometimes the shuttle is latched to the bottom of the ISS. Sometimes it’s at the side. So, there’s also ISS’s orientation + velocity + distance….you name it…. :|

I haven’t really gotten into depth here. So, I highly recommend watching this video of Soyuz undocking, re-entry, and landing:

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II) How NASA’s Mission to Pluto Was Nearly Lost

This was a very insightful essay about the complexity of space travel: how even a small imprecision can have a catastrophic impact.

Here, the space probe New Horizon's main processor had malfunctioned, especially when it was scheduled to pass by Pluto. The team had to re-send every bit of instructions to reboot the main processor and finally set the flyby sequence.

Right before that failure, the teams had sent a final command for the probe to be prepared for the flyby. When the probe got the command, it was already doing one computationally intensive task. This task was compressing images to be sent to the Earth. That compression + loading of the new command caused an overload to the processor. It halted and the secondary processor was handling some of the mechanics.

Immersed in work that afternoon, Alan was busy preparing for the flyby. He was used to operating on little sleep during this final approach phase of the mission, but that day he’d gotten up in the middle of the night and gone into their Mission Operations Center (MOC) for the upload of the crucial, massive set of computer instructions to guide the spacecraft through its upcoming close flyby. That “command load” represented nearly a decade of work, and that morning it had been sent by radio transmission hurtling at the speed of light to reach New Horizons, then on its approach to Pluto.

However, there was a much greater problem: the secondary computer didn't have any sequences related to the flyby. They'd have to re-send everything to the probe. (The whole point of this mission was to get as much data as possible about Pluto.)

The flyby was approaching soon and they had only 3 days to get the main computer running.

Re-sending the instructions is very challenging because of the communication lag. Even at the speed of light, it takes around 9 hours of a round-trip between the probe and the Earth. If they failed, it'd be a decade worth of works being wasted.

Anyway, they did it with sleepless nights.

This essay made me think about a few important things for a space mission:

(a) Communication lags and autonomy

Since we're talking about astronomical distances, it's necessary that we'd have to have autonomous vehicles. In these distances, even the speed of light starts to become slow. Just to get a “feel” of that lag know that even a round-trip between Mars and Earth has 6 minutes of lag. Now scale that factor with large distances, and we’ll have a significant lag.

In the case of New Horizon, the team couldn’t “just wait” for a day or two to kickstart the main computer because it wasn’t some static rover on a planet. It was hurling through space, ready to kiss Pluto.

If this were an orbiter, or a rover safely on an alien surface, the team could take its time to analyze the problem, make recommendations, try different courses of action. But New Horizons was a flyby mission. The spacecraft was rushing toward Pluto at over 750,000 miles per day—more than 31,000 miles per hour

(b) Uncertainties

Who would have thought that the processors would halt? There are always uncertainties despite having simulated every possible worst-case scenario.

(c) Coding complexity is exponential

Just imagine writing a code and having to wait for 9 hours to get the result. Even before sending out the actual code, it should be tested rigorously.

The team from the New Horizon mission had a simulator NHOPS (New Horizons Operations Simulator) for that. Even if they coded multiple sequences parallelly, the simulator would only allow one simulation at a time. Luckily, they had a backup simulator.

Related:

• Why does it take so long to build software?

• We Never Know Exactly Where We’re Going in Outer Space

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III) Is pluto a planet?

This question arises because Pluto is highly dissimilar to the rest of the planets in the solar system.

At that time when the debate was going on, Pluto was already smaller than the 10 of the moons in the solar system.

Plus, Scientists also discovered the [[Kuiper belt]] where we can see a lot of Pluto-like bodies. Pluto is more alike to these “icy” bodies than the rest of the planets.

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IV) If rockets were transparent

Fascinating animation on rocket launches to orbit. The animation consists of Fuel Burn and Staging.

4 rockets are used:

• Saturn V

• Space Shuttle

• Falcon Heavy

• the Space Launch System (SLS) rocket

(I had shared this animation in Bits-and-Paradoxes-04. This time, it’s more relevant.)

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V)

This XKCD-2386 is so poignant, yet beautiful. Randall Munroe's then-fiance (now wife) was diagnosed with Cancer 10 years ago and now the treatment has progressed. I felt that “love” between them while reading this comic. :)

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VI)

Yet another daily dose of existential crisis: I just realized that 89% of 2020 is already gone.

This year has certainly drifted away in the blink of an eye. The reason “might” be because we are all locked up from COVID-19, that we could barely make new memories (like going out, exploring, having fun, and such). So, psychologically it feels “the same”.

(Re: Bits-and-Paradoxes-15 on Memories and Experiences)

Year Progress @year_progress

▓▓▓▓▓▓▓▓▓▓▓▓▓░░ 89%

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Ending Thoughts

I’ve been listening to this song the whole week: Brisa del Desierto by Los Natas. The English translation is “Desert Breeze”.

If my life had background music I guess this would be the “one”. The song has touched me in a way I can't express in words. Just listen to it and “feel”!

Also, I did my own rendition of the song. Might not be any close to the original, but that’s that. :)

Picture: A snapshot of Mardi Himal trek.

I hope this increasing boredom in life doesn’t kill my curiosity. It’s lonely out here in my mind-cave.

:)

To infinity and beyond,
Nish

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#Footnotes

[0] - Well! I like to think that we’re all space “shit”, made of star-stuff. How about “space poop”? Haha