#aerobraking

[gumbuk9]

i am so disappointed i never knew of the terms aerobraking, hydrobraking, and lithobraking until now, but i am so so happy to now be aware of the terms aerobraking, hydrobraking, and lithobraking. i so want to use these words in a videogame in some capacity

To be fair, a lot of goofy-sounding rocketry/aerospace terminology has a legitimate nomenclatural role beyond just being silly euphemisms.

"Unplanned rapid disassembly", for example, exists as the necessary counterpart to planned rapid disassembly: sometimes a rocket is legitimately supposed to fall apart or blow up, so you need a specific term to emphasise that it wasn't supposed to do that.

Similarly, "lithobraking" was coined by analogy with aerobraking (shedding velocity via atmospheric friction) and hydrobraking (shedding velocity by landing in water), and it does have some intentional applications; the Mars Pathfinder probe, for example, was deliberately crashed into the Martian surface while surrounded by giant airbags, and reportedly bounced at least 15 times before coming to rest.

(That said, aerospace engineers absolutely do use these terms humorously as well, because engineers are just Like That.)

[jurph]

Coming Back

A little obsessed with re-entry as a concept these days. The idea of a long cold journey that is arduous, but safe, and all that is required is to endure... followed by a few minutes of being baptized in searing white plasma, no radio communications, some outer layer you thought of as "yourself" being excised as an inevitable cost, a mostly-ballistic trajectory.

It's "mostly ballistic": once you pick your lane, once you shoot your shot, you make the last few trim adjustments with your hydrazine-or-whatever thrusters: and now you've placed your bets. There's not really anything you can do on re-entry where adding energy will help, because the fundamental problem is one of shedding energy. The speed that got you through the journey is now a hazard. You have to re-acclimate to moving slowly. You have to come back, adopt a speed that is more favorable to atmosphere and breathing and humanity, and that means aerobraking. Every part of that is basically deterministic though: too steep and the heat builds up too fast and cooks you; you couldn't absorb the change fast enough. Too shallow and the exposure to heat over dozens of minutes wears you down: you didn't rip the band-aid off fast enough, you overshot your target, you spent so long getting back to normal that you left yourself vulnerable.

So every re-entry trajectory is this Goldilocks thing where you come back, talk to some experts on the far end and say "what is the best way to finish this" and trust them. The final exam is setting your course, knuckling down, and coming through the short dark window of loneliness to a place where you can open the parachutes and splash down safely, and wait for someone to pick you up and say "welcome home. you made it."

[professionalchaoticdumbass]

holy fuck i've probably recorded like, 20 gb of jool 5 so far and the laythe landing isn't even finished

[cuprohastes]

Ludicrous speed.

Let me tell you about humans. They’re shit. No exoskeleton, they need to pour water into their face all the time, no plumage, they can���t even sense magnetism.

They’re wobbly squishy things who walk around looking at the world with jelly blobs, leaking their most important resource out of their skin.

And you hear that they’re the Galaxy’s most dangerous species.

And they’re not, they really aren’t.

The Ixnar are. The Ixnar will get halfway through a genocide before they start to wonder why they’re doing it. The Ixnar will fire relativistic weapons and not give a solitary nnuniq what they’ll hit later on down the line.

Humans? They start by coming up with a reason to be terrifying, and then they refine it as they go. See? They give you fair warning. They think about stuff. They’ll talk to you first, then do something horrifying.

But if you don’t give them that chance, then… well, that’s on you.

And I never believed that reputation. I’d worked with humans for years, and I’ve never seen them do anything more than carry stuff, sing songs, eat barbaric food and sleep. About what you’d expect from a pack animal - Useful, affable, but…. dangerous?

It is to laugh.

Anyway.

The Ixnar.

They sent a raiding party to my homeworld. I couldn’t believe it, I was in shock when their ships entered atmosphere and started firing on our cities.

I was ready to go down and help the survivors - Of course I was!

The Humans?

Well they got angry. Like angrier than they had a right to be. And they’re humans, right? They get angry, they do something with it.

They didn’t want to go down and help the survivors, they wanted to go down and murder the raiders.

You know… they actually hailed the Ixnar and asked them, begged them, even tried to trade with them to stop their attack.

The Ixnar hung up and… the Humans dropped hell on them.

In a cargo freighter. A human cargo freighter.

They love their aerobraking. So they have these huge shields and magnetic fields to manage plasma: They come in, and they trade speed for heat and then coast and shed the heat.

Not this time. I thought we were going to die - They pointed the ship at the planet, and they came down so hard I could hear the air through the hull.

We didn’t even need cabin lights.

And then… they lit the main drives. A thing no sentient would ever do in atmosphere. Because it’s suicide. Absolutely: We were already moving at fifty times faster than the speed of sound, and then they decided they needed to be faster.

And they got it. Because they were angry on behalf of people they never met. They just decided that physics didn’t matter. The hull wasn’t important. Fuel? Engines? Ha! Who cares, right? They’ll just get out and flap their arms if they need to, with a kitchen knife between their teeth.

You know what happens if a fighter skiff gets hit with a shockwave like that? They go away. They stop being anything you could call a thing.

And you know, Humans don’t send out Cargo ships without protection. I mean, their hulls alone are insane. But they also like to carry a little punitive hardware.

About as much as most species warships.

Beam weapons, ballistic slugs, missiles, Field spinners, and those fucking Polaron cannons.

Yeah, nobody has worked out how that works. They’re Polarons. And the humans figured out how to make them hurt.

And they were firing on these little warships from inside a cloud of plasma. And really that shouldn’t work at all, And they just did it anyway. It was terrifying, and I was on the inside, looking out and I was scared.

Then the humans aimed the nose at the mothership. The captain said… And I won’t stop hearing those words ever: “If the Polaron cannons won’t do it, let’s see if ramming speed will do the trick.”

And the crew cheered. They cheered!

I can only imagine the Ixnar command looking down and seeing a hole ripped in the atmosphere, seeing their skiffs flash into non existence and then a boiling finger of cloud just reaching up to point at them.

Did they even remember the human cargo ship that reached out to them? Did they even recognise the glowing white-hot dot of pure fury coming for them?

And when the Polaron cannon lit up, did they even recognise what was happening before their bridge melted?

I hope so. I hope that for a moment they realised they’d fucked up so badly that they got everyone killed and the humans were Big Mad at them.

Me? I was trying not to scream. I was pretty sure that I was going to die, but also? Die like a human. You really understand what blaze of glory means when you’re actually on fire and it doesn’t matter.

Anyway we didn’t have to kill the Ixnar by slamming into them, but the Captain had to eject the engines, and most of the hull because uh, well it was kind of on fire.

Two days later the rescue and relief team picked us up and let me tell you, we were all really drunk at that point.

But yeah.

Humans aren’t dangerous. And yes I would very much like another drink, most kind of you to offer.

[piratesexmachine420]

Copy and pasting the following from a discussion of this video in a discord server I'm in, because I think it's a point worth making:

It's very annoying to see how telephone game'd the Mars Climate Orbiter failure has become.

It didn't crash into Mars, it was simply too low when it went for an aerobrake pass. It definitely didn't leave "a scar that you can see from the other orbiters". Mark is probably either thinking of Beagle 2 or Mars Polar Lander, or maybe one of the more recent unmanned lunar landers (Beresheet, maybe?).

It wasn't a mixup of inches and centimeters, it was a mixup of pound force-seconds and newton-seconds.

Lockheed weren't idiots, and it's frankly insulting to all teams involved to claim so. The actual MCO mishap investigation report -- which Mark clearly either hasn't read or hasn't read thoroughly -- clearly states throughout that while the direct cause of failure was the faulty data in the Angular Momentum Desaturation modeling file (not just incorrect units, but also formatting issues and just plain errors), the root causes were multivalent:

The ops. team were understaffed and running three missions simultaneously.

Team members were inadequately trained.

Inadequate onboard navigation ("total reliant on [the] Earth-based Deep Space Network")

Contingency maneuvers that could have saved the mission, weren't taken because the teams weren't prepared (or able to prepare) for them.

End-to-end testing of the software stack, which should have been performed beforehand, never occurred.

And more! You can read the MCO phase I mishap report here and phase II here, if you're interested in learning what actually happened, instead of just blaming Lockheed for being stupid degenerate Americans with no safety culture.

You might notice with a sense of dramatic irony that the MCO phase I report makes a lot of recommendations for the concurrent MPL program; that mission would similarly fail less than a month after the report's publication for related reasons (not the units mixup part, the other ones).

MCO was not an isolated incident and it's frankly malpractice to ignore that (by omission or otherwise). The 90s were bad for space programs, mostly down to budget pressures. The MCO phase II report goes deep into the problems with NASA "Faster, Better, Cheaper" philosophy at the time.

Let me summarize: MCO was not a failure of software design. It was not a failure of unit conversion, either. It was a failure of project management. While the course (in)corrections were what doomed MCO directly, it was always going to be something. The team running MCO simply could not have succeeded given the conditions they were in. If it was anyone's fault, it was Congress' fault for not funding the deep space program enough.

[spacetimewithstuartgary]

New SpaceTime out Wednesday

SpaceTime 20241023 Series 27 Episode 128

Scientists date the Moon's oldest impact crater

Scientists believe they’ve pinpointed the age of the massive South Pole-Aitken basin largest and oldest impact crater on the Moon finding it to be over 4.32 billion years old.

Scientists recreate the sound of Earth's magnetic polar flip

With growing evidence that the Earth’s magnetic poles are about to flip, scientists have recreated the sound of Earth's magnetic polar flip.

X-37B Space Shuttle undertakes pioneering aerobraking manoeuvre

The United States Space Force's X-37B space shuttle has just completed a novel aerobraking manoeuvre to adjust its orbit flight path around Earth.

The Science Report

A new study has found that deaths tend to increase in the days after an extreme rain event.

The real health effects of Mediterranean style diets on young people.

New energy-efficient bricks using scrap materials, including glass, that are normally destined for landfill.

Alex on Tech is your car spying on you.

SpaceTime covers the latest news in astronomy & space sciences.

The show is available every Monday, Wednesday and Friday through Apple Podcasts (itunes), Stitcher, Google Podcast, Pocketcasts, SoundCloud, Bitez.com, YouTube, your favourite podcast download provider, and from www.spacetimewithstuartgary.com

SpaceTime is also broadcast through the National Science Foundation on Science Zone Radio and on both i-heart Radio and Tune-In Radio.

SpaceTime daily news blog: http://spacetimewithstuartgary.tumblr.com/

SpaceTime facebook: www.facebook.com/spacetimewithstuartgary

SpaceTime Instagram @spacetimewithstuartgary

SpaceTime twitter feed @stuartgary

SpaceTime YouTube: @SpaceTimewithStuartGary

SpaceTime -- A brief history

SpaceTime is Australia’s most popular and respected astronomy and space science news program – averaging over two million downloads every year. We’re also number five in the United States.  The show reports on the latest stories and discoveries making news in astronomy, space flight, and science.  SpaceTime features weekly interviews with leading Australian scientists about their research.  The show began life in 1995 as ‘StarStuff’ on the Australian Broadcasting Corporation’s (ABC) NewsRadio network.  Award winning investigative reporter Stuart Gary created the program during more than fifteen years as NewsRadio’s evening anchor and Science Editor.  Gary’s always loved science. He studied astronomy at university and was invited to undertake a PHD in astrophysics, but instead focused on his career in journalism and radio broadcasting. Gary’s radio career stretches back some 34 years including 26 at the ABC. He worked as an announcer and music DJ in commercial radio, before becoming a journalist and eventually joining ABC News and Current Affairs. He was part of the team that set up ABC NewsRadio and became one of its first on air presenters. When asked to put his science background to use, Gary developed StarStuff which he wrote, produced and hosted, consistently achieving 9 per cent of the national Australian radio audience based on the ABC’s Nielsen ratings survey figures for the five major Australian metro markets: Sydney, Melbourne, Brisbane, Adelaide, and Perth.  The StarStuff podcast was published on line by ABC Science -- achieving over 1.3 million downloads annually.  However, after some 20 years, the show finally wrapped up in December 2015 following ABC funding cuts, and a redirection of available finances to increase sports and horse racing coverage.  Rather than continue with the ABC, Gary resigned so that he could keep the show going independently.  StarStuff was rebranded as “SpaceTime”, with the first episode being broadcast in February 2016.  Over the years, SpaceTime has grown, more than doubling its former ABC audience numbers and expanding to include new segments such as the Science Report -- which provides a wrap of general science news, weekly skeptical science features, special reports looking at the latest computer and technology news, and Skywatch – which provides a monthly guide to the night skies. The show is published three times weekly (every Monday, Wednesday and Friday) and available from the United States National Science Foundation on Science Zone Radio, and through both i-heart Radio and Tune-In Radio.

[gumbuk9]

favorite word?

Either the set of "Aerobraking", "Hydrobraking", "Lithobraking"; or "Concussion". with a possible runner up being "Dongle"

[lonestarflight]

The Space Shuttle's vertical tail is 27 feet high and 22 feet long at the base. It ensures the stability and the direction of the orbiter in flight. It supports the mobiles elements which are used to oriente the orbiter or to slow down (areobreak). These last ones are jointed with four pieces and controlled by an electrical engine. The box of the vertical stabilizer is made of two strengten pieces mashin-finished from one piece, panels. The box is settled to the rear part of the fuselage by ten bolts. The mobile parts (direction and aerobrake) are made of aluminium alloy and panels in honeycomb structure.

All were built by Fairchild Republic Company, in Long Island, New York.

source

Boeing Images: B1230615

[feybeasts]

Today in flight sim shenanigans: landing at 200+ knots after losing an engine to a Tunguska site, for SOME REASON my aerobraking was only about... half... as effective?

[jayahult]

Eight

Eight crew-members. This ship is supposed to run with eight crew-members.

That thought kept echoing in my head as I stared out the window towards the inky black, pulling away from the fray. I couldn't look behind me. Allison was behind me. She was behind me. I checked the damage control display again, as if it would make things better. We were running on one of six thrusters remaining. The ECM was spasming, shooting out false signals, eight on our tail, sixteen, one, twenty-five. I hit the switch to try to purge the system. I didn't even want to think that he had an active fusion reactor sitting towards the tail of the ship. I couldn't bring myself to check it again. Levi had patched the leak, the poor bastard. I checked the life-support. The missile had torn open the side of the ship like can-opener. A large portion of the oxygen had gone with our cramped quarters; the carbon recyclers were several miles behind us, alongside our emergency oxygen kits. I punched an approximation of our status into the computer. Levi thumped his foot behind me. We had about twenty hours before we'd all suffocate.

I sighed, and looked back at Allison. She was dead. I had no idea how she got this far. She must have been just getting through the locks when she was exposed to the vacuum. Our suits were designed for helping with rapid decompression, but there was only so much that they could do. Her face was red with blood, her eyes desperate and sad and trapped that way forever. Levi was alive for now. He was near to the reactor. He saw it nearly breach. Fusion reactors don't melt down, not like the old fission systems were prone to, but a leak on a functioning reactor core could and would release massive amounts of radiation. His face was ruddy and sad. He couldn't meet my eyes. He was the oldest among us, twenty-seven.

The radio crackled to life, startling me. I kicked the other chair as I turned around and Allison floated against the chair that I had crudely locked her into, and her dead mouth lolled open as if to speak what was said over the channel:

"Attention, attention, all vessels - retreat has been ordered. Repeat - retreat has been ordered. Repeat -"

I checked the TMCS, and the fuel reserves. Technically we weren't dead in space, but we were as close to it as we could get. We wouldn't make it back to carrier in time for the retreat. That meant capture, or re-entry. By everything I'd heard being taken prisoner by the RTs would make you wish you were dead. We weren't built for re-entry. Even if we got a stable trajectory that wouldn't kill us by lithobraking, there was the problem of shutting down the reactor in time to minimize damage to ourselves and the local environment. The local comms opened up as well.

"Is anyone alive up there?"

It was Silvia. Still alive. She was in the engine room when the breach happened, which means that she'd be cut off from the rest of us.

"We're alive!" I said frantically, "It's Juno and Levi. Seems like we're the only other survivors. Listen, do you have an EVA suit near you? I need you at the bridge. Allison is dead. Levi is-"

I glanced at him.

"He's injured. He's going to need medical attention, but first we need to burn and re-enter Calvin-22-"

"Are you insane?"

"I've already weighed the options, Silvia. We're going to either die in orbit, in aerobrake, in lithobrake or we'll be executed by tribunal by some RTs, or we can take our best chance."

"You are insane," she said, "Thruster three looks like it could still function if I make a quick fix. I'm going to try that and head to you."

"Thank you," I said.

"You're welcome, ma'am."

The comm crackled again, and went silent, and I slumped in the chair, confused. It was only a few moments later that I realized that since Allison was dead, I was the highest-ranking person on the ship left. Levi waited for a moment.

"So, how do you feel about the promotion?"

"What?"

"I- nevermind," he said, "Thought it'd make you laugh. Ma'am, you entered the numbers wrong."

"Hm?"

He reached over to the life support panel, and tapped the backspace lightly before entering three instead of eight. I hadn't even noticed my mistake.

[persephones-stenographer]

So assuming my google skills and graphs from the early Apollo missions get me close, the required dV to return from the surface of the moon is roughly 3,000-4,000m/s*. That's how much something has to accelerate (slow down) from the moon's orbit and "fall" to earth. We'll pretend the atmosphere doesn't exist otherwise the bullet would instantly vaporize and this whole fun mission would be impossible.

From another quick google, most high powered rifles max out at around 1,200m/s muzzle velocity, and a theoretical "perfect" system that transfers all of the explosive energy into projectile velocity would maybe get up to just over 1,800m/s. That means that we would need to use something that isn't a gun, because we'd shoot a bullet that would slow down, and just fly toward the earth, but end up missing by about half the distance to the moon.

So let's try something else. How about a rail gun? Another google indicates current rail guns can hit upwards of 2,500m/s at sea level, and I'd be willing to bet in a vacuum and with some fancy classified tech, you could easily hit the 3,000-4,000m/s required! Aiming? Who cares about aiming, at that speed you're going to hit a lot more than a tree.

*there's some error here because the Apollo missions relied on aerobraking, using the atmosphere to slow down, so they didn't actually need to hit earth, just get close to it. The atmospheric resistance did the rest and slowed them down enough to land. Since we're ignoring atmospheric resistance so that the bullet doesn't vaporize instantly, our numbers are a bit higher than theirs were. If anyone wants to correct me with more accurate numbers, please do.

I want to be the first person on the moon to shoot a sniper rifle at earth and hit a wasp nest.  my whole life so far is leading up to that moment

[c3realkill3r]

Episode 15: X-37B's Groundbreaking Aerobraking Maneuver and the Future of Space Operations

[dcnewsroom]

The Boeing-built X-37B will soon perform a series of advanced aerobraking maneuvers, taking the spaceplane from a Highly Elliptical Orbit, where it’s been operating since December 2023, and lowering its altitude using minimal fuel. [Full story]

[teamugdraws]

"That sounded like too much work, so I tried using a liter of powdered starfish instead."

"You j..."

"Oh! And I mixed in some iron-filings 'cause I figured stardust was more, ya'know, mineral-y, than actual starfish."

"Hang on, I'm still stuck on the part where you found a magic cookbook."

"At this point I'm thinking more 'sufficiently advanced', but yeah."

"Fair. But still, you found it. You made multiple dishes from it, enough to figure out the next-page trick."

"Yeah, they're really tasty! I think I use it for maybe four out of five meals, now."

"What's the fifth meal?"

"Coffee."

"Huh. Anyway, your magic book"

"Sufficiently Advanced"

"Too many syllables. Your 'magic' book, gives a design for a spaceship."

"Yep."

"And you decide not to build it?"

"Yep."

"WHY NOT?"

"Ok, two reasons: First, trying to get my hands on that much uranium would probably get me shot."

"Avoid lead poisoning, fair. And?"

"And second, the rocket design includes an ascent stage, but no way to come back down. No aerobrake shell, no parachute, nothing."

"Ok? Bit of an oversight there, but I mean if you're already building..."

"AND! And, the book is titled How To Live A Delicious Life."

"... I don't follow."

"To Serve Man?"

"What?"

"Second base."

"What?"

"You need to learn your classics. Point is, I think the ship is meant to be one-way."

"...sure? Why?"

"I think its the lure on the anglerfish. I think the book is bait."

"What does... Oh, I get it. So what, the rest of the book, those recipes, are just to get your guard down?"

"Some, yeah. Maybe also as seasoning. Like, um, those Japanese cows that are fed the special grass. Is that a thing? My brain is telling me that's a thing."

"..."

"..."

"WHY ARE YOU STILL EATING THOSE RECIPES?"

"Because they're delicious."

You discovered an abandoned one thousand page cookbook one day, and strangely, you found that you can’t flip to the next recipe without making the current dish. Flipping the page, you see the next dish calls for a liter of star dust and gives a “simple” explanation of how to build a starship.

[lonestarflight]

“SPACE TRANSPORTATION EVOLUTION”, circa 1981-90.

Shape of things to come.... sadly, it wasn't meant to be.

Top row (L-R): Shuttle II Orbiter, Aerobrake Orbital Transfer Vehicle (AOTV).

The (AOTV) was a two-stage vehicle with a common module and expendable lunar lander.

Middle row (L-R): an unknown shuttle variant, Shuttle-C, unknown, unknown, unknown spaceplane

Eagle Engineering photo: 5312