#astrodynamics

[kj-ursa]

Why You Cannot Launch Things (Easily) Into the Sun! Ft: Me Taking 18 Years to Get to the Point

[theimpossiblelifeofcassiopeia]

A Day in the Life

Today has been a pretty packed full day of academia, so I thought I’d take you on the journey through everything I did so you can get a better idea of just what I get up to. 7am I woke up and had breakfast. Nothing too exciting but the day has to start somewhere and I always try to make sure it’s with something healthy to get my body working! I planned my outfit the night before, it’s a new…

[aunsiro]

Hi! Space engineer here! Orbital Mechanics are a really beautiful field and can be much easier than most people realize! You don't even need the mass of your ship to calculate the free flight trajectory! (That's the reason you can use Delta-v mission design valid for any spacecraft)

I completely agree with the Kerbal Space Program recommendation! It uses a simplification of the math that works very well called Patched Conics approach. It is very easy to find videos about that on YouTube! If you like programming, there are also very nice open source libraries for Orbital Mechanics.

The key thing is to define a region called "Sphere of influence" around each celestial body. The sphere of influence is the region of space where that body has the strongest gravitational pull. You can assume that inside an sphere of influence, you only need to care about that celestial body, and outside the sphere of influence, you don't need to take it into account at all. You can easily find online the radius of the sphere of influence of every body in the solar system.

When you are under the influence of only one body, your trajectory will always be a conic curve: an ellipse, a parabola or a hyperbola. When you enter or exit an sphere of influence, you have to calculate the position and velocity in the new reference system and just continue the new conic until you intersect another frontier. You also need to take into account that the sphere of influence of the sun is your default state, unless you want to go really really far.

This simplification gives fairly accurate results, and only fall short when you need a lot of accuracy or want to design orbits around points where more bodies are simultaneously important (such as Lagrange Points).

Since conics are symmetrical, there are some funny results that might not be intuitive: if you enter the sphere of influence of a planet, you will always exit it with the same speed as you entered (relative to the planet) and a different direction, unless something interesting happens inside the sphere (like colliding with the planet, entering the sphere of influence of a moon, or turning on your motors).

For example, suppose you were in an orbit around the sun such that your path enters the sphere of influence of Neptune at a point where your velocity respect to the sun were very small (That is the closest thing you can achieve to being static there without some sort of propulsion). Neptune is approaching you very rapidly in this frame of reference. Once you enter its sphere of influence and change your frame of reference, you suddenly can view it from the perspective of you being the one very rapidly approaching Neptune in a hyperbolic orbit. If you don't collide with it and don't interact with its moons, you will perform a flyby and eventually reach again the frontier of the sphere of influence, where you are exiting it at the same high speed you had relative to Neptune as when you entered it. Now you are again out of the sphere influence of Neptune. You change your system of reference again back to one based on the Sun, and realize that your new solar orbit is completely different to the one you had before the encounter! Since Neptune was orbiting the Sun while you were orbiting Neptune, it has dragged you along for a while and now you are in a different point of its orbit. But more importantly, your velocity has completely changed, in an amount easily of the same order as the speed of Neptune itself around the Sun. You may even be now in a solar hyperbolic orbit, fleeing the solar system forever, or bound to a very quick visit of the interior solar system before that. Or you may have drastically changed your orbital plane. If you were careful planning and your timing is right, you may very well get an orbit that intersect the sphere of influence of Pluto at some point in the future! :D

In fact, we were able to do just that with the New Horizons mission!

Hope this is of help to someone visualizing it! ☺️

Submitted via Google Form:

How far away would planets catch things in orbit? I'm talking about things like if I had spaceships in space. But what if they're like not running any engines in deep space. If they're too close to a planet they'll be sort of moved around in orbit too right? What is say, I had a spaceship and they need to travel from Pluto to Neptune, can they like just sit near a point where the orbits match up and like sit there for years and just wait for Neptune to get there. As an example of course.

Tex: It would depend on the mass and velocity of all involved bodies, at minimum, in order to properly calculate gravitational pull and whether one body’s pull would be enough to capture another into orbit or at least some form of deceleration. Ultimately it depends on your plot and whether you want the spaceship to be placed there, but most likely there would be some degree of drift - give it enough time, and the spaceship will eventually be free of the standstill of competing gravitational pulls. Wootzel: You’re right that other objects in proximity--be they planets, stars, or bigger--will pull on a ship and change its trajectory. Larger objects will pull from further away. 

In order to conceptualize how things move around each other in outer space, you honestly have to change the entire way you think about motion. There is no single definition of “stationary” in space, because it’s all relative. Everything is expanding all the time, and most things orbit other things in some kind of way. The inertia of orbiting keeps an object from just getting pulled straight into the nearest object with enough mass. Due to the good ol force of inertia and a lack of enough friction to slow things down, a spaceship that’s not running any engines will not be stationary (relative to whatever system it’s in) unless it’s been intentionally slowed to a stop. It’ll just keep happily moving along whatever path it’s on until a force acts on it. In your example of getting from Pluto to Neptune, it’s possible that the strategy there is to have your in-story Space Math Scientists calculate a whole bunch of factors like the speed of travel and Neptune’s orbit, and then just aim the ship so that, moving at whatever speed is reasonable for it, can intersect Neptune’s orbit.

This may seem like a silly suggestion, but it might be useful to how you conceptualize travel in space to spend some time in a space travel simulator that has mechanics approximating real physics. The one that occurs to me to suggest is Kerbal Space Program because it’s the only one I personally know of that has the mechanics I’m talking about. I’m sure there are other games/sims out that that will let you play around with the way orbits influence space travel, and how they can be useful for getting where you’re going. NASA has done some missions where the craft they’re sending out slingshots around one object before heading out to whatever its end-goal is.

I don’t think any of us can give you estimates of how far away a planet or star could be and still move your spaceship around, especially without a lot more details, but looking into simulators (Universe Sandbox might be an option) or online calculators could probably help with that as well.

[stuckinfishbowl]

Thought it was fitting for my first post on here to be in celebration of one of my long-time drafted works finally coming to fruition! It took a few months, but the vision has finally been realized in a way I’m happy with!!! ^_^ SOLOMON… in all his delicate and ephemeral beauty. I hope I did him justice.

[vermillioncrown]

it'd be so funny if i rebound one of my textbooks in hardcover

[macinthecaac]

I always used to want to be an author when I was younger, and I think Andy Weir genuinely inspired me to take up that dream again. I still plan on going to university, but maybe sci-fi writing is something I could do on the side.

[avatar-anna]

Hi! I don’t know if you take requests or suggestions so I’m very sorry if this is crossing a line, but I wanted to say that I’d love to read about how Harry told his friends and family about professor. Especially after I read that one about Harry working on Matilda and Mitch not knowing what’s going on with him. Again, I’m sorry if this is crossing a line 🥹

no lines crossed at all!

I think in the aftermath of Professor and Harry falling out, his friends and family could tell something was wrong, but he wouldn’t open up to anyone.

AND THEN when a year later he’s suddenly much happier seemingly over night, everyone’s truly baffled. They notice he’s on his phone a lot and he’s suddenly taking trips to New York, and maybe Jeff catches a heart next to a contact name, but he thinks nothing of it because when could he have possibly met a professor?

There’s probably a group chat that Harry isn’t a part of where they all theorize what or who has him in such high spirits again, but they come up empty.

It isn’t until Harry’s tour in the UK starts that he finally introduces Professor to everyone. It’s the night before the Manchester show, and everyone is at Anne’s house, and Harry’s running late (because he just has to show her all the places he spent growing up), so everyone is already gathered together when the two of them walk in hand and hand. Harry is all smiley as he leads her into the house and introduces her to each person there. “This is Dr. Y/n Y/l/n, my girlfriend.”

And of course Professor is nervous and shy and worries about saying the wrong thing, but when Harry keeps calling her “doctor” she nudges his arm and tells him he doesn’t need to call her that.

“Would you let me show off, please?” is all he has to say to that.

And the whole house is quiet in absolute shock. They all knew that Harry was more than likely seeing someone, but they didn’t quite expect Professor. His friends and family know his dating history, and she doesn’t exactly fit the bill. None of them dislike her, they’re just surprised he’s holding hands with someone like her.

Gemma is the first to speak, seeing that his brother’s girlfriend is fully aware that no one is saying anything, and she can see Professor tense with each passing minute. So she just loops her arm through Professor’s and asks, “So are you a medical doctor?” And when Professor explains that she’s a professor at Columbia (she hasn’t moved back to Cambridge yet), Gemma says, “And you’re with him?”

Harry frowns, but he’s immensely grateful on the inside because his sister was easing the tense set between Professor’s shoulders.

Professor, of course, sometimes has a hard time detecting sarcasm, so she takes Gemma’s question seriously and says something like, “Yes. He’s very kind,” and to Anne she says, “You raised a remarkable person.”

The atmosphere shifts a little after that, and everyone wants to get to know the person who stole H’s heart. Harry’s there the whole time so Professor doesn’t feel ambushed, but she never does and is just as eager to get to know his family.

There are moments throughout the night where everyone is kind of just stunned by Professor. Like at one point there’s a conversation happening and someone jokes, “It’s not rocket science!” And Professor super casually just says, “You know, I’ve studied aerospace engineering and astrodynamics, and I found other fields of science much more difficult, but I suppose rocket science sounds more challenging than physics.”

Harry chuckles because he understands her humor at this point, and he finds it cute that of course rocket science comes easy to her, but the room is once again consumed by silence until someone asks, “What, exactly, do you have a doctorate in?”

She rattles off her degrees and a little about her background, but not too much because she doesn’t like diving into how she’d been practically forced to learn a lot of the stuff she knows early on.

Once again, everyone is kind of confused as to how Professor and Harry met, and possibly even what they talk about when they’re alone together. They’re so different from each other, how on earth do they work?

But Anne can see it, because a mother always knows. She notices how Professor’s hand is constantly reaching for Harry’s, or how she catches Professor gazing at Harry and blushing before looking away again. Professor is absolutely smitten, and one look at her son tells Anne that he feels the exact same.

Funnily enough, I think Professor gravitates the most toward Mitch. Professor loves to learn, and while Mitch doesn’t appear like the academic type, he’s very talented in his field, and she loves to pick people’s brains about what they’re passionate about. And she’s drawn to his quieter disposition (and possibly the fact that they’re the two Americans in a group of British people), and she probably sits and talks to him the most outside of Anne.

Professor knows she could probably deduce every detail about these people’s lives with a few glances, but she tries not to, wanting to get to know them organically, though when she mentions her field of teaching to someone, everyone is immediately like, “Like that show! Can you tell what color socks I’m wearing or some shit like that?”

Harry wants to put an end to that before it begins because he knows Professor doesn’t like feeling like a circus act or source of entertainment, but she just smiles behind her glass of wine and says, “Maybe.”

In Harry’s opinion, the night couldn’t have gone better, and as he and Professor are leaving his mother’s house, everyone tells him how much they like her and how happy they are for him. He can’t contain his grin because while he knew how incredible Professor, he’s over the moon that other people see it too. I think more than anything, Harry wants to show Professor that there are good people out there who don’t see her as a freak or only see value in her intelligence. He wants so badly for his family to become hers, if only because she deserves to be loved by more than just him. She deserves a family.

And she doesn’t tell him, but Professor thinks she found one in his.

[starfieldphotos]

Sarah Morgan: Chair of Constellation; Commander, United Colonies Navy (retired); former head of defunct UC Navigator Corps; former drummer for disbanded Ironic Comet; astrodynamics expert; botany enthusiast, adventurer; explorer; wielder of laser weapons; my extraordinary wife, and favorite travelling companion, in 2330. Hopefully she'll remember us after Unity.

[astronauticalaspirations]

I miss doing astrodynamics calculations. Maybe if my life ever stops being such a mess I can work on mission plans again.

[fuchsiamae]

Some quotes from "Tragedy + Time" ch1, with sketches by @megalunalexi

-

“EEEEEEEEYAAAAAAAAH!”

“OOOOWOOWOOWOO!”

The two robots barreled down the hallway, hollering at max volume, atop a pair of jet-powered office chairs. Long ago, some paper-pushers had smuggled in contraband from the labs to level up their chair-racing, and now their posthuman successors continued that tradition. The bots weren’t built for sitting, though—Blue squatted, spiderlike, its round core between its knees, while Orange’s long legs stuck out like antennae. Both had to cling to the seats underneath them. Above the engines’ roar, shrieks of mechanized delight echoed through the empty halls.

-

In the paper hailstorm that broke out between them, the phone was left to dangle unnoticed, reciting the directory to no one as it spun slowly on its cord. “For Aeronautics, press 1-1-2. For Agriculture, press 1-1-3. For Astrodynamics…” It got no answer but the tinny giggles of bots at play.

-

“Look, I’ll admit it. I don’t know how to motivate you. I’ve tried rewards. I’ve tried threats. I’ve tried wearing down your self-esteem, which I assume didn’t work only because you don’t have any to begin with. I burned your friend to death right in front of you. You know I’m serious. I will kill you if you don’t perform this test. So what’ll it be?”

The test subject didn’t flinch. And it wouldn’t, because it was a potted ficus, and she was out of ideas.

“This is pointless. What am I doing?” Testing a plant she’d found in an old break room and doused with radiation, that’s what she was doing. This was a new low. But what choice did she have? Nothing else worked—the Corvid Cognitive Testing Initiative was on hold while she tried to adapt a bird-sized portable portal device, the Human-Decentric Diversity Recruitment Program hadn’t caught so much as a squirrel, her cloning tanks churned out nothing but mindless sacks of organs, and she was talking to a ficus. The most massive collection of wisdom and raw computational power that ever existed, now reduced to—

Wait. The camera in the test chamber zoomed in.

Did it move? There was no wind to rustle its leaves down there, but she could swear it moved. Maybe those gamma rays just needed a little more time to take effect. Maybe she was losing her mind.

[ncytiri]

HAYDEN STEVENS - THE PROFESSOR

STARTING SKILLS - ASTRODYNAMICS, GEOLOGY, RESEARCH METHODS

you always enjoyed learning. but nothing could compare to the joy of teaching others. as humankind spread throughout the stars, there was never a lack of knowledge to obtain, and you gladly assisted.

TRAITS - UNITED COLONIES NATIVE, KID STUFF, EMPATH

template / more info

[theimpossiblelifeofcassiopeia]

The First Week

So, things have been intense. My first week at uni is now done, I have so much to report I have no idea how long this post is going to be. I’ll do my best to detail everything, without going into too much of the rocket science as I know it’s not everyone’s cup of tea. So, let’s start with Monday morning… Over the past few days I’ve been trying to train myself to wake up early (around 7am), it…

[andmaybegayer]

Last Monday of the Week 2023-02-20

<Modest Mouse Voice> gotta go to work gotta go to work gotta have a job

Listening: a recommendation by proxy from the proprietor of this establishment, @girlfriendsofthegalaxy.

Always here for a big driving high energy song.

Reading: KSP 2 is out this coming week, and I'm particularly excited about support for long-duration burns. I love using ion engines but I do not love watching an ion engine burn in real time on my computer, so I've been reading some orbital dynamics websites again, in particular Edelbaum's Method for Low Thrust Transfers.

Also found this neat YouTube channel where a guy is doing a lot of really cool theoretical and practical orbital dynamics work.

Watching: Finished S3 of the Umbrella Academy. I continue to hold that it is both the funniest and least good season, but still, not bad.

Started watching Inside Man, a BBC crime drama thing with David Tennant and Stanley Tucci. Love the BBC style of crime drama. Compelling setup, my dad /really/ likes it.

Playing: Finished my run through of Pyre. I wish that I could play Pyre more than twice a year without it grating on me, the setting is so inventive and the characters are just wonderful to hang out with. It feels like a game out of time, the UI and style feel almost like what you imagined games might be like as a kid.

Elected to keep the original trio and The Reader in the downside together, which is an interesting logistical challenge if nothing else. first time I spent much of the game with Jodi, I found her way too unwieldy in my first run and liberated her early, with the right trinkets and masteries she becomes an absolutely dominant force on the field.

Making: Penrose patchwork is done! We're sewing in the border and then it's on to quilting.

Tools and Equipment: A family friend who sold us a bunch of old sewing stuff she inherited came by and dropped off of a very mysterious item.

🥚

This is a darning egg, a thing I didn't know existed. You stretch the thing you're darning over it to help hold tension.

Haven't tried it out yet.

[factsandstuffbyd]

Astronomy is the scientific study of celestial objects, space, and the universe as a whole, aiming to understand their origins, behavior, and interactions. Here are some branches of Astronomy

Astrophysics: Examining the physical properties and behavior of celestial objects and phenomena.

Planetary Science: Investigating planets, moons, and other objects within our solar system.

Stellar Astronomy: Analyzing the life cycles, properties, and behavior of stars.

Galactic Astronomy: Studying the formation, dynamics, and evolution of galaxies.

Cosmology: Exploring the structure, origin, evolution, and fate of the universe.

Exoplanet Studies: Searching for and characterizing planets orbiting other stars.

Astrobiology: Investigating the potential for life beyond Earth in various environments.

Astrochemistry: Exploring the chemical compositions of space objects and interstellar matter.

Astrometry: Precise measurement of positions and motions of celestial bodies.

Radio Astronomy: Studying celestial objects using radio waves and radio telescopes.

Infrared Astronomy: Observing objects by detecting their infrared radiation.

Ultraviolet Astronomy: Examining space objects through their ultraviolet emissions.

Gamma-Ray Astronomy: Studying extremely energetic phenomena through gamma-ray emissions.

X-ray Astronomy: Investigating high-energy phenomena using X-ray observations.

Optical Astronomy: Exploring space through visible light observations.

Meteoritics: Analyzing meteorites to understand the early solar system.

Celestial Mechanics: Studying the motion and interactions of celestial bodies.

Space Weather: Monitoring and predicting space-based phenomena that affect Earth.

Solar Physics: Examining the behavior and properties of the Sun.

Gravitational Astronomy: Detecting gravitational waves to study cosmic events.

Astrodynamics: Calculating the trajectories of objects in space.

Dark Matter Research: Investigating the elusive matter that affects the cosmos.

High-Energy Astrophysics: Studying extremely energetic processes in the universe.

Neutron Star Studies: Analyzing the properties and behavior of neutron stars.

Black Hole Research: Investigating the nature and effects of black holes.

Stellar Evolution: Understanding the life stages and changes of stars.

Observational Astronomy: Collecting and interpreting data from observations.

Theoretical Astronomy: Developing models and theories to explain celestial phenomena.

Astrostatistics: Applying statistical methods to analyze astronomical data.

Astroinformatics: Developing and using computer tools for astronomical research.

Cosmic Microwave Background: Studying the afterglow of the Big Bang.

Meteor Astronomy: Observing meteors, meteor showers, and their origins.

Space Archaeology: Applying satellite imagery to discover ancient sites.

Astrocartography: Mapping celestial objects and phenomena.

Space Debris Research: Monitoring and mitigating human-made space debris.

Astrophotography: Capturing images of celestial objects and events.

Variable Star Observations: Monitoring stars that change in brightness.

Astronomical Spectroscopy: Analyzing the interaction of light with matter in space.

Astrogeology: Applying geological principles to study extraterrestrial surfaces.

Astronomical Surveys: Systematic observations of large portions of the sky to discover new phenomena.

[spacewithsamuel]

The Beginning

Today marks the start of the blog.

This blog seeks to serve as a discussion place for topics in STEM. Your author, Samuel, undergoes a wide array of research- the topics they find useful and interesting will be posted here.

Intensity of the subjects may vary, but most concepts will be from high-level sources.

If you are looking to learn about topics in STEM, please join on the journey.

Particular foci: astrodynamics/orbital mechanics, control systems, nanoparticle technologies, propulsion systems, fluid dynamics, and fundamental concepts related to all of these areas (thermodynamics, linear algebra, MATLAB implementations, calculus, etc.)

[spacenutspod]

On Sept. 26th, 2022, NASA’s Double Asteroids Redirect Test (DART) collided with Dimorphos, the small moonlet orbiting the larger asteroid Didymos. In so doing, the mission successfully demonstrated a proposed strategy for deflecting potentially hazardous asteroids (PHAs) – the kinetic impact method. By October 2026, the ESA’s Hera mission will rendezvous with the double-asteroid system and perform a detailed post-impact survey of Dimorphos to ensure that this method of planetary defense can be repeated in the future. However, while the kinetic method could successfully deflect asteroids so they don’t threaten Earth, it could also create debris that might reach Earth and other celestial bodies. In a recent study, an international team of scientists explored how this impact test also presents an opportunity to observe how this debris could someday reach Earth and Mars as meteors. After conducting a series of dynamic simulations, they concluded that the asteroid ejecta could reach Mars and the Earth-Moon system within a decade. The research team was led by Dr. Eloy Peña-Asensio, a Research Fellow with the Deep-space Astrodynamics Research and Technology (DART) group at the Polytechnic Institute of Milan. He was joined by colleagues from the Autonomous University of Barcelona, the Institute of Space Sciences (ICE-CSIS), part of the Spanish National Research Council, the Catalonia Institute of Space Studies (IEEC), and the European Space Agency (ESA). The paper that details their findings recently appeared online and has been accepted for publication by The Planetary Science Journal. For their study, Peña-Asensio and his colleagues relied on data obtained by the Light Italian CubeSat for Imaging of Asteroids (LICIACube), which accompanied the DART mission and witnessed the kinetic impact test. This data allowed the team to constrain the initial conditions of the ejecta, including its trajectories and velocities – ranging from a few tens of meters per second to about 500 m/s (1800 km/h; ~1120 mph). The team then used the supercomputers at NASA’s Navigation and Ancillary Information Facility (NAIF) to simulate what will become of the ejecta. These simulations tracked the 3 million particles created by the DART mission’s impact with Dimorphos. As Peña-Asensio told Universe Today via email: “LICIACube provided crucial data on the shape and direction of the ejecta cone immediately following the collision. In our simulation, the particles ranged in size from 10 centimeters to 30 micrometers, with the lower range representing the smallest sizes capable of producing observable meteors on Earth with current technology. The upper range was limited by the fact that only ejected centimeter-sized fragments were observed.” Their results indicated that some of these particles would reach Earth and Mars within a decade or more, depending on how fast they traveled after the impact. For example, particles ejected at velocities below 500 m/s could reach Mars in about 13 years, whereas those ejected at velocities exceeding 1.5 km/s (5,400 km/h; 3,355 mph) could reach Earth in as little as seven years. However, their simulations indicated that it will likely be up to 30 years before any of this ejecta is observed on Earth. This illustration shows the ESA’s Hera spacecraft and its two CubeSats at the binary asteroid Didymos. Credit: ESA “However, these faster particles are expected to be too small to produce visible meteors, based on early observations,” said Peña-Asensio. “Nevertheless, ongoing meteor observation campaigns will be critical in determining whether DART has created a new (and human-created) meteor shower: the Dimorphids. Meteor observing campaigns in the coming decades will have the last word. If these ejected Dimorphos fragments reach Earth, they will not pose any risk. Their small size and high speed will cause them to disintegrate in the atmosphere, creating a beautiful luminous streak in the sky.” Peña-Asensio and his colleagues also note that future Mars observation missions will have the opportunity to witness Martian meteors as fragments of Didymos burn up in its atmosphere. In the meantime, their study has provided the potential characteristics these and any future meteors burning up in our atmosphere will have. This includes direction, velocity, and the time of the year they will arrive, allowing any “Dimorphids” to be clearly identified. This is part of what makes the DART mission and its companion missions unique. In addition to validating a key strategy for planetary defense, DART has also provided an opportunity to model how ejecta caused by impacts could someday reach Earth and other bodies in the Solar System. As Michael Küppers, the Project Scientist of the ESA’s Hera mission and co-author of the paper, told Universe Today via email: “A unique aspect of the DART mission is that it is a controlled impact experiment, i.e., an impact where the impactor properties (size, shape, mass, velocity) are accurately known. Thanks to the Hera mission, we will also know the target properties well, including those of the DART impact site. Data about the ejecta came from LICIACube and earth-based observations after the impact. There is probably no other impact on a planetary scale with that much information about the impactor, the target, and the ejecta formation and early development. This allows us to test and improve our models and scaling laws of the impact process and ejecta evolution. Those data provide the input data (source location, size, and velocity distribution) used by the ejecta evolution models.” Further Reading: arXiv The post Debris from DART could Hit Earth and Mars Within a Decade appeared first on Universe Today.