I am very happy that you folks are showing interest but I am also terrified because this thing is definitely not ready for primetime, yet.
The discerning astrodynamicist and/or rustacean will surely find things which are less than optimal or plain wrong.
I am also preparing for a trip so I won't be able to monitor this thread closely but I'll try to answer question wherever I can.
Hey, this is really impressive stuff, talk about a dream job! Two quick questions if you find the time+interest:
1. What does "safe" imply? Type safety, maybe? Or just a general synonym for "few bugs/well tested"?
2. What kind of industry is this primarily envisioned for use in...? I have experience in the satellite industry (GRE and TT&C) but I was surprised to not see the usual buzzwords on this page, namely "TLEs". I get that it clearly does way more than terrestrial orbital work, but AFAIK that's, say, 99.9% of the current space industry.
In other words: is this library for ESA missions??? That would be rad as hell, if so.
also P.S. I love AI art compared to most, but I would def recommend carving out that cool crab and putting on a background of real stars. As you may or not be aware, many scientists have been a tad radicalized about AI, and AI art in particular -- would be a shame if that slowed adoption of a cool project!
Ground Receiving Equipment, Telemetry, Tracking, & Control, and two line rlement sets. Apparently everything you need to predict orbits of a satellite are contained inside TLEs metadata and is considered a good way to share orbital information between disparate parties.
Heh, you actually highlight a funny frustration from my time there: TLES technically has a capital "S" too, but it's basically always discussed in the plural -- so I would very frequently forget to capitalize the "S" to the veterans' chagrin. Clearly, I haven't shaken the habit!
In hindsight, I guess it's the industry's fault for not pronouncing it "Tee Ell Eee Esses"...
EDIT: And I appreciate the explanation, personally! That's the best part of HN. To be clear to passers-by, a TLES is a string of characters that describes the orbit of a single satellite (artificial or otherwise) based on its position & momentum at some given start second. They have to be updated pretty frequently to account for gradual stochastic drift, which is both an interesting technical problem and a compelling philosophical metaphor.
Can I build a solar system simulator with this? Looking for calculating the absolute positions of planets and moons with the sun at 0,0,0 given a datetime. Kepler calculations for planets, moons etc would be fine, as long as I can insert arbitrary objects and calculate their trajectory using gravity. Can this project do that?
We already have the possibility to get positions of celestial bodies with very high precision via JPL ephemerides but you would have to write and integrate your force model yourself.
Shower thought:
People vote for Trump because he is actually predictable.
You never have to guess whose interests he is protecting. It's always his own.
You never have to guess whether he is lying. He sure as hell is but there is also no hidden agenda. It's unfiltered mental diarrhea but it's raw and authentic.
I think a lot of the unease and disdain for the Western political class stems from their attempts to be inoffensive and appeal to everybody. Whatever policy you enact there is always going to be a trade-off, winners and losers, and if you do now acknowledge that, how can I be sure that you are acting in my interest?
“Me? I'm dishonest, and a dishonest man you can always trust to be dishonest. Honestly. It's the honest ones you want to watch out for, because you can never predict when they're going to do something incredibly... stupid.”
― Captain Jack Sparrow
He is not predictable, mere selfish interests doesn't make him so, he doesn't have an ideology and therefore very flexible on what he will do, is easily manipulated by anyone and also there are many more dangerous people who will run his administration(RFK is in-charge of health!) while he spends his days on the golf course.
I think authenticity is being hugely underrated as a factor for why Trump won. People inherently trust someone who is visibly flawed and speaks off-the-cuff. This preference for authenticity has always existed, but is extra strong as a reaction to social media.
I owe my career to the incompetence and greed of Arianespace. For my master's thesis I reverse engineered launcher ascent simulations for ESA because Arianespace was unwilling or unable to answer basic questions such as "how much payload can rocket X transport to orbit Y which is not GTO" without charging an obscene amount of money and needing months of lead time.
A few years later at one of the Lunar X-Prize startups, my team and I sat together with Arianespace's mission analysts and we had to explain to them why you cannot have a 24-hour launch window when you want to fly to the Moon. The bloody thing moves!
After SpaceX published the video from the first successful grasshopper flight it was clear to me and basically everyone else I talked to in the industry that an expendable Ariane 6 was DOA. But the pork must flow...
The corruption, nepotism, and incompetence runs deep in the European space industry. ESA is an organization where people get passed over for promotion because they are "too technical" or don't belong to the right old boy network.
Geo return (the geographic return rule) excacerbates all these problems by creating quasi-monopolies. As an example, the market leader for astrodynamics software in Europe is at the top because their national delegation heavily invests in programs that benefit them and not much else. Thus, they "need" to win a lot of contracts to balance the scales and make a luxurious living by repackaging the same old Fortran77 garbage over and over again.
Maybe a dumb question, but why do you need to launch directly to the moon instead of launching to earth orbit then doing a transfer? How much better is the direct method delta v?
I don't know if one trajectory is more efficient than the other, but space propulsion systems are quite tricky and if I remember correctly the X prize was trying to incentivize doing things on a budget to "democratize" access to the moon. It was basically the cubesat of moon rovers. If you think of technical decisions through that lens, it therefore makes sense to ask your launch provider to do as much of the work as possible since they already have a second stage capable of getting you there, instead of designing a bigger payload with a more capable propulsion.
Yeah, Moon flight trajectories could be somewhat head-scratching.
Imagine the Moon orbit is in the plane of the Earth equator (it's not) and you're launching your rocket also to the equatorial plane. Moon rotates around the Earth in one month, LEO period is about an hour and a half, so every approximately 1.5 hours you're passing via point in orbit which has the necessary phase (angular) distance relative to the Moon. If you, for example, going via a Hohmann orbit - half-ellipse from LEO to Moon orbit - you just start translunar injection burn at the point of LEO (approximately) opposing to the Moon. Life is good, you don't need to think much and plan ahead - just gas 'n go.
Now, real world. Moon orbit is 5.1 degrees from ecliptic plane (the plane of the Earth orbit around the Sun), and Earth axis is 23.44 degrees from ecliptic, and there are no convenient spaceports on equator - Alcantara still doesn't launch, and Sea Launch is out of business. So the plane of your LEO orbit is likely different from the plane of the Moon orbit. What does it mean? Two different planes intersect in just one straight line - which in this case passes through the Earth center (or somewhat close to it). If you'd start your engines near the intersection point - when your position on LEO will be near that intersecting line of LEO plane and Moon orbit plane - then you'll raise your apogee and it will hopefully bring you to the vicinity of the Moon orbit. Now, the question: will Moon be there, near that point of its orbit? If you carefully waited on LEO - or launched to LEO in the proper time, taking all this into account - then it might. If not - well, your spacecraft will fly to the Moon orbit and back, as did some Zonds launched in USSR. So here we clearly see the need for the correct launch window.
(And if you won't start your engines close to that intersection point - then you might get as far as the radius of the Moon orbit, but will be away from the orbit itself - the Moon orbit is just a circle, and you'll fly towards some point of the sphere with the radius of the Moon orbit. Could be completely different areas of space, so you need to take the plane of the Moon orbit into account)
Theoretically we might try to change the orbital plane. It's either very expensive in terms of delta-V - you usually don't have nearly the amount of fuel needed - or takes some less fuel and a lot of time - as you need to travel far away, to make the plane change cheaper in the region where the orbital velocity is much smaller.
Realistically it's better to launch towards correct plane and in correct time, and plan ahead. Funny, the Earth-Moon system seems rather simple, and yet we still need to be smart enough to navigate here.
I have quit caffeine twice in the past few years with the longest abstinence being around one year. Before that I was chugging up to four double espressi per day which I replaced with decaf. The inital withdrawal was brutal with migraine-strength heachaches (including feeling very sensitive to light and nausea) on the first day and milder headaches for another week or two. I noticed small improvements to my sleep, e.g., falling asleep a bit faster, but I am a bad sleeper in general and having a newborn child did not help.
The biggest benefit was not being dependent on caffeine and not consuming lots of bad coffee as a result (Starbucks et al.). I remember one instance were I was on vacation snowshoeing in the Alps. The cabin were we slept only offered coffee that was absolutely undrinkable and I had a lousy day as a result. Not great...
That being said, I am back on caffeine again because I realized that it acts as a mild anti-depressant for me. It seems to have an effect on my dopaminergic system as well and helps me focus and get stuff done.
Since I started drinking coffee again, I have not had a day where I do not feel like doing anything (not even goofing off) and get nothing done at all. This happened regularly when I was off caffeine.
I manage the negative side effects by not drinking coffee after 2 PM and I limit myself to three cups/espresso shots per day. Seems to work as well.
A second degree acquaintance of mine in Germany had his house raided by police and all of his electronics (including his work laptop and phone) temporarily confiscated on suspicion of possession of child pornography because...
...an anonymous member of a child pornography forum used the handle "$NAME_$YEAR" and had his location set to $TOWN. The innocent bystander's middle name is $NAME and he was born in $TOWN in $YEAR but had not lived there for decades. He only learned about this absolutely nonsensical justification and got his stuff back by hiring a lawyer who requested access to the DA's investigation file.
If you can get a judge to sign a warrant with flimsy non-evidence like this, what will they do when the robot says "95% match detected".
Disclaimer: I am one of the (many) engineers working on the project.
Before COVID I worked for a European lunar exploration startup and access to a constellation like this would have changed everything. The plan was to provide an end-to-end payload transportation service to the lunar surface and we wanted to fly our own two rovers as a demo mission.
While you can accomplish all communications (TM/TC, HD video) and navigation (orbit determination, surface nav) tasks with terrestrial ground stations, it is hellishly expensive.
Just as an example, the good thing about the Moon (in contrast to Mars) is that it is very close and you can drive a rover almost in real time due to the comparatively low latency (that's what the Russians did with the Lunokhods: https://en.wikipedia.org/wiki/Lunokhod_programme). That means you can cover more ground than on Mars which was also very important to us because the plan was to drive to one of the Apollo landing sites (where you must land outside the exclusion zone) and we would have had only 10-12 days of daylight for our operations until the lunar night would have killed our electronics. For that you need good video feeds from the rover's cameras which again required downlink via X band antennas due to the Moon's distance from Earth. There are not that many X band ground stations and all the interplanetary missions are constantly fighting for the limited capacity.
We would have then needed even more ground station time for ranging operations, i.e. performing orbit determination during the transfer and prior to landing and determining the rovers' exact positions on the surface. In the end, we would have needed to pay several million EUR for ground station time alone. A reasonably priced Project Moonlight constellation would have been a godsend and significantly reduced the complexity of our operations. Cash-strapped startups are not the best customers, though...
I can only assume that all the companies in the NASA CLPS program are facing the same issues. The problem is that they are planning their missions and are designing their spacecraft now. If this constellation becomes a reality, it will certainly be too late for the first batch.
As for the ideas about Starlink, satellites are designed around their payloads, i.e. all subsystems (power, thermal, comms, on-board computer, propulsion) are designed to fulfil the requirements of a specific payload and its mission with some margins. Very rarely can you swap or add additional payloads without redesigning the whole system especially if your starting point is as streamlined a design as Starlink's is.
I am a huge fan of all things SpaceX but they are not miracle workers. Also Starship has not reached orbit (yet) and Super Heavy has not flown (yet).
Finally, the costs. As some others have commented, this is a paper study right now which is comparatively cheap (no idea how much exactly but my educated guess would be single digit millions). Whether this will be funded for real and becomes an actual program will be decided at ESA's next ministerial. In the grand scheme of things this is not a lot. Compared to of ESA's annual budget of ~6 billion EUR it is almost negligible. That again is a joke compared to NASA's annual budget of ~22 billion USD. Which still pales in comparison to the up to 1.3 trillion EUR that the German federal and state governments alone spent on the mitigation of the pandemic (https://www.zdf.de/nachrichten/politik/corona-novemberhilfen...) or the economic cost of climate change which is also in the trillions.
Yes, space hardware is too expensive, there is too much red tape, and frankly too much nepotism in OldSpace. But taking the few billions spend on space every year away and spending them on the "big problems of our time" would accomplish very little.
TL;DR: The technical benefits are real whether it becomes a reality and is commercially viable remains to be seen. SpaceX is great, Starship is great, Starlink is great, but it is also not magic. Space sounds expensive but really isn't when you do the math.
