AckSed

The actual proposal: http://www.geoffreylandis.com/lightsail/Lightsail89.html The force on the deceleration stage would feel the incident pressure, but would not cancel out, as the light-collecting area of the first stage is greater, and all of that would (somehow) be focused on the deceleration stage... aaand it's been answered. :-) Dealing with the energy focused on this smaller sail would be another problem. The proposal was to use dielectric mirrors made of refractory substances that reflects 99.5% of the energy with minimal absorption, and can take extreme temperatures. Personally, if you have these fancy focusing arrays on the sail, I think you could leverage Y. K. Bae's photonic thrusters by coating the back of the deceleration sail with a thin-film laser gain medium. That way, you have a laser cavity that bounces the light back and forth, recuperating the energy and increasing the thrust with less thermal load. They do say that a staged array of a hundred 500km lenses would be more achievable.

ISRO launches a robotic two-satellite mission designed to test docking technologies... called SpaDeX: https://spacenews.com/india-launches-space-docking-experiment-with-pslv-rocket-advancing-major-ambitions/ Well done for the pun, but it's a groaner.

https://spacenews.com/china-to-debut-new-long-march-and-commercial-rockets-in-2025/ Mostly kerelox, a few methalox, one or two solids... and a case of research institutions designing two different-ish rockets. CALT has proposed the ol' reliable kerelox Long March 8A, while SAST is going for the gold ring with possible new methalox engines and a VTVL test for the Long March 12A.

No master list for everything. This gives a fair approximation: https://www.factoriesinspace.com/ We may have some rather mad ideas tried, and most will fail. No-one in the industry saw Starlink's breadth and scale succeeding, though OneWeb was first, and Iridium and Echostar satellite telephones were before that. Any in-space manufactory that orbits the Earth is a potential application. There are lots of things that are difficult or downright impossible inside a gravity well, that are easier in orbit: crystallisation is the big one, as that's the final stage behind forging, semiconductors, pharmaceuticals and more. In microgravity it's more controlled and even. You can also magnetically or electrostatically suspend materials without touching the walls of the crucible, while heating it in freely-available vacuum - a further advantage for semiconductor manufacturing. Then you can take your boule and go home. Cargo storage in, and delivery from, orbit is an application I couldn't quite believe, but the USA's Space Force is throwing money around to make this Helldivers mechanic happen IRL. Cheap mass to orbit may be the dawn of Big Dumb Flat-pack Satellites, and K2 Space are hopefully building the bus for your application. Cheap kick-stages and on-orbit delivery vehicles to higher orbits will eventually lead to true space-tugs, that shift satellites around, reboost and/or refuel from depots. This may also lead to high-impulse rocket engines. What else... The classic wishlist of any astronomer - larger telescopes. However, someone will have to stick their neck out and volunteer to sell a mass-produced version. Cheaper cube-sat versions are being proposed, but some entrepreneur with more gumption than brains could break into this (small?) market. Asteroid mining will have to be after higher-impulse engines, or cheaper space-tugs, or both.

There are some initiatives to make a bioregenerative, fully-closed life-support system: ESA has been refining a bacteriological-technological system, MELiSSA, for years while NASA founded CUBES in 2017 to study genetically-modified microorganisms as part of the LSS, with an eye towards food, therapeutic pharmaceuticals and bioplastics, with oxygen as a side-product. The atmosphere, and the potential dust and soil and mould problems seem to be shoved to the side with, "We're working the food and waste problem! Hell with it, the ISS system is Good Enough, use that." Personally, I think a partial open-loop system that recovers water, nitrogen and heat, bubbles the waste atmosphere through a supercritical water reactor to sterilise before venting, and takes in oxygen from the regolith electrolysis and/or CO2 electrolysis would also be Good Enough. Perhaps something like activated carbon could be produced from the left-over carbon, as it's used in an extruded form to filter noxious odours and chlorine.

Impacting at 2% c, though... that's when solid matter stops being matter and begins to approach plasma. Maybe even fusion fuel. No idea how you make a crasher stage for that. But to bring it back, the key here is to send a train of the presumably mass-produced probes, passing through the focal point one after the other.

To paraphrase a certain spaceman: Spaceplane! Spaceplane! SPACEPLANE!

Son of a booster, they did it.

Parker Solar Probe about to kiss the sun full on the corona for the first time: https://arstechnica.com/space/2024/12/were-about-to-fly-a-spacecraft-into-the-sun-for-the-first-time/

Geothermal might work - in the right place. The Cerberus Fossae has all the signs of an active magma plume the size of the United States underneath it: https://www.sciencedaily.com/releases/2022/12/221205121545.htm Even if you don't use it to generate power, boring down to tap it for hab heating and factory process heat is viable, as there are companies that make heatpumps for these applications. Ground-source heatpumps: https://www.kensaheatpumps.com/is-a-ground-source-heat-pump-right-for-you/ Overview of steam-generating heatpumps of various types: https://www.sciencedirect.com/science/article/pii/S0196890423012281 ---- Regarding ISRU batteries, there are battery chemistries of differing complexities and capabilities. The most basic would probably be nickel-iron, as popularised by Edison. Good: very tough and long-lasting, easy to make. Bad: lose charge faster than other chemistries, uses water and sulphuric acid as electrolyte. Lead-acid is similar, but slightly better. Lead-mining on Mars is probably a no-go, though. Molten sodium-sulphur or NAS batteries are a small fraction of grid-storage batteries on Earth, and an early electric car used them as well, because they are simple to make and use readily-available materials: steel, aluminia, elemental sulphur, sodium metal. The show-stopper is that you have to keep them hot with insulation and integrated heating elements. Not so bad on Earth, more difficult on Mars but not impossible. Personally I'd use vacuum-insulation panels or, failing that, basalt-fibre mats. Other molten-salt or low-melting metal chemistries are possible: https://en.wikipedia.org/wiki/Molten-salt_battery ---Past this point we move out of possible workshop or small factory bootstrap construction and into needing to import factory equipment.--- Lithium-iron phosphate (LFP) is the current champion of grid storage, and the elements can be obtained on Mars. It's probably even easier to make the synthetic graphite from the readily-available CO2. The electrolyte and the water used is a problem, though. Sodium-ion batteries are a much newer thing, but already attracting attention for the availability of the base materials and the possibility of solid electrolytes. Lower energy density, though we don't particularly care if it's being used for stationary storage.

Found the paper: https://digital.library.unt.edu/ark:/67531/metadc1070838/

I read the entire thing. Man, I think I experienced roughly the same feelings reading it: glad you had the opportunity, wincing at the mess-ups. I sympathise with feeling out of your depth at uni, though not to the extent of working on hardware that was made to be launched. All I did was a BSc in Internet Computing circa 2009, and my ill-chosen final-year project nearly broke me. (Don't choose fuzzy-logic when you barely know how to make a database.) I would like to hear "How not to design for assembly" next.

Tiny payload ready for launch on massive rocket: https://www.blueorigin.com/news/blue-ring-pathfinder-payload

The water collected after passing through the catalyst has enough ammonia to add to the plants to supply the nitrogen they need. So if you had a drip-feeder or hydroponics mister for the plant's roots, this could be added to the apparatus. The Nafion polymer is, surprisingly, the pricey part due to its production cost.

Hang on, could we use hesco bag construction? Very quick, very simple, flat-packed cubical fibreglass bags made to be filled with dirt to construct walls. Combine it with locally-quarried stone beams and pillars, or a composite inner frame, plus an inflatable pressure vessel inside, more overfill on the top, and you have a home. More whimsically, I'm imagining triple-glazed windows inset into the sides that double as 1 metre-thick water tanks.

It actually works slightly better in warmer and drier areas, too. And the power requirements are minimal compared to the Haber-Bosch process; if you wanted, you could use ambient wind instead of a fan or spray, and maybe passive cooling to condense the enriched water.

Efficient, yes. Nice to live in? Hmm. One design I saw for a Mars hab was to, essentially, have a sod regolith roof atop a bungalow, and use mirrors to reflect sunlight into the interior. It'd need sturdy construction and maybe cleaning of the mirrors after a dust storm, but if you're making and shaping steel and glass and plastic on-site (and we could and should) it's no hardship to build tough. We have robots that brush dust off solar panels on desert solar farms, so those could be adapted for the mirrors.

Stanford University researchers have created a process for making ammonia from thin air, at ambient temperature and pressure, by utilising an iron-oxide/Nafion catalyst and the properties of water microdroplets: https://www.science.org/doi/full/10.1126/sciadv.ads4443 It goes like this: a fan draws air in through the air filter, through the catalyst, and onto a chilled condenser plate, where the ammonia-enriched water condenses and drips down into a holding tank. They achieved concentrations of ammonia (120 micro-mol/L) on-site, suitable for some plants. By upscaling a bit, recycling the captured solution and passing it through zeolite filters, then washing it out with a bit of hydrogen chloride, they increased it to 1.4 millimol/L. The experimental setup is notable for how low-energy and low-tech it is:

Vertical farming? This lets me bring up the BioPod, a proposal for a self-contained greenhouse that can work on Earth, in orbit or on Luna or Mars. Flashy site aside, this is a legitimate effort that's been steadily developed since at least 2018.

I think it's akin to the Apollo Applications program, had it not been sunk prematurely by the cancelling of Saturn V in 1968. A true, in-orbit refuellable space-tug would make its resemblance complete. It's not 1:1 - a lot of the hardware and expertise is coming from CNSA or its satellite campuses/companies, farmed out to private entities who develop them. It's like if NASA was also a military aerospace contractor... and MIT.

Small Business Innovation Research/Small Business Technology Transfer (SBIR/STTR) grants may play a larger part in getting and staying on the Moon: https://payloadspace.com/nasa-cozies-up-to-industry-with-2025-sbir-plans/ So, though the awardees typically display the "valley of death" where after stage 2 funding finishes, about 1 in 6 reach Stage 3 (commercialisation), this says (hopes) that they have a better idea how this year. One of them is outright propping up entrepreneurs and commercial companies with SBIR Ignite. Now, it's no free ride, they have to reach certain benchmarks, but this lets companies access NASA technology and patents when they are just starting. This year it's: Aviation-Ready Electrical Energy Storage for All-Electric or Hybrid Electric Aircraft (heavy drones and certification for such) Leak-Free Cryogenic Valves and Quick Disconnects (valves and disconnects that will work on the ground and in space) Decision Support Tools Leveraging NASA Earth Science Data (processing all the data under the Earth Science To Action initiative)

The thing is, an organic, livable city on Mars starts to bring up questions of "What is perceived as an organic, livable city on Earth?" In my opinion, it should not be based around the car. That, and zoning laws, isolate people inside their castles, moated by your lawns, and bubble you in your pickup truck. It is ridiculous how large American houses are. Public transport should be cheap & available. Walkable streets, large communal spaces, modest living quarters. That's part of the recipe. Not the whole one, I don't have all the answers, but part of it.

Can it be done with mathematics? Going to try. Random site I found says: For the dome with 11.3 m diameter, 5.65m radius and 100m2 of floor area, and assuming radius = height, that's an area of 200.58 m2. Punch that in... Water dome on Mars: 1000 * 3.72 * 1 * 200.58 = 746,158N/m2 Water dome on Luna: 1000 * 1.625 * 1 * 200.58 = 325,943N/m2 On Mars, the temperatures measured in e.g. Gale Crater can range from 20 deg. C all the way down to -84 deg. C... in summer. In winter, knock 20-30 degrees off each of those. Mars gets cold. The dust storms are no fun, either, blocking up to 99% of light. Water stays ice, most of the time. On Luna, it ranges from -173 deg. C to 116 deg. C at the equator. The water might boil.

https://www.thehindu.com/news/cities/bangalore/scientists-and-astronomers-meet-at-raman-research-institute-to-explore-moon-as-vantage-point-for-studying-the-universe/article68948159.ece

Moon Monday Report on the Chinese-hosted Galaxy Forum. Featured former NASA astronaut Donald Thomas as a speaker. Goals for International Lunar Research Station (IRLS): Learn about our Moon’s evolution & structure; Conduct lunar-based astronomy for doing cosmology and studying habitable exoplanets; Observe the Sun and Earth from the scientifically unique vantage point of our Moon; Conduct lunar-based experiments like studying plant growth. NAOC/CAS target launch year for the proposed lunar orbital satellite constellation called Discovering Sky at Longest wavelength (DSL) is 2027. It will have a 'mother' satellite and eight trailing 'daughters'. Thailand's NARIT, one of the partners in the IRLS, has ambitions of launching a Lunar Pathfinder nanosat, possibly to be launched on a Chinese rocket. The slide opposite detailed NARIT's 40m radio telescope, which will be used to track spacecraft in conjunction with China's own Deep Space Network: a 25m one in Xinjiang Astronomical Observatory, Nanshan, and the massive 65m one in Tianma, Shanghai.