I am not a satellite tech. & not trained regarding satellites. You may wish to follow along with my thoughts below: partly basic satellite info. I searched out & share, & partly my own personal opinions & conclusions. Your own thinking & conclusions are also necessary. Hopefully I can save you some time by sending some of your thoughts in helpful directions & towards useful questions.
Earth satellites are currently accumulating quickly. As of a few months ago it was calculated by experts that, in the (near?) future, “more than a million satellites [might be] headed into low-Earth orbit”. Yikes. That number was added up by reviewing “recent filings in the [database of the] International Telecommunication Union (ITU) … a United Nations agency”. The number of satellites that will actually make it up into space may differ. Some think that huge projected nos. are “likely inflated by hype”, that predicted numbers can vary wildly (“many of the proposed satellites may never be launched … researchers say.”)
Worldwide, nations have proposed launching So very many satellites. Distributed across 300 “megaconstellations” (= vast networks of satellites that work together). The no. of satellites proposed is “115 times higher than the no. of functional satellites currently circling Earth”. Recently counted: “9,413 manmade objects [currently] circling Earth”.
Wooden satellites?: One of the surprising answers (to harmful space debris) being proposed: make satellites out of wood instead of metal; then they can/may burn up on re-entry. While current/older satellites if/when re-entering Earth’s atmosphere “burn & create tiny alumina particles which [can] float in the upper atmosphere for many years”, eventually affecting Earth’s environment. Because “aluminum damages the ozone layer”.
After sending various “wood samples … to the International Space Station”, testing showed magnolia wood to be “the most resistant to splitting”. Though apparently all of the wood tested so far “performed surprisingly well”. So magnolia wood has now been used to build the “LignoSat probe”. That LignoSat probe (“the world’s first biodegradable satellite”) is being sent into space on a 6-month mission beginning this Summer 2024. It’s very small, “about the size of a coffee cup”. Its performance will be studied/reviewed & if it performs well, it could be the beginning of more wood satellites sent to space.
Rockets: Generally, we launch satellites into space by putting them on rockets. & “Particles … in rocket exhaust — chiefly alumina & black carbon — … really matter”. They scatter & absorb sunlight, & “change the temperature & circulation of the stratosphere…” It is considered that “frequent future rocket launches could have a significant cumulative effect” on Earth’s climate. How many launches / how frequent the launches, before affecting the climate? Projections (guesses?) not yet seen by me. I surmise: likely Very difficult to know in advance.
Space debris in general: Is accumulating & apparently becoming a big problem. A study found that “10% of particles in the upper atmosphere now contain bits of metal from rockets or satellites falling out of orbit & burning up.” In low-earth orbit “objects can collide at ~ 23,000 mph”, meaning that even the tiniest debris could e.g. potentially damage the International Space Station.
Entities are starting to test ways to clean up space debris. Example: using strong magnets to capture such “moving space targets”. Enter: “the emerging field of orbital debris removal.” Although (per the Internet) we are advised that “uncontrolled reentry of massive [space debris] objects … is fairly uncommon”. I have read there that most objects that re-enter through Earth’s atmosphere “usually burn up”. A 1-in-10,000 probability threshold is mentioned, “for the casualty risk of a single uncontrolled reentry”.