Frequently I wish I could afford to have a personal orbital dynamics minion that I could have run analyses for me whenever I have a complex orbital dynamics question and would like to test my intuition. Unfortunately, Altius isn’t successful enough yet for me to afford that luxury, and while we have friends and advisors with the relative skills, I don’t have enough money to have them run every analysis I’m interested in. So I figured maybe I could toss this out as a potentially useful topic for someone’s PhD dissertation instead.
Short version: I’d like to do an analysis to see how hard it is (in delta-V, travel time, and launch window frequency) to get from one NEO to another, versus going from a NEO to a planet and back.
I’ve got a lot of friends (bless their hearts) who like to turn up their nose at poor benighted planetary chauvinists, and who go on and on about “once you’re out of a gravity well, why would you want to go back into one?” My intuition suggests they may be wrong, but I’d like to see numbers to either back up my opinion, or shoot it down. My intuition suggests that without atmospheres or the Oberth effect, you’re going to pay big delta-V penalties at each end of the trip, unless the synodic periods are really really long.
My thoughts on how to run the analysis:
- Before you start, pick some subset of the NEO population above a certain size (say 100m diameter, or maybe 1km depending on available computing resources). Gather ephemeri for all of them.
- Pick a random NEO in that group.
- Depending on computing resources pick some specific number of other asteroids to analyze (say 50 or 100 or 1000), and randomly select them from the population.
- Calculate pork-chop plots for travel from the initial asteroid to the other asteroid, and then back again.
- Automatically extract from the pork-chop plots say the minimum delta-V for both legs of the trip, and the associated trip times, stay times, and estimated revisit frequency.
- Run steps 4 and 5 using the Earth, Mars, and Venus as destinations, both with and without aerocapture/aerobraking at the planet end.
- Repeat steps 3-6 a bunch of times (say 100 or 1000 times depending on how much parallel computing capability you have, and how thorough you want to be).
- Analyze the data.
My hunch says that especially if you have aerocapture, you’re going to find that most of the time it’s easier for a given NEO to regularly “trade” with planets than it is with other NEOs, because you can both take advantage of the Oberth effect on departures from the planets, and you can take advantage of aerocapture on the way in. But I’d love to see someone run the numbers–I could be completely wrong.
An analysis like this would be really useful for figuring out what trade networks might look like in the future between NEOs and other solar system entities. If it turns out it’s much harder to get from one NEO to another on a regular basis, as my intuition suggests, it would suggest planets may remain the trade hubs with NEOs being more mining bases. If my hunch is wrong, maybe I owe my NEO-chauvinist friends an apology. 🙂
Bonus points if you can run the analysis using both high-thrust impulsive maneuvers as well as low-thrust, high-Isp maneuvers (like Solar Electric Propulsion systems can provide), to see if SEPs noticeably change the equation–I really have no intuition on how realistic SEPs change or don’t change the equation for NEO transportation.