>"Quite precise data for thousands of NEOs is available, but its needs converted to position and movement vectors to use in this simulation." https://github.com

>"Quite precise data for thousands of NEOs is available, but its needs converted to position and movement vectors to use in this simulation." https://github.com/strainer/fancy https://github.com/strainer/fancy Thanks for the good discussion. I'm still unconvinced that asking for climate models to report on conservation of energy is "undue speculation", but I really don't know how big a deal it is. Anyway, I looked at my old code and here is some R to get the JPL data and convert to state vectors, hopefully you can use/translate it to easier test your sim: dlHorizons <- function(ObjName = "Apophis", sd = "2000-Jan-01", st = "00:00:00", ed = "2000-Jan-02", et = "00:00:00", stepSize = "1", stepUnit = "d"){ root = "http://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&" start = paste0("START_TIME%20=%20%27", sd, "%20", st, "%27&") end = paste0("STOP_TIME%20=%20%27", ed, "%20", et, "%27&") tble = "TABLE_TYPE%20=%20%27Vector%27&" RefPlne = "REF_PLANE%20=%20%27Ecliptic%27&" RefCntr = "CENTER%20=%20%27@000%27&" VecTab = "VECT_TABLE=%20%272%27&" step = paste0("STEP_SIZE= %27", stepSize, "%20", stepUnit, "%27&") Cmd = paste0("COMMAND=%20%27",ObjName, "%27") res = scan(paste0(root, start, end, tble, RefPlne, RefCntr, VecTab, step, Cmd), what="") return(res) } extractEphemeris <- function(input){ ends = grep("(\\$\\$SOE)|(\\$\\$EOE)", input) input = input[ends[1]:ends[2]] dates = input[grep("(TDB)", input) - 2] times = input[grep("(TDB)", input) - 1] start = grep("(TDB)", input) + 1 end = start + 5 ret = as.data.frame(matrix(nrow = length(start), ncol = 8), stringsAsFactors=F) colnames(ret) = c("Date","Time", "px", "py", "pz", "vx", "vy", "vz") for(i in 1:length(start)){ ret[i,3:8] = as.numeric(input[start[i]:end[i]])*1000 } ret$Date = dates ret$Time = times return(ret) }