def _create_tles(ep, source, fragments):
res = []
ep_date = (datetime.datetime(2000, 1, 1) +
datetime.timedelta(ep)).timetuple()
ep_day = ep_date.tm_yday + ep_date.tm_hour / 24. + ep_date.tm_min / 24. / 60. + ep_date.tm_sec / 24. / 60. / 60.
ep_str = (str(ep_date.tm_year)[2:] + '{:12.8f}'.format(ep_day))[:14]
# TODO change satellite ID and posibly alter international identifier?
line1 = source.line1[:18] + ep_str + source.line1[32:-1]
line1 += str(_checksum(line1))
for fragment in fragments:
r, v = source.eph(ep)
v = np.array(v) + fragment[-3:] # add dV
el = kep.ic2par(r, v, source.mu_central_body)
try:
n = math.sqrt(source.mu_central_body /
(4. * math.pi**2 *
el[0]**3)) * kep.DAY2SEC # mean motion in days
except:
continue
# continue to next fragment
M = el[5] - el[1] * math.sin(el[5])
if M < 0:
M += 2 * math.pi
line2 = source.line2[:8]
line2 += '{:8.4f} '.format(el[2] * kep.RAD2DEG) # inclination (i)
line2 += '{:8.4f} '.format(el[3] * kep.RAD2DEG) # RA (W)
line2 += '{:.7f} '.format(el[1])[2:] # eccentrictiy (e)
line2 += '{:8.4f} '.format(el[4] *
kep.RAD2DEG) # argument of perigee (w)
line2 += '{:8.4f} '.format(M * kep.RAD2DEG) # mean anomaly (M)
line2 += '{:11.8f}'.format(n) # mean motion
# line2 += source.line2[63:68] #'{:5d}'.format(1) # revolutions
line2 += '{:5d}'.format(0) # revolutions
line2 += str(_checksum(line2))
# sometimes there is an error 'Eccentricity out of range'
try:
res.append(kep.planet.tle(line1, line2))
except:
pass
return res
def _create_tles(ep, source, fragments):
res = []
ep_date = (datetime.datetime(2000, 1, 1) + datetime.timedelta(ep)).timetuple()
ep_day = ep_date.tm_yday + ep_date.tm_hour/24. + ep_date.tm_min/24./60. + ep_date.tm_sec/24./60./60.
ep_str = (str(ep_date.tm_year)[2:] + '{:12.8f}'.format(ep_day))[:14]
# TODO change satellite ID and posibly alter international identifier?
line1 = source.line1[:18] + ep_str + source.line1[32:-1]
line1 += str(_checksum(line1))
for fragment in fragments:
r, v = source.eph(ep)
v = np.array(v) + fragment[-3:] # add dV
el = kep.ic2par(r, v, source.mu_central_body)
try:
n = math.sqrt(source.mu_central_body/(4.*math.pi**2*el[0]**3)) * kep.DAY2SEC # mean motion in days
except:
continue
# continue to next fragment
M = el[5] - el[1] * math.sin(el[5])
if M < 0:
M += 2 * math.pi
line2 = source.line2[:8]
line2 += '{:8.4f} '.format(el[2] * kep.RAD2DEG) # inclination (i)
line2 += '{:8.4f} '.format(el[3] * kep.RAD2DEG) # RA (W)
line2 += '{:.7f} '.format(el[1])[2:] # eccentrictiy (e)
line2 += '{:8.4f} '.format(el[4] * kep.RAD2DEG) # argument of perigee (w)
line2 += '{:8.4f} '.format(M * kep.RAD2DEG) # mean anomaly (M)
line2 += '{:11.8f}'.format(n) # mean motion
# line2 += source.line2[63:68] #'{:5d}'.format(1) # revolutions
line2 += '{:5d}'.format(0) # revolutions
line2 += str(_checksum(line2))
# sometimes there is an error 'Eccentricity out of range'
try:
res.append(kep.planet.tle(line1, line2))
except:
pass
return res
def computeSpatialDensities(planets):
altStart = 200 # altitude from [km]
step = 20 # size of bins [km]
spaceDens = []
for alt in range(altStart, 2000, step):
noOfPlanInAlt = 0
for i in range(1, len(debris)):
try:
r, v = debris[i].eph(16 * 365)
except:
continue
el = kep.ic2par(r, v, debris[i].mu_central_body)
altitude = (el[0] - 6378000) / 1000
if altitude >= alt and altitude < (alt + step):
noOfPlanInAlt += 1
vol1 = (alt + 6378)**3 * math.pi * 4 / 3
vol2 = (alt + step + 6378)**3 * math.pi * 4 / 3
totVol = vol2 - vol1
spaceDens.append(noOfPlanInAlt / totVol)
return spaceDens
def computeSpatialDensities(planets):
altStart = 200 # altitude from [km]
step = 20 # size of bins [km]
spaceDens = []
for alt in range(altStart, 2000, step):
noOfPlanInAlt = 0
for i in range(1,len(debris)):
try:
r, v = debris[i].eph(16*365)
except:
continue
el = kep.ic2par(r, v, debris[i].mu_central_body)
altitude = (el[0]-6378000)/1000
if altitude >= alt and altitude < (alt+step):
noOfPlanInAlt += 1
vol1 = (alt+6378)**3 * math.pi * 4 / 3
vol2 = (alt+step+6378)**3 * math.pi * 4 / 3
totVol = vol2-vol1
spaceDens.append(noOfPlanInAlt/totVol)
return spaceDens
def _create_tles(ep, source, fragments):
res = []
ep_date = (datetime.datetime(2000, 1, 1) +
datetime.timedelta(ep)).timetuple()
ep_day = ep_date.tm_yday + ep_date.tm_hour / 24. + ep_date.tm_min / 24. / 60. + ep_date.tm_sec / 24. / 60. / 60.
ep_str = (str(ep_date.tm_year)[2:] + '{:12.8f}'.format(ep_day))[:14]
ep_year = ep_date.tm_year
line10 = source.line1[:18] + ep_str + source.line1[32:-1]
r0, v0 = source.eph(ep)
v0 = np.array(v0)
for fragment in fragments:
v = v0 + fragment[-3:] # add dV
r = r0
el = kep.ic2par(r, v, source.mu_central_body)
try:
n = math.sqrt(source.mu_central_body /
(4. * math.pi**2 *
el[0]**3)) * kep.DAY2SEC # mean motion in days
except:
continue
# continue to next fragment
M = el[5] - el[1] * math.sin(el[5])
if M < 0:
M += 2 * math.pi
# added by Alex Wittig to include also individual drag coefficients for fragments
bstar = 0.5 * 2.2 * fragment[
2] * 2.461e-5 # compute B* from A/m and assumed CD=2.2 (see https://en.wikipedia.org/wiki/BSTAR for magic constant)
logb = np.log10(abs(bstar))
iexp = int(logb)
if logb >= 0:
iexp = iexp + 1
mant = 10.0**(logb - iexp)
line1 = line10[0:53] + '{:1s}{:05d}{:1s}{:01d}'.format(
' ' if bstar >= 0.0 else '-', int(mant * 100000),
'0' if iexp >= 0 else '-', abs(iexp)) + line10[61:]
line1 += str(_checksum(line1))
line2 = source.line2[:8]
line2 += '{:8.4f} '.format(el[2] * kep.RAD2DEG) # inclination (i)
line2 += '{:8.4f} '.format(el[3] * kep.RAD2DEG) # RA (W)
line2 += '{:.7f} '.format(el[1])[2:] # eccentrictiy (e)
line2 += '{:8.4f} '.format(el[4] *
kep.RAD2DEG) # argument of perigee (w)
line2 += '{:8.4f} '.format(M * kep.RAD2DEG) # mean anomaly (M)
line2 += '{:11.8f}'.format(n) # mean motion
line2 += '{:5d}'.format(0) # revolutions
line2 += str(_checksum(line2))
try:
tle_new = kep.planet.tle(line1, line2)
tle_new.set_epoch(int(ep_year), float(ep_day))
tle_new.mass = fragment[3]
tle_new.radius = (tle_new.mass / (
(4. / 3.) * math.pi * 92.937 * 2**(-0.74)))**(1 / 2.26)
tle_new.name = tle_new.name.strip() + "-DEB"
res.append(tle_new)
except:
pass
# print kep.planet.tle(line1, line2).mass
return res