A Low-Cost Mission for LISA Markus Landgraf, Florian Renk, Pierre Joachim, Rüdiger Jehn HSO-GFA LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 1
Overview Basic working assumptions Operational orbit: heliocentric slow drift-away Soyuz launch from Kourou Transfer scenarios Total delta-v budgets Conclusion LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 2
Basic assumptions V-config L=10 6 km basic angle 90deg, no difference in delta-v for 60deg LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 3
Circular Heliocentric Trailing For slow drift (15deg over 5 years) Stop manoeuvre is required Initial trailing angle 10deg to avoid disturbance of the formation Third body perturbation by the Earth is compensated by drift in the HCW frame Full numerical simulation and minimisation of breathing performed LISA Kick-Off June 15 th, 2011 CDF HSO-GFA Page 4
Drifting LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 5
Constellation Breathing LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 6
Constellation Arm Length LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 7
Constellation Range Rate LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 8
Interplanetary Transfer vinf [m/s] decl [deg] rasc [deg] Δv arr [m/s] mother 162 11 +25 154 daugther1 329 +26-7 130 daughter2 274-26 +19 104 LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 9
Soyuz Launch from Kourou LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 10
Soyuz Launcher Performance LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 11
Transfer Scenarios Baseline: Double launch lunar fly-by 1. Soyuz launches 2 Daughters into HEO at 15deg inclination Daughters perform lunar fly-by to reach escape condition 2. Soyuz launches Mother directly into i=65deg departure hyperbola Option 1: Double launch direct: same launch scenario as in baseline, but without lunar fly-by, but split manoeuvres are performed after leaving the Earth s sphere of influence Option 2: Single launch direct: launch all spacecraft on one launcher, all three perform a split manoeuvre after leaving the Earth s sphere of influence LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 12
Lunar Fly-by transfer Example transfer: Injection of S/Cs into HEO with rapo = 400,000 km - Orbital plane is equivalent to lunar orbital plane (LOP) (accessibility from Kourou TBD, see next slide) At apogee both S/C change the inclination with respect to the LOP by 10.5 DEG (both planes are then 21 DEG apart) At next perigee pass the apogee must be raised to reach the required v after the fly-by - Apogee raising ΔV = 40 m/s Lunar fly-by approaching the moon from different hemispheres leads to required v vectors LISA Internal Final Study Presentation July 8 th, 2011 CDF HSO-GFA Page 13
Lunar Fly-by transfer Insertion in lunar orbital plane (LOP) not always possible Restrictions on the launcher inclination due to walking impact point of 3 rd stage GAIA launcher scenario with 15 DEG parking orbit Unbalanced ΔV for rotation of orbital planes - Required rotation now 3 DEG and 24 DEG Manoeuvre 11 and 80 m/s, respectively Declination of the moon is 50 % of the time below 15 deg and can then be reached from a 15-deg inclination HEO Lunar flyby time slot from MJD=7153.5 to 7159.5 Example case: flyby on 8 Aug 2019 (7159.07) with v =731 m/s at an altitude of 200 km LISA Internal Final Study Presentation July 8 th, 2011 CDF HSO-GFA Page 14
Delta-v budget LGA transfer, double launch mother daughter 1 daughter 2 launcher disp 36m/s 5m/s 5m/s perigee raise - 40m/s 40m/s plane change - 11m/s 80m/s apogee raise - 40m/s 40m/s arrival 154m/s 130m/s 104m/s navigation 20m/s 20m/s 20m/s launch window reserve, gravity loss (20%) 42m/s 46m/s 50m/s total 252m/s 272m/s 299m/s LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 15
Delta-v budget direct transfer, double launch mother daughter 1 daughter 2 launcher disp 36m/s 5m/s 5m/s perigee raise - 10m/s 10m/s apogee raise - 773m/s 773m/s split - 148m/s 148m/s arrival 154m/s 130m/s 104m/s navigation 20m/s 20m/s 20m/s launch window reserve, gravity loss (20%) 42m/s 218m/s 212m/s total 252m/s 1304m/s 1272m/s LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 16
Delta-v budget direct transfer, single launch mother daughter 1 daughter 2 launcher disp 5m/s 5m/s 5m/s perigee raise 10m/s 10m/s 10m/s apogee raise 773m/s 773m/s 773m/s split 167m/s 167m/s 167m/s arrival 154m/s 130m/s 104m/s navigation 20m/s 20m/s 20m/s launch window reserve, gravity loss (20%) 226m/s 218m/s 212m/s total 1355m/s 1304m/s 1272m/s LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 17
Consequences of Longer Arms Cost is 100m/s per 1 million km in arrival delta-v, distribution between individual S/C is TBD LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 18
Conclusion (1/2) The heliocentric drift-away formation has the potential to minimise the LISA propulsion system (in size, minimum thrust, and cost) other options do not provide the required formation stability, require significant stationkeeping or large distances in the Earth Increasing the arm length costs approximately 100m/s per 1 million km Soyuz provides 1,933kg for the mother launch (i=65deg escape), 2,210kg (15deg HEO with apogee at 400,000km, 2,277kg minus 3% margin due to unconfirmed launcher optimisation) LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 19
Conclusion (2/2) Delta-v budget provided for three transfer scearios double-launch with daughters performing lunar fly-by double-launch with direct transfer single launch with direct transfer LISA Internal Final Presentation July 8 th, 2011 CDF HSO-GFA Page 20