A Low-Cost Mission for LISA - TAPIR at...

LISA | Internal Final Presentation July 8th, 2011| CDF | HSO-GFA |

A Low-Cost Mission for LISA

Markus Landgraf, Florian Renk, Pierre Joachim, Rüdiger Jehn

HSO-GFA


Overview

  Basic working assumptions

  Operational orbit: heliocentric slow drift-away

  Soyuz launch from Kourou

  Transfer scenarios

  Total delta-v budgets

  Conclusion


Basic assumptions

  V-config

  L=106km

  basic angle 90deg, no difference in delta-v for 60deg

LISA | Kick-Off June 15th, 2011| CDF | HSO-GFA |

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


Drifting


Constellation Breathing


Constellation Arm Length


Constellation Range Rate


Interplanetary Transfer

vinf [m/s] decl [deg] rasc [deg] Δvarr [m/s] mother 162 11 +25 154 daugther1 329 +26 -7 130 daughter2 274 -26 +19 104


Soyuz Launch from Kourou


Soyuz Launcher Performance


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 8th, 2011| CDF | HSO-GFA | LISA Study

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 Presentation July 8th, 2011| CDF | HSO-GFA | LISA Study

Lunar Fly-by transfer

  Insertion in lunar orbital plane (LOP) not always possible •  Restrictions on the launcher inclination due to walking

impact point of 3rd 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


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


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


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


Consequences of Longer Arms

Cost is 100m/s per 1 million km in arrival delta-v, distribution between individual S/C is TBD


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 station-keeping 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)


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

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