The Mission - LISA
LISA Mission Description
This table summarises the basic mission elements and characteristics of LISA.
Science Objectives |
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Study the formation and evolution of compact binary stars in the Milky Way Galaxy | |
Trace the origin, growth and merger history of massive black holes across cosmic ages | |
Probe the dynamics of dense nuclear clusters using extreme mass-ratio inspirals (EMRIs) | |
Understand the astrophysics of stellar origin black holes | |
Explore the fundamental nature of gravity and black holes | |
Probe the rate of expansion of the Universe | |
Understand stochastic gravitational wave backgrounds and their implications for the early Universe and TeV-scale particle physics | |
Search for GW bursts and unforeseen sources | |
Event rates |
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Frequency band | 1 × 10−4 Hz to 1 Hz, (2 × 10−5 Hz to 1 Hz as a goal) |
Massive black hole mergers | 1 yr−1 to 1000 yr−1 |
Extreme mass ratio insiprals | 1 yr−1 to 100 yr−1 |
Galactic Binaries | ∼25 000 resolvable out of a total of ∼30 × 106 in the LISA band |
Mission |
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Duration | 4 years science orbit, (∼ 6.5 years including transfer and commissioning) |
Orbits | Three drag-free satellites in heliocentric orbits, semimajor axis approx. 1 AU, eccentricty e ≈ 0.0096, inclination ı ≈ 0.96° |
Spacecraft bus | Provides power, communication, and attitude and orbit control (AOCS) on science orbit. Micronewton propulsion system, magnetically and gravitationally controlled design |
AOCS | Derived from test mass position and received laser, star tracker as backup |
Pointing | Spacecraft attitude jitter < 10 nrad/√Hz |
Mass | Mass (spacecraft incl. payload): 1898 kg |
Power | Science mode: 1.6 kW |
Constellation | Equilateral triangle, 2.5 × 106 km armlength, trailing Earth by ~20°, inclined by 60° with respect to the ecliptic. Armlength variation < 1 %, angular variaton ±0.8°, relative velocity between spacecraft < 20 m/s |
Communications | Data generation rate 17 kbps per spacecraft, downlink via X-band, downlink data rate 150 kbps during 8 hours contact. |
Contact schedule | One 8 hour pass per day to one spacecraft. Data of other two s/c transferred to master via laser link |
Total mass | Including margin, launch adapter and propellant: 6642 kg |
Launcher | Ariane 6.4 |
Launch date | 2034 |
Payload |
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Laser | 2 per spacecraft, 2 W ouput power at end-of-life, wavelength 1064 nm, frequency stability (pre-stabilised) 300 Hz/√Hz, fractional power stability 10−3/√Hz |
Optical bench | 2 per spacecraft, material with low thermal expansion (Zerodur), monolithic construction (hydroxy-catalysis bonding) |
Inteferometry | heterodyne interferometry, 10 pm/√Hz requirement. Inter-spacecraft ranging to ∼1 m, clock tone transfer |
Gravitational reference sensor | 46 mm × 46 mm × 46 mm test mass made from AuPt alloy (73:27), electrostatically controlled, optical readout, residual acceleration <3 × 10−15 m/s2/√Hz (10−9 m/s2 at DC) |
Telescope | 2 per spacecraft, 30 cm off-axis telescope. Changing inter-spacecraft angle compensated by telescope movement. |
Mass | Net mass per payload: 475 kg |