LISA Pathfinder is a mission of the European Space Agency that was launched on December 3rd, 2015 and will be performing science operations until May 31st , 2017. It has paved the way for the future L3 mission (L-class mission) of ESA devoted to gravitational-wave astronomy from space, with the goal of implementing the science of the white paper The Gravitational Universe.
LISA Pathfinder has tested in flight the very concept of gravitational wave detection: it contains two test masses in a near-perfect gravitational free-fall and an optical (laser) metrology system that controls and measures their motion with unprecedented accuracy. LISA Pathfinder is using the latest technology to minimise the extra forces on the test masses, and to take measurements. The inertial sensors, the laser metrology system, the drag-free control system and an ultra-precise micro-propulsion system make this a highly unusual mission. LISA Pathfinder also carries a NASA payload, an alternative micro-propulsion system.
On June 7th, 2016, the LISA Pathfinder collaboration announced at the European Space Astronomy Center (ESAC) the success of the LISA Pathfinder mission by showing an acceleration noise sensitivity curve much better than the required initially (improvement factors are typically 5-1000 depending on the frequency range) and very close to the one required by the classic LISA mission.
Aim of our participation
The ICE leads the Spanish contribution to the mission through the Gravitational Astronomy – LISA group. Spain is one of the eight signatories of the Multilateral Agreement (MLA) between ESA and Germany, Italy, United Kingdom, Spain, France, the Netherlands and Switzerland. The Spanish contribution started on 2004, led by Prof. Alberto Lobo, and consists in the Data and Diagnostics Subsystem (DDS), which include the payload control computer, also known as the Data Management Unit (DMU) and a set of high-precision and high-estability sensors and actuators to monitor the environment of the test masses in LISA Pathfinder, the Diagnostic Items (ITs).
The DMU is the main computer of the LTP (a mission critical component) which interfaces with the On Board Computer (OBC), the LPF master computer which communicates with the ground stations and distributes tasks to the various subsystems of both the satellite and the payload. The DMU also controls the diagnostic subsystem. The DMU contains fully duplicated hardware (redundancy). The Boot (BSW) and Application software (ASW) for the DMU have also been the responsability of the Spanish group.
The DIs consist of: (i.1) Thermal Diagnostics that use 24 precision thermometers and 14 precision heaters. (i.2) Magnetic diagnostics that use 4 sensitive 3-axes magnetometers (fluxgate class) and 2 precision induction coils. (i.3) Charged particle counting and spectroscopy by means of a Radiation Monitor.
The group has contributed also some parts of the LISA Technology Package Data Analysis (LTPDA) tools, a MATLAB tool developed for the analysis of the LISA Pathfinder data.
After the LISA Pathfinder launch, the scientific operations started officially on March 1st, 2016. During the operations several members of the group have travelled to the European Space Operations Center (ESOC) in Darmstadt (Germany) to participate in the operations and in particular in the data analysis, leading several times the team on duty. Our team has been in charge of the definition of several experiments on-board involving heat injections in highly sensitive locations and application of controlled magnetic fields to the free-falling test masses. We are also hosting and maintaining the web service with the different instrument daily reports. We are responsible, as hardware providers, of the monthly reporting of the Data and Diagnostics Subsystem to ESA. In addition, members of the group have made important contributions to the data analysis pipelines used in LISA Pathfinder.
M. Armano et al (LISA Pathfinder collaboration; 99 authors): Constraints on LISA Pathfinder’s self-gravity: design requirements, estimates and testing procedures, Classical and Quantum Gravity, 33, 235015 (2016)
M. Armano et al (LISA Pathfinder collaboration; 119 authors): Sub-Femto-g Free Fall for Space-Based Gravitational Wave Observatories: LISA Pathfinder Results, Physical Review Letters, 116, 231101 (2016)
M. Nofrarias, N. Karnesis, F. Gibert et al (22 authors): Optimal design of calibration signals in space borne gravitational wave detectors, Physical Review D, 93, 102004 (2016)
Senior Institute members involved
, LL. Gesa, J. Isern, I. LLoro, M. Nofrarías