23 research outputs found
Multiple Sun–Earth Saddle Point flybys for LISA Pathfinder
LISA Pathfinder is an ESA mission due to be launched in the next two years. The gravity gradiometer onboard has the sensitivity required to test predictions by gravitational theories proposed as alternatives to Dark Matter such as TeVeS. Within the Solar System measurable effects are predicted only in the vicinity of gravitational saddle points (SP). For this reason it has been proposed to fly LPF by the Earth–Sun SP, at some 259,000 km from Earth. This could be done in an extension to the nominal mission which uses a Lissajous orbit about the Earth–Sun L1 point. The responsibility for LPF mission design lies with ESA/ESOC, who have designed the transfer trajectories, orbits about L1, and station keeping strategies. This article describes an analysis performed by Astrium to support a suggestion for a possible mission extension to a saddle point crossing. With only very limited fuel availability, reaching the saddle point is a significant challenge. In this article, we present recent advances in the work on trajectory design. It is demonstrated that reaching the SP is feasible once the LPF mission is completed. Furthermore, in a significant enhancement, it is demonstrated that trajectories including more than one SP flyby are possible, thus improving the science return for this proposed mission extension
Design of a dual species atom interferometer for space
Atom interferometers have a multitude of proposed applications in space
including precise measurements of the Earth's gravitational field, in
navigation & ranging, and in fundamental physics such as tests of the weak
equivalence principle (WEP) and gravitational wave detection. While atom
interferometers are realized routinely in ground-based laboratories, current
efforts aim at the development of a space compatible design optimized with
respect to dimensions, weight, power consumption, mechanical robustness and
radiation hardness. In this paper, we present a design of a high-sensitivity
differential dual species Rb/Rb atom interferometer for space,
including physics package, laser system, electronics and software. The physics
package comprises the atom source consisting of dispensers and a 2D
magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap
based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein
condensate (BEC) creation and interferometry, the detection unit, the vacuum
system for mbar ultra-high vacuum generation, and the
high-suppression factor magnetic shielding as well as the thermal control
system. The laser system is based on a hybrid approach using fiber-based
telecom components and high-power laser diode technology and includes all laser
sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and
switching of the laser beams is carried out on an optical bench using Zerodur
bonding technology. The instrument consists of 9 units with an overall mass of
221 kg, an average power consumption of 608 W (819 W peak), and a volume of 470
liters which would well fit on a satellite to be launched with a Soyuz rocket,
as system studies have shown.Comment: 30 pages, 23 figures, accepted for publication in Experimental
Astronom
STE-QUEST - Test of the Universality of Free Fall Using Cold Atom Interferometry
In this paper, we report about the results of the phase A mission study of the atom
interferometer instrument covering the description of the main payload elements, the
atomic source concept, and the systematic error sources