Claudio Bombardelli

SPECS: the kilometer-baseline far-IR interferometer in NASA's space science roadmap

Ultimately, after the Single Aperture Far-IR (SAFIR) telescope, astrophysicists will need a far-IR observatory that provides angular resolution comparable to that of the Hubble Space Telescope. At such resolution galaxies at high redshift, protostars, and nascent planetary systems will be resolved, and theoretical models for galaxy, star, and planet formation and evolution can be subjected to important observational tests. This paper updates information provided in a 2000 SPIE paper on the scientific motivation and design concepts for interferometric missions SPIRIT (the Space Infrared Interferometric Telescope) and SPECS (the Submillimeter Probe of the Evolution of Cosmic Structure). SPECS is a kilometer baseline far-IR/submillimeter imaging and spectral interferometer that depends on formation flying, and SPIRIT is a highly-capable pathfinder interferometer on a boom with a maximum baseline in the 30 - 50 m range. We describe recent community planning activities, remind readers of the scientific rationale for space-based far-infrared imaging interferometry, present updated design concepts for the SPIRIT and SPECS missions, and describe the main issues currently under study. The engineering and technology requirements for SPIRIT and SPECS, additional design details, recent technology developments, and technology roadmaps are given in a companion paper in the Proceedings of the conference on New Frontiers in Stellar Interferometry.

Detector Configurations for Equivalence Principle Tests with Strong Separation of Signal from Noise

Testing the Equivalence Principle (EP) at a level of accuracy substantially higher than the present state of the art requires resolving a very small signal out of the instrument’s intrinsic noise and also the noise associated with the instrument’s motion and gravity gradients. In the test of the Equivalence Principle in an Einstein Elevator under development by our team, the acceleration detector spins about a horizontal axis while free falling for about 25 s inside a co‐moving capsule released from a stratospheric balloon. The characteristics of the instrument package and the configuration of the detector play a key role in the ability to extract an EP violation signal at the desired threshold level out of dynamics‐related noise. Numerical simulations of the detector’s dynamics in the presence of relevant perturbations, having assumed realistic errors and construction imperfections, show the merits of the detector configuration selected. The results illustrate that the effects of dynamics and gravity gra...

GNC Design for Asteroid Orbit Modification Missions

This paper shows the GNC design process for a mission aiming to find, approach andmodify the orbit of a small asteroid. A large number of such bodies are orbiting the Sun in our Solar System, and some of them might become a real threat for the Earth during next few decades. While the size of the asteroid, besides its orbit, greatly determines the attention that should be given to any specific body, it is also necessary to start developing the concepts and technologies required to face these kind of challenges. For this purpose, these small asteroids represent a good training opportunity, since they allow testing the intended orbit modification principles with reasonable mission/system needs and with no impact risk for the Earth.

Electrodynamic Tether for Scientific Mission at Low Jovian Orbit

An electrodynamic bare tether is shown to allow carrying out scientific observations very close to Jupiter, for exploration of its surface and subsurface, and ionospheric and atmospheric in-situ measurements. Starting at a circular equatorial orbit of radius about 1.3/1.4 times the Jovian radius, continuous propellantless Lorentz drag on a thin-tape tether in the 1-5 km length range would make a spacecraft many times as heavy as the tape slowly spiral in, over a period of many months, while generating power at a load plugged in the tether circuit for powering instruments in science data acquisition and transmission. Lying under the Jovian radiation belts, the tape would avoid the most severe problem facing tethers in Jupiter, which are capable of producing both power and propulsion but, operating slowly, could otherwise accumulate too high a radiation dose . The tether would be made to spin in its orbit to keep taut; how to balance the Lorentz torque is discussed. Constraints on heating and bowing are also discussed, comparing conditions for prograde versus retrograde orbits. The system adapts well to the moderate changes in plasma density and motional electric field through the limited radial range in their steep gradients near Jupiter.