Brett N. Shapiro | Searcharxiv

arXiv2025

Vibration Isolation for the Laser Interferometer Lunar Antenna

The Laser Interferometer Lunar Antenna (LILA) presents a novel concept for observing gravitational waves from astrophysical sources at sub-Hertz frequencies. Compared to the Earth, the seismic environment of the moon, while uncertain, is known to be orders of magnitude lower, opening the possibility for achieving this sub-Hz band. This band fills the gap between space-based detectors (mHz) and Earth-based detectors (10 Hz to a few kHz). The initial version of LILA, known as LILA Pioneer, calls for non-suspended optics, relying on the moon's resonant modes to respond to gravitational waves. However, the follow-on design, LILA Horizon, requires suspensions to realize in-band free floating test masses and to filter the residual seismic background. This paper will establish baseline designs for these suspensions for different assumptions of the seismic background.

gr-qc↗

arXiv2023

Successful Kinetic Impact into an Asteroid for Planetary Defense

While no known asteroid poses a threat to Earth for at least the next century, the catalog of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid. A test of kinetic impact technology was identified as the highest priority space mission related to asteroid mitigation. NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale test of kinetic impact technology. The mission's target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by DART's impact. While past missions have utilized impactors to investigate the properties of small bodies those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft's autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in Dimorphos's orbit demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary.

astro-ph.EP↗