Pushing the boundaries of space exploration with X-ray polarimetry


The IXPE with the roll-up boom deployed during testing. The boom provides a focal length of 4 meters and positions each of the mirror module assemblies above its respective X-ray detector unit. Credit: Ball Aerospace

The secrets that lurk in the vast expanse of outer space have puzzled mankind for centuries. The invention of the optical telescope in the 17th century allowed humans to see stars appear as mere twinkling dots in the night sky. Thanks to scientific innovations over the next four centuries, we can now launch telescopes into space to better observe astronomical objects and even study them at wavelengths beyond the visible spectrum. The Imaging X-ray Polarimetry Explorer (IXPE) launched by NASA on December 9, 2021 is one such expedition into the cosmos.

The IXPE is a space observatory developed in collaboration with the Italian Space Agency (ASI). It contains three identical telescopes, each with an X-ray imaging detector sensitive to the polarization of light at its focus. Equipped with these, IXPE can explore some of the brightest cosmic X-ray sources in our universe, such as pulsars, black holes and neutron stars. With a basic two-year mission, IXPE will start by surveying dozens of X-ray sources in its first year, followed by more detailed observations of the chosen targets in the second year.

Conceived in 2017, this multinational project became a reality in 2021 thanks to the participation of several space agencies that came together to carry out different aspects of the mission. A recent article published in the Journal of Astronomical Telescopes, Instruments and Systems provides a detailed description of IXPE’s optics and detectors and the science objectives of the mission.

IXPE was launched on a reusable Falcon 9 rocket from Kennedy Space Center into an equatorial orbit at an altitude of 600 km. This orbit was chosen to reduce the charged particle background, maximize the Explorer’s lifetime, and allow for easier regular data downloads to primary and backup ground stations (Kenya and Singapore, respectively). The observatory uses an array of 12 solar sensors, a three-axis magnetometer and two star trackers to maintain its trajectory in space.

Pushing the boundaries of space exploration with X-ray polarimetry

Photograph of the IXPE observatory in a stowed position on a vibrating table during the observatory’s environmental tests. Credit: Ball Aerospace.

Each telescope at the IXPE observatory includes a mirror module assembly (MMA). MMA focuses X-rays into polarization-sensitive (DU) detection units. DUs, in turn, aid in energy and position determination by providing timing information and polarization sensitivity data. The information collected by the DUs is relayed to the detector service unit (DSU) which processes the data and transmits it to the ground. A lightweight, rollable boom is deployed after launch to ensure the correct focal length and to align the MMAs with the DUs. Additionally, a tip-tilt-rotate mechanism exists on board, which can also be used to align the mirrors with the detectors.

After the initial alignment and calibration stages, IXPE began its core mission, providing high quality polarization data from a variety of sources. The first imaging data was reported in February. The IXPE team expects that the most striking early images will likely come from shell-like supernova remnants (a supernova that emits most of its radiation from a shell of shocked material). They believe the IXPE will also be able to image active galaxies, the galactic center of the Milky Way galaxy, and “blazars”, a type of galaxy that emits powerful jets of ionized matter and radiation. This will provide an opportunity to push the boundaries of observations even further by exploring new types of sources of special interest to obtain physical information.

“The astrophysical community has been eagerly awaiting this capability – IXPE opens a new window into the X-ray sky by offering orders of magnitude higher sensitivity than previous X-ray polarimeters in space,” said Megan Eckart, Editor. Deputy Chief of JATIS.

A marvel of science and engineering, IXPE will provide the first information on X-ray polarization for many astronomical sources. With its state-of-the-art telescopes and detectors, IXPE has the potential to expand the horizons of our knowledge of the universe.

NASA’s new IXPE mission begins science operations

More information:
Martin C. Weisskopf et al, Imaging X-ray Polarimetry Explorer: pre-launch, Journal of Astronomical Telescopes, Instruments and Systems (2022). DOI: 10.1117/1.JATIS.8.2.026002

Provided by SPIE – International Society for Optics and Photonics

Quote: Pushing the Boundaries of Space Exploration with X-ray Polarimetry (2022, April 25) Retrieved April 25, 2022 from https://phys.org/news/2022-04-boundaries-space-exploration-x-ray -polarimetry.html

This document is subject to copyright. Except for fair use for purposes of private study or research, no part may be reproduced without written permission. The content is provided for information only.


Comments are closed.