Design of a telescope for the search for life – Kosmonautix.cz

A powerful new space telescope could help find the answer to the question of whether we are (or aren’t) alone in space. NASA is already preparing for its new flagship mission, which will follow the Nancy Grace Roman Telescope (launch is currently scheduled for 2027). The Habitable Worlds Observatory (abbreviated HWO) telescope design is based on two earlier mission designs called LUVOIR (Large Ultraviolet Optical Infrared Surveyor) and HabEx (Habitable Exoplanets Observatory), sometimes also referred to as “Super Hubble”. If realized, it will be able to directly image exoplanets the size of our Earth. Using ultra-precise optics and a mirror the size of the James Webb Telescope, HWO could thoroughly study the atmospheres of these worlds and search for signs of life.

“It is the first observatory truly designed to characterize exoplanets as complex worlds and not just to discover them,“explains Giada Arney, a member of the START team that assesses the science tasks of the HWO mission from Goddard, adding: “It’s really fascinating to me as a planetary scientist.” But it won’t just be a search for life. HWO will be designed to function as a multipurpose observatory similar to Hubble or JWST. The telescope is supposed to study the processes that drive the growth of galaxies, and could trace the origins of elements and molecules in the young universe. It would also serve to monitor worlds much closer to us.

“I am excited about the possibility of observing oceanic worlds in the Solar System such as Neptune’s moon Triton or Jupiter’s Europa,” says Lynnae Quick, a planetary scientist at the Goddard Center specializing in ocean worlds, adding: “HWO may be a tool to help us better understand the volatile cycle on Triton as its seasons change.However, building a next-generation space observatory that would search for life and expand our understanding of the universe will be a challenging and expensive project. The start of the telescope cannot be expected before the beginning of the 1940s. But the wait should be worth it.

The preview image of today’s article certainly does not represent the final form of the observatory. Nobody knows what the HWO will look like in the end, because the design of the telescope is still in the early design phase. However, some basic requirements already exist, and in this case we can thank a study by American academics, which recommends to the NASA agency what it should focus on in the next decade. HWO is supposed to have a mirror of a size comparable to the mirror on JWST. After all, the location of the telescope will also be the same – the L2 libration point of the Sun-Earth system at a distance of 1.5 million kilometers from the Earth, further away from the Sun.

Like the legendary Hubble, the HWO telescope is supposed to be serviceable. This means that future astronauts could travel to it for repairs and improvements. There is also another thing similar to Hubble. HWO is supposed to collect light at shorter wavelengths of visible and ultraviolet radiation, where certain biosignatures tend to be more pronounced. Shorter wavelengths also work best on a key technology for observing exoplanets – the coronagraph. These devices are used to block starlight to reveal fainter nearby objects. Without a coronagraph, it’s like trying to watch a firefly next to a searchlight. Spotting smaller exoplanets (perhaps the size of Earth) would require the most advanced coronagraph ever.

“We need a coronagraph that is a thousand times more capable than the best space coronagraphs to date,” describes Giada Arney, adding, “In addition, we need an optical system that will be absolutely extremely stable.The coronagraph technology demonstrator for HWO is scheduled to fly on the aforementioned Nancy Grace Roman Telescope. Rather than blocking the star’s light with a disc, the coronagraph on the Nancy Grace Roman Space Telescope will use a series of mirrors and masks to separate the light to the exoplanet from the star’s light. These mirrors will be controlled so precisely that their position can be adjusted to a distance smaller than the diameter of the DNA strand.

A computer simulation shows how a HWO with a coronagraph would see the Solar System at a distance of 33 light years.
Source: https://planetary.s3.amazonaws.com/

This comparison sounds quite extraordinary, but the requirements for the optics for the coronagraph at HWO are even more stringent. They require the ability to correct in the order of tens of picometers (1 picometer is 10⁻¹² or trillionth of a meter), which is less than the diameter of an atom! HWO is to explore the atmospheres of at least 25 potentially habitable worlds, searching for biosignatures that could indicate the presence of life. However, the detection of biosignatures requires context to rule out confounding by inanimate processes. Key biosignatures that the HWO will look for include oxygen, ozone and methane, with other substances being considered. Scientists will need to apply their knowledge of the planets and moons in our Solar System to interpret conditions on the exoplanets that HWO will explore.

Photos of NASA experts working on the HWO project. The image was created during a meeting between the START and TAG teams.
Source: https://science.nasa.gov/

“This type of “ground truth” is very important as we search for life,” says Lynnae Quick, adding, “To understand how the possibility of life on Earth-like exoplanets may be affected by geological processes on their surface, we must first understand how these processes on Earth (and potentially habitable bodies in our Solar System such as Europa, Mars and Titan) have affected them over time time their suitability for life.The work on the HWO concept is divided between two teams – START (Science, Technology, Architecture Review Team), which focuses on the scientific tasks of the mission, and TAG (Technical Assessment Group), which works on the technical requirements.

In NASA jargon, the project is in the pre-formulation phase. A project office at NASA headquarters could be established this year, moving HWO into Pre-Phase A. The project will need several years to mature the technologies needed for HWO and have the telescope ready for launch. however, one day (in the not-so-distant future) a new observatory might set its sights on a star system not unlike ours and perhaps detect the first traces of life on another cosmic body.

Translated from:
https://www.planetary.org/

Image Sources:
https://planetary.s3.amazonaws.com/web/assets/pictures/possible-hwo-design.jpg
https://upload.wikimedia.org/…/1920px-Rendering_of_LUVOIR-A_observatory%2C_2019.png
https://www.jpl.nasa.gov/habex/assets/images/mission/[email protected]
https://planetary.s3.amazonaws.com/web/assets/pictures/hwo-video-still.png
https://science.nasa.gov/wp-content/uploads/2024/03/20240311-161631.jpeg