Next-gen space telescopes could leverage deformable mirrors

Checking out faraway objects isn’t a walk in the park, all thanks to our planet’s dense and hazy atmosphere. When light travels through the upper layers of our atmosphere, it gets bent and messed up, making it a real challenge to spot things that are really far away in space (we’re talking billions of light years) and tiny objects in neighboring star systems, such as exoplanets.

Astronomers basically have two options to tackle this issue: either shoot telescopes up into space or deck them out with mirrors that can adapt to counteract the atmospheric fuzziness. Since 1970, NASA and the ESA have sent over 90 space telescopes into orbit, and 29 of them are still up and running, so we’re pretty sorted on that front! Looking ahead, though, more and more Earth-based telescopes will start using adaptive optics (AOs), gearing up to do some top-notch astronomy.

NASA’s Deformable Mirror Technology project

That involves the study of exoplanets, and the cool thing is, upcoming telescopes will be able to directly watch them using fancy tools like coronographs and smart mirrors that adjust on their own. With this tech, astronomers can grab spectra straight from the atmospheres of these exoplanets and figure out if they could be cozy enough for life.

NASA is working on getting adaptive optics in gear through its Deformable Mirror Technology project. This project is happening at the Jet Propulsion Laboratory at Caltech and is backed by NASA’s Astrophysics Division Strategic Astrophysics Technology (SAT) and the NASA Small Business Innovation Research (SBIR) programs.

Dr. Eduardo Bendek from JPL and Dr. Tyler Groff from NASA’s Goddard Spaceflight Center (GSFC), who are heading up the DM Technology Roadmap working group, are taking the lead on this research. Joining them are Paul Bierden, the founder and CEO of Boston Micromachines (BMC), and Kevin King, the Program Manager at Adaptive Optics Associates (AOX).

Also Read: What does ISRO have in store for the future?

Diving straight into Earth-sized worlds

The study of exoplanets has boomed lately, boasting 5,539 confirmed candidates in 4,129 systems and another 10,000 waiting for the green light. Spotting habitable planets in this sea of possibilities is key to unraveling the big question: are we the only ones in the Universe? Thanks to better tools, smart data analysis, and sharing info, the focus is shifting from just finding exoplanets to really understanding them. But, so far, most exoplanets have been found using indirect methods.

For scientists to really nail this, they’ve gotta directly check out exoplanets. It’s called the Direct Imaging method, where astronomers look at the light bouncing straight off an exoplanet’s atmosphere or surface. They then use spectrometers to break down that light and figure out what chemicals are in there, helping them figure out if a place is habitable. But, here’s the hitch – it’s super tough to get a good look at smaller, rocky planets huddled close to their parent stars (where Earth-like ones are supposed to hang out) because the stars’ brightness totally steals the show.

Things are expected to shake up with super cool telescopes like James Webb, plus the next-gen gang including the Extremely Large Telescope (ELT), the Giant Magellan Telescope (GMT), and the Thirty Meter Telescope (TMT). These Earth-based crews will team up massive 30-meter mirrors, high-tech spectrometers, and coronographs (gadgets that kick out pesky starlight). Deformable mirrors play a crucial role in coronagraphs, fixing even the smallest telescope glitches and wiping out any leftover starlight sneaking in.

This is a big deal because if the mirrors aren’t aligned right or their shape changes, messing with the telescope’s optics, it can cause annoying glare that hides the little rocky exoplanets. Plus, catching an Earth-like planet in the act needs super precise optics, down to the size of a hydrogen atom (we’re talking 10s of picometers). That means having tight control over a telescope’s mirrors in real-time to fix any interference messing with the view.

How will Deformable Mirrors function in telescopes

Deformable Mirrors (DM) work by using controlled actuators, kind of like tiny pistols, to tweak the shape of a reflective mirror. On Earth-based telescopes, these DMs help fix the path of incoming light, ironing out issues like atmospheric turbulence or misalignments in the telescope. In space, DMs don’t have to worry about Earth’s atmosphere, but they do need to handle the little optical hiccups that pop up as the space telescope and its gear heat up and cool down in orbit.

Deformable mirrors on the ground have been put to the test and are rocking top-notch performance. But when it comes to space-based DMs for upcoming missions, we still need to up our game. There are two key player technologies in the works for space missions: electrostrictive tech and electrostatically-forced Micro-Electro Mechanical-Systems (MEMS). In the first one, actuators are linked up to the DMs and contract to tweak the mirror’s surface when volts come into play. The second one involves mirror surfaces getting a shape-up through an electrostatic force between an electrode and the mirror.

Various squads backed by NASA are pushing ahead with DM technology, with some heavy-hitters like MEMS DMs from Boston Micromachines Corporation (BMC) and Electrostrictive DMs from AOA Xinetics (AOX). BMC’s mirrors have been through the wringer with vacuum tests and launch vibration trials, and AOX’s mirrors have not only faced vacuum tests but are also certified for space travel. Even though the BMC crew has shown their stuff with ground-based DMs, like the coronagraph instrument at the Gemini Observatory, there’s still work to be done to get DMs ready for the next-gen space telescopes.

Also Read: Is living on Mars really possible or just a far-fetched dream?

Will this tech power future telescopes?

NASA’s got big plans to show off what DMs can do by sending a chronograph tech demo up with the Nancy Grace Roman Space Telescope (RST) in May 2027. The know-how gained from this trial run will pave the way for a super fancy setup for the Habitable Worlds Observatory (HabEx). If all goes according to plan, NASA aims to launch this mission by 2035, and it’s geared to directly capture images of planetary systems around stars like our Sun. But here’s the kicker: The HWO is going to need DMs with around 10,000 actuators, each relying on high-voltage connections, and designing that is going to be a major challenge.

The HWO is going to demand some next-level wavefront control, like down to single-digit picometers, with a stability target of around 10 picometers per hour. Meeting these demands isn’t just about improving DM tech but also tweaking the electronics that boss them around. The quality of the commands the controller sends is a big deal for resolution and stability, and it depends a lot on keeping electronic noise in check. NASA’s Astrophysics Division is on the case, gearing up to create a Technology Roadmap that’ll take DM performance up a notch to make the HWO possible.