Future space telescopes could be 100 meters across, constructed in space, and bent into a precise shape

It’s an exciting time for astronomers and cosmologists. Since the James Webb Space Telescope (JWST), astronomers have been exposed to some of the sharpest and most detailed images of the universe ever taken. Webb’s powerful thermal imager, spectrometer, and coronagraph will enable much more in the near future, from investigating the early universe to direct imaging studies of exoplanets. Additionally, several next-generation telescopes with 30-meter (~98.5 ft) primary mirrors, adaptive optics, spectrometers, and coronagraphs will become operational in the next few years.

Even with these impressive instruments, astronomers and cosmologists look forward to the time when even more sophisticated and powerful telescopes become available. proposed a telescope with a 100-meter (328-foot) primary mirror that is built autonomously and bent into shape by electrostatic actuators. His proposal is one of several concepts selected this year by NASA’s Innovative Advanced Concepts (NIAC) program for Phase I development.

Corder is a Boeing Career Development Professor of Aeronautics and Astronautics at MIT and a member of the Aerospace Materials and Structural Laboratories (AMSL) and Small Satellite Center. His research integrates and develops expertise in process science, mechanics, and design. new material Construction of new aerospace applications. His proposal is the result of collaboration with Professor Jeffrey Lang (from his Electronics and the Microsystems Technology Laboratories at MIT) and his team of three students at his AMSL, including his PhD. Student Harsh Girishbai Bundiya.

Their proposed telescope addresses a key issue for space telescopes and other large payloads that are packaged for launch and then deployed into orbit. That is, the trade-off between size and surface precision limits the diameter of deployable space telescopes to tens of meters. Consider the recently launched James Webb Space Telescope (JWST). This is the largest and most powerful telescope ever sent into space. The telescope was designed so that it could be folded into a more compact shape to fit in the payload fairing (on top of the Ariane 5 rocket).

This included the primary mirror, secondary mirror and awning, all deployed once the space telescope was in orbit. Meanwhile, the primary mirror (the most complex and powerful ever deployed) is 6.5 meters (21 feet) in diameter.Its successor, the Large UV/Optical/IR Surveyor (LUVOIR) uses a similar folding assembly and primary mirror 8 to 15 meters (26.5 to 49 feet) in diameter depending on the design chosen (LUVOIR-A or -B). Bhundiya explained to Universe Today via email:

“Today, most spacecraft antennas are deployed in orbit (such as Northrop Grumman’s Astromesh antenna) and are optimized for high performance and gain. 2) Rotation becomes more difficult as the size of the antenna increases.3) There is a trade-off between diameter and accuracy. , the accuracy decreases as the size increases. This is a challenge for realizing astronomy and sensing applications, which require both large aperture and high accuracy (e.g. JWST).

Many in-space construction methods have been proposed to overcome these limitations, but detailed analyzes of their performance for building precision structures (such as large-aperture reflectors) are lacking. For their proposal, Cordero and his colleagues performed a quantitative, system-level comparison of materials and processes for space fabrication. Ultimately, they determined that this limitation could be overcome using advanced materials and a new space fabrication method called bending.

Invented by AMSL researchers and described in a recent paper co-authored by Bhundiya and Cordero, the technique relies on a combination of computer numerical control (CNC) deformation processing and layering. high performance material. As Hersh explained:

“Bendforming is the process of manufacturing a 3D wireframe structure from metal wire feedstock. It involves bending one strand of wire at a specific angle at a specific node and adding joints at the node to create a rigid structure. It works by: Given a structure, you convert it into bend instructions that can be implemented on a machine like a CNC wire bender to manufacture from a single strand of raw material. , is to manufacture the support structure for large antennas in orbit.This process is suitable for this application. low power, can be manufactured in highly compressible structures and has essentially no size limit. ”

In contrast to other space assembly and manufacturing approaches, bending is low-power and uniquely enabled by the cryogenic environment of space. Additionally, this technology enables smart structures that leverage multifunctional materials to achieve new combinations of size, mass, stiffness, and precision. Additionally, the resulting smart structures leverage multifunctional materials to achieve unprecedented combinations of size, mass, stiffness, and precision, design paradigms that limit traditional truss or tension-tuned space structures. break down

In addition to their inherent precision, large bend-formed structures can use electrostatic actuators to outline reflector surfaces with sub-millimeter precision. This will improve the accuracy of antennas manufactured in orbit, Harsh said.

“The method of active control, called electrostatic actuation, uses forces generated by electrostatic attraction to precisely shape a metal mesh into a curved shape that acts as an antenna reflector. , to apply a voltage between the mesh and the “command surface”. It consists of a bent support structure and deployable electrodes. By adjusting this voltage, the reflective surface can be precisely shaped to achieve a high-gain parabolic antenna. ”

Harsh and his colleagues speculate that this technology will enable deployable mirrors over 100 meters (328 feet) in diameter that can achieve surface accuracies of 100 m/m and specific areas over 10 m. .²/kg. This capability surpasses existing microwave radiometric techniques and could lead to significant improvements in storm forecasting and a better understanding of atmospheric processes such as the water cycle. This has important implications for Earth observation and exoplanet research.

The team recently demonstrated a one-meter (3.3 ft) prototype was demonstrated. , Maryland. With this Phase I NIAC grant, the team plans to mature the technology with the ultimate goal of creating a microwave radiometric reflector.

Going forward, the team will use bendforming in geostationary orbit (GEO) to achieve a field of view of 15 km (9.3 miles), a ground resolution of 35 km (21.75 miles), and a proposed frequency span of 50–56 GHz — ultra-high frequency and Ultra high frequency range (SHF/EHF). This will allow telescopes to obtain temperature profiles from the atmospheres of exoplanets. This is an important feature for astrobiologists to measure habitability.

“NIAC’s current goal is to implement bendforming and electrostatic actuation technologies in space,” said Harsh. “We envision manufacturing 100m diameter antennas in geostationary orbit with bend-formed support structures and electrostatically actuated reflective surfaces. It will enable a new generation of spacecraft with improved power capabilities.”