It’s Time NASA Built A ‘Cosmic Dawn’ Telescope On The Moon—And It Has Four Astonishing Plans To Choose From

Let’s do astronomy from the Moon. Spurred on by the collapse of the Arecibo radio telescope in Puerto Rico, the continuing degradation of the night sky by light pollution and the coming era of mega-constellations of satellites come four projects that seek to take astronomy to the Moon’s far side. 

Lunar astronomy is an idea that’s been around since the 1960s, but new engineering and technology is at last making astronomy on the Moon a real possibility.

Why bother? About 240,000 miles/380,000 kilometers from Earth, observations can be made of low frequency radio in radio-quiet conditions and also in ultraviolet light—something blocked by Earth’s atmosphere—that could help reveal the unexplored early cosmos. And since it takes the Moon 27 days to orbit Earth, a telescope would be in darkness for half the month and able to observe the same object for almost two weeks at a time. 

Astronomy has been done before both by Apollo astronauts and, since 2013, by China’s Chang-e rovers. Should NASA now commit to building the next big space observatory on the lunar surface?

Here’s everything you need to know about the Lunar Crater Radio Telescope, the Ultimately Large Telescope, FarView and the Gravitational-Wave Lunar Observatory for Cosmology—four astonishing concepts for telescopes on the Moon’s far side: 

1. Lunar Crater Radio Telescope

Type: radio telescope (parabolic reflector)

Size: half-a-mile/1 kilometer wide

Proposed location: 700m deep crater on far side of the Moon

The recipient last April of a $500,000 Phase II grant from NASA's Innovative Advanced Concepts is the Lunar Crater Radio Telescope. The published concept is the brainchild of Saptarshi Bandyopadhyay, a robotics technologist at NASA’s Jet Propulsion Laboratory in California, the LCRT is an early-stage NASA concept for a radio telescope within a crater on the far side of the Moon. 

The LCRT is designed to measure the long-wavelength radio waves generated by the “dark ages”—the few hundred million years after the Big Bang, but before stars were formed. They’re reflected by Earth’s ionosphere. 

“Radio telescopes on Earth cannot see cosmic radio waves at about 33 feet/10 meters or longer because of our ionosphere, so there’s a whole region of the Universe that we simply cannot see,” said Bandyopadhyay. “But previous ideas of building a radio antenna on the Moon have been very resource-intensive and complicated, so we were compelled to come up with something different.”

Bandyopadhyay’s plan is to create an antenna over half a mile/1 kilometer wide in a crater over 2 miles/3 kilometers wide. “Our receiver sits inside a 700m deep crater. We are suspending both the receiver and the mesh—the reflector— inside the crater. The mesh sits at the bottom of the crater and the receiver sits 500m above it, but still 200m below the rim of the crater,” said Bandyopadhyay. “We can suspend everything—and suspending on the Moon is significantly easier because it has one-sixth of the gravity of Earth.”

That immediately gets away from large construction problems. The mesh is held in place at 16 points around the rim and the density is such that it passively holds the parabolic shape required. 

The LCRT would be made from a thin wire mesh taken to the Moon by spacecraft along with a fleet of JPL’s DuAxel rovers. Tethered together, one of these two-piece rovers would act as an anchor at the rim of the crater while the other drives into the crater to connect cables. 

Even if the project doesn’t result in a completed LCRT it should help further robotic technology capable of building off-Earth structures. 

2. The Ultimately Large Telescope

Type: optical (rotating cryogenic liquid mirror)

Size: 328 feet/100-meters

Proposed location: a crater at the Moon’s north or south pole

No telescope can study the first stars in the Universe … except one. Shelved by NASA a decade ago, there’s been a revival of interest in the Ultimately Large Telescope (ULT), an ambitious vision of “mid-century technology.”  

Published in The Astrophysical Journal by a group of astronomers from the University of Texas at Austin, it’s proposed that the ULT—an upsized version of the 2006’s Lunar Liquid-Mirror Telescope (LLMT)—could be powerful enough to detect light from when there were no galaxies, just stars about 13 billion years ago. They’re known as Population III stars—and the “first light”—and could be 100 times the size of our Sun.  

The ULT would point at all times at the zenith from a crater at the Moon’s north or south pole that’s permanently in shadow. Powered by solar panels at another location in permanent sunlight, it would operate autonomously and send its data back to Earth via an orbiting relay satellite. 

Instead of using glass, to reduce the weight it’s proposed that the LCRT’s shielded mirror is made from a reflective metallic liquid that would permanently spin to retain its paraboloid shape. However, the authors do worry that lunar dust may affect observations, so in-situ tests would be required.

3. FarView

Type: 150-200 subarrays

Size: 62 square miles2/100 square kilometers

Proposed location: a flat area close to the centre of the Moon

Another lunar radio telescope whose furthest study is being funded by a NASA Innovative Advanced Concepts grant—in this case a $125,000 Phase I—is FarView.

A partnership between the University of Colorado and Lunar Resources, Houston, FarView would be a network of hundreds of miles of 150-200 radio antennas (a bit like old broadcast TV antennas) fabricated by robots on the Moon using materials extracted from it. It will create an interferometer with a total observatory area of over 62 square miles2/100 square kilometers—and it could be ready to go by the early 2030s. 

“FarView will be the most sensitive astronomical observatory in history … and we can build it using almost exclusively lunar materials,” said Dr. Ronald Polidan, principal investigator of FarView and director of programs at Lunar Resources Inc. “Our two key technologies are the ability to extract metals from oxide rich material—such as lunar regolith—and our ability to take those metals and evaporate them and build structures with them.” 

The observatory will get an image of the entire hemisphere above the lunar horizon every five or 10 minutes. “Yes, that is a lot of data, but it greatly expands our science scope and opens the door for unexpected discoveries,” said Polidan.  

Lunar Resources is a space industrial company that specializes in lunar resource extraction and in-space manufacturing technologies. “With those technologies we can build physical structures, antennas, the wiring, and everything else that goes with it,” said Polidan. “So we need to take very little from Earth with us—we can do in-situ production of everything we need.” 

The plan is to send a small rover to go lay just one antenna on the surface to see how it performs, adding a few more on subsequent visits. “Through utilization of the resources on the Moon, we could build FarView at about 10% of the James Webb Telescope cost and operate for more than 50 years. That’s game changing,” said Dr. Alex Ignatiev, chief technology officer of Lunar Resources.

Although like the LCRT it will be able to explore the cosmic “dark ages,” it’s hoped that FarSide will also be able useful in space weather forecasting, detect lightning storms on nearby planets and detecting magnetic fields around distant exoplanets. 

“FarView looks very feasible,” said Polidan. “We have even started to develop precursor mission concepts to validate both the science and enabling technologies.”

4. Gravitational-Wave Lunar Observatory for Cosmology

Type: interferometer

Size: TBC

Proposed location: the Moon

Just last week a study was published that make the case for a gravitational wave infrastructure of unprecedented sensitivity on the surface of the moon to unlock “new physics.” Gravitational waves are disturbances in the curvature of spacetime and could help astronomers measure the Hubble expansion rate—how fast the Universe is expanding.

A Gravitational-Wave Lunar Observatory for Cosmology would take advantage of the Moon's lack of atmosphere and significant seismic activity to analyze mergers of black holes, neutron stars and dark matter within 70% of the observable Universe.

“One of the most challenging spectrum of gravitational waves can be measured better from the lunar surface, which so far seems impossible from Earth or space,” said lead author Karan Jani, an astrophysicist at Vanderbilt University in Nashvile, Tennessee. “Unlike space missions that last only a few years, the great investment benefit of GLOC is it establishes a permanent base on the Moon from where we can study the Universe for generations, quite literally the entirety of this century.” Jani hopes to develop a pathfinder mission on the Moon to test the technologies of GLOC. 

New physics and the early universe is calling, and we must go … to the Moon. 

Wishing you clear skies and wide eyes.