Space

Looking for aliens from the far side of the moon [COMIC]

Planned telescopes would use the moon to block out Earth’s noisiness

A composite image showing Earth's moon, from the far side, in front of Earth

One side of the moon always faces away from Earth. This far side is the perfect spot to place space telescopes: There, they wouldn’t have to deal with interference from Earth’s light and radio pollution. Now scientists are planning for what those telescopes could look like.

NASA's Scientific Visualization Studio

By Matthew R. Francis and Maki Naro

Text on the image: Finding distant planets is hard enough, but looking for life is even trickier. Not only are the color of plants or light from cities difficult to see from Earth, but our own light and radio pollution can drown out dim signals from space. Image: A three-eyed alien perched on the moon yells “quiet down!” at an Earth-based city.
Text on the image: Even space telescopes catch that noise. But there’s one guaranteed quiet spot: the side of the moon that always faces away from Earth. In other words, the moon itself is a shield from all our noise. Image: Wavy lines representing signals from Earth bend around the moon. The panel gives the comic’s title: Looking for Aliens from the Far Side of the Moon, by Matthew R. Francis and Maki Naro.
Text on the image: Telescopes planned for the far side of the moon would be sensitive to the extremely long wavelengths of radio waves. If a far-off planet has a magnetic field similar to Earth’s, then it will hum with these radio waves. Earth’s magnetic field shields us from deadly radiation from the sun, helping make life possible. So such a field could be sign that a planet harbors life. Image: Curvy blue lines of a magnetic field surround a red dot, representing Earth.
Text on the image: Catching big wavelengths requires very big telescopes, and they probably won’t look like any telescope you’ve ever seen. “For this kind of science, it's just metal sticks arranged in different ways,” says Nivedita Mahesh. (Astronomer, California Institute of Technology in Pasadena.) “50 to 100 meters long!” Image: A brown-haired scientist wearing a lavender sari describes a telescope. To the bottom left, a miniature of her stands between two long sticks arranged in a V-shape (“50 to 100 meters long!”) Above her are arranged three telescopes — a big, Earth-based telescope, a smaller telescope that an individual might own, and the James Webb Space Telescope — are each outlined in a red circle with a slash drawn across.
Text on the image: Take the planned telescope FARSIDE. FARSIDE stands for Farside Array for Radio Science Investigations of the Dark ages and Exoplanets. FARSIDE’s 128 antennas, made of pairs of metal sticks, will be arranged like a 10-kilometer-wide (6.2-mile-wide) four-petal flower. Image: In the upper right is a yellow circle with a rover that would deploy the FARSIDE array. In the middle is a four-leaf clover shape with a red dot in the middle that represents what the array would look like. To the left is an orange three-eyed alien saying “Neat!” And below that is a circle with an antenna node — a square with two lines running out from either side.
Text on the image: Human astronauts wouldn’t build this telescope. Instead, each pair of sticks would be attached to its neighbors using a tether, which would be wound up on a spool. A small robotic rover would unwind the tether and roll the antennas out onto the moon’s surface, attaching each pair of sticks to the ground as it goes. Image: A rover with black wheels sits on the moon’s surface. Behind it stands an astronaut in a space suit carrying a shovel, looking at the rover.
Text on the image: FARSIDE would also study the structure of the universe before the first stars formed over 13 billion years ago. Scientists call this the “cosmic dark ages”. Mahesh: “The only way of doing that is to look for a signal from hydrogen [gas], and the only way we can get that signal to go to the far side of the moon.” Image: A brown-haired scientist wearing a lavender sari stands outside in the dark, with tiny stars in the background. She lights up her face from the underside with a flashlight.
Text on the image: Scientists still need to solve some problems before FARSIDE can be built. The detectors need to be kept cold, for instance, and the moon’s surface can reach 120º Celsius (250º Fahrenheit) during the day. And the moon’s soil could affect the antennas in unknown ways. Prototype experiments sent to the moon will probably test those within the next year. Image: An astronaut standing on the moon’s surface holds an umbrella over a telescope part that looks with a square box with lines coming out of each side.
Text on the image: FARSIDE is only one possible option. NASA is considering using a crater on the Moon’s far side like a giant satellite dish. And the European Space Agency is looking at a design for a big telescope printed on an inflatable pad that can be unrolled like a blanket. Image: The top half of the panel depicts a telescope built in a moon crater. Below is a picture of a giant square-shaped pad divided into four parts with a circle in the middle.
Text on the image: You will never see the far side of the moon from Earth. But putting telescopes there will show us parts of the universe we can’t see from anywhere else. Image: An orange, three-eyed alien sits on a red planet with eyes closed. In the distance is the moon with a large telescope made of four petals.

Power Words

More About Power Words

antenna: (plural: antennae or antennas) In biology: Either of a pair of long, thin sensory appendages on the heads of insects, crustaceans and some other arthropods. (in physics) Devices for picking up (receiving) electromagnetic energy.

array: A broad and organized group of objects. Sometimes they are instruments placed in a systematic fashion to collect information in a coordinated way. Other times, an array can refer to things that are laid out or displayed in a way that can make a broad range of related things, such as colors, visible at once. The term can even apply to a range of options or choices.

astronaut: Someone trained to travel into space for research and exploration.

astronomer: A scientist who works in the field of research that deals with celestial objects, space and the physical universe.

crater: A large, bowl-shaped cavity in the ground or on the surface of a planet or the moon. They are typically caused by an explosion or the impact of a meteorite or other celestial body. Such an impact is sometimes referred to as a cratering event.

exoplanet: Short for extrasolar planet, it’s a planet that orbits a star outside our solar system.

hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues. It’s made of a single proton (which serves as its nucleus) orbited by a single electron.

magnetic field: An area of influence created by certain materials, called magnets, or by the movement of electric charges.

metal: Something that conducts electricity well, tends to be shiny (reflective) and is malleable (meaning it can be reshaped with heat and not too much force or pressure).

moon: The natural satellite of any planet.

NASA: Short for the National Aeronautics and Space Administration. Created in 1958, this U.S. agency has become a leader in space research and in stimulating public interest in space exploration. It was through NASA that the United States sent people into orbit and ultimately to the moon. It also has sent research craft to study planets and other celestial objects in our solar system.

prototype: A first or early model of some device, system or product that still needs to be perfected.

radiation: (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

radio waves: Waves in a part of the electromagnetic spectrum. They are a type that people now use for long-distance communication. Longer than the waves of visible light, radio waves are used to transmit radio and television signals. They also are used in radar.

satellite: A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.

star: The basic building block from which galaxies are made. Stars develop when gravity compacts clouds of gas. When they become hot enough, stars will emit light and sometimes other forms of electromagnetic radiation. The sun is our closest star.

telescope: Usually a light-collecting instrument that makes distant objects appear nearer through the use of lenses or a combination of curved mirrors and lenses. Some, however, collect radio emissions (energy from a different portion of the electromagnetic spectrum) through a network of antennas.

tether: A tie or cord that loosely anchors some object to a semi-fixed position. Or the process of tying some object to a cord that will keep it loosely affixed to that position. (Consider the child’s game tether ball, whereby a cord it attached to a ball on one end and an anchoring pole on the other end.)

universe: The entire cosmos: All things that exist throughout space and time. It has been expanding since its formation during an event known as the Big Bang, some 13.8 billion years ago (give or take a few hundred million years).

wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.

wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.

More Stories from Science News Explores on Space

  1. Earth

    Scientists Say: Van Allen belts

    By Katie Grace Carpenter
  2. Space

    Fast, mysterious clouds swarm around our galaxy

    By Stephen Ornes
  3. Earth

    Scientists Say: Supermoon

    By Katie Grace Carpenter
  4. Space

    Scientists caught a black hole ringing like a bell

    By Emily Conover
  5. Space

    Let’s learn about spooky ‘dark energy’

    By Maria Temming
  6. Space

    The Vera Rubin Observatory is set to revolutionize astronomy

    By Lisa Grossman
  7. Space

    Scientists Say: Space junk

    By Katie Grace Carpenter
  8. Space

    Analyze This: Ice around baby stars may hint at origins of Earth’s water

    By Carolyn Wilke