NASA Approves Mission to Launch “Artificial Star”

NASA has new plans to launch a tiny satellite mimicking a star into space. The goal of the laser-carrying, bread-box-size orbiter is to calibrate telescopes by using the satellite as a pseudostar with precisely known features. The resulting boost in accuracy for these observatories may one day help reveal new details about exoplanets around distant stars, as well as the mysterious “dark energy“ that is accelerating the expansion of the universe.

The newly approved US $19.5 million Landolt mission, scheduled to begin in 2028 or 2029, will launch a satellite about the size of a 12U CubeSat (about 20 by 20 by 34 centimeters). The plan is for the satellite to orbit Earth roughly 35,800 kilometers above the equator, which is far enough away to look like a star to telescopes on the ground. The orbit will also be a geostationary one that will keep the satellite off the southwest coast of the United States, where telescopes in California, Chile, and Hawaii can see it.

“To save costs, we’re hitching a ride with other spacecraft, so the orbit will ultimately depend on the available launch opportunities,” explains Peter Plavchan, the mission’s principal investigator and an associate professor of physics and astronomy at George Mason University in Fairfax, Va.

“I’m very excited about how improving our knowledge of stars can improve our knowledge of planets around those stars.” —Peter Plavchan, George Mason University

The current design for the satellite calls for eight lasers with wavelengths ranging from 488-nanometer blue light to 1,550-nanometer near-infrared light. “That range spans typical wavelengths astronomers look at with their telescopes,” Plavchan says. “These wavelengths are also ones in lasers that have previously been demonstrated to work in space. We’re not going to use something that hasn’t flown before.”

The lasers will range in power from 0.1 to 0.5 watts. The artificial star will not be bright enough to be seen with the naked eye on Earth but will be visible with a personal telescope at home. “Everyone hears that we’re launching space lasers, and everyone gets excited, ‘pew pew,’ ” Plavchan says. “But these will be more than 100 times dimmer than the faintest thing the eye can see in the darkest locations.”

The satellite will use fiber lasers, “which are very stable sources of light,” Plavchan says. The aim for the Landolt mission is to emit photons at known reliable rates, which telescopes can use as baselines for their estimates of the brightness of anything else in the sky.

Currently, when it comes to how accurate modern telescopes are at measuring how bright a distant star is—how many photons from it arrive per second—“some say they are accurate within 1 percent, some 2 or 3 or worse,” Plavchan says. “This mission aims to decrease this uncertainty to less than 0.5 percent.”

“Everyone hears that we’re launching space lasers, and everyone gets excited, ‘pew pew.’ ” —Peter Plavchan, George Mason University

Better estimates of brightness are key to deducing the distance of events and objects in space, such as type Ia supernovae. These happen when a white dwarf star explodes after siphoning off too much mass from a companion star. All type Ia supernovae are relatively similar in brightness, so astronomers use them as “standard candles” to measure cosmic distances. The dimmer a type Ia supernova appears to be, the farther away it is from Earth. More accurate readings of a standard candle’s brightness leads to better estimates of the brightnesses of millions of stars.

The Landolt mission will indirectly shed light on dark energy, the mysterious phenomenon that scientists believe is pushing the universe apart. Researchers suggest dark energy could make up about 70 percent of the cosmos. Better estimates of how far away everything is can help pin down the rate at which dark energy is accelerating the expansion of the universe, which can then help scientists figure out which models might best explain dark energy.

Better estimates of a star’s brightness can also help astronomers improve their understanding of many of its other properties, such as its age, size, and temperature. This in turn can reveal many details about any potential exoplanets orbiting those stars, such as whether they lie within their stars’ habitable zones, Plavchan says.

“I’m an exoplanet astronomer, so I’m very excited about how improving our knowledge of stars can improve our knowledge of planets around those stars,” Plavchan says.

Now Plavchan and the rest of the researchers involved in the mission just need to be sure they’ll be ready to launch on time. “The idea of launching in four years means we’re dealing with a very aggressive timescale,” Plavchan says. “Honestly, it’s a little bit scary. We’ve got a lot to do.”