Ask an astronomer: What makes neutron stars so special?

Astrophysicist Michelle Thaller talks ISS and why NICER is so important.

  • Being outside of Earth's atmosphere while also being able to look down on the planet is both a challenge and a unique benefit for astronauts conducting important and innovative experiments aboard the International Space Station.
  • NASA astrophysicist Michelle Thaller explains why one such project, known as NICER (Neutron star Interior Composition Explorer), is "one of the most amazing discoveries of the last year."
  • Researchers used x-ray light data from NICER to map the surface of neutrons (the spinning remnants of dead stars 10-50 times the mass of our sun). Thaller explains how this data can be used to create a clock more accurate than any on Earth, as well as a GPS device that can be used anywhere in the galaxy.
  • Astronaut Garrett Reisman took in countless indescribably beautiful views while he lived in space. But most shocking, he says, was observing the thinness of Earth's atmosphere.
  • You can compare the thickness of the atmosphere to the diameter of Earth to the skin on an apple, or the shell of an egg. It's incredibly thin and shows just how seemingly fragile our planet is.
  • But to put this into perspective, whereas the atmosphere reaches a height of 300,000 feet from Earth's surface, the deepest part of the ocean only reaches 35,000 feet, ten times thinner than Earth's atmosphere. Everything we experience on Earth, from sea to sky, exists on just a tiny slice of precious surface coating.
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Space exploration is the ultimate plan B. Here’s why.

Why did the dinosaurs go extinct? Because they didn't have a space program.

  • Space exploration is more than just the ultimate adventure, our study and investigation of space yields great scientific rewards, says astronaut Garrett Reisman.
  • Earth is wonderful, but it won't last forever, so it's important that we maintain a big picture view to ensure the survival of the human species.
  • Exploring space is our ticket to "the ultimate plan B," according to Reisman. If there were to occur a mass extinction event on Earth, the humans that inhabit another planet in our solar system will be the only hope of human survival.
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NASA reveals plans for a base camp near the Moon's south pole

The space agency is ready to establish a base camp by 2024.

Photo by Megan Jelinger/SOPA Images/LightRocket via Getty Images
  • NASA's Artemis program plans on establishing a base camp on the Moon as soon as 2024.
  • After testing technologies and securing resources on the surface of the Moon, NASA plans on exploring Mars.
  • A number of robotic missions will first establish the Gateway, the flight path between Earth and the Moon's south pole.
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Image source: NASA/JPL-Caltech
  • One of NASA's most important telescopes has been put to sleep in space.
  • The infrared Spitzer Space telescope made a number of science-shaking discoveries over the course of its 16-year lifespan.
  • Without Spitzer, we wouldn't know about the TRAPPIST-1 exoplanets.

It was one of NASA's four Great Observatories. Each of the telescopes was tuned to its own wavelength of light, watching the universe in its own way. Together, the quartet presented to scientists a universe of unprecedented detail. There was the Hubble Space Telescope, the Chandra X-ray Observatory, the Compton Gamma Ray Observatory, and the Spitzer Space Telescope, capturing infrared light. Last Thursday, at 2:30 p.m. PST, Spitzer was decommissioned after 16 years of invaluable observations, and 11 years after its original mission ended. It now continues to orbit the Sun in safe mode some 266,600,037 kilometers from Earth.

While not as well-known as other telescopes, particularly the Hubble, Spitzer's contributions were nonetheless equally as important. According to NASA's Thomas Zurbuchen, "Spitzer has taught us about entirely new aspects of the cosmos and taken us many steps further in understanding how the universe works, addressing questions about our origins, and whether or not are we alone." Moreover, Zurbuchen points out, "This Great Observatory has also identified some important and new questions and tantalizing objects for further study, mapping a path for future investigations to follow. Its immense impact on science certainly will last well beyond the end of its mission."

Spitzer will be replaced by the Webb telescope, launching in 2021.

Spitzer, take a bow

Spitzer image of the Tarantula Nebula

Spitzer image of the Tarantula Nebula

Image source: NASA/JPL-Caltech

Spitzer weighs about 865 kilograms (nearly a ton) and is about 4 meters tall. For its sensors to detect infrared light, their temperature control is critical — they have to operate at about 5 degrees above absolute zero (That's -450 F or -268 C). Other equipment on the telescope needs to be relatively warms, so its body is divided into the frigid Cryogenic Telescope Assembly and the spacecraft itself.

In the Cryogenic Telescope Assembly is a 0.85-meter telescope, as well as a multiple instrument chamber containing the Infrared Array Camera, the Infrared Spectrograph, the Multiband Imaging Photometer, and the Cryostat, in addition to the Outer-Shell Group. The Assembly was cooled with liquid helium, though by the end of the original mission in 2009 it had been depleted. Since that time, just two of the Infrared Array Camera's four wavelength bands have been scanning the stars.

The spacecraft itself contains what you'd expect: navigation, communication, solar panels, and so on.

TRAPPIST-1 exoplanets

Artist representation of Trappist-1 system

Representation of Trappist-1 system

Image source: NASA/JPL-Caltech

Probably the most famous of Spitzer's accomplishment is its discovery of the TRAPPIST-1 exoplanets, seven Earth-sized bodies orbiting a single star. Three of them occupy the habitable zone around their sun, which is a bit cooler than ours, and are potentially capable of supporting life. Spitzer provided some 500 hours-worth of observations of the TRAPPIST-1 system.

Big babies

Big mature galaxies as seen by Spitzer in an early universe.

Big mature galaxies as seen by Spitzer in an early universe

Image source: NASA/JPL-Caltech/ESA

Spitzer was especially good at detecting distant, ancient young galaxies. The oldest infrared light it captured was from about 13.4 billion years ago, just 400 million years after the universe's birth. Spitzer also revealed and identified a set of "big baby" galaxies that were unexpectedly well-developed for their relative youth — the implication being that larger galaxies may not have resulted from collisions of smaller ones after all, but came together quickly on their own in the early days of the universe.

Great buckyballs in space!

Artist rendering of NGC 2440 nebula

Artist rendering of NGC 2440 nebula

Image source: NASA/JPL-Caltech

Buckyballs are spherical carbon molecules whose hexagon-pentagon-patterned surfaces make them look like soccer balls. They belong to a molecule class called buckminsterfullerenes, named after the famous dome-shaped buildings designed by architect Buckminster Fuller. Spitzer found buckyballs in space orbiting a dying star called Tc 1.

So much more

JPL photo of Spitzer's final ovation

The final ovation

Image source: NASA/JPL-Caltech

Spitzer's been incredibly productive over the years, and NASA's compiled a page of 15 of its most notable accomplishments. "Everyone who has worked on this mission should be extremely proud today," said Spitzer Project Manager Joseph Hunt. "There are literally hundreds of people who contributed directly to Spitzer's success, and thousands who used its scientific capabilities to explore the universe. We leave behind a powerful scientific and technological legacy."