11 NASA astrophysics missions face risk of cancellation

Both Hubble (top) and JWST (bottom) are reflecting telescopes. Light from distant objects enters the telescope, reflecting off of the large primary mirror sending it to the smaller secondary mirror. The secondary mirror reflects that light back through a hole in the primary mirror where it comes to a focus and enters each of the telescope’s many instruments located behind the primary mirror. Telescope diagrams are not to scale, but JWST’s position 1.5 million kilometers from Earth, as opposed to Hubble’s ~500-600 km distance from Earth, represents a huge difference in the temperatures the observatories can operate at.

This map shows a 1-year view of the entire gamma-ray sky from NASA’s Fermi satellite. As a complement and successor to Fermi, COSI will survey the entire sky in the low-energy gamma-ray band (from 0.2-5 MeV), providing the best map of sites in the Galaxy where matter and antimatter collide and annihilate, as well as constraining the geometry of the gamma-ray sources.

This artist’s illustration shows a hot Jupiter exoplanet in a very close orbit around its brighter, hotter, more massive parent star. Planets like hot Jupiters were among the first exoplanets discovered in the 1990s, not because they’re the most common, but because they’re the easiest type of exoplanet to detect.

This complex of some 20 independent star-forming regions is within a 3-degree span and inside the Milky Way’s galactic plane. Taken with the far-infrared Herschel spacecraft, this region, Westerhout 43, is located at the intersection of our central galactic bar and one of our spiral arms. Herschel has been defunct since it ran out of coolant in 2013, and no far-infrared space telescope has ever matched its capabilities since.

This computer simulation of a neutron star shows charged particles being whipped around by a neutron star’s extraordinarily strong electric and magnetic fields. X-ray missions with polarimeters, such as PRAXyS, can probe both the spatial distortion around compact objects, especially black holes, while also studying the properties of strong magnetic fields around compact objects, particularly neutron stars.

Cosmic ray spectrum of the various atomic nuclei found among them. Of all the cosmic rays that exist, 99% of them are atomic nuclei. Of the atomic nuclei, approximately 90% are hydrogen, 9% are helium, and ~1%, combined, is everything else. Iron, a low-abundance but important example of the heavy, high-energy atomic nuclei found, may compose the highest-energy cosmic rays of all.

This dust map of the Orion Nebula was constructed with the use of three space-based telescopes: Spitzer, WISE, and Herschel. No stars are visible here, but dust of various temperatures are revealed in these views.

In concert with JWST, next-generation X-ray observatories like Lynx (proposed for NASA) or Athena (under development in the ESA and supported by NASA) could serve as the ultimate complement for understanding the Universe. Without either of them, the X-ray community will remain underserved, still reliant on Chandra’s now-ancient capabilities.

With three equally spaced detectors in space connected by laser arms, periodic changes in their separation distance can reveal the passing of gravitational waves of appropriate wavelengths. LISA will be humanity’s first detector capable of detecting spacetime ripples from supermassive black holes and the objects that fall into them, from high-mass binary black hole companions to lower-mass objects, like stellar mass black holes or even neutron stars and possibly white dwarfs as well.

The Hubble Ultra-Deep Field, shown in blue, is the largest, deepest, long-exposure campaign undertaken by humanity thus far, even in the JWST era. For the same amount of observing time, the Nancy Grace Roman Telescope will be able to image the orange area to the exact same depth, revealing over 100 times as many objects as are present in the comparable Hubble image.

This illustration compares the relative sizes of the areas of sky covered by two surveys: the upcoming Nancy Roman Telescope’s High Latitude Wide Area Survey, outlined in blue, and the largest mosaic led by Hubble, the Cosmological Evolution Survey (COSMOS), shown in red. In current plans, the Roman survey will be more than 1,000 times broader than Hubble’s, revealing how galaxies cluster across time and space as never before, enabling the tightest constraints on evolving dark energy, and revealing more microlensing events, including possibly extremely close black holes, than ever before. Euclid is wider-field than Roman, but with inferior depth, resolution, and wavelength coverage.

Ideally, the new space telescope Habitable Worlds Observatory, with capabilities between those of the previously-proposed HabEx and LUVOIR (shown here), will be large enough to image a large number of Earth-like exoplanets directly, while still having the desired properties to keep it on-budget and not require the development of wholly new, untested technologies. This observatory, known as Habitable Worlds Observatory, will be NASA’s next flagship mission after the Nancy Roman space telescope.

If the Sun were located at the distance of Alpha Centauri, the future Habitable Worlds Observatory, either with a starshade or a sufficiently advanced coronagraph, would not only be able to directly image Jupiter and Earth, including taking their spectra, but even the planet Venus as well. The farther out giant planets, including Saturn, Uranus, and Neptune, would all be perceptible as well.

The prospect of detecting and characterizing the atmosphere of a true Earth-like planet, i.e., an Earth-sized planet in the habitable zone of its star, including both red dwarf and more Sun-like stars, is within our reach. With a next-generation coronagraph, a large ultraviolet-optical-infrared mission could find dozens, or even hundreds, of Earth-sized worlds to measure.