NASA will release HiRISE's highest-resolution images of interstellar comet 3I/ATLAS on Wednesday; the photos were taken during the comet's Oct. 3 flyby of Mars at about 18 million miles. Publication was delayed by a 43-day U.S. federal government shutdown that furloughed roughly 83% of NASA staff. ESA previously released lower-resolution views and used the Mars encounter to improve the comet's orbit tenfold. 3I/ATLAS will pass about 168 million miles from Earth on Dec. 19, offering another opportunity for observations.
NASA to Release Sharpest HiRISE Images of Interstellar Comet 3I/ATLAS on Wednesday
NASA will release HiRISE's highest-resolution images of interstellar comet 3I/ATLAS on Wednesday; the photos were taken during the comet's Oct. 3 flyby of Mars at about 18 million miles. Publication was delayed by a 43-day U.S. federal government shutdown that furloughed roughly 83% of NASA staff. ESA previously released lower-resolution views and used the Mars encounter to improve the comet's orbit tenfold. 3I/ATLAS will pass about 168 million miles from Earth on Dec. 19, offering another opportunity for observations.
11:09 AM, 11/19/2025Science
NASA will publish its highest-resolution images yet of interstellar comet 3I/ATLAS on Wednesday. The photographs were captured by the High Resolution Imaging Science Experiment (HiRISE) camera aboard the Mars Reconnaissance Orbiter during the comet's close pass of Mars on Oct. 3.
At that encounter the comet came within roughly 18 million miles of Mars, producing the most detailed views so far of the third confirmed interstellar object to enter our solar system. NASA plans to unveil the HiRISE imagery during a live broadcast at 3 p.m. EST on Wednesday via NASA+, the agency’s website, its YouTube channel and Amazon Prime.
3I/ATLAS was first identified on July 1 by the ATLAS (Asteroid Terrestrial-impact Last Alert System) facility. The object poses no risk to Earth: it will not approach closer than about 168–170 million miles. Its close pass by Mars, however, let orbiting assets image it at much higher spatial resolution than Earth-based telescopes could achieve.
Earlier observations from the Hubble Space Telescope on July 21 provided a baseline view, but HiRISE—designed to survey the Martian surface from orbit—can resolve far finer detail for objects passing near Mars, offering roughly three times Hubble's spatial resolution for such targets.
The release of the HiRISE pictures was delayed by a 43-day U.S. federal government shutdown, during which an estimated 83% of NASA staff were furloughed. The data became accessible again after operations resumed under a continuing resolution on Nov. 12.
While the imagery was unavailable, 3I/ATLAS reached perihelion (its closest point to the Sun) on Oct. 29 and brightened as surface ices vaporized. Separately, on Oct. 7 the European Space Agency released lower-resolution views from the ExoMars Trace Gas Orbiter and Mars Express spacecraft; those images showed the comet as a bright, elongated smear but confirmed a natural coma. ESA scientists also used the Mars encounter to tighten the comet's predicted path, reporting roughly a tenfold improvement in orbital accuracy—information that helps astronomers point instruments more precisely.
Researchers continue to document several unusual characteristics of 3I/ATLAS, including its atypical inbound trajectory and pronounced anti-tail features. Those oddities have prompted speculative theories that the object might be artificial; Harvard astrophysicist Avi Loeb has been one of the more vocal proponents of that idea, while the broader astronomy community regards natural explanations as far more likely.
Loeb criticized the delay in releasing the HiRISE images during the shutdown, writing that time-sensitive scientific data should take precedence over bureaucratic rules so that follow-up observations can be planned while the object remains observable.
The comet will make its closest approach to Earth on Dec. 19 at roughly 168 million miles, offering another observing window. Several research teams plan to collect fresh data during that pass, and the upcoming HiRISE release may help refine follow-up observations and analysis in the weeks ahead.