A crewed SpaceX mission to the International Space Station has been postponed by a day due to weather concerns downrange of the launch site, NASA said Wednesday.

Liftoff had been scheduled for Thursday but because of unfavorable conditions along the Atlantic coast, it will now be set for 5:49 am (0949 GMT) Friday.

"For crewed missions we need to look downrange to make sure weather's good for a potential launch escape, and for recovery of the crew," acting NASA Administrator Steve Jurczyk told reporters.

The Crew-2 mission will carry four astronauts in the second routine taxi ride by SpaceX to ISS since the United States resumed crewed space flight, and the first with a European.

Matter in the hearts of neutron stars—dense remnants of exploded massive stars—takes the most extreme form we can measure. Now, thanks to data from NASA's Neutron star Interior Composition Explorer (NICER), an X-ray telescope on the International Space Station, scientists have discovered that this mysterious matter is less squeezable than some physicists predicted.

The finding is based on NICER's observations of PSR J0740+6620 (J0740 for short), the most massive known neutron star, which lies over 3,600 light-years away in the northern constellation Camelopardalis. J0740 is in a binary star system with a white dwarf, the cooling remnant of a Sun-like star, and rotates 346 times per second. Previous observations place the neutron star's mass at about 2.1 times the Sun's.

"We're surrounded by normal matter, the stuff of our everyday experience, but there's much we don't know about how matter behaves, and how it is transformed, under extreme conditions," said Zaven Arzoumanian, the NICER science lead at NASA's Goddard Space Flight Center in Greenbelt, Maryland.