Hubble Space Telescope reaches 42 "milepost marker" for space, time

NASA's Hubble Space Telescope recently reached a new milestone in its nearly 30-year mission of helping scientists measure the expansion rate of the universe.

According to Science Daily, researchers have been attempting to measure the rate of the universe's expansion rate for decades, and in 1998, scientists discovered "dark energy," a mysterious repulsive force responsible for accelerating the universe's expansion. Currently, Hubble has calibrated more than 40 space and time "milepost markers," used by scientists to precisely measure the expansion rate of the universe.

Nobel laureate Adam Riess of the Space Telescope Science Institute and the Johns Hopkins University leads a scientific collaboration called Supernova, H0, for the Equation of State of Dark Energy (SH0ES). Riess' team has completed the largest and likely the last major update on the Hubble constant, which is a critical value for estimating the age of the universe. 

The new results will be published in The Astrophysical Journal, and more than doubles the prior sample of cosmic distance markers, encompassing more than 1,000 Hubble orbits. 

The team has measured 42 of the supernova milepost markers with Hubble, which is about as many as possible for measuring the universe's expansion. The Hubble constant is a crucial number that can be used to test our understanding of the universe from the distant past to the present.

"You are getting the most precise measure of the expansion rate for the universe from the gold standard of telescopes and cosmic mile markers," Riess said, according to Science Daily.

Astronomers have discovered a discrepancy between the expansion rate of the local universe and the primeval universe. According to recent measurements by the SH0ES team, the Hubble constant is estimated to be 73 kilometers per second per megaparsec, while the combination of the standard cosmological model and measurements from the Planck mission predict a lower value of 67.5 plus or minus 0.5 kilometers per second per megaparsec.

Despite the large sample size, the chance that astronomers are wrong due to an unlucky draw is incredibly unlikely, prompting cosmologists to take this discrepancy seriously. Although the exact value of the Hubble constant is not the main concern for astronomers like Riess, the discrepancy offers an opportunity to learn more about the universe's dynamical evolution and could point to the need for additional physics.

Intrigued by these findings, cosmologists are looking forward to using NASA's new James Webb Space Telescope to further study these cosmic milepost markers at greater distances with sharper resolution than the Hubble Space Telescope can provide. 

The Hubble Space Telescope is a joint project between NASA and the European Space Agency, with NASA's Goddard Space Flight Center managing the telescope and the Space Telescope Science Institute conducting Hubble science operations.