Bridenstine said that 2028 would stand as the target for "sustained operations" on the lunar surface, but that the $1.6 billion for fiscal year 2020 would help NASA to marshal its forces for a single touchdown near the moon's south pole in 2024.
The Moon is shrinking as its interior cools, getting more than about 150 feet (50 meters) skinnier over the last several hundred million years. This creates stair-step cliffs called thrust faults as part of the crust is pushed up and over another close part of the crust.
By comparing lunar orbital imagery from NASA with seismic readings obtained almost half a century ago from equipment left on the moon by the Apollo missions, researchers believe they've figured out what's behind a pattern of mysterious moonquakes that have frustrated scientists for decades, seemingly originating from the upper few miles of the moon's crust: our neighboring satellite, believed to be a cold lifeless rock, is actually geologically alive, just like Earth.
Still, in order to meet the ambitious five-year goal, Nasa has said it would scale back the scope of the Gateway, at least initially.
Bridenstine said the mission was named Artemis after the Greek mythological goddess of the Moon and twin sister to Apollo, namesake of the program that sent 12 American astronauts to the Moon between 1969 and 1972. Researchers believe that these quakes would have measured between 2 and 5 in the "Moment Magnitude scale" if they had been on earth. To Nicholas Schmerr, an assistant professor of geology at the University of Maryland, this data sounded very similar to earthquakes produced by tectonic faults. Researchers made this conclusion after analysing images taken by NASA's Lunar Reconnaissance Orbiter.
Instead of going directly to the surface of the moon, as Nasa did during the Apollo missions of the late 1960s and early 70s, it is instead looking to build a more permanent presence by building an orbiting outpost known as the Gateway.
The relative proximity of the quakes to the faults suggest that they were triggered by geological activity rather than asteroid impacts or tremors from much deeper within the rocky body.
Additionally, six of the eight moonquakes recorded near the faults occurred when the Moon was at its farthest point from Earth in its orbit - its apogee. These features appeared relatively bright in the images, suggesting that they were produced recently.
A team, led by Thomas Watters from the Center for Earth and Planetary Studies at the Smithsonian Institution, looked at 28 moonquakes that had been recorded by Apollo seismometers. The instruments successfully detected 28 moonquakes that were likely caused by friction at tectonic faults before they were decommissioned in 1977. Those that appear brighter indicate freshly exposed lunar rock, suggesting an event like a "moonquake", which is an quake that takes place on the moon. The astronauts also examined boulders and boulder tracks on the slope of North Massif near the landing site.
With almost a decade of LRO imagery already available and more on the way in the coming years, the team would like to compare pictures of specific fault regions from different times to look for fresh evidence of recent moonquakes. This makes it easier for the Moon's crust to slip along the thrust faults.
"This additional investment is a down payment on Nasa's effort to land humans on the moon by 2024", Bridenstine said in a call with reporters Monday evening. The innermost planet Mercury boasts numerous thrust faults.
"For me, these findings emphasize that we need to go back to the moon".
"For me, these findings emphasise that we need to go back to the moon".