SPACEFLIGHT NOW April 19, 2017 Stephen Clark
NASA managers say the WFIRST mission, the next in the agency’s line of powerful observatories after the Hubble and James Webb telescopes, could cost around $3.2 billion after budgeting for a novel first-of-its-kind instrument to probe the make-up of planets around nearby stars and a bigger-than-expected launch vehicle.
The observatory will be stationed at the L2 Lagrange point, a gravitational balance point about a million miles (1.5 million kilometers) from Earth, to survey the cosmos for dark energy and detect the the faint starlight reflected off of planets in other solar systems, allowing scientists to measure the composition of their atmospheres and surfaces.
WFIRST could help cosmologists and astronomers get closer to answering two fundamental questions: What is driving the expansion of the universe, and where might scientists find an Earth analog around another star?
The space agency formally kicked off development of WFIRST in February 2016, a year ahead of schedule, after several years of technological research and mission concept studies. Congress approved extra money for the project, allowing NASA to press ahead with the mission on a faster schedule than expected.
The Wide Field Infrared Survey Telescope, or WFIRST, is scheduled to be ready for launch by September 2025, employing one of two primary mirrors donated to NASA by the National Reconnaissance Office, the U.S. government’s spy satellite agency.
The NRO no longer needed the mirrors, which were developed for a cancelled surveillance mission that would have carried a downward-looking telescope to capture detailed images of military and strategic targets around the world.
WFIRST’s repurposed primary mirror, made by Harris Corp., did not come with the detectors and instrument needed to make it a functional telescope. Engineers are also making changes to the mirror for WFIRST’s astronomical mission.
After the NRO gifted NASA the two excess mirrors in 2012, the space agency revamped its plans for the WFIRST mission, doubling the size of the mission’s telescope to accommodate the spy assets.
The mirror measures 7.9 feet (2.4 meters) in diameter, the same size as Hubble’s, giving WFIRST the same sensitivity as NASA’s flagship space observatory. But WFIRST will see a swath of the sky 100 times bigger than Hubble’s field-of-view, allowing it to extend Hubble’s deep vision across the cosmos.
NASA officials originally planned for WFIRST to have a telescope half the size of Hubble, and the observatory was to be placed into a geostationary orbit around 22,000 miles (nearly 36,000 kilometers) above Earth.
That would have allowed WFIRST to fit on a rocket like United Launch Alliance’s Atlas 5.
But the bigger spacecraft, coupled with a decision to station WFIRST at the more distant L2 Lagrange point, will mean the observatory must launch aboard a more powerful — and perhaps more expensive — rocket.
NASA is currently looking at ULA’s Delta 4-Heavy or SpaceX’s Falcon Heavy rocket to send WFIRST into space, according to Dominic Bedford, the mission’s program scientist at NASA Headquarters.
The James Webb Space Telescope, a partnership between NASA, the European Space Agency and Canada, is set for launch in October 2018 with an even bigger primary mirror — more than 21 feet (6.5 meters) in diameter — comprised of 18 hexagonal segments. But JWST is like Hubble, crafted to peer deep into the universe, not a wide field surveyor like WFIRST.
“WFIRST is like 100 Hubbles, relative to the field-of-view, and it’s going after science that is really compelling,” said Thomas Zurbuchen, associate administrator of NASA’s science mission directorate.
More:
https://spaceflightnow.com/2017/04/19/with-an-eye-on-growing-cost-nasa-aims-for-2025-launch-of-next-great-observatory/
