Remember the Hubble telescope? NASA launched it in 1990. Since then it’s been orbiting 353 miles above Earth. Hubble transmitted information about the age of the universe and space phenomena, including dark matter and quasars. The mission should extend beyond 2020.
But it wasn’t always smooth sailing.
For instance, a minor flaw in the main mirror caused the telescope to send back blurred images. In other words, Hubble needed glasses. After spacewalking astronauts made repairs, the pictures were stellar. Though the mission had rough patches, the telescope contributed vastly to human space knowledge.
NASA, in conjunction with the European Space Agency and the Canadian Space Agency, is now preparing the James Webb Space Telescope — JWST — a bigger and better device for space. After its launch in 2018, JWST will circle almost one million miles above the earth’s surface.
The new telescope’s design, construction, and purpose makes the Hubble look quaint. James Webb will search for the earliest possible data: the start of the universe. Its massive mirrors will explore light far, far away in both distance and time: perhaps 150 million years after the Big Bang.
The Journey — and the Challenges
JWST is a massive project, and there have been bumps along the way. The telescope has been in development since 1995. At that point, the estimated cost ran between $500 million and $1 billion. Fast forward to 2016, and the price has jumped to $8.8 billion.
The launch timeline has been problematic, as well. It was pushed back from 2010 to 2014 to the current 2018 estimate. A 2010 independent review ordered by Congress found problems with NASA’s organization and management. Though many production steps were completed on time, others were delayed. For example, the spacecraft propellant tank should have been finished by March 2015, but completion stalled until June due to a welding problem.
The space agencies don’t want to launch another Hubble. They need to remove all bugs from the new telescope system prior to launch, since it will be so far from earth that astronauts won’t be able to drop in for a quick fix. JWST has been undergoing rigorous testing, which will continue for many more months.
Though construction of the telescope ended in November 2016, it will undergo important inspections beginning at NASA’s Goddard Space Flight Center in Greenbelt, Maryland:
- Baseline readings: In November 2016, JWST passed its Center of Curvature test. The trials assessed the accuracy of the primary mirror. Initial readings are essential, because upcoming mechanical tests might change the mirror’s function.
- Simulated launch conditions: Space exposes the telescope to excessive noise and vibrations. Tests will monitor how well the device holds up against sounds of blasting rockets and forces far stronger than gravity. Scientists must be certain that space travel won’t negatively affect the mirror’s shape and alignment.
- Reassessment of mirror: The mirror’s precision must be double-checked after exposing JWST to launch-like conditions. Knowing that the telescope can survive the pressures and high speeds of a rocket launch will reassure scientists that James Webb will work properly in space. Scientists will do this by comparing the results to earlier measurements.
Once scientists determine that it will survive launch, they must establish that it will survive space conditions. When testing at Goddard is complete, they’ll transport the telescope to the Johnson Space Center in Houston, Texas. The telescope and its instruments must undergo environmental assessments. They’ll be exposed to temperatures as low as minus 370 degrees Fahrenheit to make certain JWST can withstand the harshness of space.
Scientists will double-check systems to make sure they’re in working order, including secondary and tertiary mirrors, support structures, a guidance system and a near-infrared camera and spectrograph.
The final testing in Houston, a site away from production locations, is key. The telescope’s optics were built and tested using the same equipment, which turned out to be faulty and led to Hubble’s optics problems in relaying images. In 2018, the full observatory — telescope, instruments, sunshield and spacecraft — will be inspected at Northrop Grumman Aerospace Systems. Then, in October, if all systems are go, JWST will be sent into space on the European Space Agency’s Ariane 5 rocket from an ESA complex near Kourou, French Guiana.
Scientists chose the launch site in part because of its proximity to the equator. Earth is spinning fastest around its middle, and the motion provides an extra push away from the planet. So in addition to the highly advanced technological skills and components needed to develop the observatory, scientists will harness the earth’s natural motion to help launch JWST.
Once launched, the James Webb Space Telescope will begin work on missions with the aim to achieve its four primary scientific goals: to search for light from the first stars and galaxies that formed in the Universe after the Big Bang, to study the formation and evolution of galaxies, to understand the formation of stars and planetary systems and to study planetary systems and the origins of life.