JWST
Over three months ago the multi-billion dollar James Webb Space Telescope
(JWST, or simply Webb) launched to study the origins of our universe. The telescope has yet to begin scientific observations. NASA engineers have spent the last few months moving the hexagonal mirror segments into the optimal alignment for observation. The instruments are just now being powered up and calibrated. This process will last until this summer. You can follow along with the calibration process here.
Many missions were delayed or received budget cuts to make up for the cost overruns during the construction of JWST. It was originally going to launch in the late 2000's, but was continuously delayed until it ended up launching on Christmas Day 2021. It is projected to cost about $9.8 billion dollars by the end of its mission. It required huge innovations, such as the invention of electronics and infrared sensors that can operate at ultra-cold temperatures, and lightweight beryllium mirrors.
The telescope has experienced multiple close encounters with cancellation and has been a major NASA commitment. Was building JWST too much of a sacrifice? After all of the delays and complexities of building it is NASA going to attempt anything at this scale again, or is it going to stick with smaller, simpler missions? Definitely not. Most astronomers agree that JWST will revolutionize astronomy. NASA is the only agency that has the funding to design and build these huge telescopes, and so they will continue the 'great observatories' series.
The Roman Space Telescope
NASA’s next big telescope is designed to study dark matter, dark energy, and planets orbiting other stars. Its 300,000,000 pixel camera and coronagraph will be the next big leap for astronomy. It has been named for pioneering female astronomer, Nancy Grace Roman, who has been given the nickname: "The Mother of Hubble”. It is scheduled to launch in 2027.
The Nancy Grace Roman Space Telescope, previously known as WFIRST (Wide-Field InfraRed Survey Telescope), is NASA’s next big telescope. It is similar to the Hubble Space Telescope because its primary mirror is enclosed in a tube. Like Webb, the Roman Space Telescope will study infrared light, but it is designed to accomplish different tasks. Roman will image huge swaths of the sky to study how our universe has formed and expanded. It will collect more data than any other previous NASA astrophysics mission.
The Nancy Grace Roman Space Telescope has a primary mirror the same size as Hubble, but a camera that will allow it to see a significantly larger portion of the sky. Its camera, the Wide Field Instrument, can image as precisely as Hubble, but over an area 100x larger. Though it can't image with the resolution that Webb has, it will complement Webb by providing context to the more detailed images that Webb takes. It can also act a a scout surveying large parts of the sky and selecting areas for Webb to study in more detail.
In addition the the Wide-Field Instrument the Roman Space Telescope has a coronagraph, which will use a complex system of filters, masks, and mirrors to block out the light coming form stars and allow for direct imaging of exoplanets, which are planets orbiting other stars.
The telescope optics that will be used for the Roman Space Telescope were actually not built by NASA. It was originally built as a spy satellite by the US Government’s National Reconnaissance Office (NRO). It was donated to NASA in 2012. Since then NASA has modified it for astronomy and begun building components of the spacecraft. These components include the light sensors that will make up the Wide Field Instrument, which have already been built and certified.
Decadal Survey
What about what comes after the Roman Space Telescope? How does NASA select a mission that will take decades to develop and build? NASA relies on a report prepared by some of the most renowned scholars in the country. This report is called the decadal survey, and it is prepared by the National Academy of Sciences (NAS).
As the name suggests, the decadal survey comes out once a decade. It is prepared by an elite group of intellectuals based on what thousands of scientists from across the country think NASA should prioritize. There are actually three decadal surveys that are submitted to NASA, one for earth science, one for astronomy, and one for planetary science.
The planetary science decadal survey will be released on April 19th and will suggest what interplanetary missions NASA should pursue. I will publish at least one blog post on the subject when it gets released.
The decadal survey released in 2001 recommended that NASA focus on JWST, while the one in 2010 suggested NASA pursue a concept that eventually became Roman. In January 2019, NASA selected four concepts to be studied and submitted to the NAS. All of these concepts would be highly beneficial to scientists, but would cost billions of dollars and require major leaps in technology. A team of scientists and engineers was assigned to each of these concepts and submitted details about their proposals to the NAS. The target launch date for these proposals was the mid-2030s Here are the four concepts that were studied:
The Lynx X-ray Observatory would detect x-rays in order to study some of the universe’s first black holes and galaxies
The Origins Space Telescope would use a primary mirror even larger than the one that Webb has to become the most sensitive infrared telescope ever to be launched into space
LUVOIR (Large UV Optical Infrared surveyor) would study ultraviolet, optical, and infrared light to gather information on many different topics, including exoplanets, galaxies, and the solar system
HabEx would study wavelengths similar to LUVOIR, but use a sunshade to block out the light of distant stars and directly image planets that orbit them
The Next Great Observatory
After months of analysis the astronomy decadal survey for the 2020’s was released in November 2021. A concept focused on studying exoplanets that combines elements from LUVOIR and HabEx was recommended. The telescope will be about the size of JWST with a 6 meter primary mirror, but be designed to detect signs of life on distant planets. It will be able to study ultraviolet, optical, and infrared light and will be a superb general purpose astronomical tool. The concept is similar to the original concept for JWST.
This far-future observatory is not set to launch until the 2040’s, and that’s only if it can get support from Congress and NASA officials. NASA learned a lot about cost and schedule management from JWST, which could prevent this telescope from having serious delays and cost overruns. However this project will still be a massive undertaking, it will span generations and require billions of dollars.
A New NASA Program
In addition to suggesting that NASA pursue this life-hunting telescope, it was recommended that NASA begin developing technologies for space telescopes that will come after the 2040’s exoplanet telescope in order to lower their costs. They also think that NASA should start a new program, to develop medium-class space telescopes.
Great observatory missions like the Roman Space Telescope, and JWST are extremely powerful, require major technological developments, and high price tags. NASA is the only space agency that has enough funding to lead these missions, and they usually can't do it without support from other space agencies. They can study a wide variety of astronomical targets.
To follow up on discoveries and answer simpler questions, NASA builds small spacecraft as part of the Explorer program. They cost a maximum of $350 million and one launches every few years. TESS is an example of an astrophysics Explorer mission, it launched in 2018 and searches the sky for exoplanets. These missions mostly use existing technology to fill in small gaps in our knowledge about the universe.
Having a program that develops medium-class missions between great observatories and Explorer missions could be really useful. The missions could accomplish many goals and be quite advanced, but not require such a high price tag or super long development times. NASA has begun work on a program that will fill this gap, the first mission will be selected in 2025 and will cost about $1 billion.
Conclusion
The Hubble Space Telescope recently discovered the most distant star ever, Earendel. Light from this star has spent 12.9 billion years traveling through the universe, and just recently landed on a camera inside the Hubble Space Telescope. The scientists building Hubble didn't know the things it would discover as they constructed it. We don't even have a clue what Webb or Roman will discover. The future is looking bright for astrophysics; as bright as a sky filled with stars.
Sources:
JWST:
The Roman Space Telescope:
Decadal Survey:
The Next Great Observatory:
A New NASA Program:
Conclusion:
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