What could be NASA’s next big space telescope mission?

Lynx

To understand space-telescopes better, it helps to know the distribution of different kinds of radiation across the electromagnetic spectrum. We have low-frequency radio waves towards one end, the visible portion of light in the middle, and X-rays and Gamma rays towards the high-frequency end. 

As you can see from the chart above, high energy waves have more frequency. So naturally, the radiation from the biggest booms and bangs from the farthest ends of the universe that reach Earth are shifted towards the spectrum’s high frequency end. This is one of the main reasons why X-ray telescopes are used in the discovery of blackholes and neutron stars. And since the earth’s atmosphere absorbs X-rays, making none available for observers on the ground, we have no option but to launch these telescopes into space.

Lynx, if and when launched, would give astrophysicists the power to view the depths of the cosmos with X-ray vision. 

What makes Lynx special is how it compares to the currently most powerful X-ray telescope - Chandra. An interim document produced last year noted that Lynx is bounds ahead of both Chandra, and another X-ray telescope currently in development - Athena.  The report added:

The report also mentions that the telescope when built according to its concept plan will be powerful enough to detect X-rays from far away black holes, and can also throw light on some of the first galaxies to have formed in the early universe. Lynx can also help us look at cosmic environments ranging from young stars and their planets, to high energy bursts coming from supermassive black holes and neutron stars. With these inputs we can better understand what forces drive the formation of galaxies, and more about how stars evolve.

Once Athena is operational, a later Lynx launch may also see the two telescopes working together, as was discussed during the symposium by astrophysicist Alexey Vikhlinin.

Earlier this year, Grant Tremblay, a team member of the Lynx study told Katie Feather of Science Friday that the telescope could be the most powerful X-ray observatory ever flown to space by several orders of magnitude, and across multiple dimensions. “It would do science from the poles of Jupiter to black holes at the edge of time and everything in between,” he told Feather.

What lies ahead for these mission concepts?

These are ambitious projects that will try to answer some of the most fundamental questions in astrophysics. But only one of them may get pushed to become NASA's next flagship telescope project- even if the launch and operation of any of these in space is definitely more than a decade away.

Later in the year, these projects will be assessed by a decadal survey conducted jointly by the Board of Physics and Astronomy, and the Space Studies Board of the National Academies. In June last year, A NASA press release noted that the cost caps of missions working towards the 2020 Decadal Survey would be narrowed down to $3-5 billion. This reflected a need for the agency to balance its astrophysics program within anticipated budget constraints.

NASA Astrophysicist Ira Thorpe's tweet following the symposium reflected what kind of budget constraint exists.

Discussions at the symposium also reflected on doubts among astrophysicists if in the current trajectory of American astrophysics, space explorers and probes would be prioritized more compared to strategic flagship missions.

In 2016, when NASA initiated these telescope studies, it aimed for them to be prioritized by the Decadal Survey for launch in the 2030s right after JWST and WFIRST. This survey matters because it is a useful resource for agencies supporting astronomy and astrophysics, the Congressional committees that have jurisdiction over those agencies, the scientific community, and the public. 

The agency’s aim in 2016 was to design a mission that could deliver the best results for the spent capital. However, with recent delays and budget constraints surrounding JWST and WFIRST, there could be a change in direction among these contenders for NASA's next flagship mission. Since the last flagship missions became operational, inflation has also made it difficult to budget for new missions, as Christopher Stark -Associate Scientist at Space Telescope Science Institute - noted in his tweet:

Hence, there's more pressure on the contendors for the next space telescope mission to submit a concept note that better ensures delivery within a quoted time and budget.

The final report on the four space telescopes is expected to be submitted to the decadal committee for review by September. According to the American Astronomical Society’s website, the survey results for the next decade is expected to be released by mid-2020.

So it will be interesting to see if there's any change in trajectory these projects may undergo after the symposium to better meet the requirements and expectations of the decadal committee.