NASA ’s James Webb Space Telescope (JWST) — arguably one of the most anticipated and talked about pieces of space hardware ever conceived — will certainly make observations of the ends of the universe that will likely shake cosmology to its core. But it would also be able to study the large super-earth — dubbed Planet 9 — that some astronomers think may lie some 900 AU (or Earth-Sun distances) away; at the outermost fringes of our own solar system.
“If a new planet is found, JWST will be able to fully characterize it,” Stefanie Milam, JWST deputy project scientist for planetary science at NASA Goddard Space Flight Center, told me. “Planet 9 is predicted to be fairly large but far, so most ground based facilities [would] barely be able to detect it.”
Milam says this would include being able to detect compounds like carbon dioxide in the putative planet’s tenuous, icy atmosphere.
Over the life of its $8.8 billion mission, JWST will also make some great, heretofore, unobtainable images of Mars and other familiar objects in our own solar system; bridging gaps in solar system science in the process.
The idea is that some six months after launch in October 2018, JWST will be able to provide near and mid-infrared observations at least until the end of the next decade. Its observing forte here locally will be monitoring many familiar solar system planets and moons for changes in their atmospheres and surface geology. That is, in ways that can’t be achieved from the ground or with current or near-term space missions.
Orbiting the Sun a million miles from Earth, JWST’s 6.5-meter primary mirror, Sun shade and four instruments will offer better sensitivity, spectral resolution, and wavelength coverage than many planetary flyby or orbiter missions. Mars itself will be one of JWST’s prime targets.
“JWST will permit instantaneous measurements of the whole observable Martian disk at very high spatial resolutions,” said Milam, “and at wavelengths not accessible from ground-based observatories.”
JWST’s other solar system targets will include:
— Asteroids and comets
Unlike flybys or landers, says Milam, JWST will have the opportunity to study multiple comets instead of one target, providing detailed studies of a statistical sample.
— Giant planets – Saturn and Jupiter and the two ice giants Uranus and Neptune.
“Uranus and Neptune are by far the least studied planets in our solar system and JWST is ideal for future studies,” said Milam.
— Outer planet satellites – all the moons of the planets in our solar system.
JWST will allow us to even follow geologic activity on active bodies such as Io or Enceladus, says Milam.
— Rings and small satellites
JWST will not only be able to characterize ring systems across the solar system, says Milam, but also detect new ones; possibly even around Pluto — if they exist.
But JWST will not be able to observe Mercury or Venus, because it can’t risk pointing towards the Sun. However, it will be able to observe objects in our Solar System beginning at the orbit of Mars on out.
And what sort of serendipitous observations will JWST enable?
Among other things, the detection and characterization of plumes or other geologic activity on natural satellites, says Milam.
“We can also conduct observations as quickly as 48 hours from the time a decision to observe a target is made,” said Milam.