from the exploring-uranus dept.
The Ice Giants Pre-Decadal Study group has proposed sending a mission to either Uranus or Neptune. Only one mission is likely to be approved due to a shortage of plutonium-238 for the radioisotope thermoelectric generators required for an outer solar system mission:
Uranus and Neptune have never got much attention from us – we've only passed each once and never hung around. But that could change. A NASA group has now outlined possible missions to make it to one of these outer worlds to gather data on their composition. This should teach us about them and similar planets in other solar systems.
"The preferred mission is an orbiter with an atmospheric probe to either Uranus or Neptune – this provides the highest science value, and allows in depth study of all aspects of either planet's system: rings, satellites, atmosphere, magnetosphere," says Amy Simon, co-chair of the Ice Giants Pre-Decadal Study group.
There are four proposed missions – three orbiters and a fly-by of Uranus, which would include a narrow angle camera to draw out details, especially of the ice giant's moons. It would also drop an atmospheric probe to take a dive into Uranus's atmosphere to measure the levels of gas and heavy elements there.
The three must-haves for each orbiter mission are a narrow-angle camera, a doppler imager and a magnetometer, while an orbiter containing 15 instruments would add plasma detectors, infrared and UV imaging, dust detection and microwave radar capability. The orbiter could be either a Neptune mission with an atmospheric probe, a Uranus probe of the same design, or a craft sent to a[sic] Uranus that ditches the atmospheric probe for the suite of 15 instruments.
Obligatory grade school humor:
Also at The Verge.
NASA's historic Voyager mission has now been exploring the heavens for four decades.
The Voyager 2 spacecraft launched on Aug. 20, 1977, a few weeks before its twin, Voyager 1. Together, the two probes conducted an unprecedented "Grand Tour" of the outer solar system, beaming home up-close looks at Jupiter, Saturn, Uranus, Neptune and many of the moons of these giant planets.
This work revealed a jaw-dropping diversity of worlds, fundamentally reshaping scientists' understanding of the solar system. And then the Voyagers kept on flying. In August 2012, Voyager 1 became the first spacecraft ever to reach interstellar space — and Voyager 2 is expected to arrive in this exotic realm soon as well.
The rest of the article is a Q&A with Voyager project scientist and former director of the NASA Jet Propulsion Laboratory Ed Stone.
No missions have been sent to Uranus or Neptune since Voyager 2 visited them in 1986 and 1989.
Astronomers are still hoping for another mission to Pluto, or perhaps another Kuiper belt object:
A grassroots movement seeks to build momentum for a second NASA mission to the outer solar system, a generation after a similar effort helped give rise to the first one. That first mission, of course, was New Horizons, which in July 2015 performed the first-ever flyby of Pluto and is currently cruising toward a January 2019 close encounter with a small object known as 2014 MU69.
[...] Nearly three dozen scientists have drafted letters in support of a potential return mission to Pluto or to another destination in the Kuiper Belt, the ring of icy bodies beyond Neptune's orbit, Singer told Space.com. These letters have been sent to NASA planetary science chief Jim Green, as well as to the chairs of several committees that advise the agency, she added. "We need the community to realize that people are interested," Singer said. "We need the community to realize that there are important, unmet goals. And we need the community to realize that this should have a spot somewhere in the Decadal Survey." That would be the Planetary Science Decadal Survey, a report published by the National Academy of Sciences that lays out the nation's top exploration priorities for the coming decade.
New Horizons 2 was already cancelled due to a shortage of plutonium-238, which still reportedly persists. One proposed target was 47171 Lempo, a trinary system. The trans-Neptunian dwarf planets Eris, Haumea, Sedna, Orcus, Salacia, Makemake, and 2007 OR10 (the largest known body in the solar system without a name - with an estimated 1,535 km diameter) have all been discovered since 2002. Several of these TNOs have moons and Haumea was recently found to have a ring system.
Now that Cassini is dead, most new NASA missions are focused on Mars and Jupiter, leaving the solar system's "ice giants" relatively unstudied:
The International Astronomical Union (IAU) famously reclassified Pluto as a "dwarf planet" in 2006. That decision remains highly controversial today, as made clear by the new note, which appeared in the July 29 issue of the Planetary Exploration Newsletter.
ON THE INSENSITIVE USE OF THE TERM "PLANET 9" FOR OBJECTS BEYOND PLUTO
We the undersigned wish to remind our colleagues that the IAU planet definition adopted in 2006 has been controversial and is far from universally accepted. Given this, and given the incredible accomplishment of the discovery of Pluto, the harbinger of the solar system's third zone — the Kuiper Belt — by planetary astronomer Clyde W. Tombaugh in 1930, we the undersigned believe the use of the term 'Planet 9' for objects beyond Pluto is insensitive to Professor Tombaugh's legacy.
We further believe the use of this term should be discontinued in favor of culturally and taxonomically neutral terms for such planets, such as Planet X, Planet Next, or Giant Planet Five.
35 researchers signed the note, including Alan Stern, principal investigator of the New Horizons mission.
Of more interest may be this proposal concerning future exploration of Uranus and Neptune:
Related: Uranus and Neptune Are Potential Targets for 2030s Missions
Another Trans-Neptunian Object With a High Orbital Inclination Points to Planet Nine
CU Boulder Researchers Say Collective Gravity, Not Planet Nine, Explains Orbits of Detached Objects
Planet Nine Search Turns Up 10 More Moons of Jupiter