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posted by martyb on Tuesday October 31 2017, @05:20AM   Printer-friendly
from the just-taking-a-stroll-through-the-neighborhood dept.

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 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:

With instrumentation ever-improving, there were two more worlds waiting for their post-Voyager close ups. It's a promise that has been painfully unfulfilled. Uranus and Neptune, it turns out, are typical of some of the most common planets in our galaxy. Understanding them would not only help us understand the Solar System, its origins, and the interactions that define the outer border of its planets. It would help us make sense of the galaxy as a whole.

Plus those planets have a collection of moons that has the potential to include Enceladus-level surprises. And Uranus is tilted on its side—its axis of rotation is more or less on the plane of the Solar System, rather than pointing perpendicular to it. And its magnetic field is 60º off that axis. It's hard to imagine there's not some amazing stuff to learn there.

The Ice Giants Pre-Decadal Study group has indicated that only one mission would likely be sent to either Uranus or Neptune in the coming decades, due to costs and the need for plutonium-238. The authors concluded that both Uranus and Neptune are of equal importance, but seem to favor going to Uranus first.

Previously: Return to Pluto? - "Scientists, including New Horizons principal investigator Alan Stern, met in Houston on April 24th to discuss the possibility of a Pluto orbiter mission..."

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Return to Pluto? 38 comments

Scientists, including New Horizons principal investigator Alan Stern, met in Houston on April 24th to discuss the possibility of a Pluto orbiter mission. The mission would likely cost $1-2 billion, compared to around $700 million for New Horizons and $467 million for the Dawn mission to Vesta and Ceres. A launch date in the late 2020s is possible, with a 2030 launch coinciding with the 100th anniversary of Pluto's discovery:

[A] Pluto orbiter mission is a long way from becoming reality, Stern stressed. He said he and his fellow researchers aim to mature the concept in time for it to be considered during the next Planetary Science Decadal Survey, a U.S. National Research Council effort that sets exploration priorities for NASA every 10 years. The next decadal survey will start in 2020, finish in 2022 and be published in 2023, Stern said.

Using the Space Launch System (SLS) could reduce travel time compared to the nine-and-half-year journey of New Horizons, but braking would be required to orbit the Pluto-Charon system, increasing the total travel time back to around seven to nine years. Other missions being considered include flybys of more distant Kuiper Belt dwarf planets (Eris, Sedna, etc.) and exploration of Neptune's moons Triton and Nereid, which are likely captured Kuiper Belt Objects. Triton has about a 14% larger radius and 64% more mass than Pluto. Voyager 2 observed 40% of Triton's surface in 1989.

Original Submission

Uranus and Neptune Are Potential Targets for 2030s Missions 15 comments

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.

Moon values: Neptune's Triton vs. Uranus's Titania, Oberon, Umbriel, Ariel, and Miranda (all rounded by gravity).

Obligatory grade school humor:

NASA wants to probe Uranus in search of gas
NASA wants to probe deeper into Uranus than ever before

Also at The Verge.

Original Submission

Ring Confirmed Around Dwarf Planet Haumea 8 comments

It's not just Saturn and gas giants such as Uranus which have rings in our solar system – as a tiny dwarf planet has just been spotted with its very own.

It's the first dwarf planet beyond Neptune to be spotted with its own ring – and could prove that such rings are not uncommon in the outer solar system.

takyon: Haumea has two known moons as well as this newly discovered ring:

A stellar occultation observed on 21 January 2017 indicated the possibility of a ring system around Haumea. As published in Nature on 11 October 2017, this occultation was confirmed to be a ring, representing the first such ring discovered for a TNO. The ring has a radius of about 2,287 km, a width of ~70 km and an opacity of 0.5. The ring plane coincides with Haumea's equator and the orbit of its larger, outer moon Hi'iaka. The ring is close to the 3:1 resonance with Haumea's rotation.

Haumea is known for its extremely elongated shape, a consequence of its rapid rotation.

The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation (DOI: 10.1038/nature24051) (DX)

Original Submission   Alternate Submission

NASA Unlikely to Have Enough Plutonium-238 for Missions by the Mid-2020s 41 comments

A Government Accountability Office report has found that the U.S. is unlikely to produce enough Plutonium-238 for NASA missions about a decade from now. The isotope has been used in radioisotope thermoelectric generators (RTGs) on missions such as Voyager, Cassini, and the Mars Science Laboratory:

Another GAO report notes: "[...], DOE currently maintains about 35 kilograms (kg) [77 pounds] of Pu-238 isotope designated for NASA missions, about half of which meets power specifications for spaceflight. However, given NASA's current plans for solar system exploration, this supply could be exhausted within the next decade."

[...] To address the plutonium problem, in 2011 NASA provided funding to the Department of Energy (DOE) to restart domestic production of the substance. The program is called the Pu-238 Supply Project. So far, the Project has produced ∼3.5 ounces (100 grams) of Pu-238. DOE identified an interim goal of producing 10 to 17.5 ounces (300 to 500 grams) of new Pu-238 per year by 2019. The goal is to produce 1.5 kilograms of new Pu-238 per year—considered full production—by 2023, at the earliest.

GAO is questioning the Supply Project's ability to meet its goal of producing 1.5 kilograms of new Pu-238 per year by 2026. For one thing, the oversight agency's interviews with DOE officials revealed that the agency hasn't perfected the chemical processing required to extract new Pu-238 from irradiated targets to meet production goals.

Only one DOE reactor is currently qualified to make Pu-238:

NASA's plutonium will be produced at two of these reactors, but only one of them is currently qualified to make Pu-238. GAO reported that initial samples of the new Pu-238 did not meet spaceflight specifications because of impurities. However, according to DOE, the samples can be blended and used with existing Pu-238.

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  • (Score: 2, Funny) by Anonymous Coward on Tuesday October 31 2017, @06:03AM (2 children)

    by Anonymous Coward on Tuesday October 31 2017, @06:03AM (#589877)

    How odd. When plutonium was named, I doubt it was known to be required for trips to Pluto.

    • (Score: 3, Insightful) by takyon on Tuesday October 31 2017, @06:05AM (1 child)

      by takyon (881) Subscriber Badge <{takyon} {at} {}> on Tuesday October 31 2017, @06:05AM (#589878) Journal
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      • (Score: 3, Informative) by c0lo on Tuesday October 31 2017, @12:27PM

        by c0lo (156) on Tuesday October 31 2017, @12:27PM (#589980)

        When plutonium was named, I doubt it was known to be required for trips to Pluto.

        [switch to Americium-241]

        Lemme guess: you hope to discover/explore a better America?

        (the major problem with Am-241 is the gamma radiation - nasty, penetrative stuff, bad for the electronics on board. By contrast, Pu-238 is alpha radiation, you know? roasted helium)

  • (Score: 2) by driven on Tuesday October 31 2017, @06:36AM (6 children)

    by driven (6295) on Tuesday October 31 2017, @06:36AM (#589885)

    Can someone tell me why a mission to Pluto would be spending limited resources in a more important way than continuing work on getting humanity another home (Mars, Titan, etc) or at least a lunar base? There will always be more data to gather first-hand about distant objects like Pluto, but I feel that should take a back seat to other higher priorities. I mean, if everyone had a massive space budget I'd say sure, but that's not the case. Not to mention that goals closer to Earth could jump start the space tourism industry and bring in real money for further technological advances.

    • (Score: 5, Informative) by takyon on Tuesday October 31 2017, @07:20AM (5 children)

      by takyon (881) Subscriber Badge <{takyon} {at} {}> on Tuesday October 31 2017, @07:20AM (#589899) Journal

      These missions are being planned decades in advance at this point due to funding and orbital dynamics. You have to make your case now if you want it built in the 2020s and launched in the 2030s in order for it to get there in the 2040s.

      Pluto is one of the closest and largest members of a huge population of KBOs, and has a large moon. It could have a liquid ocean, and yes, it could even have life: [] []

      New Horizons has cost about $700 million, not that much compared to other missions, and it will reach one or more additional KBO targets. It also made some flybys of the Galilean moons [].

      Uranus and Neptune have gained importance as Kepler has taught us that smaller "ice giants" are very common in the galaxy. Our understanding of the Uranian moons [] is sorely lacking, and Neptune's moon Triton [] is a great target too: 7th largest moon in the solar system, larger than Pluto, theorized to be a captured KBO, geologically active, retrograde orbit, possibly inhabited by microbes in a subsurface ocean...

      The Moon, Mars, Titan, Enceladus, Europa (Callisto instead due to radiation?), and other bodies would be great for manned missions. But we are hurrying to these locations at a time when manned space travel is in its infancy. We have to get to the locations fast enough to avoid damage to the astronauts (call this a political reason if you are into the "die on Mars" plan instead), and the science that can be done there could be replicated by robots to a degree (and they are always getting better - sometimes even by software updates []). Costs are astronomical not only because of today's crap propulsion (which could be improved in a decade or three by fusion rockets, VASIMR, whatever) but due to the expensive vehicle we are being forced to use: SLS. We could cut a lot of expense if we give SpaceX a few billion to turbocharge their Mars plans instead, and have lots of money left over from the killed SLS to accomplish great unmanned probe science.

      Let's say we postponed significant manned space travel plans by a couple of decades. SpaceX, Boeing, Blue Origin, China, etc. will ALL be using reusable rockets. Launch costs per kilogram will plummet, travel times could be cut using in-orbit fuel tankers []. We could land stuff on Mars for cheap in advance of humans assembling a base. We could get humans to Mars in 1-3 months instead of 6.

      In the meantime, we should continue launching things that are unmanned, so that it doesn't matter that it takes 15 years to reach its destination. We should have a good idea of what is going on in the outer reaches of our solar system. We could send cheap(er) probes and orbiters to all of the dwarf planets, especially big ones like Eris, Sedna, Haumea, and Quaoar. The big bucks can get spent on figuring out how to get a probe to travel 30 AU a year in order to get to as far out as the hypothetical Planet Nine within our lifetimes (or to a spot where we can use the Sun as a [] gravitational [] lens [] to get great imagery of exoplanets).

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      • (Score: 2) by bzipitidoo on Tuesday October 31 2017, @07:39AM (2 children)

        by bzipitidoo (4388) on Tuesday October 31 2017, @07:39AM (#589904) Journal

        I'd like the top priority for outer solar system exploration to be orbiters for Uranus and Neptune.

        Next on my list is Planet 9. For Planet 9, a flyby would be good, but an orbiter would be better. But how to do that? Planet 9 is never closer than 6 times Neptune's distance from the sun. At the speeds of the Voyagers and New Horizons, a probe would take at least 50 years to reach Planet 9. Have not heard that we built any probes that can last that long. To put an orbiter into orbit about Planet 9 is much harder. If it is sent fast, it may have a hard time entering orbit. If slow, it may run out of power before arriving.

        It'd be great to send probes past each of the unexplored dwarf planets.

        • (Score: 2) by takyon on Tuesday October 31 2017, @07:52AM

          by takyon (881) Subscriber Badge <{takyon} {at} {}> on Tuesday October 31 2017, @07:52AM (#589910) Journal

          But how to do that?

          You have to get damn creative:



          While it would be a blow to get only a flyby and no orbiter, Planet Nine will be such a uniquely hard-to-reach target compared to Jupiter, Saturn, Uranus, and Neptune that scientists will take anything they can get. Although successors to Hubble starting with JWST will hopefully be able to see it better than Hubble can.

          I'm hoping that Planet Nine will have a stupidly large Hill sphere [], which, when combined with its location among far-flung low mass solar system objects, could mean that it has more moons than Jupiter. Discovering most of its moons would require a flyby or orbiter.

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        • (Score: 0) by Anonymous Coward on Tuesday October 31 2017, @10:31AM

          by Anonymous Coward on Tuesday October 31 2017, @10:31AM (#589951)
          That's assuming Planet Nine actually exists. It's still somewhat hypothetical at this point, and until we know enough to at least be able to point Hubble in its general direction and get perhaps a faint image I'd not think about probes just yet.
      • (Score: 2) by bob_super on Tuesday October 31 2017, @06:51PM (1 child)

        by bob_super (1357) on Tuesday October 31 2017, @06:51PM (#590146)

        > due to the expensive vehicle we are being forced to use: SLS

        While the Pentagon's budget gets raised just in case we find more Nazis abroad than locally, and SLS and similar projects produce pork for Senators, India and China will launch the next major probes, carrying European and Japanese instruments to do those missions you dream about.
        The Chinese are very keen to put a major accomplishment, or ten, on the board. Deep space probes and planet exploration are definitely in their sights.

        • (Score: 2) by takyon on Tuesday October 31 2017, @07:18PM

          by takyon (881) Subscriber Badge <{takyon} {at} {}> on Tuesday October 31 2017, @07:18PM (#590165) Journal

          China could waste a lot of money in the near term on a Tiangong-2/ISS successor:


          There are some planned Mars missions [] but nothing to suggest they will leapfrog the U.S. and put humans on the surface of Mars before 2035-2040.

          It's true that they have the money to significantly advance their space program and potentially put it on par with NASA. But they are also massively increasing defense spending.

          I also welcome ISRO, NSSC, ESA, JAXA sending out probes and space telescopes. If China launches a Hubble successor, that would be great for everyone, even if U.S. scientists would likely not get initial access to the data.

          As for China beating the U.S. to Mars, while it would be a national embarrassment, is would not be some kind of existential threat to U.S. science. It's bragging rights, and would likely lead to increased investment. Investment that could actually do something given SpaceX's reusable rocket REVOLUTION.

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