# UpdatesMission to a Hidden Ocean: The Europa Clipper

#### K_Jameson

##### New member
I agree.

What about a non-plutonium RTG? I heard something about Americium-241. It is far less efficient than plutonium, but cheaper and easiest to produce.

#### Urwumpe

##### Not funny anymore
Donator
I agree.

What about a non-plutonium RTG? I heard something about Americium-241. It is far less efficient than plutonium, but cheaper and easiest to produce.
And also far less suitable for spaceflight applications, since it produces only 1/4th of the power of Pu and generates more harmful radiation that must be shielded for not disturbing science.

#### K_Jameson

##### New member
Indeed. Is what i said. Nevertheless, Americium is taken into account for space applications.

http://www.lpi.usra.edu/meetings/nets2012/pdf/3043.pdf

"While the specific power of a 241Am fuelled RTG is unlikely to match that of 238Pu fuelled units (except perhaps at small size) the design work undertaken provides confidence in the capability and performance of potential 241Am systems for future space mission opportunities."

#### Urwumpe

##### Not funny anymore
Donator
Yeah, but the feasibility for spaceflight does not mean that they are automatically better than other energy sources. It just means that they are qualified to be even considered as alternative.

#### K_Jameson

##### New member
Yeah, but the feasibility for spaceflight does not mean that they are automatically better than other energy sources.
I don't say that Americium is automatically the better alternative... only that is AN alternative... ;-)

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#### Urwumpe

##### Not funny anymore
Donator
I don't say that Americium is automatically the better alternative... only that is AN alternative... ;-)
Well, gotcha.

I just dislike the decay chains for Americium - that's really a problem.

#### K_Jameson

##### New member
:yes:

We have other radioactive materials suitable to be used in RTG?

#### Urwumpe

##### Not funny anymore
Donator
:yes:

We have other radioactive materials suitable to be used in RTG?
Not that many. Sr90 is pretty popular for Russian RTGs, but those have a pretty short service life and very low power as well.

Pu is the best choice there, but producing Pu is not that popular, despite it being around anyway.

#### Unstung

##### New member
Spaceflight Now: "NASA invites ESA to build Europa piggyback probe"
After walking away from a previously planned joint mission to Jupiter, NASA has asked the European Space Agency if it can furnish a lander or ice-penetrating probe for a rejuvenated U.S.-led robotic spacecraft to visit Jupiter’s moon Europa.

[...]

One outcome of NASA’s engagement with ESA could be a mission similar to Cassini-Huygens, which included a U.S.-built Saturn orbiter and a European lander that descended to the gas giant’s methane-shrouded moon Titan.

“We’re trying to recreate some of the excitement we had at Saturn and Titan with one of our most valued partners,” said Jim Green, manager of NASA’s planetary science division.

In an interview at the Lunar and Planetary Science Conference in March, Green said NASA requested ESA examine whether it has the interest and the funding to contribute something to the Europa mission.

“It could be a lander, it could be a penetrator, or it could be a probe to fly through the plumes,” Green said, referring to supposed detections of watery eruptions from Europa’s icy crust. “These are the things we have asked ESA to look at.”

[...]

“…$175,000,000 is for an orbiter with a lander to meet the science goals for the Jupiter Europa mission as outlined in the most recent planetary science decadal survey. That the National Aeronautics and Space Administration shall use the Space Launch System as the launch vehicle for the Jupiter Europa mission, plan for a launch no later than 2022, and include in the fiscal year 2017 budget the 5-year funding profile necessary to achieve these goals.” - Final budget law for Fiscal Year 2016 regarding NASA’s Europa mission While there’s at least eight years until it launches, this has been a pivotal year for developing NASA’s Europa mission. Last spring, NASA selected a rich and highly capable instrument set. This summer, following a design concept review, the mission moved from concept studies to an official mission. And just last week, Congress directed NASA to expand the mission by adding a small lander as well as launch the mission by 2022 and use the Space Launch System. These latter aren’t just suggestions: they are the law. There’s been almost no official information on the lander. What we know comes from a long article from Ars Technica’s Eric Berger on the then possible addition of a lander and a dedicated plume flyby sub-satellite. Berger is a long time space reporter and has developed a good relationship with House Appropriations Subcommittee Chairman John Culberson (R-TX). (I make sure I read all of Berger’s articles.) As Berger describes in detail in his article, Culberson has been the driving force behind the aggressive funding for this mission. In addition to an earlier launch, .Culberson also has wanted to see the mission carry a lander in addition to the mother craft that would make at least 45 close flybys of the moon. In prior years, Culberson added funding to NASA’s budget specifically to study a lander option, and the Jet Propulsion Laboratory’s engineers have been studying options. Berger’s story is focused more on Culberson, but it does provide a number of facts about the possible design for the lander: “The leading concept for the lander would be a small lander, perhaps about 230 kg with 20-30 kg for instruments. For comparison, the 1996 Mars Pathfinder lander had a mass of 265 kg. The lander would be delivered to Jovian orbit by the main spacecraft and then released in a high parking orbit well outside the intense radiation fields at Europa’s orbit. The main spacecraft would study Europa’s surface for two to three years during its flybys to find the best combination of a scientifically interesting and safe landing spot. The actual landing would use the same skycrane approach used by the Curiosity Mars mission to deliver the lander safely to the surface. The lander would likely last perhaps 10 days on the surface using battery power. During the lander’s lifetime, it would investigate the chemistry of the surface using a mass spectrometer and possibly a Raman spectrometer. A lander could add$700M or more to the mission cost. The last cost estimate I heard for just the main spacecraft was $2.1B. We don’t know how firm the lander cost estimate is. Adding a lander would delay launch from a possible 2022 to 2023.” [...] [TABLE="head;width=42"] "In the mid-2000s, NASA studied a small Europa lander that would have had similar mass and capabilities to those reportedly be considered for the approved Europa mission. Credit: NASA/JPL."[/TABLE]​ #### Unstung ##### New member As a result of the new Ocean Worlds Program, NASA will be including Titan and Enceladus proposals in the next New Frontiers mission. As for Europa, the Planetary Science program is still not certain of which booster will be used. According to Van Kane, the idea for an ESA daughter spacecraft has actually been dropped. This will enable a four-and-a-half year EGA trajectory to Jupiter using a Delta IV Heavy. Future Planetary Exploration: "Defining the Missions for the Ocean Worlds" [...] The only currently approved mission in the Ocean Worlds program is the Europa multi-flyby spacecraft. This mission, estimated to cost ~$2 billion, will orbit Jupiter and will take approximately 45 toe dips into the high radiation belts surrounding this moon to make close flybys. In between flybys, the spacecraft will have time to transmit the volumes of data it collected up close back to Earth. (This presentation gives a good overview of the mission design and science goals while this presentation summarizes the instrument payload.)

The mission is well into its design phase. At the CAPS meeting, the project manager, Barry Goldstein with the Jet Propulsion Laboratory, updated the committee members on refinements to the design.

Until recently, NASA’s managers had hoped that the main spacecraft could carry a 250 kilogram free flying daughter spacecraft to conduct complimentary studies. Ideas ranged from a simple Europa lander, to a spacecraft that would divert to flyby the volcanic moon Io, to a spacecraft dedicated to flying through any plumes ejecting material from the surface of Europa. NASA had invited the European Space Agency to propose (and pay for) a daughter spacecraft. In addition, a group at NASA’s Goddard Space Flight Center had developed a proposal for a free flyer that would swoop even lower to the surface than the main spacecraft to fly through any plumes while carrying a mass spectrometer more tuned to identifying bio signatures than the main spacecraft’s instruments.

Unfortunately, it appears that NASA has decided to drop the idea of a daughter spacecraft. I’m told that ESA’s managers determined that they had no way to fund such a spacecraft on the timeline for the Europa mission. NASA’s managers may have also decided they lacked the funding to build their own daughter spacecraft.

[...]

"The current baseline plan for launching the Europa multiple flyby mission is the Space Launch System. A new backup plan under consideration could reduce the alternative flight from over seven years to less than five years. Credit: NASA/JPL"[/TABLE]​

---------- Post added at 09:14 PM ---------- Previous post was at 09:14 PM ----------

I better not forget the lander!

[...]

In addition to providing an update to the Europa multiple flyby mission, JPL’s Goldstein provided the first public look at the current concept for a Europa lander. In the normal progression of exploring a world, NASA would not look at detailed plans for lander until the results from a mission orbiting that world (replaced with multiple flybys for Europa) were in. However, Congress has directed NASA to add a lander to the currently planned Europa mission.

JPL’s engineers have decided to make the lander an entirely separate spacecraft from the multi-flyby spacecraft. To find the spot on this moon that best combines scientific value and landing safety, the multi-flyby spacecraft must first complete its examination of the surface. As a result, a landing would come at least two to three years after the arrival of the multi-flyby spacecraft. The lander spacecraft could either launch with the multi-flyby spacecraft and park itself in Jovian orbit while waiting for the reconnaissance to be complete or the lander could be launch later. (I’m betting on the latter. NASA’s Green described the current design state of the lander concept as “immature” and it’s not clear that NASA will receive sufficient time or funding to mature the design in time for launch with the multi-flyby spacecraft.)

The lander itself would look much like and be about the size of the Mars Pathfinder that landed on the Red planet in 1997 (but without the Pathfinder’s small rover). The lander would be encased in petals that would deploy, allowing the lander to right itself if necessary after touchdown and that could also act as “snowshoes” in case the landing is on a soft surface. A mass spectrometer and a Raman spectrometer would study the composition of the surface material, panoramic and microscopic cameras would provide context and close up images, and a geophone would provide seismic measurements. The lander would include an arm that could scoop or drill samples from the surface to deliver to the instruments. Batteries would power the lander for up to 21 days.

While the initial target for this lander design is Europa, Goldstein pointed out that the design could be used to land on a number of ocean worlds including Enceladus and Jupiter’s Ganymede. (As discussed above, a Titan lander will need enter and descend through a thick atmosphere and then float on a sea. Its design is likely to be quite different.) Perhaps, if the funding gods are kind, we could see both multiple flyby missions to these moons and landers for these moons launch in the next decade or two.

[...]
|

"A Europa lander, whose design could be used for landing on other ocean worlds, would consist of four major elements, a carrier craft that would also relay the lander's data, a solid rocket motor to slow the lander, a sky crane descent stage, and the lander itself."|There's no caption for this so, yo dawg, I think that's a pretty slick Pathfinder-esque lander. Not only is it gonna violate David Bowieman's orders, it may even drill into the forbidden world. That's like far out. Star Child gonna be mad. Do people even read this anyways?[/TABLE]​

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#### Nicholas Kang

##### Spaceflight News Reporter
Tutorial Publisher
NASA "Europa Clipper" Flyby Mission Updates

NASA: https://www.nasa.gov/feature/jpl/nasas-europa-flyby-mission-moves-into-design-phase

A mission to examine the habitability of Jupiter's ocean-bearing moon Europa is taking one step closer to the launchpad, with the recent completion of a major NASA review.

On Feb. 15, NASA's Europa multiple-flyby mission successfully completed its Key Decision Point-B review. This NASA decision permits the mission to move forward into its preliminary design phase, known as "Phase B," beginning on Feb. 27.

A highlight of Phase A was the selection and accommodation of 10 instruments being developed to study the scientific mysteries of Europa. The new mission phase is planned to continue through September 2018, and will result in the completion of a preliminary design for the mission's systems and subsystems. Some testing of spacecraft components, including solar cells and science instrument detectors, has already been underway during Phase A, and this work is planned to continue into Phase B.

In addition, during Phase B subsystem vendors will be selected, as well as prototype hardware elements for the science instruments. Spacecraft subassemblies will be built and tested as well.
Mission Info:

The Europa mission spacecraft is being planned for launch in the 2020s, arriving in the Jupiter system after a journey of several years. The spacecraft would orbit Jupiter as frequently as every two weeks, providing many opportunities for close flybys of Europa. The mission plan includes 40 to 45 flybys in the prime mission, during which the spacecraft would image the moon's icy surface at high resolution and investigate its composition and the structure of its interior and icy shell.

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#### K_Jameson

##### New member
This is absolutely one of the two missions (the other is JUICE) that I'm waiting with more impatience.

#### Nicholas Kang

##### Spaceflight News Reporter
Tutorial Publisher
And we call it Europa Clipper!

https://www.nasa.gov/feature/jpl/nasa-mission-named-europa-clipper

NASA's upcoming mission to investigate the habitability of Jupiter's icy moon Europa now has a formal name: Europa Clipper.

The moniker harkens back to the clipper ships that sailed across the oceans of Earth in the 19th century. Clipper ships were streamlined, three-masted sailing vessels renowned for their grace and swiftness. These ships rapidly shuttled tea and other goods back and forth across the Atlantic Ocean and around globe.

In the grand tradition of these classic ships, the Europa Clipper spacecraft would sail past Europa at a rapid cadence, as frequently as every two weeks, providing many opportunities to investigate the moon up close. The prime mission plan includes 40 to 45 flybys, during which the spacecraft would image the moon's icy surface at high resolution and investigate its composition and the structure of its interior and icy shell.

Details:

"During each orbit, the spacecraft spends only a short time within the challenging radiation environment near Europa. It speeds past, gathers a huge amount of science data, then sails on out of there," said Robert Pappalardo, Europa Clipper project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.

Previously, when the mission was still in the conceptual phase, it was sometimes informally called Europa Clipper, but NASA has now adopted that name as the former title for the mission.

The mission is being planned for launch in the 2020s, arriving in the Jupiter system after a journey of several years.

#### boogabooga

##### Bug Crusher
I'm sure the name will get changed again after the budget and scope of mission ebb and flow over the next decade.