Raumfahrt - NASA´s Europa Clipper Mission auf der Jagd nach Leben´s Nischen

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A model of the Europa Clipper mission concept displayed at NASA's Jet Propulsion Laboratory, Calif., on Feb. 2, 2015. The spacecraft's 'vault' is shown in red.
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As NASA applauds its boosted White House budget request for 2016, scientists at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., are excited to see a robotic mission concept to Europa take a big step towards being launched in the mid-2020s.
During a conference call to reporters on Monday, NASA chief financial officer David Radzanowski said the US space agency is requesting $30 million for preliminary studies into a mission to Europa for the year that begins Oct. 1. This is in addition to the $100 million Congress added to NASA’s budget to begin design work for a Europa mission last year.
In response to this news, and after 15 years exploring Europa mission concepts, JPL senior research scientist Robert Pappalardo said that most mission concepts have either been too small, too big or just too expensive, but “we believe we have now found the one that is just right.”
“We call this concept the Europa Clipper,” he said.
The Clipper concept has been an idea undergoing preliminary studies for some time, consisting of a Jupiter-orbiting spacecraft that will make multiple flybys of the Jovian moon Europa over a 3 year period. The spacecraft will dive deep into Jupiter’s radiation belts to fly over Europa’s surface approximately 45 times during its primary mission.
NASA’s Cassini spacecraft, which is currently orbiting Saturn, has carried out similar flybys of moon Titan, constructing a comprehensive map of its surface and measuring the moon’s thick atmosphere. The Europa Clipper will be focused on Europa in an effort to understand its habitable potential.
Europa’s Biological Mystery
Europa is thought to possess a vast sub-surface ocean beneath its thick icy crust, kept in a liquid state via tidal interactions with the gas giant. Possibly containing three times the volume of water held in Earth’s oceans — and because on Earth, where there’s water, there’s life — astrobiologists hypothesize that Europa’s ocean might be quite a cozy place for biology to gain a foothold.
“Europa’s ocean, to the best of our knowledge, isn’t that harsh of an environment,” said astrobiologist Kevin Hand, JPL’s Deputy Chief Scientist for Solar System Exploration, at a special JPL “Icy Worlds” media event on Monday.
Although Europa’s ocean may be up to 100 kilometers (62 miles) deep, the conditions at the bottom of that monstrous abyss may be akin to the environment at the bottom of Earth’s comparatively shallow Mariana Trench, the deepest region of the Pacific Ocean, which is 11 kilometers (6.8 miles) deep. Complex biology has evolved in Mariana’s cold, dark environment, so it’s not such a stretch to think that if there is life in Europa’s ocean, it may also be thriving, extracting energy not from the sun (via photosynthesis), but from chemosynthesis near hydrothermal vents.
Europa’s deep ocean owes its potential habitability to the moon’s size. It’s only the size and approximate mass of Earth’s moon and therefore has comparable gravity, ensuring ocean pressures are not too extreme for biology to evolve. It’s possible that, through the constant tidal heating of Europa’s core, the moon will also have hydrothermal vents spewing the heat and chemicals needed for Europan life.
What’s more, the icy crust of Europa would shield the ocean from the powerful radiation above.
“The radiation is stopped in the upper 10′s of centimeters to a meter” of icy crust, said Pappalardo, who is principal investigator for the Europa Clipper concept.
But this radiation isn’t all bad; the high-energy particles trapped in Jupiter’s magnetosphere trigger chemical reactions in Europa's surface ice layers, producing nutrients. Previous studies have shown that there may be an icy equivalent to plate tectonics continually refreshing Europa’s surface. Subduction zones may drag the collected nutrients below, supplying any hypothetical biosphere.
Europa’s life-giving potential is exciting — it has liquid water, a heat source and possible nutrient cycling — but the JPL scientists are keen to point out that the Europa Clipper concept will not be a life-hunting mission.
“The way we framed the Europa mission science objectives is not to specifically look for life, but to understand habitability; the ingredients for life,” said Hand. To search for life, argues Hand, a surface mission would be required, a technological feat that is currently out of our scope.
The instrumentation to be chosen to fly on the Europa Clipper spacecraft will observe Europa’s finest scales of a few feet, a scale that we currently know nothing about. Of particular interest will be what the famous reddish veins across Europa’s icy crust are composed of and whether they contain any organic compounds. Also, as the spacecraft will fly close to the moon, it could ‘sniff’ Europa’s possible water-rich geysers that the Hubble Space Telescope recently detected.
Like Saturn’s moon Enceladus, it’s possible that Europa has vents in its ice that eject subsurface water into space, leaving forensic evidence of the salts and other compounds it contains for any flyby spacecraft to collect and analyze.
Radiation Threat
For the Europa Clipper to explore the moon at such close proximity would require some tough shielding and clever orbital planning to protect the spacecraft’s sensitive electronics.
“It’s a jungle out there around Jupiter! It’s a jungle of radiation,” said Sara Susca, Europa Clipper payload systems engineer.
Jupiter’s magnetic field acts as a powerful particle accelerator, blasting anything within its magnetosphere with particles traveling at 50-200 meters per second. So when these particles hit things, they can be lethal for spacecraft.
To mitigate this problem, Susca envisions a highly elliptical orbit that will take the Clipper deep into Jupiter’s radiation belts for short periods of time, amassing the lowest possible dosage of radiation per orbit. In addition, the Clipper concept will have a “vault”; a section of the spacecraft with heavy shielding that will act like a ‘skull’ to the orbiter’s ‘brains.’
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Overall, “the spacecraft will be quite big,” added Susca. “It will have two large solar panels both about 29 feet by 4 feet.” The main body of the vehicle will be about 18 feet (5.5 meters) tall, approximately the size of school bus.
NASA’s Galileo mission, which orbited Jupiter from 1995 to 2003, had a height of 17 feet (5.2 meters) and measured 36 feet (11 meters) from spacecraft body to the end of the magnetometer boom. As Galileo was powered by a radioactive power source, it didn’t use solar panels, so the solar powered Europa Clipper would dwarf Galileo. NASA’s incoming Juno mission, however, will be bigger than the Clipper, with three 29 x 8.9 feet (8.9 x 2.7 meters) solar arrays — the first mission to the outer solar system using large, efficient solar panels to collect the weak sunlight. Juno will arrive at Jupiter orbit in 2016.
Should the Europa Clipper spacecraft be ready for launch in the next decade, there could be a wonderful opportunity for a fast-track to Europa. Currently under development is NASA’s Space Launch System (SLS), a powerful rocket that could send the Clipper from Earth to Jupiter orbit in “under 3 years,” according to Pappalardo. The alternative, sending the spacecraft via a number of gravity assists around the solar system, could take 7-8 years.
Although Monday’s good budget request news is only the start of a long road to Europa, it takes the Europa Clipper from concept to planning, so hopes are high that the Europa Clipper will follow NASA’s Juno spacecraft as the next big mission to explore Jupiter’s enigmatic moon.
“We are really looking forward to next spring when, hopefully, we’ll become another flagship mission,” added Susca.
Quelle: D-News
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Update: 22.02.2017
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NASA's Europa Flyby Mission Moves into Design Phase

 

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This artist's rendering shows NASA's Europa mission spacecraft, which is being developed for a launch sometime in the 2020s.
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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.

 

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.

 

The life cycle of a NASA science mission includes several key phases. At each step, missions must successfully demonstrate that they have met the agency's requirements in order to indicate readiness to move forward into the next phase. Phase B includes preliminary design work, while phases C and D include final design, spacecraft fabrication, assembly and testing, and launch.

Quelle: NASA

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Update: 10.03.2017

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The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this reprocessed color view
The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. Image credit: NASA/JPL-Caltech/SETI Institute
› Full image and caption

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 the 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.

Europa has long been a high priority for exploration because it holds a salty liquid water ocean beneath its icy crust. The ultimate aim of Europa Clipper is to determine if Europa is habitable, possessing all three of the ingredients necessary for life: liquid water, chemical ingredients, and energy sources sufficient to enable biology.

"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 formal 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.

JPL manages the mission for the agency's Science Mission Directorate in Washington.

Quelle: NASA

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Update: 12.03.2017

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An artist's rendering shows the Europa Clipper flying by Europa. On its mission, it will make 40 to 45 flybys of this moon.

NASA’s New Mission to Europa Is All About Finding Aliens

On Thursday, NASA announced that a flyby mission to Jupiter’s moon Europa, planned for the 2020s, will be called Europa Clipper and it will look for signs of habitability and life on the moon.

Right now, scientists are working with limited data, because most of the information from the Galileo probe focused on Jupiter itself. But NASA is moving forward with the mission to Europa because of the compelling possibility of finding extraterrestrial life. Europa has an icy crust, but underneath, it’s an ocean world. And water means one thing: the potential for alien life to make a home for itself.

 

After the six-ton Clipper spacecraft is launched, it will reach Jupiter in 2.7 years. Once it reaches its destination, it will sail past Europa every two weeks and make 40 to 45 flybys.

During this time, it plans to find the best place on Europa for finding life in a future landing mission, whether it’s near plumes, fresh ice, or somewhere else. It will also take high-resolution images of the icy surface, investigate the composition and structure of Europa’s interior and shell, and test the technology needed for the lander.

Here are three things you need to know about upcoming missions to Europa.

Why do scientists suspect there might be life on Europa?

On the outside, Europa looks like a deserted planet, prone to deadly radiation from Jupiter.

Europa
Europa, one of Jupiter's moons, has an icy shell, but scientists believe there is an ocean beneath. Since Europa has water, future missions will search for signs of life.

But beneath the crust, there’s an ocean scientists believe is over 60 miles deep, which is exactly where the Clipper will search for signs of life. Scientists believe that Europa has twice as much water than Earth, and the radiation on the surface may actually benefit life in the oceans.

 
 

That’s because radiation from Jupiter’s magnetosphere breaks down water molecules into hydrogen and an oxygen-hydrogen molecule, and over time, those molecules combine to form hydrogen peroxide. This eventually decays into hydrogen and oxygen. And while the lighter hydrogen molecules escape into space, the heavier oxygen stays on the surface.

The age of Europa’s surface varies between 10 million and 100 million years old, which means periodically some parts of the ice shell are brought into the ocean, delivering oxygen into the water.

At the bottom of its ocean, Europa likely has hydrothermal vents or similar structures. In Earth’s oceans, life thrives in the superheated water spewing from hydrothermal vents.

With oxygen, energy, and water, Europa might just have aquatic life swimming beneath its icy shell.

What’s going to happen on the upcoming mission to Europa?

So far, the Clipper team already selected ten instruments for this mission and tested some spacecraft components. 

The Clipper mission recently entered Phase B, or its preliminary design phase, where the team will continue testing components, do preliminary design, select prototype hardware elements for scientific instruments, and start building and testing spacecraft subassemblies. 

In February, NASA received a report for a possible landing mission to Europa, which has been in the works since June 2016. In the landing mission, a probe will search for evidence of alien life on Europa, assess its habitability, and characterize the surface and subsurface for future explorations to this moon and its ocean.

NASA has also made progress in the problem of planetary protection, or the concern that microbes from Earth can contaminate Europa’s ecosystem. To solve this problem, before launching, a lander will bake at extremely high temperatures to kill contaminants, and when its work on Europa is done, it will self-destruct.

Clipper will cost $2.7 billion, and this doesn’t include the launch vehicle and some other vehicles. In total, it will likely cost $3 to $4 billion, and the landing mission will cost about the same. In total, these missions to Europa will cost NASA as much as $8 billion.

It’s a gamble whether we’ll find life there, but a lander has higher chances of finding life because it can test the ice.

What would a lander do on Europa?

The lander would burrow 10 cm below Europa’s surface to search for signs of life. The lander features a sampling arm with a “cutter,” or a small rotary saw. Since Europa is so cold, the ice is harder than granite, but engineers have tested 35 types of blades on 25 different surfaces to find the best tool for cutting ice. In total, the lander would collect five samples.

An artist's rendering shows the design for a possible future landing mission to Europa. The lander features a sampling arm to collect samples from the moon's surface.
An artist's rendering shows the design for a possible future landing mission to Europa. The lander features a sampling arm to collect samples from the moon's surface.

Besides the cutter, the lander would also bring a microscope capable of seeing cells, as well as spectrometers to corroborate evidence of life. In August, there will be a call for proposal submissions to build instruments, and they’ll be selected in May 2018.

Besides searching for life, the lander would also analyze the habitability of the oceans, such as the water’s chemistry and the ice shell’s thickness, as well as study Europa’s physical features for future expeditions.

The surface mission should last 20 days, as the batteries have a capacity of 45kWh. This is the same amount of energy as a MacBook Pro operating at full capacity for a straight month.

Quelle: INVERSE

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Update: 1.04.2017

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Europa lander work continues despite budget uncertainty

 

WASHINGTON — The NASA team studying a lander mission to Jupiter’s moon Europa says their work is continuing even though the White House is requesting no funding for the mission in its latest budget.

In a presentation at a meeting of the Committee on Astrobiology and Planetary Science at the National Academies here March 29, Barry Goldstein of the Jet Propulsion Laboratory said that ongoing studies of the proposed lander are continuing, including a mission concept review scheduled for June.

“We still have enough funding to make it through the end of the year for development,” he said. “We’re going to pursue the mission concept review and let the chips fall where they may as we proceed.”

 

The administration’s fiscal year 2018 budget blueprint, released March 16, proposed a record-high $1.9 billion for NASA’s planetary science program, including support for the Europa Clipper mission that will go into orbit around Jupiter and make dozens of flybys of Europa.

However, the document explicitly ruled out funding for the follow-on lander mission. “To preserve the balance of NASA’s science portfolio and maintain flexibility to conduct missions that were determined to be more important by the science community, the Budget provides no funding for a multi-billion-dollar mission to land on Europa,” the document stated.

The lander mission, along with Europa Clipper, has enjoyed strong support from Congress, notably from Rep. John Culberson (R-Texas), chairman of the House appropriations subcommittee that funds NASA and an advocate of exploration of the icy moon that scientists believe is potentially habitable. Culberson, in recent years, has provided funding for Europa Clipper well above any administration request and at one point called for launching both Europa Clipper and the lander simultaneously.

Culberson did not mention the budget proposal in brief comments at the end of the public lecture about Europa exploration here March 29, but did reiterate his support for sending both orbiter and lander missions there.

He said he reached final agreement with fellow appropriators for a fiscal year 2017 spending bill that must be passed by April 28, when the continuing resolution that currently funds NASA and other federal agencies at 2016 levels expires. He didn’t provide details about the contents of that bill, which has not yet been formally introduced, but said, “You’ll be very pleased with the result.”

Goldstein, at the committee meeting, said the funding the proposed mission has received has helped make major progress on its design. “We’ve done an enormous amount of not only technical design, but also programmatic design, evaluating the capabilities and how long it will take to make this mission come to fruition,” he said.

That design, he said, permits a launch no earlier than October to December of 2025 on a Space Launch System rocket. No other launch vehicles, he said, have the performance to launch the lander mission, and even an SLS launch requires the use of an Earth gravity assist that would send the spacecraft to Jupiter, arriving in mid-2030.

The choice of launch vehicle and trajectory is driven by the spacecraft’s mass of 16.6 metric tons. By comparison, he said, Europa Clipper weighs 6 metric tons, and will be the largest spacecraft JPL has built to date. “Almost all of that mass is either liquid of solid propellant” to place the spacecraft into orbit around Jupiter and then Europa, and for the landing itself, he said.

The lander itself will be able to accommodate a payload of 42.5 kilograms of science instruments, with a notional suite of five instruments proposed by scientists in a report released in February. Those instruments would support the goals of looking for evidence of life on Europa, assess its habitability and characterize the moon to support future missions there.

The lander will use a “skycrane” landing system similar to that employed to the Mars Curiosity lander. Goldstein said early concepts of the lander looked similar to the 1990s Mars Pathfinder spacecraft, with petals to stabilize the spacecraft.

“The team looked at that quite a bit and realized… that it was very susceptible to ‘pathological’ landing cases that would end the mission,” he said, referring to the jagged terrain seen on much of the moon’s icy surface. The lander will instead use what Goldstein described as the “cricket” design, with four landing legs in lieu of petals. 

The battery-powered spacecraft is designed for a 20-day mission after landing, although that could be extended depending on how many samples the spacecraft collects and processes with its robotic arm. At the end of the mission, the spacecraft will self-destruct using a “thermite-based incinerator” to comply with planetary protection requirements. That system can also be triggered if the spacecraft loses contact with the Earth.

“Like in ‘Mission Impossible,’ we’ll hit the self-destruct button and sterilize,” he said.

Quelle: SN

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