An artist's rendering of the Europa mission's spacecraft. Main Image: NASA/JPL-Caltech Banner Image: NASA/JPL-Caltech
An artist's rendering of the Europa mission's spacecraft. Main Image: NASA/JPL-Caltech Banner Image: NASA/JPL-Caltech

How Will the Europa Lander Search for Life?

An artist's rendering of the Europa mission's spacecraft. Main Image: NASA/JPL-Caltech Banner Image: NASA/JPL-Caltech
An artist's rendering of the Europa mission's spacecraft. Main Image: NASA/JPL-Caltech Banner Image: NASA/JPL-Caltech

Water, chemistry, energy: three key components for life. We only have confirmation of life on Earth so far, but we're always looking elsewhere. One of the biggest targets in the solar system is Europa, one of Jupiter's moons. We're aiming for that target with the Europa lander, which will launch for the Jovian moon around 2024. The mission will be the first on-site search for evidence of life on another world since Viking 1 and Viking 2 landed on Mars in 1976.

Last month, the team behind the Europa Lander released the mission’s scientific objectives [PDF], and at the recent 48th Lunar and Planetary Science Conference in The Woodlands, Texas, scientists answered questions and led a discussion about the trip with the wider planetary science community.

They explained that the Europa lander is not like the spacecraft Cassini or the Mars rovers—expeditions with big initial objectives, but quiet hope for decades of continued operation and science experiments. In contrast, this mission will live hard and die young. It will have to: The radiation environment at Europa is punishing, so the communications relay orbiter that will act as go-between for the lander and Earth won’t last more than a month or two. The lander will have enough power to run for just 20 days on the surface and will run on batteries; nuclear power was considered but discarded as being too expensive and challenging to launch. Batteries also have the advantage of being “quieter,” providing less vibration, magnetic, and electromagnetic disruption to sensitive instruments.

The lander will launch on a Space Launch System rocket and will spend years traveling to Europa. Upon arrival, the relay orbiter―which during the cruise phase to Jupiter acts as a carrier―will release the lander to Europa’s surface. As the communications satellite establishes its Europan orbit, the lander will use a mini sky crane system to land, looking and acting much like the rover Curiosity on Mars.

But notably, the scientists don’t call this process “Entry, Descent, and Landing” (EDL), but rather DDL, for Deorbit, Descent, and Landing—there’s no atmosphere around Europa for a lander to “enter.” This makes the job of landing much easier than on Mars, whose tenuous atmosphere is insufficient for parachutes alone, and yet enough that it makes a pure supersonic retropropulsive landing a challenge.


This artist's rendering illustrates a conceptual design for a potential future mission to land a robotic probe on the surface of Europa. Image Credit: NASA/JPL-Caltech

The lander is a square about the size of a large riding lawnmower with four long, articulated cricket-like legs that will each compress independently on landing, allowing it to touch down on an uncertain or jagged surface and still remain level. (If it landed on a ledge, for example, one leg might remain fully extended along the drop, and three legs might compress fully, bringing the belly of the robot even and near the ground.) A communications antenna will then deploy and establish communications with the relay orbiter.

The lander will host a payload of science instruments weighing nearly 94 pounds. “That is a considerable mass for getting science done on any world,” Kevin Hand of the Jet Propulsion Laboratory, co-chair of the science definition team, said. To get the science done, the lander will carry five instruments: a gas chromatograph mass spectrometer and a Raman spectrometer, which can identify the contents of a sample; a context camera, which should return some spectacular images, including a giant Jupiter hanging in the black sky over the ice world; and a geophone, used for seismometry, the study of seismic activity. Except for the camera, these instruments will live inside of the lander, which will protect them from the worst of the radiation.

The most crucial tool for gathering material is a sample collection arm: essentially an angled, twin-bladed boring instrument that will carve strips of granite-hard Europan surface at a depth of 4 inches or deeper. (Regolith at such a depth is not radiation-processed, increasing the likelihood of observing indicators of life.) The collected material will be loaded into a dock in the lander’s side, and the instruments within will begin their analyses. Over the course of the mission, the lander will collect and analyze a minimum of five samples with a minimum volume of .4 cubic inches from five different regions within the lander “workspace”―that is, the radial reach of the collector arm.


Two views of the trailing hemisphere of the ice-covered Europa. Image Credit: NASA/JPL/DLR

An Earth day is called a “day.” A Mars day is called a “sol.” A Europan day is called a “tal.” The carrier relay will orbit Europa every 24 hours―this is a happy coincidence with Earth, but wasn’t planned that way―and return three to four gigabits of data per orbit. Mission operations are therefore planned in 24-hour intervals.

At the start of a tal―00:00—the carrier relay will receive its commands from Earth to determine that period’s working schedule. The lander receives those instructions at 01:00, when the carrier is in view of the lander in its orbit. On an ordinary tal, the lander will start collecting samples for the next five hours. At 06:00, the lander will upload engineering data to the relay, which will, in turn, send that data to Earth.

The lander will then get to work on sample analysis, and at 11:00, upload its findings, and go to sleep. At this point, the carrier relay orbiter will be out of range of the lander. Two hours later, it will have a clear shot at Earth, and will send the data back here for analysis. Humans will use this data to plan the science and engineering for the next day, and will generate commands to that effect. At 23:00, those commands and instructions will be sent to the relay orbiter, and the cycle will repeat itself.

The baseline science mission will be achieved in 10 days. Depending on what the lander finds, the team might decide to prioritize different things—for example, focusing on collecting samples or image acquisition.


Reddish spots and shallow pits pepper the ridged surface of Europa. Image Credit: NASA/JPL/University of Arizona/University of Colorado

There is no such thing as a “life detector.” Instead of a single magic reading, the lander will look for many organic biosignatures that, taken together, reveal life. Instruments will look for signs and abundance of organic material, cell-like structures, chirality (molecular properties, like those found in amino acids), and biominerals (minerals produced by living things)—among many other things.

Individually, none of these biosignatures can reveal life, but if found collectively, the evidence will be all but irrefutable. A biosignature matrix of positive and negative results is, in essence, plotted on a spreadsheet. Hand called this “biosignature bingo.” Not all of the biosignatures are necessary, but some combination of them are; finding, for example, an abundance of organics, cell patterns, chirality, and microscopic evidence but no signs of biominerals would still conclude life with certainty. On the other hand, if none of these features were found but biominerals and cell patterns were, we wouldn't call that evidence of life.

Sampling will be done in triplicate to confirm life findings. Three samples will have to confirm the biosignatures. The lander team is confident about this process. “It would be very hard to have a false positive, especially after replicating it three times,” Hand told mental_floss. “We use life on Earth as a guide, and so applying that matrix to life on Earth, both past and present, we would have a hard time leading to a false positive.”

The lander, of course, will not be the first spacecraft to arrive at the Jovian moon. The Europa Clipper spacecraft will have arrived and studied Europa years earlier, and will have ably characterized the habitability of that world. What Clipper finds, Lander will build upon. The Clipper’s work will determine one of four possible outcomes: Europa is not habitable, in which case the lander will figure out why (for example: geological activity); Europa is maybe habitable, in which case the lander will resolve the ambiguity of the finding; Europa is habitable, in which case the lander will try to find life; and Europa is inhabited―Clipper outright finds life on Europa, in which case the lander will confirm the finding and set the stage for future exploration. In addition, Clipper will act as a backup plan for the lander should the relay orbiter fail. The lander can talk to Clipper, which will in turn send the information back to Earth.

Despite the recent White House budget request that notably failed to earmark money for the Europa lander, these missions are realistically in no danger. Congressional appropriators have made it clear that the Europa lander is going to happen, and, just as in the case of Clipper (which the Office of Management and Budget ignored for years), it is still expected to receive billions of dollars over the next decade.


Images from the Viking mission on Mars. Image Credit: NASA

NASA undertook its last true life-finding mission—Viking’s mission to Mars—decades ago. There’s a reason for this time gap: Viking didn’t find life. Scientists had previously held out hope that animals might be scurrying about on the Martian surface. When the red planet was found to be creature-less, interest was quickly lost in the Mars program. Viking is thus sometimes criticized as being a failure. But Hand disagreed. “Viking is vindicated by Europa,” he said. “If Pathfinder had gone back and found a golf course on Mars, someone could say Viking made mistakes. Viking worked beautifully. Mars did not cooperate. Life detection experiments should provide valuable information, regardless of the biology results.”

Even in the absence of life, scientists will learn a lot about Europa as an ocean world, and as a world with liquid water recycling through the sea floor. In the absence of biology, they will still advance the sciences of geochemistry and oceanography.

“As exciting as a positive result for biosignatures would be, a negative result is equally profound. It gets to the question of what does it take for the origin of life to occur,” Hand said. Today, for example, hydrothermal vents are thought to have been critical to the birth of life on Earth. If Europa—which also has hydrothermal vents—is dead, perhaps hydrothermal vents are not that important after all.

Science has marched rapidly since the Viking missions, which means if life exists on Europa, we’re more likely to find it now than Viking scientists on Mars were. When the Viking landers set down in the mid-1970s, the structure of DNA had only been known for about 20 years. In the years since Viking, hydrothermal vents were discovered on Earth, and a whole new domain of life was discovered in the microbial realm, like cryptoendoliths in Antarctica—not to mention the “polymerase chain reaction” was developed, allowing the human genome to be sequenced. Last year, a new tree of life was created based on this research. So going into the lander mission, Hand and his team are cautiously optimistic.

“We don’t know if biology works beyond Earth,” Hand said. “We have every reason to believe it should and could, but we have yet to do that experiment.” The Europa lander team hopes to change that.

New NASA Satellite Called TESS Could Discover Thousands of New Planets

Since NASA’s Kepler spacecraft launched in 2009, the space agency has found and confirmed a whopping 2343 new planets. Of those, 30 are considered to be situated in a “habitable zone,” an area in which a planet’s surface could theoretically contain water.

A new satellite, set to launch today, is expected to find thousands more planets outside of our solar system, known as exoplanets. TESS, short for the Transiting Exoplanet Survey Satellite, is NASA’s latest effort to plumb the depths and darkness of outer space in search of other Earth-like planets—including those that could potentially support life.

TESS is slated to complete a two-year survey of the “solar neighborhood,” a general region which comprises more than 200,000 of the brightest nearby stars. To find these outlier planets, NASA scientists will be keeping an eye out for temporary changes in brightness, which indicate that a planet is blocking its host star.

According to Martin Still, the program scientist working on the TESS mission, the launch comes “with certainty” that TESS will find many nearby exoplanets. "We expect to find a whole range of planet sizes, between planets the size of Mercury or even the Moon—our Moon—to planets the same size as Jupiter and everything in between,” Still said in a NASA interview.

While the Kepler mission was considered a major success, NASA noted that most of the planets it recorded are those that orbit faint, faraway stars, making it difficult to conduct follow-up observations. The stars that TESS plans to survey will be 30 to 100 times brighter than those observed by its predecessor. This allows for newly detected planets and their atmospheres to be characterized more easily.

“Before Kepler launched, we didn't know for sure if Earth-sized planets existed,” Elisa V. Quintana, a NASA astrophysicist, told Reddit. “Kepler was a statistical survey that looked at a small patch of sky for four years and taught us that Earths are everywhere. TESS is building on Kepler in the sense that TESS wants to find more small planets but ones that orbit nearby, bright stars. These types of planets that are close to us are much more easy to study, and we can measure their masses from telescopes here on Earth.”

The most common categories of exoplanets are Earth- and Super Earth–sized masses—the latter of which are larger than Earth but smaller than Uranus and Neptune.

TESS is scheduled to launch from the Cape Canaveral Air Force Station in Florida on a SpaceX Falcon 9 rocket at 6:32pm EDT today.

For more information about TESS, check out this video from NASA.

J. Malcolm Greany, Wikimedia Commons // Public Domain
An Astronomer Solves a 70-Year-Old Ansel Adams Mystery
Ansel Adams circa 1950
Ansel Adams circa 1950
J. Malcolm Greany, Wikimedia Commons // Public Domain

Ansel Adams was a genius with a camera, but he wasn’t so great about taking notes. The famous 20th century landscape photographer did not keep careful records of the dates he took his photos, leading to some debate over the origin period of certain images, including Denali and Wonder Lake (below), taken in Denali National Park in Alaska sometime in the late 1940s.

A black-and-white photo of Denali as seen from across Wonder Lake
Denali and Wonder Lake
Collection Center for Creative Photography, The University of Arizona, © The Ansel Adams Publishing Rights Trust

To settle a debate about when the photograph (known as Mount McKinley and Wonder Lake until the mountain's name was officially changed in 2015) was taken, Texas State University astronomer Donald Olson looked to the sky, using astronomical hints to determine the exact date, time, and location it was shot. Olson—who has solved other cultural mysteries related to topics such as Edvard Munch's paintings and Chaucer's writing using the night sky—writes about the process in his new book, Further Adventures of the Celestial Sleuth.

Adams did take some technical notes during his photography shoots, writing down the exposure time, film type, filters, and other settings used to capture the image, but he wasn’t as meticulous about the more mundane parts of the shoot, like the date. However, during his research, Olson found that another photo, Moon and Denali, was taken the night before the image in question. Because that one featured the moon, he could use it to calculate the date of both images—once he figured out where Moon and Denali was taken.

The moon hangs in the sky over Denali in a black-and-white photo
Moon and Denali
Collection Center for Creative Photography, The University of Arizona, © The Ansel Adams Publishing Rights Trust

To do so, Olson used topographical features such as cirques, hollowed landforms carved by glaciers, that were visible in Moon and Denali to identify several areas of the park where Adams may have been working. He and his student, Ava Pope, wrote a computer program to calculate the view from each possible location along the park road Adams drove along during his trip, eventually determining the coordinates of the location where the photographer shot Moon and Denali.

He could then estimate, using the position of the waxing gibbous moon in the photo, the exact time —8:28 p.m. on July 14, 1948—that Moon and Denali was taken. Denali and Wonder Lake would have been taken the next morning, and Olson was able to calculate from the shadows along the mountain where the sun would have been in the sky, and thus, when the photo was taken.

The answer? Exactly 3:42 a.m. Central Alaska Standard Time on July 15, 1948.


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