It is one of the most profound questions posed in modern astronomy. But although our understanding of the cosmos has grown significantly, the question remains unanswered. We know that Earth-like planets are common, as are the building blocks necessary for terrestrial life, and yet we still haven’t found definitive evidence for life beyond Earth. Perhaps part of our problem is that we are mostly looking for life similar to our own. It is possible that alien life is so radically different from that of Earth it goes unnoticed.
In our search for exoplanets, we have found more than three dozen potentially habitable worlds. It’s estimated that there are 8 to 20 billion potentially habitable, Earth-like worlds in our galaxy alone. But there is a big difference between potentially habitable and actually habitable, and scientists are starting to narrow their definitions.
In 2023, NASA plans to launch the Europa Clipper mission, a robotic explorer that will study Jupiter’s enigmatic moon Europa. The purpose of this mission is to explore Europa’s ice shell and interior to learn more about the moon’s composition, geology, and interactions between the surface and subsurface. Most of all, the purpose of this mission is to shed light on whether or not life could exist within Europa’s interior ocean.
This presents numerous challenges, many of which arise from the fact that the Europa Clipper will be very far from Earth when it conducts its science operations. To address this, a team of researchers from NASA’s Jet Propulsion Laboratory (JPL) and Arizona State University (ASU) designed a series of machine-learning algorithms that will allow the mission to explore Europa with a degree of autonom.
In a major move forward on a long dreamed of mission to investigate the habitability of the subsurface ocean of Jupiter’s mysterious moon Europa, top NASA officials announced today, Tuesday, May 26, the selection of nine science instruments that will fly on the agency’s long awaited planetary science mission to an intriguing world that many scientists suspect could support life.
“We are on our way to Europa,” proclaimed John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington, at a media briefing today outlining NASA’s plans for a mission dedicated to launching in the early to mid-2020s. “It’s a mission to inspire.”
“We are trying to answer big questions. Are we alone?”
“The young surface seems to be in contact with an undersea ocean.”
The Europa mission goal is to investigate whether the tantalizing icy Jovian moon, similar in size to Earth’s moon, could harbor conditions suitable for the evolution and sustainability of life in the suspected ocean.
It will be equipped with high resolution cameras, radar and spectrometers, several generations beyond anything before to map the surface in unprecedented detail and determine the moon’s composition and subsurface character. And it will search for subsurface lakes and seek to sample erupting vapor plumes like those occurring today on Saturn’s tiny moon Enceladus.
“Europa has tantalized us with its enigmatic icy surface and evidence of a vast ocean, following the amazing data from 11 flybys of the Galileo spacecraft over a decade ago and recent Hubble observations suggesting plumes of water shooting out from the moon,” says Grunsfeld.
“We’re excited about the potential of this new mission and these instruments to unravel the mysteries of Europa in our quest to find evidence of life beyond Earth.”
Planetary scientists have long desired a speedy return on Europa, ever since the groundbreaking discoveries of NASA’s Galileo Jupiter orbiter in the 1990s showed that the alien world possessed a substantial and deep subsurface ocean beneath an icy shell that appears to interact with and alter the surface in recent times.
NASA’s Europa mission would blastoff perhaps as soon as 2022, depending on the budget allocation and rocket selection, whose candidates include the heavy lift Space Launch System (SLS).
The solar powered probe will go into orbit around Jupiter for a three year mission.
“The mission concept is that it will conduct multiple flyby’s of Europa,” said Jim Green. director, Planetary Science Division, NASA Headquarters, during the briefing.
“The purpose is to determine if Europa is a habitable place. It shows few craters, a brown gum on the surface and cracks where the subsurface meet the surface. There may be organics and nutrients among the discoloration at the surface.”
Europa is at or near the top of the list for most likely places in our solar system that could support life. Mars is also near the top of the list and currently being explored by a fleet of NASA robotic probes including surface rovers Curiosity and Opportunity.
“Europa is one of those critical areas where we believe that the environment is just perfect for potential development of life,” said Green. “This mission will be that step that helps us understand that environment and hopefully give us an indication of how habitable the environment could be.”
The exact thickness of Europa’s ice shell and extent of its subsurface ocean is not known.
The ice shell thickness has been inferred by some scientists to be perhaps only 5 to 10 kilometers thick based on data from Galileo, the Hubble Space Telescope, a Cassini flyby and other ground and space based observations.
The global ocean might be twice the volume of all of Earth’s water. Research indicates that it is salty, may possess organics, and has a rocky sea floor. Tidal heating from Jupiter could provide the energy for mixing and chemical reactions, supplemented by undersea volcanoes spewing heat and minerals to support living creatures, if they exist.
“Europa could be the best place in the solar system to look for present day life beyond our home planet,” says NASA officials.
The instruments chosen today by NASA will help answer the question of habitability, but they are not life detection instruments in and of themselves. That would require a follow on mission.
“They could find indications of life, but they’re not life detectors,” said Curt Niebur, Europa program scientist at NASA Headquarters in Washington. “We currently don’t even have consensus in the scientific community as to what we would measure that would tell everybody with confidence this thing you’re looking at is alive. Building a life detector is incredibly difficult.”
‘During the three year mission, the orbiter will conduct 45 close flyby’s of Europa,” Niebur told Universe Today. “These will occur about every two to three weeks.”
The close flyby’s will vary in altitude from 16 miles to 1,700 miles (25 kilometers to 2,700 kilometers).
“The mass spectrometer has a range of 1 to 2000 daltons, Niebur told me. “That’s a much wider range than Cassini. However there will be no means aboard to determine chirality.” The presence of Chiral compounds could be an indicator of life.
Right now the Europa mission is in the formulation stage with a budget of about $10 million this year and $30 Million in 2016. Over the next three years the mission concept will be defined.
The mission is expected to cost in the range of at least $2 Billion or more.
Here’s a NASA description of the 9 instruments selected:
Plasma Instrument for Magnetic Sounding (PIMS) — principal investigator Dr. Joseph Westlake of Johns Hopkins Applied Physics Laboratory (APL), Laurel, Maryland. This instrument works in conjunction with a magnetometer and is key to determining Europa’s ice shell thickness, ocean depth, and salinity by correcting the magnetic induction signal for plasma currents around Europa.
Interior Characterization of Europa using Magnetometry (ICEMAG) — principal investigator Dr. Carol Raymond of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California. This magnetometer will measure the magnetic field near Europa and – in conjunction with the PIMS instrument – infer the location, thickness and salinity of Europa’s subsurface ocean using multi-frequency electromagnetic sounding.
Mapping Imaging Spectrometer for Europa (MISE) — principal investigator Dr. Diana Blaney of JPL. This instrument will probe the composition of Europa, identifying and mapping the distributions of organics, salts, acid hydrates, water ice phases, and other materials to determine the habitability of Europa’s ocean.
Europa Imaging System (EIS) — principal investigator Dr. Elizabeth Turtle of APL. The wide and narrow angle cameras on this instrument will map most of Europa at 50 meter (164 foot) resolution, and will provide images of areas of Europa’s surface at up to 100 times higher resolution.
Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) — principal investigator Dr. Donald Blankenship of the University of Texas, Austin. This dual-frequency ice penetrating radar instrument is designed to characterize and sound Europa’s icy crust from the near-surface to the ocean, revealing the hidden structure of Europa’s ice shell and potential water within.
Europa Thermal Emission Imaging System (E-THEMIS) — principal investigator Dr. Philip Christensen of Arizona State University, Tempe. This “heat detector” will provide high spatial resolution, multi-spectral thermal imaging of Europa to help detect active sites, such as potential vents erupting plumes of water into space.
MAss SPectrometer for Planetary EXploration/Europa (MASPEX) — principal investigator Dr. Jack (Hunter) Waite of the Southwest Research Institute (SwRI), San Antonio. This instrument will determine the composition of the surface and subsurface ocean by measuring Europa’s extremely tenuous atmosphere and any surface material ejected into space.
Ultraviolet Spectrograph/Europa (UVS) — principal investigator Dr. Kurt Retherford of SwRI. This instrument will adopt the same technique used by the Hubble Space Telescope to detect the likely presence of water plumes erupting from Europa’s surface. UVS will be able to detect small plumes and will provide valuable data about the composition and dynamics of the moon’s rarefied atmosphere.
SUrface Dust Mass Analyzer (SUDA) — principal investigator Dr. Sascha Kempf of the University of Colorado, Boulder. This instrument will measure the composition of small, solid particles ejected from Europa, providing the opportunity to directly sample the surface and potential plumes on low-altitude flybys.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
For all of the talk about aliens that we see in science fiction, the reality is in our Solar System, any extraterrestrial life is likely to be microbial. The lucky thing for us is there are an abundance of places that we can search for them — not least Europa, an icy moon of Jupiter believed to harbor a global ocean and that NASA wants to visit fairly soon. What lurks in those waters?
To gain a better understanding of the extremes of life, scientists regularly look at bacteria and other lifeforms here on Earth that can make their living in hazardous spots. One recent line of research involves shrimp that live in almost the same area as bacteria that survive in vents of up to 750 degrees Fahrenheit (400 degrees Celsius) — way beyond the boiling point, but still hospitable to life.
Far from sunlight, the bacteria receive their energy from chemical combinations (specifically, hydrogen sulfide). While the shrimp certainly don’t live in these hostile areas, they perch just at the edge — about an inch away. The shrimp feed on the bacteria, which in turn feed on the hydrogen sulfide (which is toxic to larger organisms if there is enough of it.) Oh, and by the way, some of the shrimps are likely cannibals!
One species called Rimicaris hybisae, according to the evidence, likely feeds on each other. This happens in areas where the bacteria are not as abundant and the organisms need to find some food to survive. To be sure, nobody saw the shrimps munching on each other, but scientists did find small crustaceans inside them — and there are few other types of crustaceans in the area.
But how likely, really, are these organisms on Europa? Bacteria might be plausible, but something larger and more complicated? The researchers say this all depends on how much energy the ecosystems have to offer. And in order to see up close, we’d have to get underwater somehow and do some exploring.
In a recent Universe Today interview with Mike Brown, a professor of planetary science at the California Institute of Technology, the renowned dwarf-planet hunter talked about how a submarine could do some neat work.
“In the proposed missions that I’ve heard, and in the only one that seems semi-viable, you land on the surface with basically a big nuclear pile, and you melt your way down through the ice and eventually you get down into the water,” he said. “Then you set your robotic submarine free and it goes around and swims with the big Europa whales.” You can see the rest of that interview here.
What lies beneath the cracked, thick ice on the surface of Europa? NASA is hoping to fly a mission to the Jupiter moon in the coming years to see if it is indeed a promising site for life. If this concept is approved in the budget, think of the mission as a recce: NASA will either orbit the moon, or do several flybys on it, to scout the surface for science and potential landing sites.
NASA just announced its desire to have science instruments proposed for the mission. Of the submitted list, 20 proposals will be selected in a year’s time, when selectees will have $25 million to do a more advanced concept study.
“The possibility of life on Europa is a motivating force for scientists and engineers around the world,” stated John Grunsfeld, associate administrator for NASA’s science mission directorate. “This solicitation will select instruments which may provide a big leap in our search to answer the question: are we alone in the universe?”
The Europa mission is not a guarantee, and it’s unclear just how much money will be allocated to it in the long run. (NASA has requested $15 million in fiscal 2015 for the mission). The mission is also subject to budgetary approvals from Congress. If it passes all obstacles, it would fly sometime in the 2020s, according to information released with the budget earlier this year.
In April, NASA sent out a request for information to interested potential participants on the mission itself, which it plans to cost less than $1 billion (excluding launch costs).
“Recent NASA studies have focused on an orbiter mission concept and a multiple flyby mission concept as the most compelling and feasible,” the agency stated.
Besides its desire to look for landing sites, NASA said the instruments should also be targeted to meet the National Resource Council’s (NRC) Planetary Decadal Survey’s desires for science on Europa. In NASA’s words, these are what those objectives are:
Characterize the extent of the ocean and its relation to the deeper interior;
Characterize the ice shell and any subsurface water, including their heterogeneity, and the nature of surface-ice-ocean exchange;
Determine global surface, compositions and chemistry, especially as related to habitability;
Understand the formation of surface features, including sites of recent or current activity, identify and characterize candidate sites for future detailed exploration;
Understand Europa’s space environment and interaction with the magnetosphere.
Any instruments must meet NASA’s landing scout goal or the NRC goals, the agency said. The instruments also must be highly protected against the harsh radiation in the area, and also meet planetary protection requirements to ensure no extraterrestrial life is contaminated with our own.
In three years, NASA is planning to light the fuse on a huge rocket designed to bring humans further out into the solar system.
We usually talk about SLS here in the context of the astronauts it will carry inside the Orion spacecraft, which will have its own test flight later in 2014. But today, NASA advertised a possible other use for the rocket: trying to find life beyond Earth.
At a symposium in Washington on the search for life, NASA associate administrator John Grunsfeld said SLS could serve two major functions: launching bigger telescopes, and sending a mission on an express route to Jupiter’s moon Europa.
The James Webb Space Telescope, with a mirror of 6.5 meters (21 feet), will in part search for exoplanets after its launch in 2018. Next-generation telescopes of 10 to 20 meters (33 to 66 feet) could pick out more, if SLS could bring them up into space.
“This will be a multi-generational search,” said Sara Seager, a planetary scientist and physicist at the Massachusetts Institute of Technology. She added that the big challenge is trying to distinguish a planet like Earth from the light of its parent star; the difference between the two is a magnitude of 10 billion. “Our Earth is actually extremely hard to find,” she said.
While the symposium was not talking much about life in the solar system, Europa is considered one of the top candidates due to the presence of a possible subsurface ocean beneath its ice. NASA is now seeking ideas for a mission to this moon, following news that water plumes were spotted spewing from the moon’s icy south pole. A mission to Europa would take seven years with the technology currently in NASA’s hands, but the SLS would be powerful enough to speed up the trip to only three years, Grunsfeld said.
And that’s not all that SLS could do. If it does bring astronauts deeper in space as NASA hopes it will, this opens up a range of destinations for them to go to. Usually NASA talks about this in terms of its human asteroid mission, an idea it has been working on and pitching for the past year to a skeptical, budget-conscious Congress.
But in passing, John Mather (NASA’s senior project scientist for Webb) said it’s possible astronauts could be sent to maintain the telescope. Webb is supposed to be parked in a Lagrange point (gravitationally stable location) in the exact opposite direction of the sun, almost a million miles away. It’s a big contrast to the Hubble Space Telescope, which was conveniently parked in low Earth orbit for astronauts to fix every so often with the space shuttle.
While NASA works on the funding and design for larger telescope mirrors, Webb is one of the two new space telescopes it is focusing on in the search for life. Webb’s infrared eyes will be able to peer at solar systems being born, once it is launched in 2018. Complementary to that will be the Transiting Exoplanet Survey Satellite, which will fly in 2017 and examine planets that pass in front of their parent stars to find elements in their atmospheres.
The usual cautions apply when talking about this article: NASA is talking about several missions under development, and it is unclear yet what the success of SLS or any of these will be until they are battle-tested in space.
But what this discussion does show is the agency is trying to find many purposes for its next-generation rocket, and working to align it to astrophysics goals as well as its desire to send humans further out in the solar system.
What a multitude of worlds! A new study suggests that the Milky Way could host 100 million planets with complex life, leaving no lack of choice for astronomers to look for organisms beyond Earth. The challenge is, however, that these worlds might be too far away from us to do much yet.
“On the one hand, it seems highly unlikely that we are alone,” stated Louis Irwin, lead author of the study and professor emeritus at the University of Texas at El Paso. “On the other hand, we are likely so far away from life at our level of complexity, that a meeting with such alien forms is extremely improbable for the foreseeable future.”
The figure came from studying a list of more than 1,000 exoplanets for metrics such as their density, temperature, chemistry, age and distance from the parent star. From this, Irwin’s team formulated a “biological complexity index” that ranges between 0 and 1.0. The index is rated on “the number and degree of characteristics assumed to be important for supporting multiple forms of multicellular life,” the research team stated.
Assuming that Europa (a moon of Jupiter believed to have an ocean below its ice) is a good candiate for life, the team estimated that 1% to 2% of exoplanets would have a BCI that is even higher than that. So to translate that into some estimates: 10 billion stars in the Milky Way, averaging one planet a star, which brings us to 100 million planets minimum.
So what does this metric mean? There’s of course no guarantee that complex life exists in any of these places — just that the conditions could be conducive to life. Also, the researchers added, don’t assume that any life in this category would be intelligent life, but more life that is more complex than a microbe. And the known planets with higher BCIs tend to be pretty far away from us. (One of the closest is the Gliese 581 system, which is 20 light-years away.)
“Planets with the highest BCI values tend to be larger, warmer, and older than Earth,” added Irwin, “so any search for complex or intelligent life that is restricted just to Earth-like planets, or to life as we know it on Earth, will probably be too restrictive.”
Extremophiles teach us that life is found in unlikely places, which is why after looking at microbes happily living in hot springs or surviving after 18 months in space, scientists are trying to expand our definition of what a habitable environment is. So perhaps this ancient Martian volcano would be an example.
Meet Arsia Mons. It’s the third-tallest volcano on the Red Planet and one of the largest volcanoes we know of in the solar system.
New research shows that a combination of eruptions and a glacier on its northwest side could have formed something called “englacial lakes”, which is water that is created inside glaciers. (The researchers compare this to “liquid bubbles in a half-frozen ice cube.”) These in sum would have been massive, on the order of hundreds of cubic miles.
“This is interesting because it’s a way to get a lot of liquid water very recently on Mars,” stated Kat Scanlon, a graduate student at Brown who led the research, adding that she is also interested to see if signs of a habitable environment turn up in even older regions, of 2.5 billion years old or more.
“There’s been a lot of work on Earth — though not as much as we would like — on the types of microbes that live in these englacial lakes,” Scanlon added. “They’ve been studied mainly as an analog to [Saturn’s moon] Europa, where you’ve got an entire planet that’s an ice covered lake.”
While the glacial ice idea is not new — it’s been talked about since the 1970s — Scanlon’s team pushed the research forward by bringing in new information from NASA’s Mars Reconnaissance Orbiter.
“Scanlon found pillow lava formations, similar to those that form on Earth when lava erupts at the bottom of an ocean,” Brown University stated.
“She also found the kinds of ridges and mounds that form on Earth when a lava flow is constrained by glacial ice. The pressure of the ice sheet constrains the lava flow, and glacial meltwater chills the erupting lava into fragments of volcanic glass, forming mounds and ridges with steep sides and flat tops. The analysis also turned up evidence of a river formed in a jökulhlaup, a massive flood that occurs when water trapped in a glacier breaks free.”
Scanlon estimated that two of the “deposits” would have had lakes of 9.6 cubic miles (40 cubic kilometers) each, while a third would have had 4.8 cubic miles (20 cubic kilometers). They could have stayed liquid for hundreds or perhaps thousands of years.
That’s a short period in the history of life, but Scanlon’s team says it could have been enough for microbes to colonize the locations, if microbes were on Mars in the first place.
You can read more about the research in the journal Icarus.
Using a phone to search for signs of life? Yeah, we can get behind that. One group of researchers has a system that they’ve been testing out in analog environments with the aim of (eventually, one day, they hope) it being applied, say, to other planets — such as Mars.
Here’s how it works:
“Initially the human astrobiologist takes images of his/her surroundings using a mobile phone camera. These images are sent via Bluetooth to a laptop, which processes the images to detect novel colors and textures, and communicates back to the astrobiologist the degree of similarity to previous images stored in the database,” read a press release on the technology.
The aim is to eventually have robots, if necessary, do the same thing on Mars or in other locations. Field tests have been done in Martian analog environments, with intriguing results.
“In our most recent tests at a former coal mine in West Virginia, the similarity-matching by the computer agreed with the judgement of our human geologists 91% of the time,” stated Patrick McGuire, who works in Freie Universität’s planetary sciences and remote sensing department in Germany.
“The novelty detection also worked well, although there were some issues in differentiating between features that are similar in color but different in texture, like yellow lichen and sulfur-stained coalbeds. However, for a first test of the technique, it looks very promising.”
You can check out more details in this paper on Arxiv, a site that publishes articles before they are peer-reviewed. The information has also been accepted for publication in the International Journal of Astrobiology.