Get ready, we’re going to Europa! NASA’s plan to send a spacecraft to explore Jupiter’s moon just passed a major hurdle. The mission, planned for the 2020s, now has NASA’s official stamp of approval and was given the green light to move from concept phase to development phase.
Formerly known as Europa Clipper, the mission will temporarily be referred to as the Europa Multi Flyby Mission until it is given an official name. The current mission plan would include 45 separate flybys around the moon while orbiting Jupiter every two weeks. “We are taking an exciting step from concept to mission in our quest to find signs of life beyond Earth,” John Grunsfeld, associate administrator for NASA’s Science Mission Directorate, said in a press release.
Since Galileo first turned a spyglass up to the skies and discovered the Jovian moon, Europa has been a world of intrigue. In the 1970s, we received our first look at Europa through the eyes of Pioneer 10 and 11, followed closely by the twin Voyager satellites in the 1980s. Their images provided the first detailed view of the Solar System’s smoothest body. These photos also delivered evidence that the moon might be harboring a subsurface ocean. In the mid 1990s, the Galileo spacecraft gave us the best view to-date of Europa’s surface.
"Observations of Europa have provided us with tantalizing clues over the last two decades, and the time has come to seek answers to one of humanity's most profound questions," Grunsfeld said. “Mainly, is there life beyond Earth?”
Sending a probe to explore Jupiter’s icy companion will help scientists in the search for this life. If Europa can support microbial life, other glacial moons such as Enceladus might as well.
Water, chemistry, and energy are three components essential to the presence of life. Liquid water is present throughout the Solar System, but so far the only world known to support life is Earth. Scientists think that if we follow the water, we may find evidence of life beyond Earth.
However, water alone will not support life; the right combination of ingredients is key. This mission to Europa will explore the moon’s potential habitability as opposed to outright looking for life.
When we set out to explore new worlds, we do it in phases. First we flyby, then we send robotic landers, and then we send people. This three-step process is how we, as humans, have explored the Moon and how we are partly through the process of exploring Mars.
The flyby of Europa will be a preliminary mission with four objectives: explore the ice shell and subsurface ocean; determine the composition, distribution, and chemistry of various compounds and how they relate to the ocean composition; map surface features and determine if there is current geologic activity; characterize sites to determine where a future lander might safely touch down.
Europa, at 3,100 kilometers wide (1,900 miles), is the sixth largest moon in the Solar System. It has a 15 to 30 kilometer (9 to 18 mile) thick icy outer crust that covers a salty subsurface ocean. If that ocean is in contact with Europa’s rocky mantle, a number of complex chemical reactions are possible. Scientists think that hydrothermal vents lurk on the seafloor, and, just like the vents here on Earth, they could support life.
The Galileo orbiter taught us most of what we know about Europa through 12 flybys of the icy moon. The new mission is scheduled to conduct approximately 45 flybys over a 2.5-year period, providing even more insight into the moon’s habitability.
In 2014, NASA issued a call to researchers asking for instrument proposals for the mission. In total, the agency received 33 submissions. The organization selected nine instruments from that.
Managed by NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, the Europa spacecraft will be fitted with two cameras—a wide-angle and a narrow-angle. Dubbed “EIS”—the German word for ice—the Europa Imaging System will map Europa’s surface at a resolution of 50 meters, and it will image certain parts of the surface with a resolution 100 times greater. By contrast, the Galileo probe mapped only 10 percent of the moon at a resolution of 200 meters. We can expect to see 3D views of the landscape from the wide-angle camera, while the narrow-angle will help map the surface and even determine a potential landing site for future missions. Together the duo will map nearly 90 percent of Europa’s surface.
"We've already seen incredible things, imagine what we'll see when we look at the rest of Europa at even better resolution," said Dave Senske, a NASA astrobiologist, at AbSciCon in Chicago last week.
The probe is equipped with dual-frequency, ice-penetrating radar designed to analyze Europa’s icy crust, from the near-surface to the ocean beneath. Named the Radar for Europa Assessment and Sounding: Ocean to Near-surface (aka REASON) this instrument will be able to give scientists a look at the structure of the ice shell.
The next two instruments—the Interior Characterization of Europa using Magnetometry (ICEMAG) and the Plasma Instrument for Magnetic Sounding (PIMS)—will work in tandem to measure the depth and salinity of Europa’s ocean and how thick the ice shell actually is. Current data suggests a thickness of 15 to 30 kilometers. The duo will also measure the magnetic field around Europa.
In 2012, NASA’s Hubble Space Telescope (HST) spotted signs of geysers erupting on Europa’s surface. Subsequent observations have not revealed any further eruptions, leaving scientists puzzled. The Europa THermal Emission IMaging System (E-THEMIS) is a thermal imaging system designed to search for active sites—places where water vapor is erupting into space—on the moon’s surface. E-THEMIS will work with the Europa Ultraviolet Spectrograph (UVS) to analyze the composition of any plumes as well as the composition of Europa’s thin atmosphere.
The SUrface Dust mass Analyzer (SUDA), together with a mass spectrometer—MAss SPectrometer for Planetary EXploration (MASPEX)—will analyze gases and small dust particles that are ejected into space to study the moon’s composition from an orbital position.
Finally, an infrared mass spectrometer, the Mapping Imaging Spectrometer for Europa (MISE), will help the probe map out the surface composition of Europa. This instrument will be able to identify any organic molecules on the surface, and it may be able to tell us what makes up the brown coating on portions of the moon’s exterior. Recent laboratory experiments indicate the material is irradiated salt originating from the subsurface ocean. If scientists can determine what the brown material is, they will have a better idea what is in the water. This is key for determining the moon’s habitability.
In the search for life, we tend to focus on Mars, but icy worlds with subsurface oceans like Europa’s could be the best places to look within our own Solar System.
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