How old is europa

The notion pulled Europa out of obscurity and into the limelight where it has remained, stoking the imaginations of people both within and outside the science community who fantasize about humans discovering life beyond Earth.

That fantasy, however, may be grounded in reality. From ground-based telescopes, scientists knew that Europa's surface is mostly water ice, and scientists have found strong evidence that beneath the ice crust is an ocean of liquid water or slushy ice. In the two Voyager spacecraft passed through the Jovian system, providing the first hints that Europa might contain liquid water. The team measured the vapor using a spectrograph at the Keck Observatory in Hawaii that measures the chemical composition of planetary atmospheres through the infrared light they emit or absorb.

As the ice shell distorts and flexes from tidal forces, warmer and less-dense ice would rise, carrying the ocean samples to the surface where a spacecraft could analyze it remotely, using infrared and ultraviolet instruments, among others.

Europa is named for a woman who, in Greek mythology, was abducted by the god Zeus — Jupiter in Roman mythology. Life as we know it seems to have three main requirements: liquid water, the appropriate chemical elements, and an energy source. Astrobiologists — scientists who study the origin, evolution, and future of life in the universe — believe Europa has abundant water and the right chemical elements, but an energy source on Europa has been difficult to confirm.

On Earth, life forms have been found thriving near subterranean volcanoes, deep-sea vents, and other extreme environments.

If we eventually find some form of life at Europa or Mars or Enceladus for that matter , it may look like microbes, or maybe something more complex. If it can be demonstrated that life formed independently in two places around the same star, it would then be reasonable to suspect that life springs up in the universe fairly easily once the necessary ingredients are present, and that life might be found throughout our galaxy and the universe.

If life were found at Europa, how might it change your view of the cosmos and our place in it? So if we replaced our Moon with Europa, it would appear roughly the same size in the sky as our Moon does, but brighter — much, much brighter. Europa orbits Jupiter at about , miles , kilometers from the planet, which itself orbits the Sun at a distance of roughly million miles million kilometers , or 5.

One AU is the distance from Earth to the Sun. Light from the Sun takes about 45 minutes to reach Europa. Because of the distance, sunlight is about 25 times fainter at Jupiter and Europa than at Earth. Europa orbits Jupiter every 3. Jupiter takes about 4, Earth days or about 12 Earth years to orbit the Sun a Jovian year. Over time, the orbits of most large satellites or planets tend to become circular, but in the case of these three satellites, the resonance produces a forced eccentricity since the satellites line up with each other at the same points in their orbits over and over, giving each other a small gravitational tug that keeps their orbits from becoming circular.

She became the queen of Crete and had a number of children with Zeus. The surface of Europa is made of frozen water and has the smoothest surface of any other objects in the solar system — i. There are very few craters on the surface of the moon because it is tectonically active and relatively young.

The moon is one of the brightest objects in the solar system with an albedo light reflectivity of 0. This reflectivity suggests a young and active surface to Europa of somewhere between 20 and million years — much less than the moon itself with is around the same age as Jupiter, 4. Radiation levels on the surface of Europa are around mSv rem per day, a dose which would cause severe illness and death in a human being exposed for just one day. Scientists believe that there is a liquid ocean somewhere around km 60 miles beneath the thick, icy crust of Europa.

It is thought that the tidal affects between Europa and Jupiter are what heat and keep the water in a liquid form. If it is proven that this ocean exists, Europa may be one of the most promising places in our solar system, beyond Earth, to search for life. This is slightly more than double the volume of water in the oceans on Earth. Launched in , the Galileo mission took 6 years to reach Jupiter and it remained in orbit from from December 8, until September 21, It provided the most detailed examination of the Galilean moons to date with numerous close flybys of Europa.

Europa and the moons of Jupiter have also been visited by a number of other spacecraft — including Pioneer 10 and 11 in and , Voyager 1 and 2 in , and the New Horizons mission as it flew through the Jovian system on its way to Pluto and beyond. One day on Europa — the time it takes for the moon to rotate on its axis — is 3. It also takes Europa 3. This means that a day on Europa takes the same length of time as one year on Europa.

Like almost all moons in the solar system, Europa is tidally locked — locked by gravity — to Jupiter and the same side of the moon always faces the planet.

This breaks those molecules into oxygen and hydrogen atoms. The hydrogen escapes the surface of Europa but the oxygen is left being — leaving a tenuous oxygen based atmosphere. The discovery of Europa and the other Galilean moons lead to the discovery of a Sun-centred solar system. The moon is named after a Phoenician noblewoman who became queen of Crete in Greek mythology. Europa is the smoothest object in the solar system. Europa is about 4. Radiation on Europa is high enough to kill a human being in one day.

Given his estimates for the moon's rate of repaving, Greenberg thinks it would have taken one to two billion years for the first surface oxygen to reach the ocean below.

A few million years after the ice-repaving process had started, oxygen levels in Europan seas reached their current levels—which exceed levels in Earth's oceans—Greenberg speculates. This timeframe actually improves the chances that life as we know it took root on Europa.

For starters, the most primitive life-forms need an absence of oxygen to form, Greenberg said. Similarly, a sudden abundance of oxygen can kill simple life-forms that aren't accustomed to the highly reactive element.

But if oxygen is introduced slowly, creatures can evolve to tolerate it and even come to depend on it—a process thought to have happened on early Earth. Greenberg's generous estimate of oxygen in Europa's ocean—and the resulting speculation that fishlike creatures may exist there—depends on the surface repaving to have happened at a relatively stable rate, in this case, a complete renewal every 50 million years. But planetary scientist Robert Pappalardo said the process may have been more intermittent, and therefore the oxygen level—and chance for fishlike life—lower.

For example, Pappalardo said, Europa is gravitationally locked with its neighboring moon Io, which has an eccentric orbit around Jupiter. This means Io may be pushing and pulling on Europa in extreme cycles, resulting in periods of high and low tidal friction on Europa. Even in this scenario, oxygen could reach the seas, though maybe not in quantities that would favor complex life-forms.

Since ice behaves like a fluid over long time frames think glaciers , he said, surface elements could be reaching Europa's ocean via solid ice. It's just that in ice it might take a hundred thousand years for a blob to rise. Meanwhile, if tidal activity on Europa comes in fits and starts, that would change the rates at which heat and nutrients from the rocky mantle become available, he said.

It might lead to much more hardy organisms"—but not necessarily complex life. Life's chances on Europa would also depend on whether tidal friction heats the moon all the way to its rocky core. If the solid core is in fact warm, he said, "then you may have black smokers pouring out heat and chemicals. In fact, even with vast amounts of oxygen in the water, astrobiologist Cynthia Phillips of the SETI Institute said, it's unlikely for Europa to house anything bigger than microbes, given its probable amounts of life-supporting chemical nutrients.

For some scientists, though, the idea of at least microbial life on Europa is plausible enough that researchers, including Shank of Woods Hole, are already eyeing Earth's superheated hydrothermal vents as possible analogues. Some microbes can thrive on the gases created from the chemicals spewed out by these vents. On Europa such chemicals could be the basis of a food chain that, with oxygen in the water, might support complex life.

One day spacecraft could be sent to Europa to penetrate the ice and explore the ocean, much as remotely operated vehicles sniff Earth's deep ocean for nutrients released by unseen hydrothermal vents, Shank said. But first scientists would have to develop sensors that can probe for DNA, RNA, and other chemical signatures of life. A submersible sent to Europa would also have to be made smaller, lighter, and with better battery life than existing models—while still being able to drill its own way through what may be miles of ice.

Robust communications capabilities would also be essential, Shank said. NASA's next step in exploring Europa, however, is more likely to be an orbiter—i. At their closest, Jupiter and its moons are roughly million miles million kilometers from Earth, so getting there can take as long as five to six years with current technology. At that distance, there's not enough sunlight for a solar-powered probe, so the craft would need to bring its own nuclear power source, Phillips said.

Pappalardo, the study scientist for the proposed Europa mission, said NASA's planned orbiter should be robust enough to last almost a year before succumbing to radiation or other environmental pressures. Such a mission, he added, could find concrete evidence for complex life on Europa.