Why Galilean moons, not Mars

In the pursuit of settling humans beyond Earth, wouldn't it be better to explore other worlds that are less hostile than Mars?

The past week has been bitter-sweet for space endeavours: While the European Space Agency’s Jupiter Icy Moons Explorer (JUICE) successfully blasted off on its mission to study Ganymede, Callisto, and Europa, three of Jupiter’s Galilean moons (except for the volcanic hotspot Io), SpaceX’s mighty rocket — the Starship Super Heavy — failed to make into the Earth’s orbit and exploded.

Both these projects are crucial in the quest for making Homo sapiens an interplanetary species. On one hand, JUICE would be looking for alien life on Jupiter’s moons, and on the other, Starship rockets are being developed to one day take humans to Mars. There is little to explain why humans are looking for habitable alien worlds: To ensure that the species survive, even as our polluting activities doom life on Earth.

A lot has already been discussed about why Mars appears to be our first choice for a home away from home (it was once an Earth-like planet that might have supported life), and the failed maiden launch of Starship reveals just the first challenges in getting there. The 50-metre-tall Starship upper stage was expected to separate from the Super Heavy first stage nearly three minutes after launch, but both stages remained stuck and began to tumble before exploding.

The space voyage would be even more treacherous. According to a Nasa study, astronauts who had been on shuttle missions and International Space Station flights were found to be more vulnerable to diseases, such as herpes, chicken pox and shingles. “So far, 47 out of 89 (53 per cent) astronauts from short-duration space shuttle flights, and 14 out of 23 (61 per cent) from long-duration ISS spaceflight missions shed at least one or more herpes viruses in their saliva or urine samples,” states the study.

Besides, they faced extraterrestrial challenges, such as cosmic radiation and microgravity.

Also, Mars is no Garden of Eden: “Mars ain’t the kind of place to raise your kids. In fact, it’s cold as hell... (Elton John in Rocket Man).”

The problems with human habitation there are, unfortunately, unfathomable — beyond just extreme cold.

For a true Mars experience, one must stay in a radiation bunker for months. Bill Nye, CEO of Planetary Society, and famously known as Bill Nye the Science Guy for his TV show that aired in the 1990s, once told reporters: “You think you want to go to Venus? We’d be vaporised in a second... And then on Mars, it’s not just there’s nothing to eat, there’s nothing to breathe. So, you know if you live in a dome and you go outside, you’re going to put on a spacesuit and you’re in another dome...”

There is another challenge: The Martian surface is dry, and ice and suspected underground water lakes there will probably be extremely salty, making it unfit for most life forms on Earth.

One solution is “terraforming”. “Elon Musk has a plan. He’s thinking of putting satellites in orbit that have big reflectors that focus sunlight that would otherwise miss the planet. Focus it down on the planet and just add more energy to the planet, heating it up, and if you do it right, you might be able to set sort of a chain reaction in place... If everything is frozen and it gets warmer, you’ll evaporate more carbon dioxide, and that’ll help trap more heat... you still need oxygen to breathe. So now you put microorganisms that eat the CO2 and they release oxygen,” astrophysicist Neil deGrasse Tyson once said in his podcast StarTalk (Source: usatoday. com). Sadly, technology isn’t there yet.

Though there would be no end to challenges in settling humans beyond Earth, isn’t it better that we look at other worlds that are less hostile than Mars, say, the ocean-bearing Jupiter moons?

Bigger than Mercury and only slightly smaller than Mars, Ganymede, the largest moon in our solar system, according to scientists, may have more water than all of Earth’s oceans in a subterranean ocean. Some also believe single-cell microbial life or extremophiles may exist there. Besides, it has a thin oxygen atmosphere. Also, Ganymede is the only moon that has a magnetic field (Mars has an extremely weak magnetic field), giving better protection from harmful radiation.

Europa is another water world with an icy crust. “Data indicates Europa may have plenty of water — a salty ocean beneath its crust that contains more water than Earth’s ocean. Scientists also think there’s a rocky seafloor at the bottom of the ocean. The interaction between the ocean and the rocks could possibly supply chemical nutrients for living organisms,” according to Nasa.

Callisto, too, has a thin atmosphere and is thought to contain an ocean, and is therefore another possible contender for life beyond Earth.

Not just these three Galilean moons, Saturn’s satellites Enceladus, Dione, and Titan and Neptune’s Triton could also be our next home.

Whether it be Mars or a moon, hopefully, we would mend our ways and counter our own invasive impact on alien worlds as we get ready to embark on extraterrestrial voyages.