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A bunch of years ago, I wrote a documentary for fulldome called MarsQuest. In it, our audiences explored the past, present, and future exploration of Mars. Over the years, I’ve watched many missions go to Mars, following the progression we imagined in our show. First, robotic explorers. Then, if all goes well, we send people to Mars to give it a close-up human touch.

Today, we’re at the stage of planning the first crewed missions to Mars. Right now, we’re using robotic probes and we’ve sent many of them. Joining them this week are the Hope mission, the Tianwen-1 mission, and the Perseverance lander with its tiny helicopter.

Exploration of Mars

Mars exploration — Imagine the first Mars explorers setting foot on its rusty, sandy surface! Courtesy NASA/JPL

Of course, people have already explored Mars in a limited way. And, we’ve always dreamed of walking its surface. But, dreams of exploration are only a first step. Unlike the explorers of old who circumnavigated Earth, people going to Mars will prepare for a most alien place. That complicates the exploration of the Red Planet quite a bit.

Humans Need Mars Water

What is the most important thing that Mars explorers are going to need? Obviously, air to breathe is one resource. So is water. The exploration of Mars has continually focused on looking for sources of water across the planet. As we all know, the surface has NO flowing water and likely hasn’t for billions of years. However, that doesn’t mean water doesn’t exist there. The upcoming missions to Mars arriving this week all will continue the search for resources, including water.

Yet, we DO know that Mars has water. That’s thanks to the spacecraft that are already “in situ” and have explored in the past. For example, the first images of Mars from the Mariners showed river beds and flood plains. Every imaging mission since that time has shown tantalizing hints of water across the planet, including the ice caps. Other missions have “sensed” the planet using radar and other instruments, looking for the chemical indications of water.

Combing the Mars Data for Water

Today, data from the Mars Reconnaissance Orbiter, Mars Odyssey, and Mars Global Surveyor missions are contributing to the mapping of water on Mars. In particular, they are chartingthe amounts of ice that we can’t see, but are buried underground.

Planetary Science institute scientist Gareth Morgan leads a team that is analyzing that data. They’re using new data-processing techniques to assess the possibilities for hidden water ice on Mars. Their system is called “Subsurface Water Ice Mapping” (SWIM). It provides maps of places around the globe that could harbor icy reserves. The science team is doing radar analysis of the surface features, which tells them something about how the features formed. They’re also using radar data to peer beneath the surface, and mapping periglacial features that indicate the presence of ice. All of these, plus several other techniques, combine to give a much clearer view of subsurface ice on Mars. All of this information will help future mission planners find the best places to land people on the planet.

Of course, water is important for sustaining life, but it’s useful in a variety of other ways. According to Morgan, the goal of his project is to provide maps of potential buried ice deposits. Such maps can support the selection of human landing sites. “The ice is a critical resource that has many uses, like the generation of water for human consumption, growing plants for food, and for the generation of methane fuel and breathable air,” he says. But the most important is to provide fuel for the return trip home to Earth. “Taking all the fuel you need for the round trip to Mars is basically not feasible. As a result, pretty much every mission concept study from the last 30 years considers exploiting the Martian environment for fuel.”

Mars: The Icy Planet

Despite the fact that it looks like a desert, Mars is actually quite an icy place, especially if you consider all the buried ice. So, it seems simple to just land near where the ice is. It may not be that easy to locate a good landing site that is also near embedded ice deposits. That’s why Morgan and the team are reassessing all the data, to locate all the icy reserves across Mars. It also matters how deeply the ice is buried. Deposits that are close to the surface are obviously going to be easier to “mine” than those deeper down. The current data sets show ice buried as shallow as a centimeter and as deep as a kilometer.

Using ice on Mars as a water resource is not a new idea. Of course, mission planners have to consider a lot of other factors when sending people to the Red Planet. Landing site safety (i.e. is the place free of giant rock piles, landslides, etc.), as well as solar and thermal specifications, have to be considered. But, finding stores of water ice is the first challenge for the crewed missions of the future. Giving them all the water they can use for life support as well as transport is important.

The next few missions to Mars: Hope (from the United Arab Emirates), Tianwen-1 (China), Perseverance (NASA-USA), will also focus on the search for water, among their other goals. This tells you how important water is — it’s the stuff of life, no matter where we go in the solar system. Understanding its history and existence on Mars is an important step toward eventual human exploration of the Red Planet.

Back when I was a beginning science writer, I had the great fortune to cover the Voyager 2/Saturn flyby mission. The spacecraft (and its sister craft Voyager 1) met many challenges during their 12-year trip to explore the giant planets of the outer solar system. After they left the planets behind, both Voyagers embarked on the next phase: getting out of the solar system and into interstellar space.

The Voyager Spacecraft — The Voyager spacecraft explored the outer solar system and are now moving beyond our place in space.

Today, they’re “doing” the Voyager Interstellar Mission. Both spacecraft are outside of the solar heliosphere now. For the foreseeable future, they will transit the outer Kuiper Belt and Oort Cloud. Currently, the spacecraft transmit intermittent messages that convey data about the conditions they encounter. They’ll do that until their transmitters stop or they run out of power sometime in the next decade or so.

A Message in a Bottle

In 20,000 years, the Voyagers will be free of any possible influence of the solar system. That’s when they will commence the final part of their mission: as messages in a bottle. For the next millions or billions of years, they’ll traverse the galaxy in a sun-like orbit. They’ll orbit the center of the galaxy (just as the Sun does). And, they may get found by other life forms. Maybe.

If that happens, and those beings wonder where the Voyagers came from, and who created them, each spacecraft contains information about its creators. How did that information get there? Scientists on the Voyager teams, led by the late Dr. Carl Sagan, created a “message in a bottle”.

It’s called the Voyager Gold Record and both have encoded on them the sounds and images of Earth. Each Voyager has one attached to its spacecraft “bus.” Protective covers protect the records. Engravings on the covers give information about how to play the records. They tell the location of Earth, what humans look like, and give some rudimentary science and mathematical symbols.

The Voyager spacecraft twins are still working and still returning data, decades after their launch. Each carries a gold record affixed to its side, containing sounds and images of Earth. Courtesy NASA/JPL-CalTech

Each of the two spacecraft is on trajectories that will take them on voyages through the galaxy for as long as they last. They won’t pass too close to stars, but they may experience interstellar clouds of gas and dust during their journeys. And, in the far distant future, they could ride out the collisions of our Milky Way and Andromeda, and interactions with the Magellanic Clouds.

Will the Bottles Survive?

Those lengthy trips through the future of our galaxy caught the attention of scientist and grad student Nick Oberg. He presented a paper at the recent AAS meeting about the futures of the two Voyager spacecraft. Essentially, he asked: what will happen to the spacecraft and will the records survive? The short answer is, of course, they could survive. However, we have no way of knowing for sure that they WILL. But, we can make some predictions.

Here’s Nick’s scenario: as mentioned above, in about 20,000 years, the Voyagers will exit the Oort cloud. Voyager 1 is on a trajectory that takes it slightly above the plane of the Milky Way. It will travel within a region where the star density is about half of what it is here by the Sun. However, the spacecraft could encounter molecular clouds and be bombarded with microparticles. If so, then the steady bombardment could erode the outside cover, but the record itself would probably be okay. Voyager 2 is on a trajectory that keeps it within the plane of the solar system. There’s some chance it could encounter some fairly thick clouds of interstellar gas and dust. Passage through the clouds could subject the covers to the bombardment by microparticles. If the bombardment is severe enough, the cover could experience more erosion. It might get breached and the record might sustain damage (or be completely destroyed).

The Voyagers’ Far Future

Assuming both Voyagers aren’t picked up by interstellar junk collectors or have collided with a rogue asteroid, both of them will ride out the collision of the Milky Way and Andromeda. They could also be silent witnesses to the interactions of our galaxy with the Large and Small Magellanic Clouds. As a result of the shock waves and other events that go along with galaxy mergers, the Voyager spacecraft would likely be flung into different orbits. They’d be moving much farther out than they are now.

Depending on whether they stay in the “new” Milkdromeda Galaxy, or if they’re tossed out to intergalactic space, the spacecraft will experience more cosmic ray damage. They could glide through clouds of thin, hot, intergalactic gases. But, they won’t be completely alone. They’d still be part of the Local Group of galaxies. Now, if that collection merges billions and billions of years from now, our spacecraft could end up orbiting a very old, very massive elliptical galaxy. That would be something like a hundred thousand trillion years from now.

It’s a lot to think about for our spidery little spacecraft. Long after our star has gone to red giant and become a white dwarf, and our planet is gone, there’ll still be two little messages in bottles out there. If their records survive, they’ll be the only proof that our planet existed and that a rich variety of life lived on its surface. Somebody, somewhere in the far distant figure will look at the craft — and maybe figure out how to play the records. And, the sounds and images of our time in the universe will unfold before their sensors, reliving of our existence on Earth.

The Spacewriter's Ramblings

Mars Water Sources Are Underground