Humans have littered quite a bit in space. Most of the discussion around trash in space in recent years has focused on low Earth orbit, where bits of decommissioned spacecraft, paint flecks, and dropped tools are currently whizzing around overhead, threatening the satellite technology we rely on in our modern lives.
But we’ve also dropped trash on the Moon: not just the spacecraft that we’ve landed and crashed there, but also all the rubbish left behind by the astronauts on the six Apollo missions. This collection of junk includes ceremonial plaques, discarded tools and boots, and bags of trash— including the bag seen in the photo above, the first taken by Neil Armstrong during his EVA on the Moon. It also includes 96 bags of human waste.
Since there’s no microbial ecosystem or weather on the Moon to break down this material, it’s all just sitting there, and will continue sitting there until humans return to the Apollo landing sites. At which point we may make an effort to preserve these locations as heritage sites, but I suspect the spacecraft and preserved bootprints are more likely to make it into the “Apollo Museum Tour” brochures than the bags of waste. Archaeologists might be interested, of course— archaeologists love studying trash— and the human waste in particular will likely have some scientific value for astrobiologists, who could study how long microbes survived in the waste.
But eventually, if we return to the Moon on a more permanent basis, there will come a time when the novelty of our extraterrestrial trash wears off, and we’ll need a better strategy for dealing with it than just “dump it out back”. Currently, astronauts on the International Space Station send their trash back towards Earth on the same cargo capsule that brought up supplies, or jettison it directly out of the station. The capsules and waste are intentionally incinerated in the atmosphere. Which is actually a shorter trip than the one taken by the trash produced at McMurdo Station in Antarctica, where residents ship their trash (including processed sewage!) back to California once a year for recycling, auction, and landfill disposal. But launching trash back to Earth won’t be economically feasible from the Moon.
Other disposal alternatives for trash on the Moon could look like OSCAR1: the Orbital Syngas/Commodity Augmentation Reactor under development at NASA to test the conversion of solid trash into gas. The gases produced could be used as supplies, or vented out of spacecraft or habitats.
Ideally, however, we’ll recycle the waste we produce on the Moon. Human waste, in particular, is made up of organic material that would otherwise need to be shipped from Earth. Recycling that material would decrease the cost of resupply. This is a plot point in The Martian, where (spoiler alert) stranded astronaut Mark Watney uses discarded human waste on Mars to create fertile soil to grow potatoes and keep himself alive until rescue. It’s also the goal of real-life closed-loop life support projects like the European Space Agency’s MELiSSA (Micro-Ecological Life Support System Alternative) team, who are looking into waste treatment solutions as well as water and air recycling.
Developing circular life support systems on the Moon could obviously benefit the rest of humanity back on Earth, not only in terms of the recycling technology but also the shift in attitude from “eh, the Moon’s big enough, what’s one more bag of trash?” to “how can we preserve and reuse every scrap of material we brought with us?”. The question is how many garbage bags we’ll fill— on Earth and the Moon— before we manage to make that change.
P.S.— I want to note that many of the links in this post came up in the chat during the “Environment and Space Science” session at this year’s excellent Space Science in Context conference, as well as in Nadia Khan’s talk on “Exploring Lunar Waste Management” during that session.
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I’ll be at Space Week in Boston on April 17-21. Come say hi, watch some panels, and get your copy of Off-Earth signed!
Current frontrunner for my favorite space tech acronym