The way in which things behave in microgravity could seem obvious to us now, after humans are venturing into space for over 50 years.
But we’ve not always been certain how space might affect certain things, like fire or planarian worms or even plants. It’s only by conducting experiments that we will learn the answers to those burning questions.
That has led to some pretty fascinating, sometimes upsetting & sometimes downright wacky experiments conducted in space.
A spacesuit gets shoved out an airlock
You may be relieved to learn that no humans were harmed in the making of this experiment, there is no one in the Russian Orlan spacesuit nicknamed Ivan Ivanovitch or Mr Smith, it’s stuffed with a bunch of old clothes & a radio transmitter.
The idea was that old spacesuits might be used as satellites. SuitSat-1, officially designated AMSAT-OSCAR 54 was deployed on 3 February 2006, but the experiment was only partially successful-reports vary, with NASA claiming the transmitter had died shortly after release and Russia reporting a final transmission a whole fortnight later. The last confirmed signal was received on 18 February.
SuitSat-1 went on to spend several months in silent orbit before entering Earth’s atmosphere & burning up on 7 September 2006.
The hammer and the feather
In the late 16th century, Galileo Galilei dropped 2 spheres of unequal mass from the Leaning Tower of Pisa in Italy. When both of them arrived on the ground at the same time, he had countered classically established views by showing mass had no bearing to gravitational acceleration. All objects, regardless of the mass should fall at the same rate, even if, it is a feather & a hammer.
On Earth, this is often tricky to demonstrate due to air resistance. But about 400 years later, a human standing on the Moon repeated the experiment.
On 2 August 1971, Commander David Scott of Apollo 15 took a geological drill in one hand and a falcon feather in the other hand. He raised them to a height of about 1.6 m off the ground & dropped them. Because the astronaut was essentially in a vacuum without air resistance the 2 objects fell in sync.
“Within the accuracy of the simultaneous release, objects were observed to undergo the same acceleration and strike the lunar surface simultaneously,” wrote NASA astronaut Joe Allen, “Which was a result predicted by a well-established theory, but a result nonetheless reassuring considering both the amounts of viewers that witnessed the experiment and the incontrovertible fact that the homeward journey was based critically on the validity of the particular theory being tested.”
Fizzy tablet in a water blob
In microgravity, if you squirt a little of water out of a nozzle, it just hangs there, all blobby & wobbling.
This can result in tons of fun. Experiments & demonstrations have included popping water balloons in the vomit comet (the plane that creates parabolic flights to make brief periods of free fall) and the ISS, attaching a blob of water with an outsized bubble inside to a speaker to watch the vibrations, and putting a GoPro camera during a water blob to film it from the within (you’ll want stereoscopic 3D glasses for that one).
In 2015, astronaut Scott Kelly colored a water blob with food coloring, then inserted effervescent tablets, watching them dissolve & release gases into the water. it had been filmed using the space station’s new 4K camera, so you’ll view the entire alien-algae-spawning thing in gloriously crisp resolution.
Fire in space
Just as water behaves differently in microgravity, so too-does fire. The Mir space staion fire of 1997 has thankfully been a one-off event thus far, but understanding how fire behaves in microgravity can help plan for fire safety for future long-term missions like the crewed mission to Mars & the permanent Moon base. It can help to tell down here on Earth, too.
To that end, variety of ongoing research projects have studied what happens to flames in space. The Burning & Suppression of Solids experiments aboard the ISS have investigated the burning and extinction characteristics of a broad range of fuel types in microgravity. Data from these experiments are often used to build more complex models to understand the finer details of combustion in Earth gravity.
Aboard Cygnus cargo spacecraft, scientists investigated how flames behave under different spacecraft conditions in the Saffire experiments. And NASA’s Flame Design investigation, a part of the Advanced Combustion through Microgravity Experiments is exploring the production & control of soot.
All of which is extremely useful & interesting, sure. But it is also insanely beautiful and we bet there are some astronauts having an absolute blast twiddling with fire in space.
In 2011, scientists set about answering the question: Can spiders adapt to space travel? They sent two golden silk orb weaver spiders (Trichonephila clavipes), Esmeralda & Gladys, for a 45 days sojourn aboard the ISS.
They were kept in a nice habitat (can you imagine spiders loose on a space station), with light conditions to simulate a night-day cycle, temperature & humidity control, and a healthy diet of juicy fruit flies.
Both spiders adapted beautifully, continuing to spin their webs & hunt their food. Orb weavers eat their webs at the end of every day to regain protein and spin them again in the morning; this, too, the spiders continued to do on a right schedule, which was interesting, since different orb weaver species on the ISS just spun their webs at any time of day.
But not everything was completely normal. In microgravity, the spiders spun their webs differently, flatter & rounder, compared to the more 3D, asymmetrical structures the orb-weavers spin on Earth.
The 2 spiders returned to Earth at the end of their stay in space. Esmeralda perished on the return journey, having lived a normal spider lifespan. Gladys returned home hale but turned-out to be a boy. He was renamed Gladstone.
Tortoises go around the Moon
Back in the 1960s, before humans had been to the Moon, it wasn’t clear exactly how, if at all getting up close & personal with the Moon would affect us physically. So, in 1968, the Soviet program sent 2 Russian tortoises (Agrionemys horsfieldii) up for a visit round Earth’s companion.
Actually, it wasn’t just tortoises. Included in the flight were wine flies, mealworms, seeds, plants, algae & bacteria. There was a dummy fitted with radiation sensors, since none of the living organisms aboard were remotely analogous to humans. Tortoises, consistent with a 1969 report, seem to have been chosen because they’re relatively easy to strap down.
The 2 unnamed reptilian cosmonauts were placed onboard the Zond-5 spacecraft on 2 September 1968, at which point they were not fed. They were launched on space on 15 September 1968, returning back to Earth (in the Indian ocean) on 21 September. They finally returned to Moscow on 7 October.
Their journey included 7 days of spaceflight, several days in tropical climates (including bobbing about in the ocean while they waited for retrieval), and transportation back to Russia. Ultimately, they spent 39 days without food. It might try anyone.
Control tortoises that remained on Earth were deprived of food for an equivalent period of time. A comparison of the 2 sets of tortoises revealed that any changes in the space-faring reptiles were mostly the results of starvation, with a little contribution from spaceflight-related atrophy.
We’d wish to say that nobody ever sent tortoises to space again, but sadly, 2 more tortoise missions took place. Zond 7 in 1969 carried tortoises. In 1975, Soyuz 20 spacecraft ferried a tortoise around for 90 days. And 2 tortoises flew on the Salyut-5 space station in 1976.
Just as we once didn’t know how space would affect animals, so too were we unaware of its effects on plants. So, when the Apollo 14 mission launched on 31 January 1971, its cargo contained something we’d now consider a bit peculiar: roughly 500 seeds.
Scientists from US Forest Service wanted to know if tree seeds that had flown in microgravity and been subjected to space radiation would sprout, grow & look the same as seeds that had never left Earth.
5 species of tree were included in the cannister: loblolly pine (Pinus taeda), California redwood (Sequoia sempervirens), American sycamore (Platanus occidentalis), Douglas fir (Pseudotsuga menziesii) & American sweet gum (Liquidambar styraciflua). They accompanied module pilot Stuart Roosa on 34 orbits of the Moon before returning to Earth.
The seeds were then planted & tended and most of them survived to grow into saplings, alongside controls that had never left Earth. Unsurprisingly to us now, there was no discernible difference between the two.
By 1975, the Moon Trees, as that they had come to be known were large enough to be transplanted, and they were shipped everywhere in America. Consistent with NASA website, but 100 Moon Trees are often accounted for today and of these, only 57 were living when the page was put together.
It means there could potentially be hundreds of Moon Trees hiding across the US, a lost relic of a time when our curiosity sent tiny seeds whizzing around space and we think that’s beautiful.