With the surprise landing of the Chinese rover Yutu 2 or Jade rabbit 2 and the Chang’e-4 lander on the far side of the moon on 3rd Jan 2019, I thought it would be interesting to see just what sort of things we’ve actually put up there on the moon and speculate on what will happen to them in the future.
Now it will come as no surprise that the Apollo missions have left the most amount of items behind but long before they were even thought of the Soviets pulled off something, that not for the first, the US thought they couldn’t do.
In 1959 the Soviet Luna 2 probe was the first man-made object to intentionally impact on to the lunar surface, the closest the US had got to the moon by then was with the Pioneer 4 but that was about 60,000 km away which was a bit of a shock because the US believed that while the Soviets had bigger rockets they were lacking the precision in their navigation and guidance.
Although these early probes were designed to crash onto the moon, in a piece of pure propaganda Luna 2 left a kind of calling card to remind everyone else that there were here first.
Luna 2 was loaded with no only experiments but also two small spheres one 7.5cm and the other 12 cm in diameter made of pentagonal pennants, each stamped with insignia of the Soviet Union and the date 1959 on the larger of the two. These spheres had an explosive core and were designed the explode and scatter the pennants on impact.
Although these were the very first man-made items to make it to the moon their fate is unknown as Luna 2 impacted at a speed of about 3.3km per second about 12,000 km/h and was probably vaporised on impact
A third sphere was in the luna 2’s rocket body which crashed about 30 mins later, that was filled with liquid and aluminium strips with the year “1959” and “Union of Soviet Socialist Republics” engraved in them.
As the space race intensified the lunar research as increased, the US sent the Ranger probes to take close up images of the moon. They did this like the Soviet Luna probes by crashing in the moon whilst transmitting live TV signals back to earth. At one point it was called the “shoot and hope” program because the first 6 out of 9 Ranger probes either failed on the launchpad, missed the moon completely or failed before the reaching surface.
This was followed up by the surveyor program to find out more about the actual surface at potential landing sites for Apollo as it was feared by some that any lander would just sink and disappear into the lunar dust. 5 out of the 7 surveyors successfully landed and proved that theory was groundless.
Also around this time, the Lunar Orbiter program was the first NASA craft to orbit and survey the moon including mapping its gravitational field again for the Apollo missions. After their missions were complete they were deorbited and crashed into the moon so they wouldn’t pose any threat to the Apollo missions with lunar Orbiters 1,2 and 3 ending up on the far side of the moon.
The Soviets had a similarly hit and miss success rate as the first 4 attempts at a soft landing failed, finally on the 3rb of February 1966 Luna 9 became the first Lunar lander achieve and survive a soft-landing.
Something which is often overlooked is that the rockets that carried the spacecraft also ended up on the moon. The third stage of the Saturn V’s that carried the Apollo missions 11, 13, 14, 15, 16 and 17 also crashed into the moon and some of their positions are well known. Apollo 12’s third stage was planned to go into solar orbit but due to venting of its fuel tanks it didn’t have enough propellant and ended up in a stable orbit between the earth and the moon.
Even though Apollo 13 never landed, its spent third stage was detected hitting the surface and the impact crater has been captured by Lunar Reconnaissance Orbiter Camera some 135km away from the Apollo 12 site.
Apollo 12 and all the following missions left behind the ALSEP or Apollo Lunar Surface Experiments Package. This included a range of experiments like the seismometer which picked up the Apollo 13 third stage impact as well as other devices for the analysis of micrometeorites, the moons gravity, magnetic field, solar radiation, atmosphere and internal structure.
Apollo 11 left the Lunar Laser Ranging Experiment which is the only lunar experiment to be still working today and is uses an earth-based LASER to measure the distance from the earth to the moon with an accuracy of about 3 cm.
The Apollo missions landed with a complete lander but they couldn’t return in the same way. Only the ascent stage of the lander took off to return the crews and they had very strict weight limits, too much weight and they might not make it back to the command module, literally every kg made a difference and was the reason for leaving behind a seemingly random list of objects as we will see later.
Once the crew had transferred from the ascent module to the command module, they were released to crash back into the lunar surface, except 2, Apollo 13 which was used a lifeboat to get the crew back to earth and burned up in the earth atmosphere and Apollo 10.
Apollo 10 was a complete dress rehearsal for Apollo 11 except for the landing. Gene Cernan and Thomas Stafford took the lunar lander to within 15km of the surface before returning. In fact, the ascent stage was deliberately short fuelled to stop the crew attempting a landing on the moon, because if they did they wouldn’t have enough fuel to make it back to the command module.
The Apollo 10 descent stage was left in orbit but fell back to the moon and its position is unknown. After the crewed had transferred, the ascent stage nicked named “snoopy” fired it engine until it ran out of fuel, this sent it out into an orbit around the sun and it’s still there, somewhere, in an orbit slightly shorter than the earth, the only manned spacecraft left in space without a crew.
If you look at the inventory of items left behind for each mission you’ll see a lot of really rather mundane items, things like, filters, urine and defecation bags, food bags, chair armrests, towels, batteries, earplugs, brushes, boots, tongs, tools, scales, in fact over 800 items. NASA has created a 22-page document listing everything on the moon which you can download and peruse for yourself.
But there also some things that you would think they would bring back like the Hasselblad cameras which were used to take on average 1500 photos each but no, they left behind 12 of the 14 taken on the Apollo missions. The astronauts were instructed to bring back just the film canisters and leave the cameras to make room for rock samples, this allowed an extra 25kg of rocks to be brought back over 6 missions in place of the cameras.
Of course, some things were just far too big to bring back, like 3 the lunar rovers along with their TV cameras, they were left behind to film the ascent from the moon by remote control from earth.
There was also the gold plated telescope, the only one to make observations from the surface of a celestial body other than Earth.
Other things left behind were symbolic on nature and not all were officially sanctioned. We all know the US flags that but Apollo 11 also left a gold olive branch as a representation of peace, an Apollo 1 patch to honour the crew of Grissom, White, Chaffee which died in a fire during testing and medals given to families of the deceased cosmonauts Gagarin, Komarov.
There was also the Moon Memorial Disc which contained goodwill statements by Presidents Eisenhower, Kennedy, Johnson and Nixon and messages from leaders of 73 countries around the world. This disc was made using the same technique as the early integrated circuits and was the size of a US 50 cent coin, with the writing visible using a microscope.
On Apollo 15, a 9cm statue called “fallen astronaut” along with a plaque commemorating the 14 US and Soviet astronauts that had died during training was unofficially placed on the moon by David Scott and on Apollo 16 Charlie Duke left a photo of himself, his wife and two children on the surface. On the back he wrote, “This is the family of astronaut Charlie Duke from planet Earth who landed on the moon on April 20, 1972.”
During and after the Apollo program, the Soviets continued to with their remote controlled lunokhod rovers 1 and 2 in 1970 and 1973. Lunokhod 2 operated for 4 months, travelling 42km and sending back 86 panoramic images and 80,000 TV pictures.
Since then there have been only satellites from Japan, India and China most of which ended up on the surface until December 2013 when the Chinese became only the third country to soft-land on the moon with the Chang’e 3 and the Yutu or jade rabbit rover.
Although the Rover succumbed to a mechanical abnormality, probably caused by the lunar dust after 2 months, the lander which is powered by a Radioisotope Thermoelectric Generator and solar cells, was still in contact with the ground control some 4-1/2 years after it landed and in theory its power supply could last for 30 years.
So what will happen to the things left on the moon, some say that with no erosion, no wind, rain, volcanic activity they will be long after the human race has come to an end in millions or even billions of years into the future but they are forgetting a few things.
Firstly the lunar dust, it covers the entire moon and was created and still is being created by meteor impact. Although there is no wind to move it around, it becomes electrostatically charged from the sun’s ultraviolet and X-ray radiation. This causes it to float and create a very thin atmosphere of dust constantly rising and falling around the terminator line as it sweeps across the surface from lunar day to night.
Recent observations and experiments show that the dust builds up at the rate of about 1mm per thousand years. That sounds like a tiny amount but in a million years all the items left on the moon would be under a meter of dust and that’s assuming we didn’t do anything to make it worse. If we start mining on the moon the amount of dust raised would be much, much more and with 1/6th gravity and no air resistance it would travel a long way.
Then there is the sun, with no protective atmosphere like the earth, anything on the surface is exposed to the full force of the sun’s ultraviolet light, X-ray and ionising charged particles. Just look at its effect here on earth on paint pigments and photos that have been left in the sun.
That lack of atmosphere also means that there is almost no temperature regulation, so in direct sunlight, the surface can reach 127 C and at night it can drop -173 C. The thermal stress of this 300 C temperature range will also take its toll.
The photo that Charlie Duke left 47 years ago is probably completely beached by now, as are the US flags and pigments in painted surfaces will have degraded and there is the sandblasting effect of micrometeorites hitting the objects directly or the nearby lunar dust which is highly abrasive.
So while they may well in some ways last a lot longer than they would be compared to being left outside on the earth, they will meet the same fate and eventually crumble to dust.
One of the reasons for Apollo leaving so much stuff on the moon was the limited weight they could carry back in the ascent module, with every kilogram of making a difference they had to choose what to bring back and what to leave.
These were just some of the myriad of problems that had to be solved often with very short notice on the missions themselves not only for Apollo but every lunar mission that has been attempted.
If you would like to challenge yourself then our sponsor for this video, Brilliant.org has something that will be right up your street.
Brilliants Dailey problems provide you with a challenge and the context and framework that you need to work them out so that you learn the concepts by applying them. If you like the daily problem, then there’s more like it so that you can explore the concept in greater detail and develop your framework. If you are confused and need more guidance, then join the community in discussing these problems. These thought-provoking challenges will lead you from curiosity to mastery, one day at a time.
So what are you waiting for? Go to Brilliant.org/curiousdroid and finish your day a little smarter and the first 200 of you to do so will get 20% off the annual subscription and to view all problems in the archives.