2234, April. Region 932 A.E.D.

It's a hot day on Xenaas-891, and the fight isn't going well for our soldiers.

"Sarge, our exosuits are going to run out of oxegyn soon! There are 2 class 3 aliens coming in from the west, and a small squad of class 5's. What do you want us to do?"

Sarge curses under his breath, and takes a look around. "Stay calm, private! AT5522 - Take AT2342 and UT1121 and see if you can find a way to get behind the class 3's. Private and I here will hold down the class 5's."

"Yes sir!" The three troopers run to into the east, when suddenly, a class 7 alien jumps out from behind a rock and leaps at AT5522. Hiss

"AT5522 got his oxygen tank stabbed! Sarge, you better come look at this!"

"What in the mother of holy barbeques is happening to that bugger? Looks like he is.... what the heck? How am I supposed to describe that in my report!?"

2234, May. Military Base 331 A.E.D.

"Regiment MC331! Form up!"

The troops quickly fall in as a resource shuttle lands in the camp.

"Alright folks, our newest experimental weapon is here. BEHOLD! Cans of Perri-air!"

A wave of applause goes up as the bay doors of the shuttle open, and massive crates of Perri-air are rolled into the camp. Each soldier is distributed several cans to carry on his person at all times.

"Listen up! We've been getting massacred out there for the last year, since none of our weapons seem to work very effectively. However, thanks to AT5522 and his mishap, we've discovered a massive weakness in the alien biology! It turns out that these aliens use a cutaneous gas exchange system, and oxygen is both extremely corrosive and toxic to them. That brings us to the two ways we can use these cans! You can throw these pressurized hunks of metal at the enemy, and shoot the can! This will allow the oxygen to disperse and act as a grenade! You can also use it as a melee weapon, if you get jumped by a class 4 or lower alien! Just open the top of the can like you would a soda and let the air go free! You are not recommended to use this on class 3 or higher aliens! It does not contain enough air to stop you from getting squashed! Am I understood?"


2236, June. Research division on The WarDoctor A.E.D.

It's been 2 years since the humans have finally gotten a fighting chance to survive on Xenaas-891. The scientists have finally developed our ultimate weapon.

"Tell me, Dr. Pepper. What exactly is this new weapon?"

"We call it the C.A.O.P.T. Once deployed, it produces enough oxygen to keep a 20 meter radius area class 3 and lower free for months. It takes about 5 minutes after deployment to flush out the area around it. You can use this to create barriers which the aliens cannot move through, or even as a zoning tool."

"It looks like a tree. What does C.A.O.P.T. stand for?"

"Ah, that's because it is a tree. A Copious Amounts of Oxygen Producing Tree, to be exact. A new breed, with thick bark for protection and quick growing roots for stability. There are some slight problems though - it doesn't handle impact from the roots very well. If we were to drop this tree in an upright position onto the ground from 3 meters up, it would shatter. Not only that, but the breed is extremely heavy. Too heavy for your largest shuttles to carry - they're close to 600 tons. We also can't manufacture these trees on the surface - we can only make them on some of our ships, namely The WarDoctor, The FrillyLizard, and The PepperoniStick. You'll have to find a way to get the trees from space to the surface."

"You mean to tell me that you don't have a method of delivery for this weapon? What the hell do we pay you for then?"

"I'm paid to develop the weapon, not the delivery system. Find someone else for that."

"You there!" Finger points at you "I have a job for you!. Design me a delivery system for this weapon!"

What delivery system do I design in order to safely deploy the C.A.O.P.T. weapon to the surface of the planet?

A quick summary:

  • The tree must not hit the ground at high impact in its upright state.
  • The tree will self-plant itself once it's in contact with the ground.
  • You cannot fly the trees to the surface via shuttle/plane, as it's too heavy.
  • You will not be able to move the tree once it's on the ground.

Extra information:

  • You can assume that the ground of Xenaas-891 is similar to the ground of Earth; mostly dirt.
  • The atmosphere is similar to that of Earth, with the exception of it containing no Oxygen.
  • Gravity is a stifling 1.2 times that of Earth.
  • The tree is flammable.
  • A.E.D. stands for "After Earth's Destruction" - technology level is futuristic, but please remain within the bounds of known + predicted science.
  • Aliens have an air force.

If there is any extra information required, please ask in the comments and I will do my best to provide.

  • $\begingroup$ Why drop the trees at all? Take the gas and drop it in cannisters on the enemy. $\endgroup$
    – Oldcat
    Aug 4, 2015 at 19:33
  • $\begingroup$ @Oldcat If we drop a gas canister, several things happen - 1) Gas disperses and you lose the long term zoning effect 2) Whatever canister you used to hold that gas in is now forfeit - in a fight on a foreign planet where you have limited resources, we don't want to waste precious metal $\endgroup$
    – Aify
    Aug 4, 2015 at 19:36
  • 3
    $\begingroup$ and as soon as exuded, it blows away with the wind. Fictional doesn't have to equal 'nonsensical' $\endgroup$
    – Oldcat
    Aug 4, 2015 at 21:04
  • 2
    $\begingroup$ Only if the tree can produce more wind than your 50 mile an hour wind, and even then you will still see the tree through a thin skin of material a fraction of an inch thick. And now this isn't a tree, its a magical device you are making up as you go along. $\endgroup$
    – Oldcat
    Aug 4, 2015 at 21:48
  • 1
    $\begingroup$ Here you go +1 my deposit, I'll return with a comment(answer) later after I skims through chapters in Sun Tzu art of war for business.👌 $\endgroup$
    – user6760
    Aug 5, 2015 at 3:39

7 Answers 7


Parachutes... uh, sir.

You've ruled out shuttling them to the surface and apparently whatever brings tanks to the surface won't work. Really big parachutes work well though. Drop them from space with a blast shield or not at orbital velocities. A blast shield, or heat shield, is a standard piece of planetary lander equipment. The shield protects the tree during entry and falls away once the tree is at terminal velocity (with the drogue). It won't get in the way of rooting.

enter image description here

If we can parachute vehicles to the surface we can do it for the trees. Adjusting the size will adjust the decent speed to whatever the tree can survive.


To save the parachute from the newly invented alien air force. Use large compressed oxygen tanks to provide oxygen for thrust to help slow and steer the tree as well as poison the air, killing any flying aliens who try to get at it.

Alternatively, if you want a more feasible solution than these weird trees which shatter with a slight impact but can support their own 600 tons without issue, you can simply drop water and perform electrolysis on it. You have a space faring civilization, it's likely that you can generate copious amounts of energy. If you're concerned about leaving canisters around then just build an electrolysis station and supply it with water drops from the shuttles. Each 60 ton load of water from a shuttle would produce 36,347,000 liters of O2. That would fill a cube 33 meters on a side with pure O2. Should be pretty effective. Just get the water from an asteroid if there isn't any on the planet.

  • $\begingroup$ Yes, this might work, but a big parachute is very slow, and liable to be taken out easily by the Alien air force. My fault for not mentioning that they had an air force. Will edit into question for future answers, but into the "extra" information section so that this answer remains valid. Also, I'm not convinced that parachuting the tree will let it survive. Consider that the tree has to be launched from space - how will the tree survive the journey? It could easily burn up while it's dropping through the atmosphere, especially since parachutes don't typically deploy right at the start. $\endgroup$
    – Aify
    Aug 4, 2015 at 17:17
  • $\begingroup$ Are parachute drops pretty accurate? To address my own concern, I suppose you could have the tree on a massive mobile platform of some sort to move it where it needs to go. Then you need a way to get it off the platform. $\endgroup$ Aug 4, 2015 at 17:21
  • 3
    $\begingroup$ @Aify You might explain then, why humans are fighting with soldiers on the ground without a way to shuttle heavy things to the surface against an enemy with an air force. $\endgroup$
    – Samuel
    Aug 4, 2015 at 17:22
  • 4
    $\begingroup$ @DoubleDouble Very accurate. We can get 27,215 kg to within 50 meters. $\endgroup$
    – Samuel
    Aug 4, 2015 at 17:23
  • 1
    $\begingroup$ @Aify The alien air force could interrupt anything going to the surface, so whatever method you have of preventing them from interrupting shuttles should work equally well for the parachutes. $\endgroup$ Aug 4, 2015 at 17:32


They take a bit longer to deploy but they're easily portable, and a little engineering and pink light should make them grow pretty quickly. They have the added bonus of being easily concealable and very tough until they're deployed. Then the window to kill them would be brief.

Drop them wrapped in a soil mat into the ocean (if applicable), let them grow, then send teams in to maneuver them into position.

You can also feed them to indigenous wildlife to infiltrate the enemy's camps.

You could even drop trillions of them on the homeworld from orbit - there'd be no way to find them all until it was too late. I used to work in a greenhouse. Ever dropped a packet of geranium seeds? enter image description here

  • $\begingroup$ This fails the "We also can't manufacture these trees on the surface - we can only make them on some of our ships, namely The WarDoctor, The FrillyLizard, and The PepperoniStick. You'll have to find a way to get the trees from space to the surface." sentence in the original post. $\endgroup$
    – Aify
    Aug 12, 2015 at 16:24
  • $\begingroup$ Fair enough. I wasn't sure that growth counted as manufacture, but I suppose it makes sense - otherwise someone would have suggested making the trees smaller. $\endgroup$
    – Josiah
    Aug 12, 2015 at 16:25
  • $\begingroup$ If it were a normal tree and not a bio engineered tree, then your idea would have worked, if we assumed that the tree could grow in that environment. $\endgroup$
    – Aify
    Aug 12, 2015 at 16:29
  • $\begingroup$ +1 because I had the same idea, with a twist from the Ice Limit by Preston and Child. $\endgroup$ Apr 26, 2016 at 17:05

If you want precision and quick deceleration you could go the route of the Mar's rover "Sky Crane Maneuver", seeing as we're deploying to another planet it's not too far fetched that this technology would be relatively standard fare(though probably still expensive) in the future. Here's a link: http://www.space.com/16878-mars-rover-landing-sky-crane-guide.html

Here's the doctored up infographic:


Additional Facts:

  1. It was developed for something moving at a velocity of 13,000 mph(21,000) kph to get down to 0 in the span of seven minutes.
  2. There is a heat shield(obviously) that will take the friction of deceleration. It will glow white-hot because of the velocity and thus needs to be jettisoned on approach to land (in this case, not to set the trees on fire I suppose)
  3. The chute created for the mars mission was the largest supersonic drogue chute ever created. A drogue parachute is simply a parachute designed to slow a fast moving object down.
  4. Once the heat shield is jettisoned there is a radar that is used to find the ground and the sky crane( which is that sweet looking thing in the second picture) comes out of the aeroshell and is used to maneuver and lower the package away from the backshell and towards the mark.
  5. After it touches down, the nylon ropes connecting from the sky crane to the package are automatically removed and the crane itself is moved away to prevent any collateral landing damage.

Sky Crane

Additional cool thing, if a tree was going to be developed to be dropped it might be a variant of the Baobab tree. It's bark is fire resistant, it's fruit is edible, and it is massive. http://www.smithsonianmag.com/travel/the-tallest-strongest-and-most-iconic-trees-in-the-world-759955/

  • $\begingroup$ Nice graphic. Don't you think the sky crane is the same thing as a shuttle dropping off the tree? Can it lift 600 tons? Also note that a drogue is used to stabilize and/or deploy a main chute, not as a primary chute to slow down a payload. $\endgroup$
    – Samuel
    Aug 4, 2015 at 19:14
  • $\begingroup$ Nice answer! I'm just worried about the application of this to a 600 ton tree instead of a small rover. It's nice to see that the picture shows that the rover can be decelerated to 1.7 mph (which is significantly less than the 17.2mph from a 3 meter fall), but this is quite similar to having a helicopter or a shuttle slowly drop it off. $\endgroup$
    – Aify
    Aug 4, 2015 at 19:16
  • $\begingroup$ Well, technically you're correct. The difference to me was that it isn't just being shuttled down which meant it made the grade in my imagination, but I suppose it may be too far out of scope to be considered. I guess I am confused by how specific we're being with the technical aspects. With every answer you're going to have to expand the idea to make it fit. Nothing's going to realistically carry 600 tons to ground in a warzone with today's technology. $\endgroup$
    – zfrisch
    Aug 4, 2015 at 19:26
  • $\begingroup$ @zfrisch Actually... a bunch of these might work en.wikipedia.org/wiki/R-36_%28missile%29. I'm surprised that this wasn't one of the first things to come up. $\endgroup$
    – Aify
    Aug 4, 2015 at 19:42
  • $\begingroup$ @Aify How do you mean? $\endgroup$
    – zfrisch
    Aug 4, 2015 at 19:54

Drop the trees, pre-planted into pots affixed onto pallets with shockabsorbing buffers. They will make oxygen fine without being planted into real dirt. When the aliens are cleared out of a region, you can land and plant them properly.


Use balloons.

The Pathfinder mission used a combination of parachutes and balloons to land on the surface of Mars.

Here is a photo of a test inflation on Earth:

So, I propose to encircle the trees in a large envelope of balloons and release them from an aircraft - similar to Samuel's idea. There are some issues with the balloons, but they can be solved:

  • Accuracy: This is an issue with all airdrops. Winds can take over and blow things off course. I think that the balloon setup is massive enough that it would take strong gusts to move it too far away. Could it bounce? Yes. Solution: Use some sort of harpoon system to secure it to the ground at initial impact. Then deflate the balloons. This harpoon system could also prevent bounces.
  • Being shot down: This is an issue with parachute operations; in World War II, pilots parachuting out of aircraft were sometimes shot down (at least during the Battle of Britain). The balloons should be able to reach higher speeds than parachutes, though, taking less time to hit the ground.
  • Descent speed: The balloons could hit the ground at high speed. They will clearly cushion the bounce, and that could be enough. If you want, you could add on a parachute at the very end, or use thrusters on the bottom.

The trees must be deployed from space. The solution is to create an even smoother analogy to the Pathfinder mission, and add in a heat shield and other necessary components.

  • $\begingroup$ I like this one a lot - +1! However, if you have balloons at the bottom of the drop, how does the tree plant its roots? $\endgroup$
    – Aify
    Aug 4, 2015 at 17:32
  • $\begingroup$ I think the main benefit of the balloons on all sides was to let the thing bounce out the energy from the decent. There is no point of balloons on all sides if it's not going to bounce. In either case the g-force experienced would be significantly more than dropping the tree from three meters, so the roots would shatter. $\endgroup$
    – Samuel
    Aug 4, 2015 at 17:37
  • 1
    $\begingroup$ @Samuel I would think that the balloons would add sufficient padding in many cases. It depends on how high the plane is flying. $\endgroup$
    – HDE 226868
    Aug 4, 2015 at 17:41
  • $\begingroup$ @HDE226868 It's apparently from space. There are no planes that can carry the tree. The balloons will simply smooth out the impact. It's still going to hit with a whole lot of force. If the balloons are too big they cover the ground and prevent the tree from auto-rooting. $\endgroup$
    – Samuel
    Aug 4, 2015 at 17:44
  • $\begingroup$ @Samuel Okay, then simply add a heat shield and related devices, to make a closer parallel to the Pathfinder setup. $\endgroup$
    – HDE 226868
    Aug 4, 2015 at 17:46

From Oldcat's answer:

Drop the trees, pre-planted into pots [...] They will make oxygen fine without being planted into real dirt. [...]

Comment thread on Samuel's answer:

[...] the alien air force is made of aliens, the tree is producing oxygen, the flying aliens can't get close to it. It's streaming oxygen as it falls, preventing them from messing with the tree [...] – Samuel

[...] the tree doesn't make oxygen until deployment is complete [...] - Aify


This could avoid a lot of complications. Pre-plant the trees, and the aliens can't mess with them. Then remove the pot once it's on the ground.

  • $\begingroup$ This didn't fit in a comment. Although it is technically a half-answer, it does mean a lot of existing answers can carry on being right. $\endgroup$
    – wizzwizz4
    Apr 26, 2016 at 16:31

Tree glider. Giant gliders were used during WW2 by the Germans. enter image description here

I found these gliders to be able to carry a cargo of 23 tons and so for a 600 ton tree they would need to be scaled up 3000%. Gliders containing trees would be dropped from orbit and so would need reentry shielding which can be jettisoned once through. They would then pull up and expend kinetic energy via air friction during lateral movement through the atmosphere, gradually getting lower. When glider and tree reach deposition site the glider would be very near the ground and moving just fast enough to stay airborne.

The glider then sharply pulls up to vertical, stalls and falls backwards a short distance. The breakaway tail of the glider absorbs some of the impact leaving the roots of the tree to gently contact the ground. Rear facing protrusions on the wings make sure the tree is oriented vertically.

Glider is then removed from around tree via the action of rain or large hoses; glider is composed of papier-mache which will break down when wet. Glider material contains tree fertilizer to ensure tree health.


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