What technologies and systems does Spacex need to work on over the next 4 years besides Starship to achieve its mars goals?
I wrote a post a few months ago (What will it take for Spacex to send humans to mars in 2024?) which did rather well. However I focused only on Starship itself, not on any of the other pieces that are just as important to achieve Spacex’s mars-sized ambitions, so let’s take a look at everything but the big shiny rocket. To be clear (like before), this is less me predicting the future and more me looking to start a discussion based on the data we have and a whole bunch of assumptions, speculations and wishes.
Let's start off by making the mother of all Big Falcon assumptions:
Starship works as intended
This is a MASSIVE leap of faith to take. While SN5’s (and now SN6’s) flight(s) did alleviate some concerns regarding Starship’s ascent, and Superheavy doesn’t really worry me with all the falcon 9 first stages Spacex has to draw experience from, there’s no guarantee that Spacex’s re-entry, descent and landing systems will work as well as they want and expect them to, since those all fall somewhere between unusual and revolutionary. Nor is the rapid and reliable reuse guaranteed to work as well as we all want it to.
Although I will say people need to cool it with claiming Starship is years and years away from orbit; the raptor works and the tanks, plumbing and command & control system are up to standards, as SN5&6 showed. If Spacex wanted to (and had enough engines) they could bolt together a Superheavy booster, stick a Starship on it and fly both expendable to put 100-200 tons in orbit right now if they had a launch pad and a humongous crane. Big waste of money and engines but they could do it. Once Superheavy hops (successfully) you can seriously argue that Starship is closer to reaching orbit than SLS, despite the latter’s development being started a decade earlier. It’s just that reaching orbit isn’t Starships main goal; getting to orbit and back down cheaply and reliably is, which is another thing entirely. To me, SN8’s 20 km flight will be the big thing to watch: if that works, Starship is ready for orbit. If not, Spacex has a nasty problem or two to solve. For the record, I will say that I think the launch, ascent and descent of SN8 will go fine, but that the flip-down has a high chance of going very, very wrong the first few times.
Just to reiterate: this is not me saying what will happen, this is me speculating what Elon plans/wants to make happen in order to put humans on the red planet basically 4 years from now, to give people something to ponder on and give their own take. Personally I doubt that humans will really depart for mars in 2024, but given Elon’s repeated statements that 2024 is still the goal, and the fact that at least at tesla his timelines are getting a little more accurate recently, I have crammed the insane amount of progress needed into the next 3-4 years to make it fit. My timeline should not be taken as a prediction but as my best guess to somehow get all the needed pieces into place given the insane objectives.
So, if we make the admittedly stomach-churning assumption that Starship works and is flying reliably and reusable sometime (early) next year, what else should SpaceX be working on? To me, it seems they need four other pieces to realize their mars ambitions:
getting Starship to mars -> orbital refueling
getting Starship back from mars -> fuel production on mars
getting the humans inside Starship to mars -> life support in space
keeping the humans inside Starship alive on the surface of mars -> life support on mars
I will go through them in order from what I consider to be least to most difficult (no part is “easy” if you ask me):
This one I’ve made a U-turn on. I used to think it was a major obstacle but recently have concluded that it won’t slow down Spacex at all. Why? Because in their Artemis bid, Spacex announced that they plan to use not just tankers, but fuel depots. This simplifies the whole operation massively. Spacex can launch a few custom Starships that consist of nothing but a giant empty fuel tank, something which they can probably build today. No heat shield, no fins, no payload bay, no life support, to maximize the fuel capacity. Only some batteries, a solar panel, rcs and a way to dock. Heck with the recent raptor improvements they might be able to stretch this type of Starship to have even more internal volume for fuel.
Now these most likely will have to be painted pitch black to prevent an angry mob of astronomers marching on boca chica with pitchforks, but that’s probably not a bad idea regardless. The fuel boil off in LEO will be a lot less than Starship will have to deal with on its way to mars due to a noticeable lack of shade during the transfer, so subjecting the LEO fuelers to as high a temperature as possible seems like a useful safety margin when designing for that.
The current Starship can hold 1200 tons of propellant with a large amount of its volume turned over for cargo. Given that a Superheavy can hold 3300 tons of propellant, let’s say that a fuel depot Starship can hold between 2000 and 3000 tons depending on how much it’s stretched, with the lower estimate being more likely. Edit: elon recently stated that they are pushing for Starship being able to hold up to 2000 tons of fuel, supporting my hunch that Starship’s length will increase.
Some back-of-the-envelope calculations show that a 250 ton Starship (100 ton dry mass, 150 ton payload) with 750 tons of fuel and an isp of 380 will have just over 5 km/s of delta V. Going from earth to mars using a hohmann transfer takes just over 4 km/s, while a much faster 3-month transfer takes around 4.8 km/s. This fits well with Elon’s step-by-step strategy. For the first flights having an extra 1000 m/s will most likely be invaluable, allowing on-route course corrections, meaningful maneuvers in martian orbit, as well as an easier landing, both due to being able to start the landing burn higher up and the fact that more fuel means more mass at the bottom of the Starship making it more stable during the flip and upon touching down. Later flights, after Spacex has a high enough confidence in their navigation, aerodynamic controls and landing system, can then start to burn more fuel to incrementally shorten that transfer time until they reach Elon’s goal of a three month transfer for humans.
Now what would this mean? If Spacex launches say three of these fuel depot Starships early next year (and they totally will have the means to build and launch these by then, all they need is a working Superheavy), they now have something to use their insane launch cadence for that is both useful and dirt-cheap. Each one of these fully fueled will provide the propellant for three mars-bound or two lunar-surface-bound Starships to reach their destinations.
Since the tankers will be able to carry between 100 and 150 tons to LEO depending on how far along the vacuum raptor engine is, this is 60 to 90 flights right here for Starship. If I’m Elon/SpaceX, all I’m doing in 2021 is flying Starship tankers DOZENS of times to bring fuel up to these depots for use in 2022. Now I know people are excited about a Starship launch putting 400 Starlink satellites into orbit in one go, but let’s remember that those still cost $300.000 a piece to make, and that’s after achieving an impressive economy of scale (120 a month). One failure on ascent and there goes over a hundred million dollars. At least for the first dozen launches, Spacex would be wise to start with fuel only imho, and move to include Starlink launches after a few months of successful fuel flights. It will give Starship a simple cheap payload to fly over and over again with minimal impact if it suffers a catastrophic failure on ascent. Simply learn and move on; nothing of significant value was lost.
While the engineers focus on decreasing the turn-around time and fixing whatever unexpected problems arise due to Starships re-entering multiple times (which there definitely will be, don’t tell yourself otherwise), the designers can spend 2021 seriously working on life support and ISRU systems, with both available to support the other should they need to. As an additional bonus, all these launches will greatly boost the confidence in Starship from both nasa and the commercial sector, paving the way for Starship’s utter domination of the commercial launch market from 2022 onward. Finally, maybe the realization that voting for Artemis meant voting for orbital fuel depots will give Shelby a well-earned heart attack (one can dream). /s
If Spacex can get 10 to 20 Starship tankers to orbit in 2021 (they can all be the same ship, they can be 3 different ships or they can be 10 different ships depending on how successful they are in their re-use objectives by then), it will give them a much easier time in 2022; “simply” fly the mars-bound or moon-bound Starship to LEO, dock with the depot and perform a single large fuel transfer. This way Spacex won’t have to worry about keeping a dozen Starship tankers in orbit at a time.
As for orbital refueling itself (wow, went a little bit of topic there), I don't see any major hurdles: if Starship’s fuel lines can handle the pressures of being fueled on the pad through the Superheavy booster as is currently the plan, than all Spacex needs to do is not exceed those pressures during on-orbit fuel transfers, which really should not be hard so long as they take their time with them.
Life support on mars
This might surprise some, but I actually think keeping humans alive on the martian surface will be much easier than keeping them alive in space due to the zero-g and radiation concerns that the latter will have to deal with. Consequently, if I were to suggest only one thing to Spacex from my very comfortable armchair, it would be to split the two: one type of Starship designed to act as a permanently inhabitable martian base that is basically an office tower with a big empty drained fuel tank and some engines at the bottom, and one designed for crewed use in zero-g as well as ascent and descent on both mars and earth. Trying to make a Starship do both is asking for trouble if you ask me, as well as greatly complicating the design (“the best part is no part”). Yes this would mean that these “base” Starships will not return to earth, but that is not that big a loss given the production rates Spacex is already achieving, plus having a few extra raptors on mars that can be cannibalised for parts or simply swapped with a malfunctioning raptor of another Starship sounds to me like good redundancy. Furthermore this split would have three enormous upsides:
1: The base ones are easier to design and build due to only being operated and inhabited under gravity after landing.
Let’s remind ourselves that if Spacex wants to send people to mars in 2024, it will be much easier to find support from nasa and the like if there already is a habitable structure waiting on the martian surface for them, which will have to be sent there in 2022. The easier base ones can be the focus of design in 2021 before being built and launched in 2022. Meanwhile the manned zero-g Starship will be granted another year to prove itself as now it won’t be needed until 2023, which is probably a good thing anyway. Even if Spacex can build these next year there is no guarantee that any agency would have enough confidence in Starship by then to provide them with astronauts. Taking another year to really prove Starship’s reliability as a launch and landing system might be enough (remember this means dozens of launches since we’re assuming Starship works) for a Starship to take on crew in LEO at the end of 2022/early 2023, probably at first using a dragon capsule to go to and from orbit as Tim Dodd and others have suggested.
2: It’s simply much safer.
Living and working in a separate Starship from the one that you land and launch in will probably be a whole lot more comfortable for the crew on mars. Sleeping well might be a bit harder if every morning the giant fuel tank a few dozen meters below you is a little bit fuller with highly combustible propellant than the day before. Compared to if the tank beneath you is completely drained while the Starship you will return in sits a few miles away being steadily refueled with you only returning to it a few hours/days before launch. Good back-up in terms of life support systems too; if something is really vitally needed you can take it with you from the landelauncher upon arrival or from the base/habitat upon leaving, as only one at a time will be housing crew. I’m sure nasa would be much more comfortable with this system too.
3: This base/habitat Starship would be perfect for nasa’s Artemis program:
While I don’t agree with Zubrin on a lot of things (seriously, he needs to stop with the whole mini-starship idea, it’s not gonna happen), he is right when he says that starship as a lunar ascent vehicle makes very little sense imo. It would be a huge investment of fuel and time for no real gain besides funding and nasa support, the latter of which is all but assured if Starship works. If instead Spacex offered Starship as a lunar base and suggested that nasa use the landers from the other two companies to go to and from the lunar surface, there’s no way nasa would say no. Imagine the offer:
“So here’s the deal: we will build a Starship interior to your specifications and wishes. Once built we will launch it, refuel it in orbit and fly it out to whatever lunar crater you want us to. Once landed, we fill drain every drop of fuel out of the tanks, lower the staircase/elevator and wait for your crew to arrive on one of those landers. It will have a thousand cubic meters of interior volume, aka more than the ISS, and you can have it on the moon in 2023 since we want to send one or two to mars in 2022 anyway. We’d like you to give us a billion dollars and a promise for martian astronauts in 2024 once we’ve landed it in exchange. Deal?”. Obviously Spacex won’t be that blunt, but I don’t believe that nasa wouldn’t fall over themselves to take an offer like that.
So what would this designed-for-gravity Starship need? Honestly, nothing fancy, which is why I suggested splitting them. Starship will have the unique luxury to simply, as musk has stated, throw mass at a problem until it is solved. As an example, let us say that a mars crew would number an impressive 12 people (one mission commandetest pilot, 4 scientists, 3 engineers, 2 botanists and 2 doctors). We know that they will be staying on mars for at least two years, but for safety let’s design it for 4 years. If they all eat like the most wasteful people on earth (cough, americans, cough...) they will consume 10 tons of food per year, with half of that being the recommended healthy amount. So.... let’s just put 40 tons of food on board. Done. 4 to 8 years of food just like that.
This is what using mass as a solution looks like. All Spacex needs is a way to store and preserve that food by either drying or freezing it for up to 5+ years, at which point that problem is solved. I’m no food expert but surely that technology exists?
Same story with water. 12 people will drink less than 10 tons of water a year, but here recycling is a well-understood and “easy” thing to implement. We’re able to reach 90+% efficiency on the ISS I think (if I’m wrong feel free to correct me), so if Spacex gets anywhere close to that (anything over 50% will do) they can put 20 or 30 tons of water on board Starship and for all intents and purposes have an unlimited supply. Recycling CO2 back into O2 is a solved problem that basically only requires power which Starship will have plenty of.
Also keep in mind that the above figures don’t assume food production or recycling, higher efficiency or using martian resources like water ice, any one of which would make surviving on mars for a few years a non-issue.
So… is that it? Well... yeah, pretty much. Spacex will need to design some ways to control temperature, humidity and (human) waste disposal as well as provide communication and spacesuits for the astronauts, but these are by no means show stoppers, especially with help from nasa and all the lessons learned from dragon. As for spare parts they can either take a 3D-printer or simply a literal ton worth of the more important components, or both if they want to.
None of the above is easy, but none of it is something that Spacex cannot obtain or build in a year (that year being 2021).
I have a design in my head for how this thing would look like on the inside but I’m a pretty bad programmemodeller. If someone who is good at that wants to model and render it and read my far too detailed description feel free to ask. Just be prepared for a very long response comment.
Life support in space
This is where things start to get “actually” difficult even if Starship works. Keeping astronauts alive during the 6+ month trip to mars will be easy. Keeping them healthy and in good condition will be very hard. Like I said with the mars base Starship, food, water and air won’t be a problem. Even basic water recycling and CO2 scrubbers will keep the crew alive just fine. Put 10 tons of food and 10 tons of water on board and there’s your problem solved. Even if they have to abort the martian landing on-route for some reason and slingshot back to earth they will be fine as they will have 1 to 2 years or more of food, water and air. No, the two big problems will be radiation and weightlessness. On mars neither of these factors are a show stopper: The gravity most likely will be fine and mars and its atmosphere will shield you from some/much of the cosmic rays, while putting the radiation shelter right below your 40 tons of food with your 20-30 tons of water surrounding it will protect you reasonably well from solar storms. None of these “easy fixes” is available in interplanetary space, as there is no planet to create gravity or block radiation (shocking I know), nor will these ones be as full of food and water to use as shielding since they will be carrying much more cargo and scientific instruments. No reason not to if there is already a base Starship full of food and water waiting on mars.
The simplest way to solve the radiation problem is some sort of physical shielding material in the walls (maybe hydrogen-rich foam?) and a solar storm shelter which is surrounded by all of the food and water on board. Whatever Spacex comes up with, this is something that I hope they work very closely with nasa on. The main problem is that they will not have much time to test this theoretical solution with humans on board until probably 2023. At the earliest Starship will be flying with crew on board in 2022, and even that’s jaw-droppingly aggressive. It would probably require Starship to reach falcon 9’s current amount of launches (a 100 basically) in less than two years (aka, one orbital launch every week on average) with little to no failures before nasa would trust Starship to launch and land safely, since I don’t see any sign of Spacex adding a launch abort system or changing the landing sequence. For the first few flights they can use a dragon to shuttle between a Starship in LEO and earth’s surface, but they can only do that a few times before the costs in both money and disposed falcon 9 second stages start adding up. No humans have ever gone beyond the earth-moon system, and no human has gone beyond earth’s magnetic shield since 1972, so this part very much has a possibility of providing some unwelcome unknown unknowns.
There is another big thing though that I think too many people ignore: weightlessness. The first flights to mars will take at least 6 months. Even with exercise, I think it’s fair to say that astronauts currently do not have the muscle and bone strength to stand up and walk by themselves after returning from a 6 month mission on the ISS without help. Mars’ lower gravity might help them recuperate faster, but this too is a complete unknown that neither nasa nor Spacex will or should count on imho. So far I’ve seen only two solutions suggested: lots of exercise on-route combined with simply letting the crew recover slowly once they land on mars, or tethering two starships together and spinning them. I don’t think either one will be an option. The first one is probably not enough, and the second one is too risky. Nasa would almost certainly go pale with that amount of inhabited mass under constant loads and stresses from circular acceleration, even if Spacex can make it work mechanically.
The only alternative I can come up with is this (and since I don’t believe for a second that I’m smarter than the teams at Spacex I’d very much appreciate someone more knowledgeable to explain to me where my thinking is flawed): You place a ring inside the pressurised part of Starship 8 meters in diameter and 3 meters in height, connected to a central pole that is bolted to the floors above and below but is free to spin. You put the sleeping accommodations on the inside of this ring with your head facing towards the centre. At the start of the sleeping shift, you spin the ring up to a lateral speed where you feel your back being pushed into the wall at a force of one g. Since your entire body is experiencing the same acceleration at every part, as the radius between your head and the pole and your feet and the pole is constant, it shouldn’t be nauseating. If there are walls on all sides of you (and one door) so that you don’t see the rotation, and your “bed” is slanted slightly to account for the coriolis effect, would it not feel just like regular gravity? Big bonus: you can start at one g and slowly move to 0.38 g over the course of several months to acclimate to mars. Small bonus: if you’re willing to pay the power cost, putting some big scoops or buckets on the outside of this ring might help with circulating the air around the ship since it will be spinning quite fast. Finally you could also spin it faster to do exercises like push-ups (basically any effort where your body remains more or less fixed to the floor could work), meaning you could compensate for being in zero g most of the day by sleeping under gravity and performing some exercises while under higher gravity [insert goku joke here].
I’m sure I have overlooked something, but it seems to me like this would work and be a reasonably effective and practical solution. Feel free to explain to me why I’m wrong.
In short, Spacex needs to find a solution to the zero-g and radiation problems by the end of 2022 at the latest. Firstly because dearmoon is scheduled for 2023 and I can’t see nasa (much less the US congress) stomach letting private civilians being the first humans to return to the moon’s vicinity since Apollo instead of nasa astronauts. If a Starship capable of sustaining humans is flying successfully in 2022 and dearmoon is set for mid-to-late 2023, I’d bet on there being effectively an order from congress for Spacex and nasa to fly american astronauts on Starship around the moon before dearmoon takes place, regardless of the state of either SLS or Artemis. And before you say that that would be massive hypocrisy, remember that these are US politicians we’re talking about.
Secondly because they really need to perform a 6 month trial run at the L2 earth-moon lagrange point to confirm that their life support, radiation protection and zero-g mitigation solutions work as intended. (This is why my money is still on humans to mars in 2026 because I can’t make myself believe that everything will work right the first time they try it). If they want to send people to mars in 2024 they will need to have this test done to satisfy nasa (or whomever is providing them with astronauts) by the end of 2023.
So my reasoning/guess is that Spacex will want the design of this version of Starship finished in early 2022, build and launch one that summer, and maybe bring some crew on board with a dragon to prove out its life support systems by the end of the year. The big year for this piece of the puzzle will be 2023, as this is the Starship type that they will most likely use for dearmoon as well as perform any major test runs in the earth-moon system, before the big launch of the first crew to mars in 2024.
Refueling starships on mars
So why do I think this is the biggest hurdle? Isn’t the sabatier process a well-understood and quite simple chemical reaction? Yes it is, and the problem as I see it isn’t with the chemistry, but with the scale, the schedule and the industrial processes that are needed.
Spacex will have to design, test and build a full-on fuel production system… and have it ready for launch roughly 18 months from now. Why so soon? Because there is no way, repeat NO WAY that Spacex will be allowed to send astronauts to mars, on a rocket that cannot get back to earth without being refueled, if there is no fuel production on mars at the time of launch. I know Elon has often said that there is a real chance that the first crew sent to mars will die, but I can’t imagine he actually believes that he can get professional astronauts and nasa support if he doesn’t take every precaution possible to ensure that they can get back home safely.
Just to be clear: I don’t mean that there needs to be a fully fuelled Starship sitting on mars when the first crew lands, but there absolutely, 100% needs to be a Starship on mars producing fuel by the time the first crew leaves earth. And this is not as easy to pull off as it might seem.
Getting the CO2 is a non-issue: mars’ atmosphere is so rich with it that you might not even need to filter the incoming air. Also as long as the crane/elevator on Starship works, setting up a large solar field won’t be that difficult provided Spacex has made the panels reasonably easy to unload and deploy (safe assumption if you ask me), and if the surrounding surface is flat. Given that Spacex has chosen a landing/base site in the northern plains (IIRC) this should also not give any major problems.
The main difficulty will be getting enough water to produce enough fuel. If Elon is serious with his recent comment about “~2 tons/day” of fuel, which I have to assume he is, that means many tons of water ice have to be excavated, moved, filtered of other materials, melted and separated into H2 and O2, per day, for over two years, with no one around to fix something if it breaks. This is orders of magnitude more intense than what we’ve done on mars before. To be blunt, we are talking nothing less than autonomous bulldozers, that weigh several tons and make Perseverance look like a toy. Scooping up and gathering a truckload of ice and rocks daily and dumping them into whatever device Spacex comes up with to separate out the ice, melt it and split it into hydrogen and oxygen (of which the former probably must be combined with CO2 and turned into methane immediately given its habit of not liking being stored and subsequently floating away), and not break down thanks to the martian dust getting anywhere crucial.
Even setting aside the fact that this operation will make the planetary protection crowd pull their hair out, the chances of it working as designed the first time are not high if you ask me. There is every chance that something wears out faster than expected, stops working due to some unknown unknown, or gets wrecked by a malfunctioning autonomous vehicle glitching out and driving into/over it. Once there are actual humans on mars, keeping these machines operational won’t be all that hard, but basic safety standards (and nasa) are going to require that the fuel farm works reliably on its own, for as long as it takes to make enough propellant for the first crew to return home safely in case of an emergency, before the go-ahead is given for that first crewed mars mission to leave earth.
I would not be shocked if Spacex manages to design, test and build a system that they think will work in 2021 and launch, refuel, transfer to and land it on mars in 2022, only to find out that some crucial part doesn’t work as designed under the martian conditions, leaving a fully habitable base Starship and an empty propellant plant Starship sitting on mars with all the accompanying parts needed to start a base (pressurised cybertruck rover, unpressurised cybertruck rover, water ice gatherebulldozer, fuel transporter, solar farm and guidance & landing beacon) present, but no way to make fuel. It will be the most infuriating and cathartic thing ever at the same time. Such a situation will almost certainly set the Spacex timetable back the full two years, as I just can’t see nasa allowing astronauts to get in a Starship and blasting off to mars if there is no way for them to get back yet. I don’t think the argument “Well once they are there they can fix the fuel farm instantly!” will hold much weight, since if something important has broken, what’s to say that something else will not go wrong unexpectedly that the crew can’t fix, leaving them stranded?
My basic reasoning is this: the other three parts can be tested in LEO or on earth with the results being representative of their supposed tasks, but this one cannot. The environment on mars is simply too different from the one on earth (especially the atmosphere), and the scale and ambition of Spacex’s plan means that the rovers currently on mars are not much of a reference either. There is no way for us to know outside computer models what a five-ton vehicle driving around on mars for years hauling several tons of regolith and ice around daily would go through in terms of wear and tear, creating a massive potential for unknown unknowns to appear where we don’t expect them. To put Spacex’s project in perspective: the first fully loaded Starship upon touchdown will probably consist of 99% of all the mass humanity has ever landed on the surface of mars. Let that sink in...
So that’s my take on Spacex’s mars ambitions. If Starship works (big if, but it seems to be getting more believable by the day), I am reasonably confident about orbital refueling and a martian habitat being ready on time, but have reservations about the human-rated Starships and am outright concerned regarding the autonomous propellant plant working as designed. As I’ve mentioned, my money if SN8’s 20 km flight goes well is on Spacex getting a Starship to mars in 2022, but not sending humans until 2026, either due to the 2022 starships not performing as well as intended (or not performing at all if they crash) or due to Starship not yet being declared safe for human flight in 2024.
Now before I go ahead and request the longest-reddit-thread-of-the-year award (I genuinely think this post is twice as long as my previous one), I’m curious as to your response to the three questions that in my opinion sum up the whole thing:
1, Did I miss something important besides the four areas I covered?
2, If you agree that these are the major roadblocks for Spacex and Starship, do you agree with my take on them? Did I badly underestimate something that is much harder than I gave it credit for? Or are certain things that I considered difficult much easier than I made them out to be?
3, Regardless of whether or not you agree with my list, ranking and reasoning, what do you think Spacex’s biggest obstacle will be to sending humans to mars in 2024, assuming Starship itself works?
Looking forward to your responses, opinions and rebuttals.
submitted by afarawayland1
Rating for all troops!
This is MY PERSONAL opinion for all troops:
Ace Pilot: (7/10) Good starter, and good mid game (as long as you upgrade it to max). Necessary for hardcore. At level 0, it is horrible. However, once you get level 1, it can really work well for most enemies (except hiddens). It can be OP, it can be horrible. Depends on the map (Trick or Threat is an example of a great map for it.) Favorite Skin: Pumpkin
Commander: (9/10) In my opinion, it doesn't really help unless you use call to arms. The damage is useless, but the fire rate buff is NEEDED for many events and maps. Very good, but only if it is level 2 or higher. Always in my loadout. Favorite Skin: Gargoyle
Commando: (0/10) Event troop for Area 51. Horrible. Never use it. Is super expensive, and the only damage dealer is really just it's rocket launcher, which still does basically no damage. Only Skin: Pirate
Cowboy: (7/10) You get it for beating badlands. Not bad. Good damage dealer, so it's a good starter and midgame troop. Gives money per wave. Favorite Skin: 2019 Pumpkin
Crook Boss: (8/10) Good starter, and ok midgame. Good damage and fire rate, and it calls in crooks and mafia, who do some good damage. I recommend using it. Favorite Skin: Soviet
Demoman: (5/10) Ok starter, but tbh, its not good any other time. I recommend getting it to level two, then ignore it. Favorite Skin: None.
DJ booth: (9/10) Similar to commander, but it gives range, and decreases costs for upgrades. Really good, I recommend not having both the commander and DJ, but having one or the other, and a friend having the other. Necessary, usually in my loadout. Favorite Skin: Neon Rave.
Electroshocker: (7/10). The stun is useful, along with the chain. It would be a 10/10 if it didn't have the cap of 2. I recommend using it. Favorite Skin: Hazmat
Enforcer (now shotgunner): (6/10) High damage, but not such a good starter due to the fact that it has such a slow fire rate. Not too bad, but unless you plan on spamming them, don't bother. Favorite Skin: Slayer.
Farm: (10/10) As long as you occasionally upgrade them, you will get SO MUCH MONEY. They are dirt cheap, and really worth the time. Really useful with mil bases and ranger because their upgrades are very pricy.
Freezer: (6/10) In my opinion, the only good thing is the Ice Age. Low damage, slow fire rate, and a lot of enemies are immune to the freezer's (not the frost blaster's) attacks. I almost never use it. Favorite Skin: MintChoco
Frost Blaster: (9/10) Unlike the freezer, a lot of troops are NOT immune to the frost blaster's freeze. Even if they are, the frost blaster deals A LOT of damage. Pretty cheap, but the event was super hard, so... yeah. I don't have any skins for this troop.
Gladiator: (6/10) Good starter, but becomes obsolete. Pretty hard event because the map was so small, and almost no places to place the troops. Has some good upgrades at the beginning, but because of the melee range, it is not good midgame/endgame. Best skin: Default.
Holiday Archer: (10/10) Great starter, and if you spam them, they are SUPER useful all the way through the game. Amazing range, has piercing, high damage (level 3 and up), and all in all, a very well rounded troop which I have in my loadout all the time!
Hunter: (4/10) Pretty bad. Low range, low damage, low fire rate, and by the time you get it to a higher level, it is mid game and it is useless. I recommend never to use it. Best skin: Blue
John (now militant): (8/10) Good range, good damage, good fire rate. Pretty spamamble. Useful mid game and kinda useful endgame. There are better troops so I don't use it much, but it is really good, and kind of underused. Best skin: Hazmat
Medic: (7/10). The healing isn't that useful, and the damage is abysmal. The savior for this unit is that when max level, it has an ability that can cleanse stunned troops, which is NECESSARY for some events, and super useful for others. Favorite skin: Cyber
Military Base: (10/10) Good starter, and good ender. It is dirt cheap, and also very cheap to get it to level 2, where it spawns trucks with 60 health. If you get five lvl 2 bases (pretty easy to get with farms), it will basically carry the beginning, and once you get tanks, they are super useful at the end. They can clutch enemies (as long as you didn't place them all at the same time, if you do that they all spawn at the same time, so it it much harder to clutch. It is better to wait 10 seconds before placing another one), and really help with killing bosses. ALWAYS have it in your inventory. Favorite Skin: Classic
Minigunner: (9/10) Low damage, but AMAZING fire rate, and it has hidden detect. If you spam them, you are almost guaranteed to win. The starting price is pretty high, but the upgrades are pretty cheap if you ask me. Recommended to use always. Favorite Skin: Ghost
Mortar: (6/10) Good starter, but that's about it. This is a cliff unit, and you want to save cliffs for rangers. If there were no rangers, this would be good, but I recommend not using it, because by the time you get to level 75, you should have rangers. Best skin: Default
Ranger (previously outlaw): (15/10) Yes, that's not a typo. 15/10. Low fire rate, but it does a crazy high amount of damage, and has such a good range. If you use a max ranger with call to arms, it can easily solo a slow boss. Only problem, you basically need farms for get it to max early. If you don't have it, you will probably lose. Not much else to say. Favorite skin: Gale
Paintballer: (2/10) Eh. Not a good starter, and forget about mid game and endgame. I recommend not using it, other units are much better.
Scout: (6/10) Call me crazy. Scout is a pretty good starter (it is far from the best, but it isn't bad, and only about level 3). Favorite Skin: Golden.
Sentry: It's gone
Slasher: (8/10) Extremely good starter and mid game. It has a small range, but if you use the power up (throwing knives) it becomes very good. I recommend using it. Favorite Skin: Spring
Sniper: (-3837/10) Horrible. Worst unit in the game. Almost no damage, super slow fire rate, and takes up precious space for rangers. Favorite Skin: Don't care, never will
Soldier: (5/10) Good starter, gold soldier is pretty OP (at least the stats are). Not good any other time, but was needed for soloing fallen. Favorite Skin: Doughboy
Swarmer: (8/10) I don't use it much, but it is really good (I should use it more) good starter, and if you use the power-up, it is good for mid-game and endgame. Event was pretty easy tbh. Favorite Skin: Default
Turret: (7/10) Great troop, but it's just too expensive. If you have farms, it's great. If you don't, don't use it. That's all I have to say. Favorite Skin: Xr500
Rocketeer: (8/10) Good damage, good splash damage, good range, and not crazy expensive. Only problem is the reload time, which just gets ignored with the max level. Favorite Skin: Black Matter
Pursuit: (5/10) Cool idea, but not that good. The only real damage dealer is the rockets, but it is just sooo expensive and annoying. I don't use it. Also super hard to get hidden detect. Favorite Skin: Default
Accelerator (11/10): Really cool idea. And it works well! Kind of expensive, but really worth it. It has small range, but everything else is great, and if you use a DJ booth, it becomes really OP. Good if set to strongest. Favorite Skin: Hazmat
Pyro (9/10) (6/10 for molten): Really good troop. Slows enemies, and deals some good burn damage. Doesn't do much damage in molten because they are immune to burn.
And that's it! Hope you enjoy!
submitted by Puzzleheaded_Ad1509