Hey Reddit! As you hopefully know by now, today we're celebrating 50 years since humans first stepped foot on the moon! Of course, this was the Apollo 11 mission with Neil Armstrong, Buzz Aldrin and Michael Collins.

I'm a guy that's basically professionally curious about all things rockets and spaceflight and I've actually made a career out of making videos about rockets and spaceflight on YouTube. My "Everyday Astronaut" YouTube channel has 350k subscribers and almost 30 million views in just over 2 years. Here's my channel trailer that helps describe who I am and what I do.

My videos get as in depth as I can possibly go, but I still start at page one so literally anyone can watch and learn! I really enjoy telling the stories behind all the engineering decisions. There's always a ton of weird random facts and nuggets I find when doing the research for these videos, and that's my favorite part!

Some of my more popular videos are "Is SpaceX's Raptor engine the king of rocket engines?" which is a 50 minute long rundown on the full flow staged combustion cycle rocket engine SpaceX is developing, "How SpaceX and Boeing will get Astronauts to the ISS" and just yesterday I posted a fun video for the 50th anniversary of Apollo 11 about a weird topic I've always wondered about, "Why were there rungs missing on the Lunar Lander's Ladder?"

I know rocket science and engineering can be intimidating and perhaps there's been a burning question you've always wanted to know the answer to, but didn't know where to even begin... well that's what I'm here for! I might not know everything about these missions, but I do have a pretty strong grasp on most of the details and certainly can help find the correct answers!

PS: Let's please avoid conspiracy theories, unless there's a legitimate question that you have and want an answer to. I'll be happy to help educate, but I don't want to pointlessly debate one of the greatest events of all time.

YouTube, Twitter, Instagram

Proof

I'll be taking questions from 12:00 - 3:00 Eastern (16:00 - 19:00 UTC), Saturday July 20th for now, and I'll be back around when I can to answer all your questions! Unfortunately my original time today got cut short by being sent out to DC to celebrate the 50th with YouTube and NASA, so I'll try and pop back in here as much as possible!

(EDIT) I should add a disclosure that I am NOT a trained expert on any of these materials, I do not work for NASA or any commercial spaceflight company, I don't have a degree in aerospace or anything actually, but what I lack in academic studies, I make up for in pure curiosity and obsession with the subject matter.

(EDIT 3:00 P.M. Eastern) - I need to head out for a few Apollo 50th related events in DC for a bit. I'll hopefully have time to answer a few more questions tonight and for sure tomorrow I'll answer some more as well!

Comments: 168 • Responses: 33  • Date: 

NotSamar15 karma

What is your favorite thing to say to somebody who doesn't believe in the moon landings?

everydayastronaut48 karma

I honestly think the biggest proof is the fact that the Soviet Union didn't call the US out. They tracked and followed the missions, so had the US not done what they said they did, the Soviet Union would've spoken up immediately. So either the Soviet Union was in on our moon hoax or we landed on the moon. To add to that, now we've had images from JAXA's KAGUYA orbiter which show the landing sites etc etc... so the conspiracy continues to fall apart as other countries and entities have awesome new observations even today.

michu17314 karma

Why is the Saturn V named after Saturn when it was ment to go to the moon (artemis)?

everydayastronaut19 karma

"The name "Saturn" was significant for three reasons: the planet Saturn appeared brighter than a first-magnitude star, so the association of this name with such a powerful new booster seemed appropriate; Saturn was the next planet after Jupiter, so the progression was analogous to ABMA's progression from missile and space systems called "Jupiter"; and Saturn was the name of an ancient Roman god, so the name was in keeping with the U.S. military's custom of naming missiles after mythological gods and heroes." - Source (Sorry I had to just straight up google that one, I didn't know the answer either) haha

iSkullmao11 karma

Hello Tom, I have been watching you for a while now. I'm trying to get into the rockets and spaceflight stuff, but for know I have zero knowledge. Do you recommend any books for me to read? or videos and stuff to watch that can help me as a beginner? thank you and keep up the good work!

everydayastronaut12 karma

I still watch a few documentaries over and over just to continually be reminded of terms and events. I think my favorite is "When We Left Earth" which does an awesome job doing an overview of Mercury, Gemini, Apollo and the Space Shuttle. It focuses on NASA and I wish it told more of the story of what the Soviet Union was doing at the time, but I still really enjoy that series.

Other than that I watch Scott Manley's videos play lots of Kerbal Space Program, and I also think Amy Shira Teitel's book "Breaking the Chains of Gravity" is a great place to start!

And hopefully my library of videos continues to grow and help provide more context for you.

ComradeCrouch5 karma

Rocket Propulsion Elements - Sutton is the biblical book of aerospace engineering, though it can be a daunting place to start. Ignition - Clark is a fun read.

everydayastronaut3 karma

AGREED. I'm just getting into the Rocket Propulsion Elements here and there, it's deeeeep.

squid50s11 karma

What would you say attributed to the growth of your YouTube channel? Was it self-promotion, a viral video, etc.?

everydayastronaut35 karma

Persistence, quality over quantity, and listening to feed back. For example, I used to always wear my high altitude Russian flight suit in my videos as the whole "Everyday Astronaut" thing started as a photography art project, but I realized it was ostracizing, distracting and uncomfortable. So I changed out from the "character" to just myself. I think by listening to the feedback (even the harsh comments), there's always something to learn and helped me hone in on the content.

chase296311 karma

Do you know what “safety margins” they operated under during the Apollo missions? I’ve heard NASA now isn’t comfortable with anything under 99.7% or something like that, did they have a fixed number back then that allowed for the faster progress where they risked more?

everydayastronaut17 karma

I think the only hard number I can find is from 1964 where they were estimating successful mission as 0.73 and 96% safety rate. But individual parts had a 6 sigma level (basically 99.99966% likely to not fail). The problem is when you have literally millions of parts, that 99.99966% still becomes a real factor, in which redundancy becomes a factor.

Then there's what the astronauts' thought their chances were - "The high risk of the moon landing was understood by the astronauts. Apollo 11's Command Module pilot Mike Collins described it as a “fragile daisy chain of events.” Collins and Neil Armstrong, the first man to step on the moon, rated their chances of survival at 50-50" Source

And then this is another good quip on NASA's change in human space flight from Apollo to the Shuttle.

"The risk to safety should always be a major concern in human space flight. NASA’s attitude toward risk was very different at different times in Apollo and Space Shuttle. The Apollo program expected that many lives would inevitably be lost. Because of this, Apollo planned its mission and built its systems to minimize risk. Nevertheless, the danger of a pure oxygen atmosphere and the possibility of a fire were casually ignored and the tragic Apollo 1 fire occurred. Responsive efforts created a safety culture. The Apollo 13 near tragedy occurred because an incorrectly planned test damaged an oxygen tank, but Apollo 1 was the only fatal accident. The amazingly favorable safety record of Apollo led to overconfidence, ignoring risk, and inevitable disasters in Shuttle. The earlier emphasis on safety risk analysis was forgotten by the Shuttle program. High risk choices were made that directly lead to the later Shuttle fatalities. The crew cabin used fragile tiles rather than a strong heat shield. The crew cabin was placed next to rather than above the rocket engines. The launch abort system was eliminated. NASA management believed and testified to Congress that the Shuttle was very safe, with a 1 in 100,000 chance of an accident. The devastating loss of Challenger let to drastic reassessments. Risk analysis was restored. The actual chance of an accident was 1 in 100, not the originally claimed 1 in 100,000. The Challenger investigation faulted the Challenger launch decision, which due to the urgency to launch, ignored concerns about the rocket booster O-ring failure that caused the accident. Future Shuttle missions were mostly restricted to building the space station. The much later Columbia accident was thought to echo Challenger, since once again the failure signs and warnings were ignored. The Shuttle was cancelled after the space station was completed because of its high risk. NASA’s latest Apollolike designs directly reverse the risky choices of Shuttle. The crew capsule with heat shield is placed above the rockets and a launch abort system will be provided." Source

The Commercial Crew Program is elevated beyond the Shuttle's success rate for human safety considerations to the probability to the loss on ascent and descent to be 1 in 500. So it is statistically more stringent than Apollo and the Shuttle.

ComradeCrouch9 karma

Does pineapple belong on pizza?

everydayastronaut15 karma

There's only one way to truly divide the internet. I will not fall for this trap :P

Bluntly919 karma

What was with the strange sounds eminating from backside of the moon. I believe the astronauts said it was like space music. I thought sound doesnt travel in space so how is this possible? Was it through the intercom? Any theory on this bizarre sound?

everydayastronaut8 karma

My friend Amy Shira Teitel has an awesome video about this. Basically, it was interference between the Apollo Command Module and the Lunar Lander which were undocked from each other, flying independently around the moon.

laugh_till_u_yeet8 karma

Do companies like SpaceX and Rocket Lab build their own ground stations around the world or do they use ground stations operated by others?

everydayastronaut11 karma

It used to be they relied on other legacy ground stations, but Rocket Lab actually developed their own tracking stations for their missions! Unfortunately a ground tracking station error led to loss of tracking of their very first electron rocket just before it made it to orbit, which required they terminate the mission, had that ground station not lost the vehicle, it would've likely been a flawless first mission.

SpaceX also now has private ground tracking stations including two former NASA dishes at their Boca Chica launch site in Texas! They've recently upgraded their tracking motors from a hydraulic system to electric motors which makes them much faster!

BeyondMarsASAP8 karma

Multiple questions Tim. None of them are pure science as there are much more capable people than me for asking those questions around here.

  1. When are we going to get that Elon interview?

  2. What is your first memory of rockets and space science?

  3. What are your thoughts on SN6 raptor?

  4. Do you think Starship prototype is 6 months away from orbit or are we going to see more of '6 months for Falcon Heavy'?

  5. Any info on the rocket garage that Elon promised us?

  6. Why don't you officially call yourself Timothy Dodette?

  7. Corn rocket when?

everydayastronaut8 karma

  1. When are we going to get that Elon interview? Oh man, I have no idea! I sure would love for that obviously, but we'll see if he ever takes me up on that invitation!
  2. What is your first memory of rockets and space science? I visited the Kennedy Space Center when I was 5 or 6 (1990 ish) and I still remember it! It was very impressionable and although I didn't really fall that much in love with spaceflight at the time, I still remember thinking it was super cool.
  3. What are your thoughts on SN6 raptor? Seems like SpaceX is really getting close to having a fully working and reliable design of a full flow staged combustion cycle rocket engine... which is nuts! I personally actually think it might be a bit overkill and I'm nervous an engine that advanced might not be as reliable by nature as more simple engine like Merlin, but I think they're getting it solved and by pushing the boundaries, they're likely to learn a lot!
  4. Do you think Starship prototype is 6 months away from orbit or are we going to see more of '6 months for Falcon Heavy'? Oh man... this one is so hard to guess. One thing StarShip has going for it that Falcon Heavy didn't is StarShip is a blank page. Nothing about it relies on other developments other than the Raptor engine. This is very different from Falcon Heavy which basically required SpaceX slowed down on the Falcon 9 development for long enough to engineer a heavy lift variant, which they weren't doing until they landed a booster. Since StarShip isn't hinging on say landing an upper stage, we will hopefully see flights of it much quicker than Falcon Heavy. As a matter of fact, things like StarShip's reuse and atmospheric entry require flights of the full StarShip vehicle to even test out. So I think we'll see a lot of development StarShips fly and in a typical SpaceX fashion, continually be honed in and evolved over years to come. I almost do think we might see a full stack StarShip flying in 2020, even though Elon recently claimed 3 months, I'm pretty confident in saying there's no way it'll fly in 3 months, if it flew in 2019, I'll be SHOCKED (but pleasantly surprised).
  5. Any info on the rocket garage that Elon promised us? I'm actually not sure what you're referring to?
  6. Why don't you officially call yourself Timothy Dodette? :shrug:
  7. Corn rocket when? Is Falcorn Heavy not good enough for you?!

MatterBeam6 karma

Hi Tim! Will you be featuring more of the in-space propulsion designs, like solar-electric rockets, in the future?

You will run out of launchers one day!

everydayastronaut10 karma

haha this is true!!!! For some reason, I really enjoy talking about launchers and haven't really found space propulsion to trip my trigger as much personally. I will be doing a video about nuclear propulsion someday soon, but I should definitely talk about solar sailing and efficient electric propulsion. My channel tends to be based on currently available and past technology because I find some things in development don't live up to their hype and I don't want to falsely spread excitement over something that might not pan out (IE aerospikes).

MatterBeam3 karma

That's reasonable. Though, I must point out that stuff like solar sails and ion engines are already flying in space!

everydayastronaut4 karma

Oh for sure. I just don't get as wowed by them for some reason. Maybe it's the lack of explosions haha. I'll do a video someday talking about their advantages over chemical propulsion.

laugh_till_u_yeet4 karma

I once asked you this question regarding the mechanism used for pumping fuel into the Falcon 9 or heavy and other rockets via the launch umbilical chords/tubes/pipes on Twitter and you replied with this. So have you found the answer yet? I would really appreciate it if you answer this question. Thanks.

everydayastronaut5 karma

It's literally on my insanely long video-to-do list!!!

SnarkofVulcan4 karma

Where do you stand on the Mars direct/Mars via Moon issue and why?

everydayastronaut7 karma

The moon and Mars are vastly different missions. While I certainly want us to go back to the moon, I think it's foolish when people talk about using the moon as a physical stepping stone to Mars. Someday, yes, we could develop fuel depots on the Moon by turning water trapped in ice on the poles of the moon, to which we could refuel large ships bound for Mars... but until then, these two missions are drastically different.

I think getting the cost of spaceflight down is the biggest factor we need to address (and are thanks to new commercial competitiveness), and from that, missions to the Moon and Mars will both benefit and become more of a reality.

A two year trip to Mars will take a lot more of everything to make possible. I do think there's some truth to testing certain elements, life support, in-situ resource utilization, etc etc on the Moon first. But again, actual Mars missions will be a lot harder and have much bigger and more dangerous challenges.

That being said, if a vehicle like StarShip pans out to do everything SpaceX hopes it can do, it actually would be a vehicle capable of any traveling to any planetary body, Moon or Mars included... to which I say, AWESOME.

ChiggyVonRichtofen4 karma

Realistically, how likely do you think it is that the Artemis program will return humans to the moon in the next six years?

I want to believe, but the way NASA's funding and priorities have fluctuated lately, it seems more likely it will be scrapped or have its timeline massively changed long before 2024.

everydayastronaut9 karma

I'm actually getting quite excited about Artemis. This is the most progress and fast tracking of plans that I've seen from NASA since I've been tuned in by a long shot. There's more than talk going on, there's plans, money, proposals, and hardware in the works. SLS and Orion are literally pretty much ready for the tasks and so are the commercial providers. I think by 2024 is a hard push, but it could actually be done in my opinion. Whether or not Gateway is in place by then is one thing, but I think we could do a one off mission with say a 3 part commercial mission to get a lunar lander out to Lunar Orbit and then Humans out there with SLS / Orion by then no problem.

laugh_till_u_yeet3 karma

How are open cycle engines started? Like when they are ignited, the turbine is not spinning so the pumps are not running. And to spin the turbine, the engine needs to be running which needs the pumps to run.

everydayastronaut6 karma

hehehe I see you're getting to the chicken and egg problem that I ran into when researching my video about the Raptor engine and the all engine cycles. Basically, there are different methods. Some engines use a literal single use explosive like the F-1 which would get the pumps spinning, other engines, like the Merlin will use compressed helium to get the pumps spinning initially and then uses TEA-TEB as an ignitor in the combustion chamber.

Jeb_Kerman13 karma

Hi I’m 18yo from Germany and will begin my 3.5 year training as a mechatronic engineer in September. Do you think i have any chance to become a US citizen and work for SpaceX, BlueOrigin or RocketLab?

everydayastronaut7 karma

Of course you have a chance, but working around ITAR (International Traffic in Arms Regulations) can make it realllllly hard for US aerospace companies to hire foreign nationals. This is why it's advantageous that Rocket Lab has facilities and their launch pad in New Zealand, it does allow for some flexibility in those areas.

Keep up the hard work, stay motivated and excited, and don't let rejection be the end. Trust me, those who stop pursuing their dreams at the first sign of rejection will never end up living their dreams.

laugh_till_u_yeet3 karma

What is you opinion on rockets being sponsored by different companies? Can these lead to uglyass rockets covered with hundreds of logos of different companies in the future?

everydayastronaut4 karma

TBH I think it could be a valid form of additional revenue, but the caveat will be whether or not it's a good idea to put your logo on something that MIGHT explode... although I guess NASCAR basically exists using this model... The problem is that there really just isn't that much marketing value in rocket launches. Views might be in the millions for a "standard" launch, and maybe billions for first crews going back to the Moon or going to Mars. So there just isn't a lot of money in the first place and likely will never be worth it. And as launches become more routine, this will dilute the potential value as a marketing piece. Just like why we don't see airliners sponsored by Coca Cola.

Natogaming3 karma

Hey tim, why doesn't spacex Throttle up the center engine to full power for the landing burn instead of using 3 engines? Also hello from Des Moines IA.

everydayastronaut8 karma

Hey fellow Iowan! So for a landing burn, especially one where you have to do a suicide burn (meaning your thrust to weight ratio will never be below 1:1), you want to have your engine(s) in the middle of their throttle setting. If your'e ever relying an engine to be at 100% for a landing burn, you might as well have lit a solid rocket motor because you have no more wiggle room to make adjustments. By having an engine at say 70% at the beginning of your landing burn, if you're coming in too fast, you can throttle up to as high as 100%, if you're coming in too slow, you can throttle down to as low as 40%. This still holds true when having three engines, there's just more wiggle room when you aren't ever relying on engines to be at 100% because you're at a hard limit with no room for adjustments.

Your-mom-is-a-bubble3 karma

Van Allen Belt: Can you explain how the crew was protected against the immense radiation once outside of our planetary electromagnetic shield?

everydayastronaut13 karma

There's a few factors at play that people might not think of.

First, the Van Allen Radiation belts aren't consistently strong around the entire area of the Earth. It's not like it's this giant bubble around the Earth where you get maximum radiation anytime you pass through it. It is, as the name implies, more like a belt, where there are areas that are stronger than others, and it's a well defined and predictable gradient. This means you can design mission parameters to fly around the bulk of the radiation (like the Apollo programs did), or if you want to test your hardware is capable of harsher radiation environments, you can intentionally spend more time in the belts like the Falcon Heavy upper stage did on the demo mission.

The other thing to remember is radiation isn't this laser beam that melts stuff in its place. Humans actually have a very very high tolerance to radiation and can be exposed to a very large amount of it for a short period of time. So duration of exposure is the other big factor, and because the Apollo spacecraft were traveling at around 25,000 km/h, the astronauts only spent about one hour in different portions of the radiation belts which resulted in about 11.4 Rads of exposure at a rate of about 13 Rads per hour, which is well below the 300 Rads in one hour which is considered to be lethal. These numbers are also if an astronaut were outside of the spacecraft, which they weren't. Being inside the spacecraft cut it down significantly, and the actual measured Rads were usually below 1 for each mission except Apollo 14 which saw 1.14 Rads.

This article has a lot of good info on this topic.

DruidicMagic3 karma

Why has ramjet/scramjet technology taken so long to develop?

everydayastronaut7 karma

Transitioning airflow from subsonic to supersonic and then to hypersonic is just crazy complicated. There's never a simple "just do this" in engineering. To make something operate in all three conditions requires considerable design challenges.

Look at the SR-71's J58 engine. Just learning about this helps make you appreciate the considerations necessary for airflow at different speeds. This video by TechLaboratories does a great job explaining it!

rickrussie3 karma

When do you think humans will successfully land on Mars? Will we be able to get some sort of video broadcast if it?

everydayastronaut7 karma

My personal guess is by 2030 humans will have walked on Mars. There will certainly be video broadcast of it! Most likely any real mission to Mars will require a better satellite and communication system than what we currently have orbiting Mars. On NASA's InSight mission, they flew with the lander two cubesats that acted as radio relay stations for the landing portion and was a good technology demonstrator for future low mass / low cost relays that could benefit potential human missions to Mars.

I think companies like SpaceX foresee a constellation like their Starlink as a possibility for Mars too which would likely be deployed before the first humans ever go.

Although we should for sure be able to get "live" video broadcasts, don't forget, it'll be delayed by 20 minutes due to the speed of light. So although it'll be broadcast in real time, we'll actually be watching a bit of history from 20 minutes ago! I mean, technically any broadcast we're watching history because even on Earth there's usually a few seconds of delay in live broadcasts, but yeah, 20 minutes will be wild!

andrutay2 karma

When and why did you decide to start your YouTube channel?

everydayastronaut9 karma

I used to do photography full time, mostly making money shooting weddings. I bought a high altitude flight suit as a joke in 2013 and started taking pictures of myself in it soon after. I fell in love with spaceflight and spaceflight history as I was busy photoshopping myself into all sorts of weird or mundane situations but adding fun historical easter eggs. By 2016 I wanted to stop doing photography and pursue "Everyday Astronaut" full time. At the time, I had NO idea what that would be. I thought it'd probably be Instagram and public speaking, but by March 2017, I realized I enjoyed breaking topics down on YouTube and after my third video, I was hooked! I got lots of positive feedback and really enjoyed studying the subjects deeper. By the end of 2017, it was quite obvious that YouTube was the right platform to do educational content on.

laugh_till_u_yeet2 karma

I have been trying to wrap my head around gimbal lock for a while now by searching it and have watched countless videos about it but I just can't find an easy explanation for it. Can you help me?

kd7uiy3 karma

Try Vintage Space's video on the subject, https://www.youtube.com/watch?v=OmCzZ-D8Wdk

laugh_till_u_yeet3 karma

THANK YOU SOO MUCH!!

everydayastronaut5 karma

This is exactly what I was going to recommend! Amy is great!

sportsfan2000xx2 karma

Hello Tim thanks for doing this AMA! Big fan of the channel. So far what has been the coolest thing you’ve done/ experienced as a result of the channel?

everydayastronaut6 karma

Thanks /u/sportsfan2000xx! That means a lot! I honestly think getting to wear Boeing's Space Suit might be one of my favorite experiences so far. I also had a ton of fun going to New Zealand to see Rocket Lab's new factory and got to interview their CEO Peter Beck who is an AWESOME guy.

Other than that, being able to see launches up close and personal never gets old. Although I might not do it that often because I tend to have a hard time offering a good live-streaming experience for my audience when I attend them in person.

Although I recently got asked if I wanted to ride in an F-16 with the Thunderbirds, which.... yeah that might take the cake! So stay tuned :)

attoj5592 karma

What do you think about the space craft technology that Bob Lazar worked on at a military base “S4” decades ago that would revolutionize transportation and space travel?

everydayastronaut6 karma

I live by "Great claims require great evidence" and TRUST ME, boy do I want all of what Bob talks about to be real. And as incredibly convincing as I think he is and the way he talks about things, I would've thought it'd be likely to see more substance come out of what he's talking about. That being said, I'm not closed minded about what he talks about as some of it sounds fun and like a possibility, but I'll keep my hat pointed squarely at skeptical until I see something substantial.

Bluntly912 karma

Do you think Elon musk's companies like space x, voring company, Tesla. Work together on new technology developed. In other words, do you think owning all this companies plays a vital role on the development of each of these companies?

After all you would think some space technology could be advantageous in a car with the tight engineers. Or some boring technology could be advantageous in space missions etc.

everydayastronaut7 karma

I'm not sure why it just hit me recently, but I realized literally every single aspect of Elon's life revolve around human's living on Mars. SpaceX (obviously), Tesla (electric motors for rovers, batteries for energy storage, solar for energy production), Boring company for Martian habitats and even his brother's food and farming efforts that Elon helps fund... all of them can be applied towards colonizing Mars. So yes, I think they all do work together and I know for a fact many of them cross pollinate ideas, technologies and even talent.

jschreifels202 karma

Why cant we recreate the F1 engines?

everydayastronaut6 karma

Well, that's kind of a funny story. We could surely physically rebuild and recreate the F-1 if we wanted to. No problem. BUT, the problem is, a lot of the little fine tunings, tweaks and notes on how to operate the engine have been lost to literally scribbled notes and the generations of engineers that developed the engine.

If we were to rebuild an F-1 engine today, it would almost certainly not be exactly like the F-1 was because we'd do things slightly differently or go down slightly different engineering rabbit holes compared to the engineers in the 60's.

Curious Droid has an awesome video on this topic.

sergalface1 karma

How did the crew and engineers solve the issue of the Van Allen Belt? I know it's a popular thing for Moan Hoaxers to spew out; how did they get around it?

everydayastronaut2 karma

I answered this question above:

There's a few factors at play that people might not think of.

First, the Van Allen Radiation belts aren't consistently strong around the entire area of the Earth. It's not like it's this giant bubble around the Earth where you get maximum radiation anytime you pass through it. It is, as the name implies, more like a belt, where there are areas that are stronger than others, and it's a well defined and predictable gradient. This means you can design mission parameters to fly around the bulk of the radiation (like the Apollo programs did), or if you want to test your hardware is capable of harsher radiation environments, you can intentionally spend more time in the belts like the Falcon Heavy upper stage did on the demo mission.

The other thing to remember is radiation isn't this laser beam that melts stuff in its place. Humans actually have a very very high tolerance to radiation and can be exposed to a very large amount of it for a short period of time. So duration of exposure is the other big factor, and because the Apollo spacecraft were traveling at around 25,000 km/h, the astronauts only spent about one hour in different portions of the radiation belts which resulted in about 11.4 Rads of exposure at a rate of about 13 Rads per hour, which is well below the 300 Rads in one hour which is considered to be lethal. These numbers are also if an astronaut were outside of the spacecraft, which they weren't. Being inside the spacecraft cut it down significantly, and the actual measured Rads were usually below 1 for each mission except Apollo 14 which saw 1.14 Rads.

This article has a lot of good info on this topic.

fragmen521 karma

What is the next launch you plan on coming to Florida for?

everydayastronaut3 karma

I'll hopefully make it to all of the upcoming commercial crew launches, including Boeing's uncrewed test flight (OFT) and the first crewed launches of Starliner and Dragon 2! I can't wait, seeing people fly will be amazing!!! I've never been to a launch with people onboard!

laugh_till_u_yeet1 karma

How much is carbon footprint of rockets? Man I love rockets. I hope it is very little.

Jeb_Kerman11 karma

I think Tim talked about making a video about that in one of the last „Our Ludicrous Future“ Episodes.

everydayastronaut4 karma

Yup! This is a very in depth video that I'm working on. Basically long story short, a rocket like say the Falcon 9, burns less rocket fuel (virtually same as jet fuel) as a 747. The Falcon 9 has about 175,000 liters of RP-1 and a 747 has 215,000 liters of Jet A.

Considering how little rockets fly, their contribution to carbon output is orders and orders of magnitude less than even the airline industry, let alone the rest of the transportation industry. In other words, the pollution of the rockets is a necessary evil and the only means of getting a substantial payload into orbit, but the total amount is such an insignificant amount compared to all other forms of transportation currently. We've got MUCH bigger fish to fry before we worry about rockets. Not to mention, methane and hydrogen rockets are carbon neutral.

Jeb_Kerman11 karma

What do you think of the idea of you making a poll for your Patreons, which I will join in September, where you take your 5 favorite video ideas and let the patreons choose or possibly even a yt poll?

everydayastronaut3 karma

Oh I constantly am asking my discord members what video should I do next. Like between every video! I often poll YouTube and Twitter too once our Discord has it narrowed down. So I think it's a good idea ;) Let the audience decide!

Elongest_Musk1 karma

Hey Tim! Thanks for doing this AMA.

So what's your opinion on the Saturn Shuttle? Do you think using a F-1 operated first stage instead of SRBs would have improved the Shuttle's design? Can you think of some problems that might have caused the designers to go the side-mounted SRBs route?

everydayastronaut2 karma

Oh man, the F-1/Shuttle would’ve been so epic. Especially if they had attempted to recover the F-1’s by using the first stage as a giant crush core / impactor. In general I don’t think SRBs were a bad decision except for the time when they were used outside of their design range, but that wasn’t hardware fault, that was an administrative issue.

But one thing that the shuttle lacked was any meaningful abort option for the first two or so minutes while the SRBs were firing. At least with a liquid engine you often have the option of turning off the engines in a major problem and perhaps could’ve pulled away from the vehicle in some instances. I don’t know how valid those abort envelopes would’ve been but I’d have to imagine there’d at least be some more options with a liquid fueled booster over SRBs.

I really like the designs where there were two shuttles where the first stage would’ve landed back at KSC on the runway. That was cool!