Rockford peaches Illinois t-shirt

December 27, 2022

One method is to simply fire a rocket to completely kill your velocity relative to Earth’s surface. Then you just have to fall the Rockford peaches Illinois t-shirt and I will buy this 400 kilometers straight down. It’s not very far. I mean, it’s 10 times farther than the highest parachute jump, but still. But this takes a lot of rocket fuel, and every drop of rocket fuel has to be carried by rocket up to the Space Station. And so rather than use rocket fuel, as much as possible they use the friction of the atmosphere to slow the returning spacecraft. That gets you free deceleration without using precious rocket fuel, at the cost of enduring substantial friction and compression heating from traveling through the atmosphere at 27,000 km/hour. That is what causes the high heat during re-entry, the use of the atmosphere to brake the re-entry vehicle. If you just fell straight down you would only have minimal heating, instead you’d be cold due to transfer of heat to the atmosphere as you fall. That is, you’d be in a cold wind as you fell, which would make you colder. But you can’t just fall straight down, because you can’t just sit still 400 kilometers above the Earth. There’s nothing holding you up, right? So you could fall 400 kilometers if you had a rocket that just shot you straight up 400 km and then let you fall back to Earth. But you wouldn’t be staying up there. Things don’t orbit the Earth because they’re up high. They orbit because they’re going fast enough sideways that by the time they’ve fallen to the Earth 100 kilometers they’re already 100 kilometers over the horizon. If you just want a parabolic up to space and back, you don’t need to worry about the heat of re-entry. It’s only if you’re in orbit that you need to figure out some way of matching velocity with the Earth’s surface that doesn’t involve your molecules strewn over a giant debris field.