Hot answers tagged

95

The film gets this mostly right. Merely taking the thrust, and, therefore, the acceleration of the rocket down to zero wouldn't throw the astronauts forward; there are a couple of other effects at work. The first is air resistance; 1st-stage cutoff happens at about 42 mi (68 km) altitude, where there's still some air; this will decelerate the vehicle but ...


41

That made me pause and wonder for myself what it is that's out there that might be worth this money, and reflect upon the many problems on Earth that could be addressed with these resources instead. Well, most of the money spent on space launches is used for launching satellites to Earth orbit. So what you're basically getting for the money is satellites, ...


40

Those are covers on the RCS thrusters. They're on all the other thrusters too, to prevent rain etc. from getting into the thrusters. For most of the program, the covers were butcher paper. Towards the end, we switched to using Tyvek. The covers are designed to get blown off during launch. On the OMS pods, it's mostly done by the shockwave of the ...


40

Long March 11 is a cold-launched rocket, based on a concept popular with military rockets. A gas charge is generated by the launch platform (often using a chemical gas generator) to eject the rocket from the launch platform before engine ignition. This saves the launch platform from having to manage hot exhaust gases, and reduces wear and tear on the launch ...


35

Sea Dragon The very large rocket was probably Sea dragon and the advantages were more on allowing a massive vehicle to be built at all rather than inherent advantages in starting underwater. (image credits) Building the launch vehicle on a slip way and floating it to the launch site bypasses a number of size constraints in building and moving large ...


26

TL;DR: it is inefficient. You should play some Kerbal Space Program and see for yourself the effects of travel in this way. Assuming, of course, you didn't really want to enter the orbit, but wanted to e.g. go to the Moon or deep space probing. Especially in conjunction with Wikipedia's note about not having to attain escape velocity to leave gravity well....


24

1. We don't talk about huge sums This is the money that countries spend today to space exploration, in the proportion of their GDP: (source) As you can see, the governments already seem to agree your view. 2. Space Exploration sometimes makes money and doesn't spend it. The long-term tendency is likely a profit-oriented race of private companies. It’...


21

If so, what was stopping this ~750Ton vehicle (launch mass minus first stage fuel)? I can't speak to the severity of the "jolt" but there would certainly be one at MECO - not because the vehicle had "stopped" but because it had stopped accelerating upwards (for want of a better word). This graph is from Apollo 8 but should be close enough for our purposes: ...


20

It absolutely could! First of all, water can be split in to hydrogen and oxygen, which can be enough to launch a rocket. Hydrogen requires a very low temperature, and the rocket engine doesn't have as much thrust as other options out there, but it is the same fuel that ran the Space Shuttle main engine, among others. Water and carbon dioxide, easily ...


20

The center of the Earth is, for any reasonable approximation, in one of the focus points of an elliptical orbit. For a circular orbit, there is only one focus point, so the center of the Earth is in the center of the orbit. The plane of the orbit thus would intersect both the center of the Earth as well as the launching site. If the launch site was on the ...


18

When in doubt for such things, http://archive.org. https://archive.org/details/youtube-Y70SgYPIBGY Or if you prefer on YouTube


17

Definition of terms: A shock wave by itself is not a "sonic boom". A sonic boom is an event, produced by the shock(s) passing over something - an observer, a building, the ground. The "boom" is characterized by a rising/falling/rising pressure disturbance called an "N-wave" because the disturbance has the shape of an N when plotted. A model in a supersonic ...


17

Don't you think there are other problems down here on earth deserves some care? This is a naive proposition. A large government cannot and must not focus all of its resources on one problem. The United States has immediate problems such as undernourished poor people, poorly maintained roads, and retired military personnel who have lost limbs in the service ...


14

For the Space Shuttle: Using the same approximate curves (with all their assumptions and limitations) used in the answer to How does the Space Shuttle's SSME engine's thrust vary after ignition?, we can integrate the SSME flowrates to get a startup propellant consumption of: 416 lbm LH2, 2246 lbm LO2 per engine, and ~ 1248 lbm LH2, 6738 lbm LO2 ...


14

The VASMIR 200 is listed as having a thrust of 5.4 newtons, and you need 9.8 newtons to lift 1kg against earth's gravity. So 700 tonnes is going to need more than a million engines and be consuming more than 254 GW of electricity. So even if the engines are weightless this is not lifting off from earth without co-opting the power generation of a sizable ...


13

What are the benefits for me and you? The benefits are many and varied. This is an incomplete list: Improved weather forecasts. These save lives every year, and save billions of dollars in damage caused by extreme weather. This also improves crop yields, etc. Improved knowledge of Earth. Lots of satellites observe the Earth in a variety of ways. This ...


13

Image source The booster has two kinds of joints between its segments, field joints and factory joints. The booster parts shipped to KSC were made up of two segments joined by factory joints. At KSC, these parts were put together using the field joints. There are three field joints and seven factory joints in a Shuttle SRB. Image Source Both kinds of ...


13

The short answer is that a spacecraft is attracted to the center point of the earth, not to the earth's rotational axis. [I]t would make sense to me that launching east would result in a 0° inclination with the orbital plane raised so it's parallel to the equator but above or below it. Here's one explanation of why that wouldn't happen that you might ...


12

6000 Kg is actually pretty big. I am sure SpaceX offered some discounts to attract a customer for Falcon Heavy. So I will ignore the other options (Atlas 5 with side boosters, Ariane 5, or Proton) and focus on why not a Falcon 9. Falcon 9's numbers are lower to GTO, Wikipedia has it around 5500kg reusable. 8300kg expendable, and SpaceX's point is, if you ...


12

@geoffc's answer explains why Falcon Heavy over Falcon 9, but the reason for why not any of the other options is likely cost. It's difficult to say with certainty what the launch costs would be, since costs are negotiated per launch, and are affected by a large number of factors (target orbit, payload mass, fuel costs, ridesharing, etc). Estimates put ...


11

Each technology has their own strengths and difficulties. It's really difficult to explain this without going in to a great detail about how rocket engines work, but let me try and give a brief overview. There are a number of different ways you can power a rocket engine. In general, for the same fuel and engine size, the higher the chamber pressure, the ...


11

Yes, it produces a sonic boom. But the shockwave travels in the same direction as the rocket (i.e. up) and doesn't reach the ground.


11

Comparison (US expenditures only): \$18 billion is spent per year on simply advertising cosmetics. \$60 billion is spent per year trying to lose weight. \$70 billion is spent per year on pets. \$230 billion is spent per year on advertising. \$0.5 billion is spent per rocket. Just think how many of the world's problems could be solved if we didn't waste so ...


11

'Loaded' means it's loaded with propellant (as opposed to something like 'inert' or no marking at all, for casings that have not been loaded). It's used to make it easy to distinguish which casing segments have been loaded with propellant and which ones haven't. Loaded segments require different handling procedures than non-loaded segments. In the military,...


10

The total mass of the rovers with their heat shield, landing stage, cruise stage, and all the other parts was about 1,063 kg each. They were launched into a heliocentric orbit (HCO) before letting the cruise stage take it to Mars. The Delta II payload capacity to HCO was 1,000 kg, so there would have been no room for a second rover to get it to that orbit. ...


10

The latitude of a launch site determines the minimum inclination that can be directly reached; launching from 28.5º latitude in the due-East direction achieves a 28.5º orbital inclination. Launching to any higher inclination is straightforward, simply by steering continuously North-of-East during the ascent. In the extreme case, if you fly due North, you ...


10

Let's refine your calculations a bit. Worldwide, less than 200 rockets are launched each year. They have an average empty weight of 30 tons (rounding up a bit), which is mostly aluminium. That adds up to 6000 tons. This is a tiny fraction (0.001%) of total aluminium production (60 million tons). if it were economically feasible to recover rocket stages ...


10

It's all covered by a payload fairing that isn't flush with the body of the spacecraft. A picture is worth a thousand words:


10

The MAKS design was supposed to do this. There is much additional info about MAKS in the answers to this question and their sources: Seeking concept art or photo of MAKS on carrier plane


9

The internet happened. Specifically, young engineers (Elon Musk and Jeff Bezos) made gigantic piles of money (more than they could ever use in their original companies), and with that money they decided to follow their interests. I.e. they had lots of money to pour into the business, and no requirement to make money within a set amount of time. This is ...


Only top voted, non community-wiki answers of a minimum length are eligible