Even a reliable workhorse like Russia's Soyuz rocket has bad days. Some missions go horribly wrong. So while the basics of rocket science are the same as ever, there are always new contenders to shake things up.
What are rockets if not hot, phallic rods?
Especially the newer ones — just cop a load of the Big Falcon Rocket, which an American space company called SpaceX hopes to launch in five years.
Look above. It's testosterone all the way.
Most rockets look like that. They are either one long shaft, with a few fuel-loaded stages. Or they're a shaft-and-a-half, with scrotum-like boosters strapped to the sides.
And they all do similar things. They fire straight up, and (some) come down again.
They tend to be made, or at least financed, by the same kind of man, obsessed with boring deeper and deeper into the depths of space. Some send people and supplies to the International Space Station (ISS), other launch satellites into orbit. And some project "deep space" probes on missions that last for decades to far-away planets.
Women make rockets too, of course, so it's not all dumb inuendo. And, sure, there's a wad of physics that goes into their design as well.
But it'd be easy to think that like the male member, if you've seen one rocket, you've seen them all.
Except you'd be mistaken.
Still going strong after 50 years: A Soyuz rocket launches from Baikonur, Kazakhstan, to the International Space Station in June 2018
Here's a little overview of some of the most often used rockets, starting with the Russian "workhorse," the Soyuz.
Since its original incarnation took flight in 1966, the Soyuz family of rockets has racked up almost 2000 missions. There's been the odd glitch; and some missions have failed outright — including one in October 2018.
But the Soyuz rocket, and its accompanying spacecraft, which transports astronauts to and from the ISS, is still considered to be one of the world's most reliable space vehicles.
From missiles to the moon
There have been at least seven major versions of Soyuz, and all have been derivatives of an early Soviet intercontinental ballistic missile (ICBM), the R-7.
One of the earliest Soyuz spacecrafts — launched with a Proton rocket — was part of the Soviets' uncrewed lunar missions in the 1960s. The current Soyuz rockets include the Soyuz-FG and a new generation Soyuz-2. But the basics have remained the same.
There's the main rocket in the middle, or core, and four engine rockets on the sides. Together they achieve a combined "sea level" thrust at liftoff of 3,357 Kilonewtons (kN).
A Newton is the standard measure of force. And if it helps to compare, Wikipedia reckons the force applied by a small car during peak acceleration is about 45 kN.
But we'll park that for now. Because all you need to understand at this stage is that the greater the number, the greater the force.
Those Soyuz engine rockets sit around the central core, and that acts as a second-stage booster.
As the Soyuz is an "expendable" rocket, the four engines fall back to Earth when their fuel is spent, and the main core is not reusable either. Newer rockets, like SpaceX's BFR, promise to be resusable. The company's Falcon 9 rocket already is partially reusable — its first stage engine lands itself back on Earth. But the Soyuz rockets get used once, and all the bits that fall back to Earth are lost forever, usually in an ocean somewhere.
It's an awfully expensive business.
The Russian space agency, Roscosmos, isn't known for being transparent about its costs. But it charges America and Europe's space agencies, NASA and ESA, just north of $80 million (€70.7 million) per seat / per astronaut, according to 2018 estimates. So, it's got to cost a lot to fly a Soyuz.
By comparison, the Falcon 9 costs $62 million per launch and its larger sibling rocket, the Falcon Heavy, costs $90 million tops.
Meanwhile, there are micro rocket-makers, like New Zealand-USA company, Rocket Lab, which is reported to charge less than $10 million per launch. Their launcher, the Electron, is tiny compared to Europe's mainstay rocket, the Ariane 5, or Atlas V, made by a conglomerate called United Launch Alliance.
At 17 meters tall, the Electron is only about half the size of Vega, an Italian rocket, which is itself relatively small, but which can launch decent-sized satellites. Rocket Lab's Electron is made for so-called CubeSats — small satellites that can be as compact as a loaf of bread.
In the United Kingdom, Orbex hopes to do the same with a rocket called Prime, which is still in development but would launch from a new spaceport in Sutherland, Scotland, or a Portuguese launch site in the Azures. Both launch sites have yet to be built.
Asian competitors, such as the Indian space agency (ISRO) and China's National Space Administration (CNSA), will be bringing up the rear, or even leading, with small launch capabilities, and potentially reusable ones at that.
Stage by stage
Most of the larger, traditional rockets are built on a similar principle to the Soyuz, with multiple stages.
There are two basic concepts.
One is called parallel staging — that's the kind used by Soyuz.
The other kind is serial staging. That's where the rocket looks like one long rod, but it consists of a first stage, and one or two upper stages tacked on top. The first stage provides an initial thrust for liftoff, while the upper stages are smaller and designed to operate at higher altitudes, where there's little or no atmospheric pressure. That results in greater force (more speed on the freeway to Mars.)
Rocket manufacturers will often quote a "thrust at sea level" and a "thrust in vacuum."
In the following list, we've focused on sea level thrust, because rockets don't start in a vacuum, and as a result, we hope it's easier to visualize. It's also the first stage, without which the rocket is never getting off the ground — unless, like commercial company Virgin Orbit's LauncherOne, the rocket is strapped to the bottom of a plane and launches mid-air, but that's a whole other article!
Delivering the payload
You get thrust by burning propellant. And that thrust allows you to overcome the weight of a rocket, and achieve orbital velocity — or whatever velocity you need for the distance you want to travel.
Propellant can be liquid, solid fuel, gas or a hybrid. Each has its advantages and disadvantages. But the one problem all rockets face is the fact that the fuel makes up most of a rocket's weight. And that can have a bearing on a rocket's maximum payload — what it can carry into space — whether that's people or cargo, like supplies for the ISS, bits for a Moon village, or satellites.
Maximum payload to low-Earth Orbit for communication satellites and the ISS:
Sustainability in space
Among the newer entrants — including many in development — are a host of reusable vehicles.
Perhaps most notable is that these include some of the biggest rockets the world has ever seen, namely Blue Origin's New Glenn and SpaceX's BFR. Those will both feature "fully reusable" hardware.
Orbex says its Prime rocket will use "a single 100 percent renewable fuel," while Rocket Lab says the Electron's Rutherford engines feature "high-performance electric propellant pumps [that] reduce mass and replace hardware with software."
In addition, SpaceX rockets are part of a new generation of self-driving launch vehicles, which aren't controlled from Earth, or manually, like a Soyuz.
All these things are clear innovations around the basics of rocket science.
"Pigs in space"
It's a new commercial vibe in space exploration that is driving this technical innovation. And it's one that is likely to bring about a new era in human spaceflight, too.
Read more about Sigmund Jähn, Germany's first cosmonaut
New "people carrier" spacecraft are on the way. Take Orion, for example, an American and European collaboration, which will launch on NASA's new super-heavy rocket, Space Launch System, and Boeing's CST-100 Starliner, which will launch on an Atlas V.
These and others will herald a greater number and more diverse set of space travelers and space engineers. So it won't just be male "pigs in space" but, hopefully, a more representative cross section of our communities on Earth. Perhaps then we'll also get away from the old-school term of "manned spaceflight" because the majority will no longer be men.
But no matter who's on board and what new innovations are hidden in your rocket, the same old truth applies: It takes a heck of a lot of power to exit planet Earth.
This overview of rocket launch vehicles was never going to be fully comprehensive or complete. There are so many more we could have — and perhaps should have — mentioned. Next time.