Why are reusable rockets so hard to make?

Why are reusable rockets are so hard to make?
Difficult. But giving it a go. Credit: EPA

SpaceX is attempting a huge feat in spacecraft engineering. It is seeking to land the first stage of its Falcon 9-R rocket on a floating platform at sea. Normally this would end up at the bottom of the ocean. If successful, SpaceX will shake the rocket launch market, by shaving millions of dollars off launch costs.

Whatever the outcome, the represents the culmination of a number of remarkable achievements in science. It marks new developments in restarting rocket engines, orientation control, guidance and navigation, thermal protection and of course, deploying landing gear. SpaceX's track record in the industry so far has been phenomenal. If other commercial providers haven't woken up to the competition, this launch might force them to pay attention.

What goes up must come down

Today's rockets are one shot wonders. They burn up fuel in a few minutes and splash down into terrestrial oceans, having put their payload on the right trajectory. This is wasteful and that is why scientists have dreamt of building building reusable launch vehicles.

The holy grail of rocket launchers is a concept referred to as the single stage to orbit (SSTO) vehicle. The idea is to use a reusable launch vehicle (RLV) which has the capability to deliver a payload to orbit, re-enter the Earth's atmosphere and land, where it can then be refuelled. The process can then be repeated with a short turnaround.

Although some steps towards this are being taken in the UK, with development of the SABRE for the Skylon SSTO vehicle, achieving such a development with reliability and within reasonable cost, remains a challenge both in terms of materials and engine technology. The SABRE engine makers propose to overcome the energetic barrier by taking at least some of the oxidiser for the combustion process from the atmosphere, switching from air-breathing to rocket-fed combinations.

The reality is that achieving orbit with a single vehicle and a pure rocket engine, whereby all of the fuel and oxidiser for combustion is stored on-board the vehicle, remains out of reach. Even with a propellant mass of 90% of the entire vehicle weight, expendable launch vehicles must tread an extremely fine line between the masses of the propellants, the supporting vehicle and the payload. This means that the payload mass which achieves final orbit is typically no more than 2% to 4% of the initial weight of the launcher.

The only way we can currently achieve orbit is by stripping away the needless mass of the supporting structure and fuel tanks as the launcher's fuel begins to empty. This creates a multistage rocket. These stages may be in series, stacked one on top of the other, as in SpaceXs' Falcon 9-R rocket, or in parallel as in NASA's Space Shuttle.

The only precedent

NASA's Space Shuttle was an attempt at producing a semi-reusable launcher, by re-entering and landing the orbiter, as well as recovering the solid rocket boosters by parachute. However, the immense recurring costs of the programmes and the Challenger and Columbia Shuttle disasters, with a loss of 14 astronauts, highlighted the difficulty in achieving true and reliable reusability.

It seems madness that we prefer to discard some of the finest and costliest examples of human science and engineering to the bottom of the ocean. Yet given the limitations, governments and agencies seem unable to consider recapturing them and reusing the technology. So for the past 50 years, expendable launch vehicles (ELV) have been the staple diet of the commercial launch industry.

SpaceX's journey so far hasn't been without difficulty. The launch is its third attempt at testing out this technology. The first two launch attempts were scrubbed because of last minute faults.

And even if SpaceX succeeds, it needs to prove that the technology is an economically feasible alternative to expendable launch vehicles. To do that it will need to avoid the long and expensive refurbishment activities that plagued the Space Shuttle programme.

This will not be easy. Re-usability means that the Falcon 9-R carries within it greater complexity, systems and mass, reducing the overall payload and decreasing its performance.

However, SpaceX is not shy of challenges and is pressing ahead with a myriad of achievements at breakneck speed. The speed at which SpaceX has moved from concept to reality has barely given time to other commercial players to assess the impact SpaceX will have on their business plans, let alone react to them.


Explore further

SpaceX to attempt rocket, cargo launch Saturday

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Jan 09, 2015
Go SpaceX ! i wonder how many rockets are lay at the bottom of our oceans?

Jan 09, 2015
Why are reusable rockets are so hard to make?

Why is correct english is so hard to write?

This is wasteful and that is why scientists have dreamt of building building reusable launch vehicles.

Sometimes I wonder, whether it would be possible to have a 'caseless' solution (for solid stage boosters).

I hope SpaceX get it working. That edge would give them an enormous boost.

Jan 09, 2015
antialias_physorg why you the english writing police? . american english is hardest language too learn ? one word can be wrote 7 diff meaning's .

Jan 09, 2015
Just still so far away!

Jan 09, 2015
antialias_physorg why you the english writing police?
@mintor4603
I got your back AA_P
re-read the title and look specifically for "Are"
Why are reusable rockets are so hard to make?
And AA_P knows far more about how difficult it is to learn English than most people

he makes a good point, too

Why is it so difficult for an Editor or author to use SPELL/GRAMMAR CHECKS when it is a simple click.... after all, it is their livelihood!

You don't see legless Firefighters in wheelchairs trying to go up stairs in a high-rise to fight fire, do you?

so you would think that anyone who relies upon the English language for a paycheck would either be well versed in its use or able to afford spelling and grammar check software (which is included in most word processing software and absolutely free in a lot of places on the internet)

Jan 09, 2015
The only precedent

NASA's Space Shuttle


What about Buran/Energia?

so you would think that anyone who relies upon the English language for a paycheck would either be well versed in its use


Protip: you aren't paying their paycheck. They rely on ads revenue, which means the more clicks they generate, the better. If that means intentionally introducing spelling errors to get people to reload the page with comments, cha-ching!

Trolling is a art.

Jan 10, 2015
And AA_P knows far more about how difficult it is to learn English than most people

From what I've been told (and my own experienc with the few other languages I have learned/tried to learn) it's far easier to learn english than most other languages. I certainly don't envy the english speaker who tries to learn german.

But seriosuly: the quip about the extra "are" was just a slight prod towards the editors. They rely all too much on spellcheck software these days and don't bother actually reading what is there anymore.
This is not particular to physorg. Reading newspapers/watching newsfeeds you can see that, while spelling snafus have almost disappeared, these types of mistakes - and the 'autocorrect' type - have multiplied.

Jan 10, 2015
They rely all too much on spellcheck software these days and don't bother actually reading what is there anymore.
@AA_P
That's for sure
the funny thing is... if they would run a Grammar check with it, it would have been caught

I've heard that German is the easiest to learn for an English speaker (and vice versa)
I picked up a lot quite quick when i lived there, and could pretty much get along
I learned the numbers, money and basics first, which i always thought the best way to approach a language as it allows one to talk money or trade

Protip: you aren't paying their paycheck.
@Eikka
I see your point, but it seems like a bad choice for a science site where the average reader is likely to be fairly literate and knowledgeable (excluding trolls like Zeph, rc and jvk, that is)

even if said site is nothing more than a Pop-sci article clearing house/distribution point
(some pop-science mag's take a lot of their content straight from here)

Jan 10, 2015
(some pop-science mag's take a lot of their content straight from here)


Which is ironic, because Phys.org itself is mostly an automated aggregator that simply copies articles from elsewhere, verbatim.

it's far easier to learn english than most other languages


There are next to no rules to english, just a massive number of words taken from every other language there is.

How the words themselves are used in sentences is down to convention with no concise rules - even over punctuation. That results in a massive number of "dialects" that are sometimes mutually unintelligible. Even within the same society you get what might as well be two different languages that simply share some lexicon, which changes over time. Upper class english and lower class english.

Which is why each and every person who learns the language essentially just learns the words and makes up the rest, in their own style - maybe imitating, or making it up completely.

Jan 11, 2015
@Captain Stumpy
@antialias_physorg
@Eikka

Why is correct english is so hard to write?


Since, I wrote the article, I may be able to shed some light. I'm a technical author and engineer/scientist, not a press article writer. We occasionally get requests to write these kind of pieces. You may be surprised to know, that the original piece I wrote which was requested, and published by 'The Conversation' was edited by at least 5 other people after I approved the article. It was at this point that a number of grammatical, spelling errors, or factually inaccurate and badly worded sentences crept in, not to mention 'dumbing down'. I've done my best to ask the publishers to amend these changes, but I guess it just goes to show that when you read these articles, don't rule out the fact that the editing process, which in this case the author has little control over, can actually compromise the original the article. Not to mention embarrass the author! :-)


Jan 11, 2015
@Captain Stumpy
@antialias_physorg
@Eikka

Why is correct english is so hard to write?


Since, I wrote the article, I may be able to shed some light. I'm a technical author and engineer/scientist, not a press article writer.


That didn't shed so much light on anything. A writer ought to be able explain something better than that thing just did. Just what are you saying there Cher?

I really like it when the article writers sign up on the physorg to shed some light. You and the JohnHew-Skippy have earned a karma point, would you like to try for the silly looking pointy cap like the one I give JohnHew?

Why are reusable rockets are so hard to make?


That's the part you should be explaining, not all the other couyon who didn't write the article.

Jan 11, 2015
@Eikka
What about Buran/Energia?

Although the Russians developed the Buran, they only flew it successfully once and recognised quite rightly that it was uneconomical, something NASA probably should have done sooner. Although it would have been nice to talk about the Buran, statistically, we have no proof that the Buran was a success in terms of reusability. If they had done a few orbital flights, then maybe we could do some useful analysis. The Buran/Energia were however amazing vehicles. You may be interested to know that the Bikal flyback booster was a jet engine booster concept with a folding wing which would help fly the rocket booster for the Buran return and land.

Jan 11, 2015
I've done my best to ask the publishers to amend these changes, but I guess it just goes to show that when you read these articles, don't rule out the fact that the editing process, which in this case the author has little control over, can actually compromise the original the article. Not to mention embarrass the author!
@Rubix
1- thank you for taking the time to get involved here with your article
2- i can understand the process, which is why it irritates me even more
-not the part about your writing the article, but the part about the editors (professionals with the purpose/job of writing and utilizing the English language mangling it when a simple Grammar check click would point out the alarmingly obvious stupid errors)

As my wife in an author and retains a great deal of rights after the fact, i must ask: is the science/technical article author somehow that different that you cannot retain at least minimal control of your own stuff?

Jan 11, 2015
There are next to no rules to english, just a massive number of words taken from every other language there is.
@Eikka
actually, there are an insane amount of rules for English.
And by that i mean PROPER English as well as clear concise communication.

What you are referring to is colloquial English or lay-English and it is known for ignoring some of the more important rules, especially regarding spelling or word use

As i live with an English Major Grammar Nazi Author Nurse, i am very familiar with this process and i regularly am berated for my communication style, which i intentionally use to irritate my wife because she knows i am educated and i know better

@Ira
Rubix is trying to pass on knowledge about the editing process for science articles and writing, which is different (apparently) than books, professional doc's or gov't publications

I've not dealt with science articles writing, so it is interesting

Jan 11, 2015
Since, I wrote the article, I may be able to shed some light. I'm a technical author and engineer/scientist, not a press article writer.
@Rubix
I have a specific question my wife wants to know:
Did you specifically agree to any edited changes to the manuscript before it went to publication?

you should have control over the copywrite & wording as it is your article/piece
and as this is also a science/news/press article, you should still retain copywrite and control

i guess i am asking if they had a signed paper where you agreed to publish it as is/agreed to allow them to make alterations without your permission?


Jan 11, 2015
@Captain Stumpy

Thanks for your comments. I must admit, it's the first online article I've submitted under a creative commons license as I understand. In answer to your question, no my approval was given after some intial edits, but before other signifcant edits were made, including the title! I have expressed my frustration with 'The Conversation', when an article is edited significantly after approval. It is more of a learning experience for me to be honest. I'm as frustrated as you that it was the professional 'editors' which introduced these issues. What does that say about online article publishing? In this case, I'm sure shortcuts were taken, as I only had an hour to prepare the article before sending it to them. In general however, I think for the layman interested in space, there are still more positives than negatives, thus I don't mind taking it on the chin this time.

Jan 11, 2015
thus I don't mind taking it on the chin this time
@Rubix
there is definitely more positives than negatives with regard to the science and content, thanks.

i would recommend that you take serious control over your articles in the future
Especially with regard to allowing others to edit after the fact

I would think, as a technical writer, you are far more worried about accuracy and clear communication, as well as comprehension and detail, correct? You should also worry about credibility for yourself
(because writers get sued all the time for what they say)

Like you said, consider this a learning experience...
for future reference, perhaps you should discuss terms and conditions before publication and insure the publishers that you are more than willing to issue litigation over what some would consider "trivialities" because they affect your credibility.

Jan 11, 2015
@Captain Stumpy

Indeed, you're correct. As an engineer/scientist you can imagine that it's very frustrating when someone mangles up something technical you've composed. But to reiterate, it's an experience and knowing this, I would pay more attention to this potential pitfall in future. In the meantime, I get far too much pleasure from research and development in advanced propulsion for this to really be of concern, however I have made it known to the publishers. I'm sure there will be plenty more opportunities to make the kind of impact I would like, and you can be sure I will not be misquoted again! :)

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