SpaceX Cargo Capsule Leaves Space Station For Home

An anonymous reader writes "The commercial cargo ship Dragon left the International Space Station, and is heading home with nearly two tons of science experiments and old equipment. From the article: 'The unpiloted Dragon departed the International Space Station at 9:26 a.m. EDT to begin a trip expected to culminate just after 3 p.m. with a parachute-assisted splashdown in the Pacific Ocean, about 300 miles west of Baja California. NASA astronaut and station commander Steve Swanson controlled a 58-foot robotic arm that pulled the Dragon from its Harmony node port at 8 a.m., then released the capsule into space 266 miles over the ocean south of Australia.'"

Comments

Slashdown confirmed

[lecithin]

Splashdown. Status below -

http://spaceflightnow.com/falc...

Re:Slashdown confirmed

[Anonymous Coward]

heading home with nearly two tons of science experiments and old equipment

nearly quadruple the load going up...impressive comrade.

Re:Slashdown confirmed

[Anonymous Coward]

heading home with nearly two tons of science experiments and old equipment

nearly quadruple the load going up...impressive comrade.

to be fair, it was going to fall out of the sky no matter how much stuff was in it.

2 tons?

[Kryptonian Jor-El]

Why would they use a measure of WEIGHT instead of a measure of MASS?

Re:2 tons?

[Anonymous Coward]

Shut up.

Re:2 tons?

[hawguy]

quote>Why would they use a measure of WEIGHT instead of a measure of MASS?

Ton is already ambiguous, but since it is a USA media article, its safe to assume that they meant what is also known as the short ton, or 2000 pounds. The pound is defined as 0.45359237 kg, so it is, by definition, a unit of mass.

Re:2 tons?

[Strider-]

So people who drive cars, and therefore use public transportation less or not at all, should pay more so that people who do use the system pay less?

More likely someone doesn't know that there is a difference between a Ton and a Tonne, and figures they're just the british and american ways of spelling the same thing. The dragon capsule is rated to return up to 2500kg of mass to the earth, so it stands to reason that this is just a lack of pedantry on the part of the author.

Re:2 tons?

[Strider-]

Don't normally reply to myself, but that was a Cut and paste out of another article here. :)

Re:2 tons?

[NoNonAlphaCharsHere]

Also, they say the capsule is 12 feet in diameter. I would prefer to know the circumference area in micro-hectares.

Re: 2 tons?

[Kryptonian Jor-El]

A pound is a unit of weight and can correspond to any kg mass, determined by the gravity of the place where it is being measured. Weight is dependent on gravity, mass is not. Welcome to 5th grade science class

Re:2 tons?

[Baloroth]

Pounds are both a measure of weight and mass, and the USA Today article uses pounds (not tons, Slashdot did that conversion) because, for better or worse, the US population is more familiar with US customary units than metric units, and USA Today is marketed at a US audience (the name is a bit of a clue). NASA also uses US units for some mind-baffling reason (maybe it likes destroying Mars Orbiter missions?) so the US units make sense in this story.

Re:2 tons?

[K. S. Kyosuke]

I would prefer to know the circumference area in micro-hectares.

What, you figure they could reduce costs by growing space cabbage on it?

Re: 2 tons?

[hawguy]

A pound is a unit of weight and can correspond to any kg mass, determined by the gravity of the place where it is being measured.

Weight is dependent on gravity, mass is not. Welcome to 5th grade science class

Which is why the metric system has separate units for mass and weight/force.

But that's not the case with the pound, it is used for both (sometimes, but not always more specifically as pound-force or pound-mass)

http://en.wikipedia.org/wiki/P...

The pound or pound-mass (abbreviations: lb, lbm, lbm, [1]) is a unit of mass used in the imperial, United States customary and other systems of measurement. A number of different definitions have been used, the most common today being the international avoirdupois pound which is legally defined as exactly 0.45359237 kilograms, and which is divided into 16 avoirdupois ounces.

Don't believe Wikipedia? How about the NIST?

http://physics.nist.gov/Pubs/S...

MASS and MOMENT OF INERTIA: To convert from pound (avoirdupois) (lb) to kilogram (kg)

http://physics.nist.gov/Pubs/S...

FORCE: To convert from pound-force (lbf) to newton (N)

The real world is not always as simple as what you learned in 5th grade science, when your teacher said "The pound is a unit of weight, not mass", he was correct and incorrect at the same time due to the ambiguous nature of the unit.

Re:2 tons?

[Anonymous Coward]

You can't blame lbf for the mars orbiter fiasco. By your own admission, engineers in the U.S. use U.S. units. It's only people that work with paper that shuffle decimal points and call it math. The creature from hell that drew up the contract for instance. How else can you slip a few billion in budget overruns unless you disguise your numbers in terms no sane individual would dream of using in the real world.
Now don't get me wrong, Metric is fine for people like theoretical physicists and government accountants. Like I said all you got to do is talk to or read some of the crap these guys come up with for a few minutes and you'll have a new respect for furlongs per fortnight.
Now Hubble. That's a different story. Those guys just suck at manufacturing. Math was just a scapegoat.

Re:2 tons?

[Teancum]

That is two metric tons or in other words about 2000 kg. 1000 kg == 1 metric ton, which is also about 2200 lbs or roughly close to a standard "short ton".

But it still is measuring mass.

Re:2 tons?

[Teancum]

With spaceflight (and SpaceX specs) it is metric tons.... but still about the same amount of mass/weight.

Re:2 tons?

[fsagx]

Because nearly everyone forgets about the slug.

Re:2 tons?

[Teancum]

People landed on the Moon with pounds, feet, gallons, and other "Imperial" measurement units. It is possible to do these things and not need the Metric system. Hell, they landed on the Moon using slide rules which performed most of the calculations and for those things that needed faster computations, NASA needed to invent a real-time operating system (something that didn't even exist prior to NASA's use of the OS).

Don't get me started on how silly the metric system is too. It has its use and is widely used, but it also has a number of limitations and shortcomings. I certainly wouldn't blame the crash of the Mars Orbiter strictly on a supposed backwardness of NASA engineers because they happen to use different units than the ones you apparently are used to using.

Re: 2 tons?

[Ksevio]

Well we can probably assume that they meant the equivalent weight on the surface of Earth, since otherwise it would be a meaningless number.

Re: 2 tons?

[Anonymous Coward]

The engineering unit for mass in the US is a slug, unless you want to confuse yourself with lb mass and lb force which may indicate the same value, but not the same thing. The lb measured with a bathroom scale is a lb force. The conversions can be found here http://en.wikipedia.org/wiki/Slug_(mass)

Example: A sack of concrete may have a mass of 50 lb, and will weigh approximately 50 lb on a legal for trade force type scale (like a common loadcell or spring scale). If you put the scale and the sack of concrete on a centrifuge, and spin it to apply 2g of acceleration, the scale will indicate 100 lb.

Re:2 tons?

[CrimsonAvenger]

Also, they say the capsule is 12 feet in diameter. I would prefer to know the circumference area in micro-hectares.

So you'd prefer it if they converted the circumference from feet to square feet, then from square feet to square decimeters?

Re:2 tons?

[Anonymous Coward]

Don't get me started on how silly the metric system is too. It has its use and is widely used, but it also has a number of limitations and shortcomings.

Such as? I expect you'll say a lack of easy divisors, but personally I can forgive that for not having to remember how many foos there are in a bar.

Re: 2 tons?

[rossdee]

But that's not the case with the pound, it is used for both (sometimes, but not always more specifically as pound-force or pound-mass)

Theres a;so the pound sterling £ which is metric. It used to be Imperial (pounds, shillings and pence)

Re:2 tons?

[rossdee]

They should stop using the term 'metric ton' . A thousand kilograms is a megagram

Re:2 tons?

[caseih]

The problem with metric is that some of the arbitrary base units are more difficult for humans to estimate and use. For example, let us take some common units of measure: centimetres are too small, decimetres are too large. Both are inferior for human estimation compared to inches. An inch can be approximated more easily using say a segment of a finger. Even feet are easier for a lot of people to estimate than metres (or yards). Especially for in-between distances that are neither small nor large. In general the idea of using orders of magnitude prefixes is a great idea, but the base unit, metres, leaves something to be desired. And lets not kid ourselves. All units of measure are arbitrary. A metre is an arbitrary length. It's currently based on some reference bar somewhere. It may have originated by dividing latitudinal distance by some factor or something, but the standard metre is completely and utterly arbitrary. We could have selected some other unit like an inch to be the base and everything would be fine, though a kilometre would be very small.

Re:2 tons?

[Anonymous Coward]

Metre is not based on physical reference, only SI unit that is still based on physical reference is kilogram and scientists are working on fixing that.
All imperial units use SI units as reference by the way, definition of inch is 25.4mm

some of the arbitrary base units are more difficult for humans to estimate and use

Thats is bs, imperial units are just as hard for me to estimate as metric units are for you, it depends on whatever you are used to. That's not the important reason to choose one measurement system over another, nor is the prefixing. The real reason is that SI unit system is complete, while imperial system is not. What is the equivalent of say ampere in imperial system? There isn't one. Lots of base units simply don't have equivalent in imperial system and therefore imperial system doesn't have most of the derived units. Unless you are going to use monstrosities like say pounds per second or candelas per square inch. And if you ever do that you deserve to die the fiery death of unit conversions.

Re: 2 tons?

[aliquis]

But since pounds is only used in the brittish empire and because that have become so small by now does it really matter any more? ;D

Everywhere it matters we'd use newton and kilograms anyway.

Just limit the usage of pounds into the queens closet already.

Re:2 tons?

[Teancum]

The term "ton" is widely used by many cultures and is a hold-over from earlier mass-weight units. If you want to call it a megagram, that is your call, but the widespread and common usage is still "metric ton" by both governments and especially industrial users. If you want to put on blindfolds and pretend that such units don't exist, that is your own problem and you will be laughed out of many conferences by being such a stupid stick in the mud about such silly things.

Go ahead and be a purist if you want, the rest of the world will continue to exist and go on its merry way. Complaining on Slashdot isn't going to change the world either.

Re:2 tons?

[Teancum]

The only real units IMHO are Plank units, but even those aren't useful for practical everyday applications.

BTW, you don't need to worry about unit conversions unless you are using different subsystems from different countries or manufacturers that aren't using the same units. It really doesn't matter what you are using even if it is centifurlonghs per microfortnights for velocity. While done as more or less a practical joke, the microfortnight was used by VMS in its timing circuits and used for various accounting purposes. It shows up in MS Windows as a portion of the VMS thread accounting system is a part of the kernel (under license from DEC from a long time ago).

Re: 2 tons?

[mrvan]

You guys are just crazy

It is a mass that accelerates by 1 ft/s2 when a force of one pound-force (lbF) is exerted on it. One slug has a mass of 32.174049 lbm or 14.593903 kg based on standard gravity, the international foot, and the avoirdupois pound

So to avoid the confusion between lbm and lbf, you make a new unit of mass that converts to the other unit of mass with the easy to remember value of 32.174049! Brilliant!

Re:2 tons?

[Eunuchswear]

"metric ton"?

ITYM tonne.

Re:2 tons?

[Alioth]

And 1000km should be 1 megameter.

Re:2 tons?

[Anonymous Coward]

They didn't. They used "tons" - a measure of mass, not weight. A ton is 1000 kilograms regardless of weight (that's a metric ton - certain countries have other definitions which pre-date this, such as the 1016kg ton in the UK and the 907kg ton in the USA, but those are mass units too).

Re:2 tons?

[Alioth]

I don't find metric any more difficult to estimate or use. I use both metric and imperial units every day, and your message is the first time I've ever seen anyone saying a centimeter is hard to estimate. I find estimating stuff in cm no more difficult than doing the same in inches.

Where metric wins *massively* is when you're having to deal with using lots of different types of measures, such as estimating things such as power requirements, energy requirements and that kind of thing because the units are designed to work with each other and are all base-10. Imperial measures are all base something-random (for instance, with weight the common things are divisions of 16, eg 16 oz in 1 lb, but in distance it's something else, 12 in to 1 foot, 3 feet to 1 yard, 1760 yards to one mile) making it absurdly difficult to do mental estimations of things involving the different units because of all the arbitrary conversion factors you end up needing. You must admit that 1000 meters = 1km is a lot easier to remember and use than 1760 yards to 1 mile. You can work out instantly how many meters a distance of 1.75km is, but not so easy to mentally figure out how many yards in 1.75 miles. OK, a trivial example that's probably not what a lot of people do every day, but just consider some things in engineering - mentally estimating the number of joules a capacitor can store at a given voltage is much easier than doing it in calories because you don't need to stick an arbitrary-seeming conversion factor into the process if you're doing it all in SI units. The lack of consistency in imperial units means you're having to do this all the time and this makes it a lot more error prone.

Re: 2 tons?

[Barefoot Monkey]

The word "pound" can refer to mass, weight, or currency. To disambiguate, terms such as "pound-force", "pound-mass" and "Pound sterling" can be used instead, but otherwise the meaning is often clear in context. In particular, the ton is defined in terms of the pound-mass (2000lb or 2240lb, depending on who you ask), although officially the various "ton" units are defined in terms of the kilogram - also a unit of mass. And of course, the metric ton is 1000kg.

Re:2 tons?

[Barefoot Monkey]

True - that's the term consistent with the current SI definitions, but I'd personally prefer calling it a kilograv :p

Re:2 tons?

[Anonymous Coward]

Circumferences have area?

Some calculations

[ilguido]

So NASA spent $1.6 billion for the CRS program, that is for 12 missions [1]. That is $75 million for mission. The payload of the CRS-3 mission, the biggest so far by the way, was 4,605 pounds (the declared maximum is 7,300 lb)[2], in other words $16,200 for pound of payload, including packaging. I'd like to know how does that compare to other space transport services.

Re:Some calculations

[symbolset]

Since there is currently no other craft available that can bring stuff back, this is pointless. Later Musks plan is to reuse all the components, which should bring the cost down a lot.

Re:Some calculations

[bbn]

The space shuttle was $450 million per mission not including development costs. That would lift 24 ton and a lot of volume to ISS. That was good for building the space station but perhaps overkill for the maintenance. They are not even using the full capability of the Dragon spacecraft.

The Dragon will only move 3.3 ton to the ISS. If you only count weight by dollar this is more expensive than a Space Shuttle launch. On the other hand you will get much more frequent deliveries which may be what is needed now.

If you count development costs, each Space Shuttle launch was 1.5 billion USD. Viewed this way, the CRS program for Space X is just one shuttle. And perhaps this is the correct way to do the accounting considering that the 1.6 billion that Space X receives also has to cover their development costs. I would expect that they can give a good discount on future launches, should NASA want more than 12.

Re:Some calculations

[Anonymous Coward]

Should be noted that the capsule was physically full. It could have carried more mass but the average density of the cargo isn't that high so it would seem that it could've taken more up while in fact it took a full load.

When resupplying the ISS, it is not all about up/downmass. Physical dimensions also matter and some cargo is lighter than others.

Re:Some calculations

[cbhacking]

Better than just discounting once development is paid off, actually... part of that R&D investment is into making the first stage, the Falcon 9 booster, re-usable. Currently they are single-use and amount to 70% of SpaceX's costs per launch. A reusable first stage would let SpaceX cut their costs by a tremendous margin.

It's really astonishing how much SpaceX is achieving with the budget they have. The space shuttle may have been a technological marvel in terms of capabilities, but it was unreliable, expensive as hell, and actually less capable than the Falcon Heavy rocket that is another main consumer of SpaceX's R&D budget. At the current rate, Falcon Heavy will be flying before the (amortized) cost of even one Space Shuttle mission is paid to SpaceX by NASA (if you amortize the 1.6B).

Re:Some calculations

[Teancum]

The COTS program never even required hauling cargo back from orbit. The contract was strictly for sending stuff up to the ISS, not for returning anything (which is why the Cygnus spacecraft doesn't have re-entry capabilities). SpaceX threw the re-entry capabilities on as an extra and offered it to NASA,which NASA is certainly using.

That the Dragon is the only vehicle currently in production which is capable of returning more than a hundred kilograms of stuff from orbit (that is the Soyuz spacecraft, where I suppose more cargo could come back at the expense of one crew member), it seems like a smart decision on the part of SpaceX too. Other than the Soyuz spacecraft, I suppose there is the Shenzhou spacecraft that the Chinese are flying that could also return cargo, but the Dragon still runs circles even around that vehicle.

For vehicles that have gone into space and currently being used, that is it though. The Shenzhou, the Soyuz, and the Dragon are the only vehicles capable of returning any payloads from space. The Dragon is the only one that measures its return payload in metric tons.

Re:Some calculations

[Teancum]

Most of the early flights of the Dragon (including this CRS-3 flight) have been flying low value cargo to the ISS. Mainly food and consumables (spare parts, batteries, a few laptops, and other small stuff) that if it was lost wouldn't necessarily be all that important. As you've mentioned, this is also somewhat bulky, but there has been spare room left over. That is why one of the surprises that SpaceX sent up was some ice cream (a very rare treat in space) and a few bags of snack food that wasn't on the formal manifest that NASA wanted to have shipped up.

The later flights are supposed to be sending up more expensive equipment and devices that are also a whole lot heavier, but NASA is gaining trust with the fact that SpaceX can deliver the intended payloads on a timely manner too.

Re:Some calculations

[CrimsonAvenger]

So NASA spent $1.6 billion for the CRS program, that is for 12 missions [1] [wikipedia.org]. That is $75 million for mission.

No, that is $133 million per mission.

$75 million is correct for $1.2 billion for 16 missions.

Re:Some calculations

[WindBourne]

Well, you can simply use Google to figure out things. However, I was curious, so I did some of this leg work. The Soyuz-ST rocket that launches 7.8 tonnes to LEO costs $61M in 2006. That was just the launch vehicle.
Now, that was just the launch, and that was almost 10 years ago. So, the price is at least 50% more (russian money has appreciated).
In addition, that does not include the costs of the progress itself. That is likely going to double the price. IOW, you are probably looking at 180M or so for a launch.
Now, how much does it launch? 2.3 tonnes. The reality is that it will carry far less due to packing material
And how much does it return to earth? 0.
So, how does it compare to SpaceX? Well, SpaceX takes up more. In addition, it is cheaper. And most importantly, it brings back items. Progress can return NOTHING. And this is a STEAL compared to the shuttle. Why? Because this needs to go up roughly 4-8 x a year to provide supplies for the ISS. The ISS does not have loads of storage. As such, the shuttle would be going up mostly empty if it was still being used right now. And it would be far too expensive (each mission was about 1500M vs less than 150 million / spaceX F9 with dragon).

Re:Some calculations

[Anonymous Coward]

That the Dragon is the only vehicle currently in production which is capable of returning more than a hundred kilograms of stuff from orbit

the Soyuz spacecraft, where I suppose more cargo could come back at the expense of one crew member

So the Russians have managed to lower the mass of three live bodies and life support gear to less than 100 kg?

Other than the Soyuz spacecraft, I suppose there is the Shenzhou spacecraft that the Chinese are flying that could also return cargo, but the Dragon still runs circles even around that vehicle

Last time I checked the Shenzhou is also capable of returning three live bodies.

Re:Some calculations

[Teancum]

No, the extra cargo that can be returned other than some cosmonauts is about 100 kg. Most of the life support for the Soyuz is also in the "orbital module" part that is left behind in space... part of what gives both the Shenzhou and Soyuz spacecraft its very distinctive shape and how it looks very different from the Orion/Apollo/Dragon capsules that don't have separate parts.

Keep in mind that the Soyuz and Shenzhou spacecraft have two parts: the re-entry capsule and the life support "orbital" module that are docked together on the launch pad. That orbital part is ejected before re-entry and simply burns up in the atmosphere, with the remaining air in the Soyuz capsule being more than sufficient for the couple of minutes needed for actual re-entry.

This Soyuz system did give the Soviet Space Agency (they were the Soviet Union at the time) some problems and unfortunate deaths because the door between these two modules was not secured properly. That has been fixed though.

BTW, I am not disputing that the Soyuz and the Shenzhou return people. What I am pointing out is that they are the only spacecraft besides the Dragon at the moment which can return anything from space. Get a clue here and actually read what I said.

Re:Some calculations

[Anonymous Coward]

Station modules would be better served by launching with a service module attached from a heavy lift rocket, which would then dock with the station. the service module would detach and burn itself up in the atmosphere. no need for a large spacecraft like a shuttle to be involved. Also, you could then start doing interesting things like launching a 2 part assembly into orbit with a basic trestle holding it together, Put the parts together to make something wider then would fit in a fairing.

this is nominally how you would put together a mars ship.

Re:Some calculations

[Anonymous Coward]

Hey dude, the Dragon has a disposable "service module" (the part with the solar panel) just like the Soyuz and Shenzhou.

I get your your point though that stuffing the reentry module (Dragon, Soyus/Progrss, Shenzhou, ATV, H-II) is complicated rocket science mastered exclusively by SpaceX, and is something the dumb Russians, Chinese, Europeans, Japanese have never solved. /sarcasm

Re:Some calculations

[Teancum]

The disposable service module on the Dragon is not habitable and in fact can't be serviced from inside of the capsule. About the only thing it really has is just solar panels... not even RCS fuel tanks or thrusters.

The Shenzhou and Soyuz both have habitable modules that contain food, life support, and even scientific experimental hardware (when applicable) that astronauts use when in orbit. It is a bit different than what the Dragon has.

Sure, both Russia and China are capable of building something like the Dragon for reentry, but SpaceX is the only organization which has bothered. The point of this sub-thread is bitching about how expensive the U.S. federal government is paying for hauling cargo back from the ISS and saying there are obviously cheaper ways to get it done. If those alternative approaches exist, show it! Regardless, even at the heavily inflated price of $16k/kg of cargo that the OP asserted is being charged by SpaceX for cargo to the ISS, it still is cheaper than the $25k-$30k/kg that the Space Shuttle program cost taxpayers (at conservative low-ball price estimates for shuttle costs too). That was also the only other vehicle capable of bringing back large amounts of cargo from space, but there is no way that will ever fly again in the future as it is firmly retired and all of the infrastructure to get a shuttle into orbit completely dismantled.

Spikey

[Impy the Impiuos Imp]

> "from its Harmony node"

Man, Buffy the Vampire Slayer has some powerful fans.

We Better Start Going BORG

[Anonymous Coward]

.....On that Space Station we've gotten up there right now. Remove old worn parts & coverings with new ones. Constantly renew it. Keep it new. (Or as new as possible)
              We no longer have the tech to transport 20 tons of parts into space anymore (space shuttle). We can only do 3.3 tons at a time.(Dragon) We lost the ability to move massive tonnage transport with the retirement of the shuttle program. Therefore we've also lost the ability to mock up another station!
  The space station is scheduled to be scuttled in the next decade or two. :(