Space On a Shoestring

An anonymous reader writes, "Three engineering students from Cambridge University plan to send an unmanned craft into space for £1,000 ($1,880) and have just sent a test mission up 32 km for a lot less. Their snaps from the upper atmosphere are impressive, and were taken by a balloon equipped with off-the-shelf technology including GSM text messaging, radio communications, and an ordinary 5-megapixel camera. They now plan to use a similar craft as a launching stage to get a cheap rocket into space." There's also a video of the balloon launch.

Very cool hobby...

[Cherita Chen]

High altitude balooning is a very cool hobby to get involved in... Two very informative links on the subject are included below.

http://www.grc.nasa.gov/WWW/K-12/Numbers/Math/Math ematical_Thinking/designing_a_high_altitude.htm [nasa.gov]

http://www.amsat.org/amsat/balloons/balloon.htm [amsat.org]

ACES

[Anonymous Coward]

I was in the same program last year at a different university (LSU). The stuff is somewhat exciting, but I don't really think it's newsworthy. I feel like it only made the news because it of the famous university name tacked on...

Regardless, what they've done is an outstanding achievement. The year before mine our school tried to take a picture up there (~100,000 feet) but it didn't work because the cold temperature changed the timing of some electronics, causing them to malfunction =/

I was in charge of the thermal stuff, and let me tell you, it's pretty hard to keep it warm but not so warm that the sun toasts it. And keep in mind the payload, as they call it, could only be 500 grams!

New Aproach?

[Faith_Healer]

This (working to launching rockets from baloons) has been done in the US for quite some time. There are plenty of student baloon payload systems and in fact this week there is a confrence going this week on adressing just this topic. As far as using baloons as a launch platform, there is group from Huntsville AL http://chapters.nss.org/al/HAL5/HALO/that [nss.org] has been launching for quite some time. Good luck to the team from the UK but if any one realy interested in getting things done, perhaps all these individual groups should join forces. Just My 2 Cents

Raw RGB?

[Anonymous Coward]

What self respecting nerd posts a 20 second 240 x 320 video using Raw RGB that weighs in at 69MB??!!

Re: GSM text messaging

[GrahamCox]

I'm sure the phones will work at more or less any height - the higher the better. The problem is that at very high altitudes, the phone "sees" hundreds of cell base stations at once, and the system isn't really designed to deal with this. Even if one cell can decide it will take the initial call, cell switching will be occurring every few seconds as the signal strength fluctuates. The problem multiplies if you are crossing those cells at 500mph. Instead the on board mini-station grabs the call and keeps hold of it, allowing a single dedicated downlink to maintain sanity in the system.

At least this is my only partially-informed assumption (a long time ago I was a radio negineer, but I don't know about the actual implementation details of GSM.) But logically, allowing in-flight GSM phone calls is a bad idea because of the reasoning above. The system is designed on the assumption that calls will be made on the ground, therefore range-limited, and thus can only possibly be routed by one or two base stations, not hundreds.

32 Kilometers = What?

[LionKimbro]

Some context, to help understand this: Earth's Atmosphere, as per WikiPedia. [wikipedia.org]

You can see that weather balloons are in the 18-50 km range, which is what we expect, because that's what they're using, and they got to 32 km.

Re:ACES

[Anonymous Coward]

"I feel like it only made the news because it of the famous university name tacked on..."
"The year before mine our school tried to take a picture up there (~100,000 feet) but it didn't work because the cold temperature changed the timing of some electronics, causing them to malfunction"

There's always the outside chance that this is newsworthy because it worked?

Re:Yes, but orbital?

[QuantumG]

For nearly half a century now we've know how to get into orbit using less energy than the brute force rocket approach. Space tethers are well understood technology that these guys could use to pick up a payload in "space" and swing it into orbit. Tethers that reach into the atmosphere are also possible but the math is just that much harder. Rockets are not the only way to space, they just require the least amount of in-orbit infrastructure. Once you have that infrastructure up there though, they really don't make a lot of sense.

Re: GSM text messaging

[tylernt]

There are indeed distance limitations to GSM. Same problem with long runs of cable in Ethernet -- signals only travel at the speed of light, so there starts to be a lag between packet transmission and packet reception. IIRC, in GSM this limit is about 27 miles. When GSM was first deployed in Australia, some remote regions could get full signal, yet not maintain a call because the lag time was too great for the TDMA (Time Division Multiple Access) timeslice to handle. In Ethernet this would be called a "late collision". A workaround was to cut cell tower capacity in half by doubling the TDMA timeslice, thus effectively doubling the range of the cell towers.

I think the main problem with phones at altititude is the farraday cage effect of the aluminum aircraft body. Signals can only exit via the windows, and at high altitude, your signals are going out horizontally instead of down to the ground and therefore the cell towers.

Re: GSM text messaging

[honkycat]

On aircraft, you have the additional problem that you are moving from cell to cell much faster than the system was designed to handle. So even if you are able to lock and stay locked to a single tower, it'll have to hand you off to the next tower before it's ready to do so.

I've experienced problems which I am pretty sure are related to hopping between towers -- not on an aircraft, but when hiking in the Smokey Mountains in North Carolina. We got up to the top and I was surprised to find that I had 4 or 5 bars! However, when I tried to make calls, I was denied and the signal strength would go up and down. I believe I was seeing towers on both sides of the mountain and the system and/or my phone was getting confused.

Re:why ruin a "good" idea?

[bangenge]

launching a giant multi-million dollar rocket filled with liquid oxygen with 2/3 of that fuel carrying just the weight of the fuel is so terribly efficient

because launching the rocket is EFFECTIVE, compared to a balloon that will only reach about midway/three-fourths of the way in the atmosphere, only to fall back to the earth. the rocket has enough to push at a force that will allow it to get into orbit. not efficient, but it's the only way we get the job done.

Re:oh boy

[Sledgy]

Imagine how much fear a group scare monger's can spread by twisting facts.

Can you say http://en.wikipedia.org/wiki/Dirty_bomb [wikipedia.org] ?

That's a sounding rocket

[Animats]

That's a sounding rocket. In terms of performance, it seems comparable to the WAC Corporal [designation-systems.net] of 1944, or maybe the Aerobee [nasa.gov] of 1947.

Nothing wrong with building one cheaply, but it's not a step forward.

Re: GSM text messaging while flying

[Technician]

I had signal for a decent phone call up to ~5,000 feet and could send SMS to around ~6,000 feet, soon after this I lost signal.

More likely you had too much signal. From altitude you tie up one RF channel on several dozen towers in range instead of running at reduced power on the closest tower. This blanket coverage of dozens of towers tying up a channel without the ability to hand your signal to a single tower and free up the frequency on other towers for use by others is why they don't permit phone use on aircraft. If the system is smart, it may have shut down your phone to clear the frequency as the towers noticed an even signal strength from one phone over dozens of towers. You simply did not get a tower assignment at altitude.

Ballons need permission??

[EmbeddedJanitor]

Ballons probably don't need the same sort of clearance. Many weather ballons are launched from weather stations which are often located at airports. I used to work for a company building weather ballon tracking equipment and we'd go test our prototype kit at the baloon launch site which was right next to the end of an international airport runway (right in the high security area next to where you see the planes land with puffs of smoke coming off their tyres). At least twice I can recall flying along at altitude in a commercial airliner and hearing the pilot say: "folks if you look out of the left window you can see a weather ballon". These things carry radar reflectors etc and pose very little danger to aviation.

Re:lunatics?!

[another_henry]

We did extensive drop tests to make sure that the payload wouldn't hurt anybody if it landed on them even if the parachute failed to open properly.
The casing is made of a type of foam that is very good at absorbing impacts, and the whole thing doesn't weigh very much.
If it landed on you with the parachute open you'd just brush it off. If it landed on you without the parachute you'd get a bruised head but would be okay.

Our launches are insured with £5m public liability cover. Arranging this insurance was quite difficult though.

Re:Very cool hobby...

[another_henry]

The CAA were very good about it actually... didn't give us any trouble at all. I think you have to apply at least a month in advance for permission to launch a balloon that will enter controlled airspace (which covers the entire UK from 24500ft up) and they will give you an "exemption" for a certain launch site for a certain period (couple of months). They issue a NOTAM to warn pilots. Then you have to notify the local air traffic control facility 24 hours and then 5 minutes in advance.

Re:Orbit

[another_henry]

Camera it is! Plus potentially scientific or student experiments that would like 3 minutes of freefall for considerably less than the price of most sounding rockets. The next step after the 100km rocket is a bit tentative but we would like to add control systems sufficient to put it through a fairly small window in space and time, as a concept demonstrator for something that would latch onto a rotating space tether. At the moment we have no plans to launch anything into orbit. Without MAJOR sponsorship and a LOT of skill and time, orbit is out of the reach of amateur and student projects IMO. See the development cost of Pegasus, or look at SpaceX and how many $M they have spent so far despite being very lean and efficient.

Re:Precise landing?

[another_henry]

We deliberately waited for a day when the jetstream was relatively calm, it was around 40 knots that day which isn't much at all. Also it helped that the low altitude winds were close to opposite the jetstream winds so it went west and then east. And we put quite a bit of excess helium in to get a rapid ascent rate, around 1000 ft/min. So it was up through the relatively shallow band of jetstream (20000~40000 ft) quite quickly. The winds above that are slow indeed. We started following it after it had reached about 28km on the ascent (we predicted that it should burst around 28-29km, the balloon ended up being a bit stronger than spec and it burst at 32km) and found it about 30 minutes after landing. The GPS is nice to have, it would have taken much longer to do it by radio direction finding. Anyway these things usually land in fields because there are lots of fields around, and despite the purple parachute they aren't blindingly obvious unless you're looking for them. So I don't think it's too likely that someone else would find it first. If they did, hopefully they'd be nice and call the phone number printed on it.

Re: GSM text messaging while flying

[pyat]

In the research center where I work, one of the guys who had worked on the GSM spec gave a talk on this.

He said that the big problem was that it is very tricky for an airborne phone to decide what cell it's closest to, since it can see loads of them and they're all pretty much the same distance (the downward distance is now very large compared to the on-ground inter-cell distance). This means your phone keeps jumping between cells, which incurs quite a lot of overhead on the network (and if you had a planeload of people doing it, it would be very chaotic!).

Re:those poor /.'d fools! Put the pics on FLICKR!-

[carpecerevisi]

Bandwidth isn't the issue. It's the server hosting it, that belongs to the Student Run Computing Facility, that is

Seems that FAA notification is easy

[Secrity]

In the US, notice/permission to launch ballons such as this can usually be done by calling the nearest FAA ATC facility 6 to 24 hours before beginning the operation and giving them the particulars. The applicable regulation is FAR Part 101. http://www.faa.gov/regulations_policies/faa_regula tions/ [faa.gov]

Re:Very cool hobby...

[Rorschach1]

See also ARHAB [arhab.org] for more on amateur radio high altitude ballooning. I have yet to put together a full payload myself, but I've provided electronics for quite a few of these.

Re: GSM text messaging while flying

[MountainLogic]

I've seen very simular problems on mountain top. On top of South Sister in Centeral Oregon (Western US) at 10,350 feet I've seen hapless users try to use their cell phones to no avail. As much as some twit on cell phones in a wilderness area chokes me I told him to just drop off the summit - any direction - and sure enough he was able to connect. His problem was too many cells. Dropping even a few meter below the summit limited his line of sight to a reasonable (and planned for) number of cells.