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.

Comments

Moo

[Chacham]

Picture this, soon their balooning costs will skyrocket to reach even greater heights.

Re:Moo

[gfody]

that direct link to a 56mb file (for 17 seconds of footage!) will be the most expensive part of the project

Re:Moo

[Anonymous Coward]

A bit of a bugger if the number in question triggers the detonator.

Re:Moo

[another_henry]

If the parachute fails (unlikely but not impossible) it will "plummet" at a stately 15 mph. We decided to have a launch criterion that it must not visibly damage a melon when dropped on it at a velocity matching the terminal velocity for a no-parachute descent. The testing for that was a lot of fun and we did get through a couple of melons before reaching the right combination of foam material, thickness and shape but now we are confident that it wouldn't hurt someone if it hit them even with a parachute failure. The chances of hitting anyone are very slim anyway, these things always land in fields. Plus we have software running on the balloon that predicts the landing location based on recorded and predicted wind speeds, and aerodynamic characteristics, and will operate the cutdown to release the payload early if it threatens to land in the sea or a heavily built-up area.

Re:Moo

[another_henry]

Someone did have the hilarious idea of putting a bike helmet on the bottom, open side downwards.

Re:Moo

[sacherjj]

Acceleration through gravity has nothing to do with terminal velocity. It describes how fast the falling body reaches its terminal velocity. The speed at which it will fall is where the forces from gravity meet the countering forces from air resistance. The payload will accelerate to a very fast speed at altitude, but slow down gradually as the density of air increases and therefore the air resistance increases. This is not a situation when you can do simple calculus with 9.81 m/s^2 and ignore air resistance.

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

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

Re:Very cool hobby...

[gkhan1]

What kind of permissions from the local flight authority does it require? Aren't they hard enough to get to prohibit hobbyist involvement?

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:Very cool hobby...

[emamousette]

Slashdot readers are an endangered species?

GSM text messaging

[ubersonic]

So GSM phones do work at that height?

Why do we need inflight GSM mini stations then?

Re: GSM text messaging

[leereyno]

Consumers don't NEED them at all. They're there so the airlines can make a buck.

Anyone familiar with the story of flight 93 knows that cell phones work at the cruising altitude of commericial jet aircraft.

Lee

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.

Re: GSM text messaging

[brandonY]

I'm sure the phones will work at more or less any height - the higher the better.

Not to be a sarcastic, literal-taking idiot, but I bet if I were, say, 0.5 AU high, my phone wouldn't work. Heck, I bet the lousy thing wouldn't even work from the moon's surface, especially if I was in a tunnel.

Re: GSM text messaging

[Technician]

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.

On the flip side, the phone can't deal with dozens of control signals from dozens of towers on the same channel. Normal operation a phone sees a control channel from several towers nearby on several frequencies. These control channels get geographly re-used. At altitude it's the ability to see many towers on the same frequency at the same time scramples the signal to the phone and breaks the phone ability to lock on to a control signal. This is the sudden loss of signal bars seen on an airbone phone. Too many towers in view at close to the same signal strength and on the same channels as each other.

Re: GSM text messaging

[another_henry]

In experiments with light aircraft and with the balloon we found that ordinary GSM mobile phones / cellphones stop working at about 2km, 6000ft altitude. There are a few ideas as to why but my best bet is that it's caused by the phone being able to see several towers operating on the same frequency, which you can rarely/never do from the ground. We had telemetry from the two 434MHz radios during the flight and the GSM phone was a backup to send the landing site location if it landed in an area of poor radio reception (which was not unlikely - when the balloon is in the air it should be possible to receive transmissions from the 10mW transmitter at a distance of at least 400km but when it's on the ground, especially with the antenna facing down, you're lucky to hear it within 1km)

Re: GSM text messaging

[AsnFkr]

Well, to be fair Flight 93 was pretty close to the ground compared to your average flight.

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 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

Yes, but orbital?

[caseih]

Sending rockets out into space is pretty easy, but the real trick is orbit. Cheap shots to the upper atmosphere don't do a lot of good in terms of launching satellites and other objects into orbit, although I'm sure they can provide experience with the technology. Achieving orbit requires a lot more energy. There's a reason missiles and rockets are the size they are.

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:Yes, but orbital?

[Martigan80]

I'm sure this is also understood. The key point here I see is that these people where able to pull of such an event at the cost they did. To me this also seems as a spirited event to prove that you don't need the government or big corps to do such things. I mean for fun this is great but it just might be the trigger to get other people/groups thinking on how to proceed with the next step.

Re: GSM text messaging while flying

[cloricus]

Having made several flights lately in light aircraft I've been rather bored and have happily sat watching the bars on my mobile phone...Now I didn't realise there was a full on tin foil hat issue here though my results are as follows:

Outbound from where I live on a Nokia 6230 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. Leaving on the way back to here I had phone signal for a call up to ~7,000 feet and lost phone and SMS at about the same time.

The Blackberry 7230 I had with me made it another 500-1000 feet over my Nokia in regards to signal though GPRS didn't fare so well. Luckily Brick doesn't require phone signal. :)

We tended to fly at around 12,000 feet most times and those observations from one trip seem about right for the rest plus I can confirm from having to drive several of the distances that there is full phone coverage a long the routes.

Re: GSM text messaging while flying

[Gordonjcp]

When I tried it from a motor glider in a fairly remote area (few cells, large areas) I got a snotty letter from Orange saying that roaming at 50kts between very non-adjacent cells made their network shit itself. I wish I'd kept the letter...

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.

Re: GSM text messaging while flying

[x2A]

For this balloon thing though, could put the GSM unit into a downward facing pringles tube, increasing the signal strength, narrowing the transmitted area, and sticking to their "cheap, very very cheap" idea :-)

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.

Costs/Point

[MikeMorley]

I actually worked in the same lab as these guys, so here's my input: The reason that this was an important launch was not the photos, although those are cool, but to test the electronics of the tracker devices they'dd designed and built. If you read their website at http://www.cuspaceflight.co.uk/ you'll see the other projects - the rocket to space, but also a controllable parachute that can descend to within 100m of a given location. All fairly impressive stuff, given that they've only jsut finished their 1st year of study. As for costs - only a couple of hundred pounds...

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.

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/

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.