A picture from the edge of Space – Planning

Here are some quick and dirty notes on a new project idea.

Background


So I would like to take a picture from the edge of space. I want to see the curvature of the earth.

After some looking around, I need a minimum high of about 35,000 feet, but it would only be possible with wide angle lens. I have seen numbers more like 60-80 ft for more sure things.

So I think I will aim to leave the troposphere and take a picture from the lower Stratosphere. Around 30km up. ( I am going to try and standardize to metric from this point onwards. ) Thats not a lot the Earth is 12,742km in diameter.

The natural way to do this is with a HAB ( High Altitude Balloon )

Things I am going to need:

  • A Balloon (Burst hight between 20-30km)
  • Payload Box
  • Parachute
  • A way of tracking it, GPS & GSM, maybe Radio
  • A camera
  • and all the bits that connect it together!
  • Permission from the Civil Aviation Authority
  • Helium

Useful links

HAB Hub

DIY Space

UK HAS Wiki

How long is it going to take?

An average weather balloon will ascend for about one and a half hour before popping out. Then, the payload boxes and the flight equipment would continue the travel, and it might take an additional half hour. The total duration of the flight would be about two hours

 What lift is required

If the payload weighs 10 lb, the lift should be at least 1.5 times that weight or at least 15 lbs of lift.

What size Balloon

High altitude balloons are listed according to the weight in grams and not by size.

Weight -> Burst height -> Payload size

200g -> 19km -> 250g
600g -> 27km -> 250g
800g -> 30km -> 800g
1.2kg -> 31km -> 100g
2.2kg ->35km -> 2.5kg

Okay, so we have a case of diminishing returns here. Looks like 0.8kg balloon might be the sweet spot for height vs weight. Looks like once you get past about 800g, payload becomes a pretty straight function of balloon weight.

I should be able to get a 800g Balloon for around £45.

Helium
Based on some guess-estimation I am going to need about 80-100 Cublic feet of a helium to fill the Balloon. (ISO! 2.25 cubic meters or about 2,250 Litres )
This sounds perfect

N10 Helium Canister Spec: Contains 2.61 cubic metres (92 cubic feet) of helium gas.

Prices on a N10 seem to Varry looks like I can get one for between £60-90

Tracker

HabHub seem like the people to help me here,

We could use a R-pi, add a radio Module like this (this guide will prove useful) and a gps module like this

Box it all together, and then we HOPE broadcast the location over radio!

Then add a Camera and maybe some weather instruments to the Pi ( and pray it has enough pins and ports )

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