Challenging terrain

We’re facing some serious challenges when it comes to planning our imaging flights and choosing a site for take-off and landing.  The high Arctic is an unforgiving place.

The Survey Area

Midtre Lovénbreen as seen from Ny-Ålesund. It’s steep! The mast in the foreground was built for Roald Amundsen to tether his airship prior to the first confirmed flight over the North Pole in 1926.

Midtre Lovénbreen, the glacier we’re surveying, rises almost from sea level (the ice begins at about 100 feet) to well over 600 feet in altitude over its lower slopes.  It goes much higher, but this is the region we’ve chosen to cover.  The flights must therefore involve a lot of climbing.  With about 120m between imaging passes, on the lower slopes the UAV must rise approximately 75 feet per pass, assuming our imaging passes are lateral, across the glacier.  If there is a noticeable wind across the glacier, we may be forced to use imaging legs that run up and down instead, which is even harder; we can’t climb and descend 500 feet on each imaging leg – the batteries wouldn’t stand it – so we’ll have to fly ‘terraces’, doing a set of imaging legs and then ascending to a new altitude to begin the next terrace.

Take-Off and Landing

Finding a site for take-off and landing is even more challenging.  Forget grassy fields, there is almost no vegetation this far north.  At this time of year there is no snow left on the ground either,  which is a shame because even if it’s packed hard snow tends to remain smooth and flat over reasonably large areas.  Our choices are:

The Tundra

This seemed promising initially, because some areas of the tundra are soft and mossy, like the site we chose for our test flights.  However:

• Near the glacier, glacial drainage has formed a wide dry river bed, entirely composed of rocks.  It’s also fairly uneven.
• Our flight permission from the Norwegian Civil Aviation Authority only covers visual line-of-sight flights, so launching from the soft tundra and flying it round the corner is out of the question.
• The distance from the tundra, over the moraines, to the glacier will significantly extend our required flight times and reduce our effective range – and the required size of the safety circle would allow flight way out over the sea, which we’d like to avoid.

The Ice

A drainage channel on the surface of Midtre Lovénbreen. Not the sort of place we want the UAV to go.  For an idea of scale, the channel is well over a metre wide at this point.

At first sight, launching from the glacier itself seems like a great idea.  Relatively few rocks across a wide open space, right in the middle of our survey area.  But again, there are risks:

• The ice is not as smooth and flat as it looks, and a lump of ice is as hard as a lump of rock as far as the UAV is concerned.
• There may well be crevasses and holes in the ice, some tens of metres deep, and if the UAV fell into any of these it would be lost forever.
• The ice is very slippery, so anything but an uphill landing could result in a very long slide – and our worry is that this could terminate in a crevasse.
• Climbing onto the ice for each launch increases the level of personal risk associated with the flight.

The Moraines

A possible launch site between the glacial moraines. Not particularly forgiving terrain, but reasonably level.

The glacial moraines – the big piles of rock left behind at the foot of the glacier as it retreats – are not an obvious place to look for a take-off and landing site.  Imagine the spoil heaps around a slate quarry, with huge piles of jagged rocks.  They’re exactly the sort of place you wouldn’t want a UAV to come down.  But at the foot of Midtre Lovénbreen, between two sets of moraines, is a large flat area of dry river bed.  It’s not unlike the area of tundra beyond the moraines, but it’s closer to the glacier and in places it’s softer, where rock dust from the bed of the glacier has mixed with water and made a thick, dry, porridge-like mud.  A landing on one of these areas would leave us with a dirty, but intact, UAV.

So for our first imaging flight we’ve decided to launch from inside the moraines.  If the landing is difficult, or we find that it is difficult to retain visual line-of-sight on the UAV at its maximum range, we may reconsider for future flights.