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A Chinese rocket launches in 2017. Does NZ need to keep a better eye on these events?
OPINION: The continued peaceful use of space for the benefit of us all requires diligent monitoring of orbital developments and in that regard New Zealand’s location is vital.
Everyone knows NZ is a unique place, but the significance of our geographical location for humankind’s activities in outer space is generally overlooked.
Consider Rocket Lab’s launch site on the Mahia Peninsula. From there satellites can be dispatched on trajectories within the arc from northeast to southwest, and the lower rocket booster stages drop harmlessly into the Pacific.
The famous complex at Cape Canaveral in Florida was built there for similar reasons, as is the second Rocket Lab site at Wallops Island, Virginia – there’s only ocean to the east.
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Compare that to Israel – which cannot launch eastwards into the preferred prograde orbits moving with Earth’s spin – because hardware would drop onto Jordan, Saudi or Iraq. The Israelis must aim westwards over the Mediterranean, meaning retrograde orbits.
Such “wrong way” paths have greater chances of colliding with other satellites, just as it’s not a good idea to drive on the other side of the road.
There is another way NZ’s geography enters into things. Satellites dispatched eastwards from (say) North Korea or China are pulled southwards by gravity, travelling as far south of the equator as their northern launch pads. They pass east of Australia (beyond the grasp of radars there), and cruise over our longitude about 15 minutes after launch.
Early warning of potentially hostile launches from our friends in North America and Europe could depend on having suitable sensors in NZ. The US just installed a space radar in the Marshall Islands, but it cannot see very far south.
In common with other nations, NZ claims an Exclusive Economic Zone stretching 200 nautical miles (370 km) from our shores. Obviously we need to know what is happening within our EEZ, so we monitor it in various ways.
A Russian satellite is following a US satellite, inspecting it, in this Nasa image.
Now think of the same distance vertically, to 370 km above us. Every day thousands of satellite passes occur lower than that altitude, or not far above it. Most satellites circuit in low-Earth orbit (Leo), the Space Station whizzing 410 km above us. NZ’s ability to monitor such transits? Essentially zero.
American company LeoLabs has built a radar in Otago to detect small orbital debris, along with other radars in Texas and Alaska, and soon in Costa Rica.
The US Department of Defense, through the Space Command, operates a network of optical and radar sensors tracking orbiting objects, making the whole dataset (bar security-classified payloads) freely available to anyone, see celestrak.com.
Canada, the UK and Australia all contribute to this space monitoring, from which one can deduce which satellites are passing over NZ and when.
But shouldn’t we have some sort of capability to see for ourselves what is happening in the skies above New Zealand? Suitable radars located near (say) Invercargill, Auckland and in the Cook Islands could track every satellite passing across a line drawn from the South Pole to the equator, and make a vital contribution to ensuring that peace is maintained in outer space.
Dr Duncan Steel, a space scientist based in Nelson, has worked for both Nasa and the European Space Agency.