Debris jettisoned from rockets launched at Mahia Peninsula will break up into at least 280 fragments, with the heaviest being the motor assembly which could weigh as much as 360kg.

Some of the jettisoned components "may" reach the Earth's surface, a report from the Ministry for the Environment says.

"Some or all" of the components will burn up in the atmosphere. All debris that reaches the Earth is expected to fall in the sea, with MfE saying "no jettisoned material is likely to impact landmasses".

ROCKET LAB Rocket Lab's launch site on the Mahia Peninsula.

An economic analysis by Sapere Research Group estimated a space vehicle launch industry could directly add $30 million to $80 million a year in value-add to the economy. That was based on between 52 and 120 launches a year.

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MfE's report said company Rocket Lab was planning to have test launches of its small Electron two-stage liquid-fuelled orbital launch vehicle in late 2016.

The company's public schedule for launches indicated one commercial launch in 2016, nine in 2017 and 12 in 2018.

The splash down areas for debris from Stage 1, nose fairing, and Stage 2 batteries originating from the test launches are shown as ellipses, while shown as red boxes are the debris areas for Sun-synchronous (to the south) and Eastern (to the east) launches. Map from Niwa, with data supplied by Rocket Lab.

MfE said Rocket Lab's longer term plan was to build towards a maximum of one launch a week of the 17-metre Electron space vehicle.

Confusingly, Rocket Lab's website said the company was "on a trajectory to provide at least 100 launches per year".

The company is advertising launch costs of $4.9 million - much lower than other options. Its rocket will be able to lift a 150kg payload to a 500kg orbit.

The Electron has a dry weight of 1250kg, and will be 10 times heavier when filled with fuel.

A report prepared by Niwa for MfE tried to assess the cumulative impact of one, 10, 100, 1000, and 10,000 launches - at a rate of one a week. Rockets could be launched over the sea either to the south or the east.

Niwa found a "low" probability of debris making a direct hit on a fishing boat. That was based on the assumption boats would avoid the debris area.

Many impacts on the environment of the rocket launches were also calculated to be low.

Exceptions included a moderate risk of noise and disturbance to marine fauna above and below water as a potential consequence of the fall of debris from up to 1000 launches over almost 20 years. The risk became high for up to 10,000 launches over almost 200 years.

There was a moderate risk by 10,000 launches over nearly 200 years that the feeding or respiratory structures of sea floor organisms could be smothered.

Direct hits on some deep sea communities and the Magenta petrel population were assessed to be a moderate risk after 10,000 launches over almost 200 years.

The ecological risks associated with a catastrophic failure near the rocket launch facility and potential effects on near-shore locations were not assessed.

The main structural material used on the rockets will be carbon fibre-reinforced polymer. Carbon filaments were chemically inert and did not react to seawater, MfE said.

Liquid oxygen and kerosene propellants would be used in the rockets, both of which had proven safety and benign handling characteristics.

There were nine 20kg engines in stage 1 of the rocket, and one engine in stage 2. "At stage 1 separation, the thrust section is likely to separate from the stage, return to Earth's surface and land in the EEZ (Exclusive Economic Zone)," the report said.

The engines were made of inconel, an inert high performance, corrosion resistant nickel alloy.

A fairing would be released from the launch vehicle shortly after stage 1. Stage 2 of the launch vehicle would continue to climb and accelerate, jettisoning two batteries before entering orbit and releasing its payload.

The batteries had a low auto-ignition temperature of 150 degrees Celsius, which meant they were highly likely to burn up in the atmosphere before reaching Earth's surface, MfE said. The batteries contained no lead, acid, mercury, cadmium, or other toxic heavy metals.

The MfE report was prepared as part of the Government's plan to make the the deposit of jettisoned material from space launch vehicles a permitted activity in the EEZ, subject to conditions.