Cosmic rays threaten future deep-space astronaut missions

Artist's rendition of the Lunar Reconnaissance Orbiter (LRO) at the moon. 

The CRaTER telescope is seen pointing out at the bottom right center of the LRO spacecraft.

Credit: Illustration by Chris Meaney/NASA

Crewed missions to Mars remain an essential goal for NASA, but scientists are only now beginning to understand and characterise the radiation hazards that could make such ventures risky, concludes a new paper by University of New Hampshire (UNH) scientists.

In a paper published online in the journal Space Weather, associate professor Nathan Schwadron of the UNH Institute for the Study of Earth, Oceans, and Space (EOS) and the department of physics says that due to a highly abnormal and extended lack of solar activity, the solar wind is exhibiting extremely low densities and magnetic field strengths, which causes dangerous levels of hazardous radiation to pervade the space environment.

"The behaviour of the sun has recently changed and is now in a state not observed for almost 100 years," says Schwadron, lead author of the paper and principal investigator for the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on NASA's Lunar Reconnaissance Orbiter (LRO).

He notes that throughout most of the space age, the sun's activity has shown a clockwork 11-year cycle, with approximately six- to eight-year lulls in activity (solar minimum) followed by two- to three-year periods when the sun is more active.

"However, starting in about 2006, we observed the longest solar minimum and weakest solar activity observed in the space age."

These conditions brought about the highest intensities of galactic cosmic rays seen since the beginning of the space age, which have created worsening radiation hazards that potentially threaten future deep-space astronaut missions.

"While these conditions are not necessarily a showstopper for long-duration missions to the moon, an asteroid, or even Mars, galactic cosmic ray radiation in particular remains a significant and worsening factor that limits mission durations," says Schwadron.

The study is the capstone article in the Space Weather CRaTER Special Issue, which provides comprehensive findings on space-based radiation as measured by the UNH-led detector.

The data provide critical information on the radiation hazards that will be faced by astronauts on extended missions to deep space such as those to Mars.

"These data are a fundamental reference for the radiation hazards in near Earth 'geospace' out to Mars and other regions of our sun's vast heliosphere," says Schwadron.

At the heart of CRaTER is material called "tissue equivalent plastic," a stand-in for human muscle capable of gauging radiation dosage. Ionizing radiation from galactic cosmic rays and solar energetic particles remains a significant challenge to long-duration crewed missions to deep space.

Human beings face a variety of consequences ranging from acute effects (radiation sickness) to long-term effects including cancer induction and damage to organs including the heart and brain.

The high radiation levels seen during the sun's last minimum cycle limits the allowable days for typical astronauts behind spacecraft shielding.

Given the trend of reducing solar output, the allowable days in space for astronauts is dropping and estimated to be 20 percent lower in the coming solar minimum cycle as compared to the last minimum cycle.

Journal Reference:
N. A. Schwadron, J. B. Blake, A. W. Case, C. J. Joyce, J. Kasper, J. Mazur, N. Petro, M. Quinn, J. A. Porter, C. W. Smith, S. Smith, H. E. Spence, L. W. Townsend, R. Turner, J. K. Wilson, C. Zeitlin. Does the worsening galactic cosmic radiation environment observed by CRaTER preclude future manned deep-space exploration? Space Weather, 2014; DOI: 10.1002/2014SW001084

Hurricane Gonzalo Threat Delays Antares Rocket Launch for NASA

Hurricane Gonzalo has pushed the next private cargo mission to the International Space Station back by at least three days.

Orbital Sciences' Cygnus spacecraft was scheduled to blast off on an unmanned supply run to the orbiting lab from NASA's Wallops Flight Facility in Virginia on Oct. 24.

But that liftoff has been delayed until at least Oct. 27 because Gonzalo is about to hit Bermuda, where key tracking equipment for Cygnus spacecraft' Antares rocket is located.

"Once the hurricane has passed Bermuda, a team from NASA’s Wallops Flight Facility Range will return to the tracking site to assess the situation and begin the process of re-enabling the site's functionality to support the launch," Orbital Sciences representatives wrote in a mission update Wednesday (Oct. 15).

"Depending on the impact of the storm on Bermuda's essential infrastructure systems such as transportation, power and communications, the launch date could be moved later" than Oct. 27, they added.

Whenever it takes place, the Cygnus/Antares launch will kick off Virginia-based Orbital Sciences' third robotic cargo mission to the space station for NASA.

The company signed a $1.9 billion deal with the agency to complete eight such flights.



California-based SpaceX also makes unmanned supply runs to the orbiting lab for NASA using its Dragon capsule and Falcon 9 rocket. SpaceX's $1.6 billion contract calls for the firm to fly 12 missions; it has completed three of them to date and is in the middle of the fourth.

Gonzalo took shape as a tropical storm on Sunday (Oct. 12) and intensified into a hurricane on Tuesday (Oct. 14). By Wednesday, Gonzalo rated as a Category 4 hurricane, meaning it boasted maximum sustained winds between 130 and 156 mph (209 to 251 km/h).

Boeing 777 and 737 cockpit display change: WiFi threat to pilots' display

The affected Boeing control panel displays are susceptible to interference from Wi-Fi devices intended for routine use by many pilots during flights, according to the FAA document. 

Credit: Getty Images

New electronic display units are to be fitted in the cockpits of Boeing 737 and 777 airliners to address fears that Wi-Fi signals might cause them to go blank in flight.

In an airworthiness directive published Wednesday, the Federal Aviation Administration (FAA) said the switchover involves 1,149 late-model 737s and 177 777s in the United States alone.

The Federal Aviation Administration's safety directive, released Tuesday, aims to ensure that essential information such as airspeed, altitude and heading doesn't temporarily disappear from certain instrument displays manufactured by Honeywell International Inc.

Each installation is estimated to cost about $10,000, said the agency, which set a five-year deadline for the work to be completed.

"We are issuing this (directive) to prevent loss of flight-critical information displayed to the flight crew during a critical phase of flight, such as an approach or takeoff," it said.

Such an incident "could result in loss of airplane control at an altitude insufficient for recovery, or controlled flight into terrain," it added.

Display units are computer screens that give pilots vital in-flight information, such as altitude, airspeed, compass heading and the aircraft's attitude relative to the horizon.

The airworthiness directive—aviation's version of an automotive recall, was prompted by fears that Wi-Fi signals might interfere with a display unit, making it go blank.

Satellite Wi-Fi is being added to a growing number of commercial airliners, enabling passengers to log on to the Internet from 35,000 feet (10,000 meters).

In a statement, Honeywell International, which manufactures the display units, said that none of the devices have ever failed in flight due to Wi-Fi interference.

"The only know occurrence was during a developmental test conducted on the ground," it said, adding that, working with Boeing, it has already come up with new display hardware.

ESA's Space Situational Awareness (SSA): Bug Eyed Telescope

The SSA-NEO system is based on syndicating and federating observation and tracking data provided by a large number of European and international sources. 

Credit: ESA - P.Carril

Spotting Earth-threatening asteroids is tough partly because the sky is so big but insects offer an answer, since they figured out long ago how to look in many directions at once.

As part of the global effort to hunt out risky celestial objects such as asteroids and comets, ESA is developing an automated telescope for nightly sky surveys.

This telescope is the first in a future network that would completely scan the sky and automatically identify possible new near-Earth objects, or NEOs, for follow up and later checking by human researchers.

But a web of traditional telescopes would be complex and expensive because of the number required.

Adding to the problem, the system must be able to discover objects many times fainter than the naked eye can perceive.

While no network can spot all potentially hazardous objects, under favourable conditions it should detect everything down to about 40 m in diameter at least three weeks before impact.

The answer is a new, European telescope nicknamed 'fly-eye' that splits the image into 16 smaller subimages to expand the field of view, similar to the technique exploited by a fly's compound eye.

The design is modular, and allows for mass and cheaper production and lower maintenance costs. It will be used to build the prototype, to be fielded by ESA's Space Situational Awareness (SSA) programme early next year.

"This novel technology is key to the future NEO survey network," says Gian Maria Pinna of the SSA office.

A new, European telescope nicknamed ‘fly-eye’ splits the image into 16 smaller subimages to expand the field of view, similar to the technique exploited by a fly’s compound eye. 

Such fly-eyed survey telescopes provide a very large field of view: 6.7° x 6.7° or about 45 square degrees. 6.7° is about 13 times the diameter of the Moon as seen from the Earth (roughly 0.5 degrees). 

Credit: ESA/Compagnia Generale dello Spazio CGS

Performance equivalent to large telescope

These fly-eyed survey telescopes offer performance equivalent to a 1 m-diameter telescope, and provide a very large field of view: 6.7° x 6.7° or about 45 square degrees; 6.7° is about 13 times the diameter of the Moon as seen from the Earth.

"The new telescopes would provide the resolution necessary to determine the orbits of any detected objects," says Gian Maria.

"If the prototype confirms the expected performance, it will pave the way to full procurement and deployment of the operational network of telescopes."


Future telescope in operation. Credit: Compagnia Generale dello Spazio – CGS

This summer, ESA signed a contract for about €1 million with a consortium led by CGS S.p.A (Italy), comprising Creotech Instruments S.A. (Poland), SC EnviroScopY SRL (Romania) and Pro Optica S.A. (Romania) for the detailed design of the advanced telescope.

It is expected that the detailed design will be followed by several additional contracts with European companies valued at up to €10 million for building and deploying the first survey prototype telescope.

"The development of the first optical sensor specific to ESA's NEO search and discovery activities is a fundamental step toward Europe's contribution to safeguarding our planet from possible collisions by dangerous objects," notes Nicolas Bobrinsky, Head of the SSA Programme.

Russia threatens to cancel Baikonur finance in 2016

Baikonur, an international spaceport, was built in 1955.

Russian Ministry of Finance are threatening to stop financing Baikonur cosmodrome in 2016, Izvestia newspaper reported Friday citing a source in Roscosmos.

An official from the Federal Space Agency was quoted as saying "In previous versions of draft budget for 2016 it was planned to allocate a $705 million (2.5 billion rubles) subsidy for Baikonur maintenance."

"The money was supposed to be spent on salaries and field maintenance. We asked for more. But when our representative in Ministry of Finance was shown the final draft there was zero."

According to the newspaper, this could mean the specialist teams at Baikonur will be left without financing.

The report also said that Ministry of Finance allegedly made the decision due to the construction of the new Vostochniy cosmodrome, which will now receive the money that previously went to Baikonur.

Baikonur, an international spaceport, was built in 1955. Russia leases Baikonur from Kazakhstan for $115 million annually. The current lease contract between the two countries expires in 2050.

New N. Korea complex for possible ICBM launch

North Korea is building a new complex at its main rocket launch site, possibly for training and launches of road-mobile intercontinental ballistic missiles, a US think-tank said.

Satellite imagery from May 10 suggests the North is conducting a number of important construction projects at the Sohae Satellite Launching Station on its western coast, the US-Korea Institute at Johns Hopkins University said Tuesday.

"One working hypothesis is that the North is building a new complex to conduct future training and launches for mobile missiles such as the KN-08 intercontinental ballistic missile (ICBM)", it said on its website, 38 North.

"Moreover, that hypothesis is consistent with ongoing KN-08 engine tests being conducted (at) Sohae's rocket engine test stand, where a probable KN-08 first stage is currently seen on the stand, possibly left there after early April 2014 tests or for use in the future".

Three KN-08 rocket engine test series have been identified for the first and possibly second stages dating back to mid-2013, the institute said early this month, adding the next technically logical step would be a flight test of the entire system.

North Korea successfully put a satellite into orbit in December 2012 on a rocket -- the Unha 3 -- that Pyongyang said was designed for purely scientific missions.

The international community said the launch was a disguised ballistic missile test and the UN Security Council tightened existing sanctions as a result.

The May 10 imagery also indicates that Pyongyang's effort to upgrade the existing Sohae launch pad to handle space launch vehicles larger than the Unha-3 is continuing but work has slowed, possibly due to the greater priority placed on these new construction projects.

"As a result, North Korea will be unable to conduct SLV (space launch vehicle) tests from this site until at least mid to late summer 2014 when work should be completed", it said.

The successful 2012 satellite launch caused serious concern, but experts stressed that it lacked the re-entry technology needed to bring an ICBM down onto a target.

Full-scale models of the road-mobile KN-08 missile were given pride of place in North Korean military parades in 2012 and in July last year.

But several experts ridiculed the models, with at least one respected aerospace engineer labelling them technically preposterous and a "big hoax".

The North is developing a working ICBM as a national priority and a successful test of such a missile would take the nuclear threat posed by Pyongyang to an entirely new level.

The institute said last week that despite fears to the contrary, satellite imagery suggests North Korea is not preparing an imminent nuclear test.

Imagery dated May 9 does show high levels of activity at the Punggye-ri test site, but most of it seems to be of a mundane, routine nature that would not be consistent with an impending test, it said last week.

Stephen Hawking: Threat to Humanity - Artificial Intelligence and Smart Weapon Systems

Stephen Hawking, in an article inspired by the new Johnny Depp flick Transcendence, said it would be the "worst mistake in history" to dismiss the threat of artificial intelligence.

In a paper he co-wrote with University at California, Berkeley computer-science professor Stuart Russell, and Massachusetts Institute of Technology physics professors Max Tegmark and Frank Wilczek, Hawking cited several achievements in the field of artificial intelligence, including self-driving cars, Siri and the computer that won the US game show Jeopardy!

"Such achievements will probably pale against what the coming decades will bring," the article in Britain's Independent said.

"Success in creating AI would be the biggest event in human history," the article continued. "Unfortunately, it might also be the last, unless we learn how to avoid the risks."

The professors wrote that in the future there may be nothing to prevent machines with superhuman intelligence from self-improving, triggering a so-called "singularity."

"One can imagine such technology outsmarting financial markets, out-inventing human researchers, out-manipulating human leaders, and developing weapons we cannot even understand."

"Whereas the short-term impact of AI depends on who controls it, the long-term impact depends on whether it can be controlled at all," the article said.

"Although we are facing potentially the best or worst thing to happen to humanity in history, little serious research is devoted to these issues outside non-profit institutes such as the Cambridge Centre for the Study of Existential Risk, the Future of Humanity Institute, the Machine Intelligence Research Institute, and the Future of Life Institute."

"All of us should ask ourselves what we can do now to improve the chances of reaping the benefits and avoiding the risks."

ESA Clean Space: Reducing debris threat from satellite batteries

So far, about 200 explosions and at least 5 collisions in space have occured. 

Further explosions and collisions are very likely. 

The explosions are mainly caused by onboard energy sources, either due to pressure build-up in propellant tanks, battery explosions, or the ignition of hypergolic fuels. 

Each explosion creates thousands of small debris objects. 

The most prominent collision event and the first known one between two catalogued objects was in 1996 between the French Cerise Satellite and a fragment of an Ariane upper stage explosion. 

Credit: ESA

Across a satellite's working life, batteries keep the craft's heart beating whenever it leaves sunlight. But after its mission ends, those same batteries may threaten catastrophe.

Space debris mitigation rules require the complete deactivation of electrical power sources aboard a satellite on retirement, to guard against explosive accidents that might produce fresh debris dangerous to other satellites.

Now a new study by ESA's Clean Space initiative – tasked with reducing the space industry's environmental impacts on both Earth and space – aims to evaluate battery behaviour after a satellite shuts down, assessing the risk of breakup and ensuring full 'passivation'.

Batteries are among a satellite's bulkier items of equipment. Typically, they feed their host with power during launch.

Once in orbit, it switches to power from its solar arrays, but the battery is an important backup to store power for eclipses and emergencies.

To reach the high reliability and performance a satellite demands, extending across many months or years, batteries are carefully designed and extensively tested in advance of launch.

By contrast, their behaviour after their parent mission has been shut down remains a relative blind spot.

As a satellite drifts freely, could batteries endure the harsh environment of orbit – including wild temperature swings, degradation of thermal control and components as well as radiation exposure – without leakage or bursting?

Some past satellite breakups have been triggered by battery malfunctions, although mostly before the 1990s and involving older non-lithium designs.

This multidisciplinary study aims to ensure a fully inert power system at the end of a mission, perhaps through physical disconnection, while also preventing accidental premature passivation.

ESA ENVISAT: De-orbiting and space debris threat from giant satellite

Artist's impression of Envisat orbiting the Earth. Credits: ESA

Physics students at the University of Leicester have pointed out that ESA's huge observational satellite Envisat, which lost contact with Earth in 2012, could potentially pose a space debris threat to the Earth.

What's more, the task of bringing the satellite back to Earth may be too costly and complex to be feasible, according to their final year paper for the Journal of Physics Special Topics, a peer-reviewed student journal run by Leicester University's Department of Physics and Astronomy.

Envisat, an £1.8 billion, 9 metre-long behemoth, was launched by the European Space Agency (ESA) in 2002, and used ten sophisticated sensors to observe and monitor Earth's land, atmosphere, oceans and ice caps.

However, ESA lost contact with the satellite in April, 2012 and declared the end of the mission soon after.

The satellite now orbits the Earth free from human control at an altitude of 790km, where the amount of space debris around the planet is greatest.

This means there is a greater chance of collision with other satellites and debris during the 150 years it is expected to remain in space.

Each year, two objects are expected to pass Envisat to within about 200m and other spacecraft have had to move out of Envisat's path.

It is possible – though unlikely - that a collision with Envisat could lead to a chain reaction effect, known as the Kessler Syndrome, where a cloud of fast-moving debris causes other collisions with orbiting bodies around the Earth.

This would not be good news for the many essential satellites and spacecraft in orbit.

It could also make it difficult for future space missions to pass through the region of Envisat's altitude, if the region becomes congested with space debris.

The fourth-year MPhys students' paper, 'De-orbiting Envisat', suggests that around 140kg of fuel would be required to move the satellite to a point where it would naturally return to Earth within 25 years.

Based on the object's cross-sectional area and its mass, the students calculated that the satellite would need to be moved to an altitude of 700km from its current position in order to return to the planet in 25 years.

The students calculated that the energy required to move the satellite 90km closer to the Earth was 2.7 billion joules, equivalent to an extra 143.1kg of hydrazine fuel.

This could be quite feasible, according to the students, if two of the craft's 80kg fuel tanks were replaced.

But actually getting this fuel to the satellite in orbit would be a pretty tall order due to the costs involved of such a mission – which has never been attempted for a satellite which wasn't designed to be refuelled.

More information: "De-orbiting Envisat." K. Raymer, T. Morris, O. Youle, B. Jordan, Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH. physics.le.ac.uk/journals

North Korea's Rockets and Missile Threat Capability

North Korea's missile program is shrouded in secrecy, which helps the outlaw nation keep the rest of the world guessing.

But Western experts have learned a fair bit about Pyongyang's stable of rockets and missiles over the years by analyzing test flights, satellite photos and other data.

Soviet Origins:
The Hermit Kingdom's missile program is based primarily on Soviet Scuds, which apparently entered the country via Egypt in the 1970s.

North Korea was building its own Scud version, called the Hwasong-5, by the mid-1980s, and moved onto bigger and more powerful missiles after that.

Poor Accuracy:
North Korea's missiles have poor record of accuracy compared to those developed by the United States and other Western powers, experts say.

Pyongyang's Hwasong missiles, for example, can reach targets a few hundred miles away, but with an accuracy of just 0.3 miles to 0.6 miles (0.5 to 1 kilometer).

A missile called the Nodong (or Rodong -1 & -2) can fly 620 miles to 800 miles (1,000 to 1,300 km), but its estimated accuracy is even worse — 1.8 to 2.5 miles (3 to 4 km).

It is believed that these missiles can't reliably hit military targets, but they can certainly strike larger targets such as cities.

Cooperation with Iran:
North Korea has apparently cooperated extensively with fellow pariah nation Iran on rocket and missile technology.

For example, the third stage of Pyongyang's Unha-2 rocket is very similar to, and reported to be based on, the upper stage of Iran's Safir-2 launcher, physicists David Wright and Theodore Postol noted in a 2009 report.

Satellite Launch Success:
North Korea joined the ranks of satellite-launching nations last December, when its Unha-3 rocket launched a small satellite to Earth orbit.

This breakthrough came after three consecutive failures — one in 1998, one in 2009 and another in April 2012.

However, North Korean officials have never admitted to these mishaps, .

For example, they claimed that the Kwangmyongsong-1 ("Bright Star 1") satellite reached orbit in 1998 and then broadcasted patriotic songs into space but there is no evidence for this.

Nuclear Warheads Possible:
North Korea has been ratcheting up its bellicose rhetoric lately, threatening to launch nuclear strikes against Washington, D.C. and other American cities.

While the rogue nation's nuclear-weapons program is thought to be at a relatively primitive stage, Pyongyang may indeed already possess warheads small enough to be carried large distances by a ballistic missile, experts say. But the world have been misled by this kind of rhetoric in the past.

"Having something that's around 1,000 kilograms, or maybe somewhat smaller than that, unfortunately does not seem impossible," Wright reported.

"We don't really know, but I think you have to take seriously that they could well be there."

Most analysts doubt, however, that North Korean missiles are powerful enough to deliver a nuclear weapon to the American mainland.

The tough talk from Pyongyang is primarily bluster aimed at wringing concessions out of the international community and building support for young leader Kim Jong-Un at home, they say.

It also follows the blocking of international bank accounts for Kim Jon-Un and three of his senior generals.

These accounts are thought to contain $$billions belonging to the people of North Korea, allegedly. 

CHINA's Openly Aggressive Strategy to Dominate Space

China is making increasingly aggressive plans to launch 20 spacecrafts this year,2013.

This will include the country's third lunar probe Chang'e-3 and manned spacecraft Shenzhou-10, China Aerospace Science and Technology Corporation (CASC) announced.

The country is scheduled to conduct a manned space docking test between orbiting target module Tiangong-1 and Shenzhou-10, the corporation said during an internal work conference.

The Chang'e-3 moon probe is expected to land and stay there during the second stage of the country's lunar probe program, it said.

According to CASC, by 2020, China will have more than 200 spacecrafts operating in orbit, accounting for about 20 percent of the world's total.

How many of the countries who are already under threat from China's expansionist plans will suffer as a consequence of their imposed domination of the space above the Earth's atmosphere?

What safeguards can be put in place to prevent their militarisation of Space and to make the Earth's atmospheric zone a de-militarised zone (DMZ)?

NASA successfully hacked 13 times last year

According to a US Government paper, NASA said hackers stole employee credentials and gained access to mission-critical projects last year in 13 major network breaches that could compromise U.S. national security.

National Aeronautics and Space Administration Inspector General Paul Martin testified before Congress this week on the breaches, which appear to be among the more significant in a string of security problems for federal agencies.

The space agency discovered in November that hackers working through an Internet Protocol address in China broke into the -network of NASA's Jet Propulsion Laboratory, Martin said in testimony released on Wednesday.

One of NASA's key labs, JPL manages 23 spacecraft conducting active space missions, including missions to Jupiter, Mars and Saturn.

The hackers gained full system access, which allowed them to modify, copy, or delete sensitive files, create new user accounts and upload hacking tools to steal user credentials and compromise other NASA systems. They were also able to modify system logs to conceal their actions.

"Our review disclosed that the intruders had compromised the accounts of the most privileged JPL users, giving the intruders access to most of JPL's networks," he said.

In another attack last year, intruders stole credentials for accessing NASA systems from more than 150 employees. Martin said the his office identified thousands of computer security lapses at the agency in 2010 and 2011.

He also said NASA has moved too slowly to encrypt or scramble the data on its laptop computers to protect information from falling into the wrong hands.

Unencrypted notebook computers that have been lost or stolen include ones containing codes for controlling the International Space Station, as well as sensitive data on NASA's Constellation and Orion programs, Martin said.

A NASA spokesman told Reuters on Friday the agency was implementing recommendations made by the Inspector General's Office.

"NASA takes the issue of IT security very seriously, and at no point in time have operations of the International Space Station been in jeopardy due to a data breach," said NASA spokesman Michael Cabbagehe.

100 Icebergs heading towards New Zealand: Threat to shipping

More than 100, and possibly hundreds, of Antarctic icebergs are floating towards New Zealand in a rare event which has prompted a shipping warning, officials said on Monday.

An Australian Antarctic Division glaciologist said the ice chunks, spotted by satellite photography, had passed the Auckland Islands and were heading towards the main South Island, about 450 kilometres (280 miles) northeast.

Scientist Neal Young said more than 100 icebergs -- some measuring more than 200 metres (650 feet) across -- were seen in just one cluster, indicating there could be hundreds more.

He said they were the remains of a massive ice floe which split from the Antarctic as sea and air temperatures rise due to global warming.

"All of these have come from a larger one that was probably 30 square kilometres (11.6 square miles) in size when it left Antarctica," Young told AFP.

"It's done a long circuit around Antarctica and now the bigger parts of it are breaking up and producing smaller ones."

He said large numbers of icebergs had not floated this close to New Zealand since 2006, when a number came within 25 kilometres of the coastline -- the first such sighting since 1931.

"They're following the same tracks now up towards New Zealand. Whether they make it up to the South Island or not is difficult to tell," Young said.

New Zealand has already issued coastal navigation warnings for the area in the Southern Ocean where the icebergs have been seen.

"It's really just a general warning for shipping in that area to be on the alert for icebergs," said Maritime New Zealand spokesman Ross Henderson.

The icebergs are smaller remnants of the giant chunks seen off Australia's Macquarie Island this month, including one estimated at two kilometres (1.2 miles) and another twice the size of Beijing's "Bird's Nest" Olympic Stadium.

Young earlier told AFP he expected to see more icebergs in the area if the Earth's temperature continues to increase.

"If the current trends in global warming were to continue I would anticipate seeing more icebergs and the large ice shelves breaking up," he said.

When icebergs last neared New Zealand in 2006, a sheep was helicoptered out to be shorn on one of the floes in a publicity stunt by the country's wool industry.