An Australian physicist has developed satellite technology that measures the world's freshwater reserves from space.

The technology is at the heart of the NASA's Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, which launched last month, and follows the first GRACE mission which launched in 2002.

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The launch was particularly stressful for Australian physicist Daniel Shaddock from the Australian National University as 15 years of his work was onboard the rocket.

"It was a little bit surreal," Professor Shaddock said.

"So many years of your life working on something — it was hard to believe it was actually happening and finally launching.

"It was very exciting when it finally went up and nothing blew up. And the most exciting part is still yet to come."

Professor Shaddock developed a retroreflector that uses lasers to measure the world's water reserves from space with unprecedented accuracy.

A SpaceX Falcon 9 lifts off from Vandenberg Air Force Base on May 22 carrying the GRACE-FO satellites. ( Supplied: NASA )

"It measures something that's really important; the presence of water — whether that's frozen form or liquid form — across the entire globe at once. And that's something you can only do from space.

"Any large body of water will generate gravity and that gravity can be picked up by GRACE."

Groundwater depleting at 'impressive' rate

GRACE has the extraordinary ability to peer beneath the Earth's surface to weigh groundwater reserves where a third of all freshwater lies.

Australian National University water expert, Albert Van Dijk, said the first GRACE mission painted a disturbing picture of freshwater loss.

Professor Van Dijk said in populated, arid parts of the world such as India, huge amounts of water is being pumped out of the ground.

"What GRACE is telling us is that a lot of that groundwater is not being replenished," Professor Van Dijk said.

"We're actually mining groundwater and the magnitude of that is actually quite impressive.

"The direct consequence is the groundwater table goes lower and lower and farmers have to deepen their wells."

Freshwater disappearing worldwide

In Australia, GRACE has shown groundwater levels in the Murray-Darling Basin still have not recovered from the Millennium Drought, which ended in 2011.

The mission also revealed that freshwater is disappearing from Greenland and West Antarctica faster than any other place on Earth as ice caps melt.

Petermann Glacier in Greenland is among the world's fresh water stores which are quickly depleting. ( Supplied: Nick Cobbing, Greenpeace )

"GRACE is giving us solid numbers about how much ice is disappearing, how much is ending up in the oceans and also how it's changing our water cycle and our water resources.

"We can see a lot of the impacts of climate change that was predicted decades ago; we can see them now.

"It's been incredibly useful in terms of seeing how climate change is rolling out.

How GRACE works

GRACE detects tiny changes in gravity caused by large masses of water on Earth, which then causes a pair of satellites to speed up or slow down.

Professor Shaddock's laser device measures these changes in speed.

"In the case of the Laser Ranging Interferometer, we can pick up changes in the separation of the spacecraft by ten nanometres. That's ten billionths of a metre — about the diameter of a virus."

GRACE works by measuring the distance between two satellites as they change speed due to minute changes in gravity. ( Supplied: NASA )

For the device to work, two laser beams from two separate satellites — each travelling at thousands of kilometres per hour — need to link with each other from a distance of over two hundred kilometres.

"Once the laser links have been acquired I'll certainly rest a little easier — that's really the biggest challenge facing GRACE," Professor Shaddock said.

"If that doesn't work we won't get any data back, and if it does work, I'm much more confident that we'll get some really valuable insights."

Australia in the space race?

Professor Daniel Shaddock and his colleagues at ANU preparing to test the GRACE F-O retroreflector. ( Supplied: Australian National University )

Professor Shaddock was able to make his contribution to NASA's GRACE-FO mission without the assistance of an Australian space agency.

Following the recent announcement that Australia is about to form its own space agency, Professor Shaddock said he is cautiously optimistic about the future of the Australian space industry.

"It's been a huge challenge to participate in GRACE, and it's only been though the generosity of our foreign partners that we've been allowed to contribute.

"Not having had a space agency up until now means we have a lot of catching-up to do.