How do you revive a dying species?

(CNN)There is only one male northern white rhino left in the world. His name is Sudan, he's 42-years old -- practically geriatric in rhino terms. His sperm count is low and his hind legs are weak -- meaning he's in no position to mate.

The recent death of Nola -- a female northern white rhino in San Diego Zoo Safari Park -- makes the situation starker than ever: their population is on the brink of extinction. Or is it?
Scientists are desperate to save the species, which over the years have fallen victim to aggressive poaching (rhino horns fetch around $60,000 per pound -- more than gold, diamonds or cocaine). They are currently testing out several new methods to save Sudan's kind -- some of which sound positively science fiction.

    Test tube rhinos

    Sudan lives at the Ol Pejeta Conservancy in central Kenya, where he is under 24/7 armed guard. There, a project is underway to extract his semen to create test tube embryos that could one day save his species.
    "What we are doing is we are saving genetic traits, which will allow rhinos, perhaps in 100 or 200 years time, to be reintroduced back into areas where these animals used to exist," says Richard Vigne, Ol Pejeta's CEO.
    The resultant embryos will impregnate some of the last surviving females of a different but closely related species: the southern white rhinos, which live at Dvur Kralove Zoo in the Czech Republic.
    "This way has never been done before," notes zoo employee Jan Stejskal. "It has been done with horses, with cattle, but not with rhinos. Due to this reason, it is quite challenging."
    Meet the last male northern white rhino
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    Genome sequencing

    White rhinos aren't the only species in peril. Black rhinos are also listed as critically endangered, and as a result are the target of a genome sequencing project.
    The Black Rhino Genome Project is made up of a group of researches that have turned to crowdfunding to fund their rhino genome sequencing work.
    By understanding the genetic differences between rhino species the group hopes to determine how scientists can assist the animals' future reproduction. Analysis could show how different rhino species evolved to what they are today, and could also show where in the animals' genes diseases might emerge.
    With funding of $16,500, the group are recording the genome of a six-year-old black rhino from South Africa named Ntomi -- the first black rhino to have its genome sequenced.

    Creating a frozen zoo

    Throwing endangered animals into the freezer doesn't seem like the most optimistic way forward for conservationists -- but cryogenic freezing could reap big rewards for conservation in future.
    The Ambrose Monell Cryo Collection (AMCC), a part of the American Museum of Natural History, stores thousands of frozen tissue specimens in liquid nitrogen-cooled vats at temperatures below -150 degrees Celsius.
    "In a time of massive species loss, such efforts are essential in order to preserve as comprehensive a record as possible of the earth's biodiversity," says the group in its press materials. AMCC are in effect creating a large scale natural history museum on ice.
    They are, they claim, creating a "searchable online catalog of specimen holdings."
    These icy libraries of DNA data aren't an immediate solution to the plight of the rhino -- but one day they may hold the key to saving the planet's extinct and endangered species.

    Stem cell research

    At the Scripps Research Institute (SRI), a U.S.-based biomedical research center, work is being done into stem cells made from rhino skin, which could, potentially, allow scientists to create other types of orgnic cells, such as eggs and sperm. Their method if successful would lead to the first test tube rhino babies -- effectively saving the animal from extinction.
    "Working with the San Diego Zoo's Conservation Research Institute, we are generating [stem cells] from endangered species, in the hope that some day these cells can be used to repopulate the species," says the SRI's Director of Regenerative Medicine, Jeanne Loring.

    Big data and monitoring

    Monitoring is a critical part of rhino conservation -- tracking habitat usage, animal movement and population dynamics. Big data and new technology are making this job more effective.
    "The knowledge that a rhino population is being kept under close demographic surveillance, so that any poaching will be detected, serves to deter would-be poachers including corrupt elements within that area's protection force," says Save the Rhino -- a rhino conservation charity -- on their website.
    Save the Rhino share their monitoring data with the South African Development Committee and other organizations. By sharing data and combining data analysis, analysts can find out more than they have ever known about the rhino's status, and can ultimately be in a better position to stop poaching.
    Kenya's black rhino success story
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    3D printed rhino horns

    One of the most radical solutions to save rhinos is to flood the rhino horn market with fakes, disrupting demand for the horn and hopefully reducing poaching attacks on the species.
    Developers at Seattle-based company Pembient are 3D printing synthetic rhino horns -- made using the proteins and DNA of rhinos.
    Rather than bolster the number of rhinos themselves, Pembient hopes that the synthesized product can help satiate demand for rhino horn, reducing the price and desirability of it in the market, and ultimately leading to less rhino killings.