杏吧原创

What鈥檚 the best thing the New Horizons probe revealed about Pluto during its fly-by last year?
That it is so amazing. Pluto is the 鈥淚t girl鈥� of the solar system. This small planet seems to have a little something for everyone 鈥� from mountains to blue skies, active geology to glacial fields, and many other types of terrain, geology and activity. It also has a big satellite system. It鈥檚 a scientific wonderland.

What鈥檚 next for New Horizons?
Our immediate goal is to fly past a small object in the Kuiper belt. This region is full of the types of object that built the planets. Our target has a really lousy name for now: 2014 MU69. We found it with the Hubble Space Telescope about a billion miles beyond Pluto. We鈥檝e already fired the engines on New Horizons to target the fly-by. This interception will occur on 1聽January 2019. After that, New Horizons could fly on into the 2030s with its power still on. All聽of its systems are healthy, so hang on for the ride.

When astronomers claimed to have evidence for a massive world at the edge of the solar system last week, you said: 鈥淗ype. There is no discovery.鈥� But looking deeper into space, do you think there may be a large planet in the Oort cloud聽鈥� the region far beyond the Kuiper belt?
Absolutely, 100 per cent. I don鈥檛 believe we can escape that idea.

How quickly could a probe get to a planet in the Oort cloud?
First we would have to find it, which is a very challenging problem. And remember, is about a hundred times further from the sun than Pluto is. New Horizons, the fastest spacecraft ever launched, took a decade to get to Pluto. The Oort cloud, by present-day technology, is a thousand-year journey.

鈥淚f you put Earth where Pluto is, it wouldn鈥檛 even qualify as a planet!鈥�

When you launched New Horizons, Pluto was a planet, but soon after was demoted to 鈥渄warf planet鈥� status. How do you feel about that?
The International Astronomical Union decided to create a definition that would limit the number of planets specifically so that schoolchildren wouldn鈥檛 have to memorise too many names. I don鈥檛 find this particularly scientific. In the outer solar system, we see objects that have the attributes of planets, but we shouldn鈥檛 worry about how many there are聽鈥� just like the stars and galaxies. I debated with an astronomer on US national radio who followed the IAU line. He said, 鈥淢y little daughter can鈥檛 possibly remember the names of 50 planets.鈥� I replied, 鈥淭hen I guess we鈥檙e going back to eight US states.鈥�

What specifically is wrong with the IAU鈥檚 definition of a聽planet?
The IAU imposed a criterion that a planet has to control its orbital zone 鈥� that is, clear it of other objects. But these zones get bigger the further you go from the sun: the zone in which Pluto orbits is larger than those of all the other planets put together. If you put Earth where Pluto orbits, it wouldn鈥檛, by that definition, qualify as a planet!

Moving closer to home, one of your initiatives, Golden Spike, involves selling tickets for commercial trips to the moon. How鈥檚 that going?
It鈥檚 a large enterprise, putting together human expeditions to the moon. It鈥檚 going slower than we initially expected. But this isn鈥檛 unique to Golden Spike: all commercial space-flight companies are running late. Take suborbital flights. Development began in 2004 and paying customers were expecting to fly into space within a few years. The first tourists are still waiting, 12 years later.

Will you get to the moon before the Chinese?
I don鈥檛 think it matters. Lots of countries want to have their people on the moon, in the same way that dozens of countries wanted to send people to the Russian space stations Salyut and Mir in the 1980s and 90s. They really didn鈥檛 care if they were second or 17th 鈥� they just wanted to join the club.

Why are you such a passionate advocate of private and commercial space exploration as opposed to government initiatives?
Government space agencies lead at the very frontier: they develop the technologies and techniques, and are generally first to orbit or make landings on other planets, for example. But they have limited resources. To really become a spacefaring civilisation, we need more than just one way to reach space. Private industry creates a big multiplier effect.

How are you involved with Blue Origin, the space-travel company created by Amazon founder Jeff Bezos?
During the four years or so that New Horizons was between Jupiter and Pluto, I consulted for a large number of commercial space companies and universities. Jeff Bezos hired me to help Blue Origin with early efforts to use its New Shepard launch vehicle for research and education purposes. I hope to travel in the New Shepard鈥檚 crew capsule.

鈥淭o really become a spacefaring civilisation, we need more than just one way to reach space鈥�

What about your work with Virgin Galactic?
Virgin hired me to help with the development of research and education. Subsequently, in my day job at the Southwest Research Institute in Boulder, Colorado, we鈥檝e developed a programme of human suborbital flights, with聽Virgin Galactic as one of our two flight providers 鈥� the other being XCOR鈥檚 Lynx spacecraft. We鈥檝e arranged three flights on Virgin to run separate biomedical, remote-sensing and microgravity experiments. Three researchers will be flying, myself included.

You also founded Uwingu, a company that for a fee allows people to name features on Mars and newly discovered exoplanets. What happens to the money you raise?
We turn the proceeds into grants for space organisations and researchers, and even space graduate students. We鈥檙e very proud of being able to take the public鈥檚 interest and create a 鈥渢riple win鈥�: the public is more engaged; it creates a revenue stream for our company; and this creates grants for space organisations and individuals.

Have people shown much interest in naming bits of Mars?
There are half a million unnamed features on Mars. In the two years that we鈥檝e been involved, almost 20,000 features have been named. We鈥檝e shown that not only do people really love doing this, but by involving the crowd, we make progress much faster in coming up with a complete map of Mars.

The IAU 鈥� traditionally the arbiter of naming solar-system objects and features 鈥� has recently launched its own public scheme for naming exoplanets. How do you feel about that?
Many IAU members have told me that Uwingu catalysed their activity. There are about 160聽billion planets in the galaxy and only 7聽or聽8 billion people on Earth, so there will be聽plenty of planets to go around.