NASA’s New Horizons Spacecraft Has Next Mission After Pluto
By KENNETH CHANG

The next destination for NASA’s Pluto probe is to be a much smaller ice ball in the outer solar system, the space agency announced on Friday.

The New Horizons spacecraft, which captured a cornucopia of photographs and data during its Pluto flyby last month, is to make a similar examination of a small, icy body known as 2014 MU69 in 2019 if NASA approves an extension to the mission.

While the vistas of this object would not be as breathtaking and varied as those of Pluto, the visit would provide a close-up look at another piece of the frigid debris beyond Neptune, part of what is known as the Kuiper belt. The debris, left over from the earliest days of the solar system, gives insight into how planets formed.

Pluto is about three billion miles from the sun; 2014 MU69 is almost a billion miles beyond Pluto.

NASA has already examined smaller icy objects like comets, some of which originate in the Kuiper belt, and Pluto, the largest Kuiper belt object. The flyby of 2014 MU69 would fill in the picture for an intermediate-size Kuiper belt object. “We want to connect the dots,” said S. Alan Stern, New Horizons’s principal investigator.

Dr. Stern had always hoped to follow up the Pluto visit with another Kuiper belt object. A concerted search using the Hubble Space Telescope turned up two viable candidates. This week, mission scientists met and decided on 2014 MU69, which is slightly smaller but easier to reach.

“It’s better science and lower risk,” Dr. Stern said.

The New Horizons spacecraft is to adjust course through a series of four thruster firings in late October and early November. New Horizons would also make more distant measurements of 20 other Kuiper belt objects en route to 2014 MU69.

Although the scientists will search for somewhere to go after that, “there are low odds that we would find something within the remaining fuel,” Dr. Stern said.

冥王星探測船 擬再向外探索

美國太空總署（NASA）廿八日宣布，冥王星探測船「新地平線號」若任務計畫獲准，將於2019年探索下一個目標，外太陽系編號「2014 MU69」的天體。

紐約時報報導，冥王星距離太陽卅億英里，「2014 MU69」則比冥王星更遠十億英里，是個比冥王星小了許多的冰狀星體。科學家認為，「2014 MU69」的景象可能不會如冥王星般令人讚嘆，卻能讓人一窺古柏帶之外的未知領域。

原文參照：
http://www.nytimes.com/2015/08/29/science/space/nasas-new-horizons-spacecraft-has-next-mission-after-pluto.html

2015-08-30．聯合報．A13．國際．編譯陳韻涵