달 뒷면 착륙, 인공혈액 수혈...2019년 주목할 과학 연구 10選 VIDEO: New Horizons in daring, historic flyby of 2014 MU69

New Horizons in daring, historic flyby of 2014 MU69

written by Chris Gebhardt December 31, 2018

Three and a half years after it nailed a perfect flyby of the dwarf planet Pluto and its five moons, NASA’s New Horizons spacecraft is set to make history once again just after midnight Eastern Standard Time on 1 January 2019 when the spacecraft performs a flyby of Kuiper Belt Object 2014 MU69.

달 뒷면 착륙, 인공혈액 수혈...2019년 주목할 과학 연구 10選 "새해 인류의 새 도전이 시작된다"    새해 첫날 미국항공우주국(NASA)의 우주탐사선 ‘뉴호라이즌스호’는 태양계 최외곽 천체인 ‘울티마 툴레(MU69)’에 3500km 거리까지 접근할 예정이다. 해왕성 너머 카이퍼벨트에서 태양 주위를 295년에 한 바퀴씩 도는 이 천체는 지구에서 약 65억 km 떨어져 있다. 인류가 탐사선을 보낸 천체 중 지구에서 가장 멀다. 지구, 화성 같은 태양계 행성이 형성되고 남은 암석과 얼음 덩어리들로 이뤄진 카이퍼벨트의 천체를 가까이서 관측하는 것은 이번이 처음이다. 원시 상태의 태양계에 관한 새 단서가 될 것으로 기대를 모은다.   Data Science: What to Expect in 2019 https://www.techopedia.com/data-science-what-to-expect-in-2019/2/33690 2019년 가장 주목해야 할 과학 이슈..."남극 빙하 연구"  VIDEO: What to expect in 2019: science in the new year https://conpaper.tistory.com/73967 edited by kcontents 2019년 기해년(己亥年)이 하루 앞으로 다가오면서 과학자들의 기대감도 한껏 높아졌다. 특히 내년에는 역사상 처음 시도되는 다양한 과학 프로젝트들이 우리를 기다리고 있다. 인류는 또 어떤 도전을 하게 될까. 이달 초 중국이 발사한 달 탐사선 ‘창어(嫦娥) 4호’는 내년 1월 3일 사상 최초로 지구에서 보이지 않는 달 뒷면에 착륙을 시도한다. 남극 에이트켄 분지에 위치한 본 카르만 크레이터에 착륙해 달 토양에 애기장대 같은 식물을 키우는 온실 실험도 최초로 수행할 예정이다. 미국 국립과학재단과 영국 자연환경연구회는 기후변화 연구를 위해 남극 대륙 5대 빙하 중 하나인 트웨이츠 빙하 일대를 탐사하는 공동 프로젝트를 내년 1월 출범한다. 빙하가 녹는 속도를 측정해 빙하가 완전히 붕괴되기까지 남은 시간을 예측한다는 계획이다. 빙하를 녹게 만드는 심층수를 관측할 무인잠수정과 센서를 장착한 바다표범도 동원된다. 유럽 연구진은 내년 말 남극 빙하를 뚫어 150만 년 전 공기를 담은 얼음코어를 찾는 시추 프로젝트를 시작한다. 얼음코어를 확보하면 고대 지구의 대기 환경을 직접 관측할 수 있다. 내년 상반기에는 지표면으로 들어오는 태양 빛을 줄여 지구온난화를 늦추는 ‘태양 지구공학’의 실증시험이 추진된다. 미국 하버드대 연구진은 빛을 잘 반사하는 방해석(탄산칼슘) 미세입자를 상공 20km 성층권에 100g가량 살포해 반경 1km의 반사층을 형성한 뒤 지구로 들어오는 태양 빛의 감소량과 온도 변화, 미세입자와 대기 중 화학물질의 상호작용 등을 관측할 예정이다. 지구공학 실험을 실제 지구 환경에서 수행하는 것은 이번이 처음이다. 세계 최초로 인공혈액을 실제 환자에게 수혈하는 임상시험도 예정돼 있다. 일본 교토대는 내년 상반기 중 유도만능줄기(iPS)세포로 만든 인공 혈소판을 빈혈의 일종인 재생불량성빈혈 환자의 혈관에 주입한 뒤 효능과 안전성을 검증할 계획이다. iPS세포는 피부세포를 원시 배아 상태로 되돌려 만든 줄기세포다. 대량 증식이 가능해 혈액세포를 대량 생산할 수 있고 환자의 피부세포를 활용하면 거부반응 우려도 없다. 연구진은 올해 9월 일본 후생노동성의 허가를 받았다. 에토 고지 교토대 교수는 “헌혈 자체도 부족하지만 혈소판의 경우 헌혈과 수혈 과정에서 상당수 파괴된다는 문제가 있었는데 iPS세포가 대안이 될 것”이라고 기대했다. 민간 주도의 우주개발 역시 내년을 기점으로 본격화될 것으로 전망된다. 2월 13일에는 이스라엘의 비영리단체 스페이스IL이 민간 최초로 달에 착륙선 ‘스패로’를 보낸다. NASA도 ‘아폴로 11호’ 유인 달 착륙 50주년을 기념해 내년 중 민간기업이 개발한 달 착륙선을 발사할 계획이다. 이를 위해 지난달 말 록히드마틴과 에어로스페이스, 문익스프레스 등 개발 경쟁에 참여할 9개 기업을 선정했다. NASA는 내년 말까지 우주비행사 2명을 처음으로 민간기업이 개발한 우주왕복선에 태워 우주로 보내겠다는 계획도 세웠다. 민간 첫 유인 우주왕복선 후보로 떠오른 미국의 우주개발기업 스페이스X의 ‘크루 드래건’과 보잉의 ‘CST-100 스타라이너’는 각각 1월과 3월 사람을 태우지 않은 채로 시험비행에 나선다. 일론 머스크가 이끄는 스페이스X의 경우 3, 4월 화성 식민지 건설을 위한 차세대 재사용 로켓인 ‘빅팰컨헤비로켓(BFR)’의 추진체 성능을 검증하기 위한 첫 시험발사를 수행한다는 계획이다. 내년 한 해 동안 전 세계에서 예정된 우주 발사 계획은 민관 총합 173회로 역대 최다 연간 발사 횟수를 기록할 것으로 전망된다. 그 밖에 세계에서 가장 큰 지름 500m의 구면전파망원경인 중국의 ‘톈옌(天眼)’이 내년 9월부터 본격적으로 가동된다. 세계 과학자들은 톈옌을 이용해 고속전파폭발(FRB)과 성간물질에서 나오는 희미한 신호 등을 관측할 예정이다. 한편 국제학술지 ‘네이처’는 올해에 이어 내년에도 필리핀 루손섬 등 동남아시아 섬 지역에서 고대 인류의 기원을 밝혀줄 다양한 화석을 많이 발굴할 수 있을 것으로 전망했다. 송경은 기자 kyungeun@donga.com 동아사이언스

edited by kcontents

The flyby will mark the farthest solar system object encounter in history, with New Horizons on a trajectory designed to ensure its safety while maximizing scientific returns from this distant, mysterious, and primal remnant of the formation of the solar system 4.5 billion years ago.

Time of closest approach will come at 00:33 EST (0533 UTC) while the spacecraft is purposely not communicating with Earth.  Confirmation of a successful flyby is expected to be received through the Deep Space Network on Earth at 10:28 EST (1528 UTC) – 10 hours after the flyby.

But investigating 2014 MU69 during the flyby will not be as easy as it was with Pluto because the exact position of MU69 is unknown, meaning the New Horizons team has had to plan an observation sequence for the spacecraft to account for all possible locations of the object in New Horizons’ instrument’s field of view.

2014 MU69 – What’s in a name:

2014 MU69 might not be a sexy and glamorous name for the public, but it is the official designation of the Kuiper Belt Object (KBO) New Horizons will encounter on 1 January 2019.

Seeking an unofficial but more public-friendly name, NASA held a contest to provide a nickname for the object, with the moniker Ultima Thule eventually chosen.

The name Ultima Thule defines a distant place located beyond the borders of the known world.

The issue with this name in terms of 2014 MU69 is that the KBO is well within the boundaries of the known solar system, with thousands of known Kuiper Belt Objects in its orbital neighborhood as well as numerous other Scattered Disc Objects, Detached Objects, Extreme Trans-Neptunian Objects, Sednoids, and Oort Cloud Objects well beyond 2014 MU69’s orbital boundary.

More so, the New Horizons team itself has not submitted a formal name for the KBO for consideration to the International Astronomical Union and have stated on multiple occasions that they will not do so until the flyby data is reviewed and a better understanding of the characteristics of 2014 MU69 are known.

To this end, NASASpaceflight will refer to the object by its official designation, not its nickname.

Getting from Pluto to 2014 MU69:

Adding to the historic nature of the encounter is the fact that 2014 MU69 wasn’t even discovered until eight and a half years after New Horizons was launched on its primary scientific mission to study the dwarf planet Pluto and its moons.

After sailing past Pluto on 14 July 2015, the New Horizons team celebrated their victory while keeping a firm focus on the now extended mission to perform up-close observations of additional Kuiper Belt Objects.

(Read about New Horizons’ encounter with Pluto here and about some of the Pluto science returns here.)

One month after the Pluto encounter, the New Horizons team, in August 2015, chose 2014 MU69 as the next flyby target.

Discovered by astronomers using the Hubble Space Telescope on 26 June 2014, MU69 will be the farthest solar system object in history to be explored up close by a human probe.

In November 2015, New Horizons fired its thrusters to alter its trajectory by 5 million km (3 million miles) to allow for a close intercept of 2014 MU69 on 1 January 2019.

Additional course correction maneuvers gradually refined New Horizons’ final approach toward 2014 MU69 while allowing scientists to use the spacecraft’s cameras to gather information on the object to avoid potential hazards in the area during the flyby.

These observations were coupled with ground- and space-based telescopic observations of 2014 MU69 which surprisingly revealed more and more mysteries than they did answers about the object.

The target: 2014 MU69 offers wonders and complications

While it speaks to the level of technological advancement we’ve reached that we are able to send a spacecraft to an object we didn’t know existed when that spacecraft left Earth, this same achievement presents significant issues, ones that the New Horizons team has had to account for when designing the flyby sequence New Horizons will perform.

(Read about some of the observational mysteries of 2014 MU69 here.)

One such issue is that the exact size of 2014 MU69 isn’t precisely known.

Even with the latest images as New Horizons approaches the KBO, it is still unknown whether 2014 MU69 is a single irregularly shaped object or if it’s a close or contact binary.

Without knowing this, it is not possible to determine a precise size for the object, with estimates ranging anywhere from “no more than 20 miles (30 km) long” and between 9-12 miles (15 to 20 km) in diameter.

Uncertainty in 2014 MU69’s size is compounded by strange observations returned from New Horizons as it approached the KBO.

One particular observation that has puzzled scientists is the object’s lack of a characteristic “light curve”.

Measuring changes in 2014 MU69’s brightness during its rotational period revealed no observed, repeated pulsations in brightness (the light curve) as would be expected from a rotating object the shape of MU69.

“It’s really a puzzle,” said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute.  “I call this [2014 MU69’s] first puzzle – why does it have such a tiny light curve that we can’t even detect it? I expect the detailed flyby images coming soon to give us many more mysteries, but I did not expect this, and so soon.”

The team already have three working hypotheses to explain the lack of a light curve, including that the rotational axis of 2014 MU69 is coincidentally aimed right at New Horizons, that the object may itself be surrounded by a cloud of dust that obscures the light curve, or even that the object may be surrounded by many tiny tumbling moons.

While the last option would be the most bizarre of the explanations currently believed possible, it is nonetheless an option – as is the possibility that the explanation for the lack of a light curve will not come from one of these three postulated options.

An additional mystery: exactly where is 2014 MU69?

That might sound like a silly question.  Of course we know where this object is. We’re flying a spacecraft by it.

While it’s true that we know the approximate location of 2014 MU69, the reality is that scientists haven’t been able to observe the object for that long because they only found it in 2014.  And because it moves so slowly across the sky due to its large orbit, scientists don’t have a great deal of information on its precise orbit.

And that results in a position uncertainty of several thousand miles – which is a major potential issue for New Horizons’ cameras and instruments which have a limited field of vision.

To account of this position uncertainty, the New Horizons team have had to program an observational flyby sequence to account for almost all of the location possibilities of 2014 MU69 in relation to the probe.

This means that New Horizons’ instruments will observe large areas of empty space at periods during the flyby as each area is searched in an effort to ensure that 2014 MU69 is observed during the flyby.

While it is hoped that the observation sequence will allow New Horizons’ cameras to capture images of the KBO at closest approach, the possibility remains that the cameras will not find the object in their field of view because of the uncertainties in MU69’s exact location.

Ground-based observations coupled with New Horizons observations during approach have given the team the best possible data set to ensure maximum scientific return.

And there is a high degree of confidence that high-resolution images will be captured during closest approach, but it is important to remember that the difficulties surrounding this flyby and the unknown elements of 2014 MU69 could result in New Horizons’ cameras missing the object all together.

The Mission Operations Center for New Horizons, where teams have carefully planned the 2014 MU69 flyby. (Credit: NASA/JHUAPL/SwRI)

Equally important to remember is that if the closest approach images aren’t captured, that does not mean the flyby is a failure as other instruments will be functioning during the flyby, returning data about the space surrounding 2014 MU69.

More so, images captured prior to closest approach are expected to be returned to Earth before the flyby.

The bottom line is that as long as New Horizons survives the flyby and doesn’t enter safe mode during the sequence, we will get data from the event – which is the exact purpose of the flyby.

The flyby sequence:

In the four days immediately preceding the flyby, New Horizons alternated between periods of scientific data collection and optical navigation imaging before turning around and downlinking that information to Earth for the teams to review.

This information led to the final uplink and tweak of the flyby sequence on the morning of 31 December EST in the United States.

The day prior, on 30 December, the first Fail Safe downlink occurred, transmitting data already gathered about 2014 MU69 to Earth.

A second Fail Safe downlink followed on 31 December before New Horizons entered the core phase of its flyby sequence.

As with the Pluto encounter in 2015, New Horizons’ communications dish will be aimed away from Earth during closest approach to allow the spacecraft’s instruments to scan the area where 2014 MU69 is predicted to be.

Closest approach, at a distance of 3,500 km or 2,200 miles (more than three times closer than the Pluto encounter), will come at 00:33 EST on 1 January 2019 (0533 UTC) while the spacecraft is out of communication with Earth.

The flyby sequence will continue for another 3 hours 47 minutes as New Horizons – as it did with the Pluto encounter – spins around to capture images and scientific data of 2014 MU69’s shadowed side.

Then, 3 hours 47 minutes after closest approach, New Horizons will end the flyby sequence and orient itself with its communications antenna aimed at Earth.

At this point, New Horizons will transmit a 17-minute phone home signal, which will be sent from the spacecraft at 04:20 EST (0920 UTC) on 1 January.

Because New Horizons will be 4.1 billion miles (6.6 billion km) from Earth at the time of this transmission, it will take the signal 6 hours 8 minutes to arrive at Earth and the Deep Space Network.

The “I’m alive and performed the flyby successfully” signal from New Horizons is expected to be received at Earth at 10:28 EST (1528 UTC) on 1 January.

Importantly, this phone home signal will not contain any scientific data or images and will simply provide a status on the overall health of the spacecraft.

The first science downlink, 3 hours 20 minutes in duration, which will hopefully contain a full global image of 2014 MU69 resolved to 300 meters per pixel, with 100 pixels total, is expected to be received at Earth from 15:15 to 18:35 EST (2015 – 2335 UTC) on 1 January.

Diagram of New Horizons’ path “over” 2014 MU69. (Credit: NASA/JHUAPL/SwRI)

This initial science downlink will also contain information from the Alice, SWAP (Solar Wind Around Pluto), and SDC (Student Dust Collector) instruments aboard New Horizons.

Several hours later, the second science downlink, 6 hours 44 minutes in duration, is expected to be received from 20:55 EST on 1 January to 03:39 EST on 2 January (0155 – 0839 UTC on 2 January).

The third initial science download, 15 hours 26 minutes in duration, will then follow, starting at 11:44 EST (1644 UTC) on 2 January 2019.

In all, the multi-hour flyby of 2014 MU69 will result in the collection of 50 GB of data, just 5 GB less than the total amount of information gathered in 2015 during the Pluto encounter.

Because of the immense distance and slow data downlink rate, it will take New Horizons 20 months to return all of the 2014 MU69 data to Earth.

https://www.nasaspaceflight.com/2018/12/new-horizons-daring-historic-flyby-2014-mu69/

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