End of the Chase for New Horizons?

Space Exploration Anton Komarov (Sept 21, 2023)

End of the Chase for New Horizons?

On the 4th of September 1989, I was avidly going through the pages of the latest edition of Newsweek. Even though I am not able to refresh my memory since the said edition is not available online, I can still vividly remember every single sentence printed in that magazine more than three decades ago. The reason behind was that I must have read it a good hundred times, back then it was another age and if I was blessed to have a PC at home, the internet of things was a dream barely envisioned and would still have a long way to go before becoming the reality of instant information that it is today. So to say that information was scarce. So scarce that I remember no less vividly buying from a school bully, a second grade photocopy of a status report of Voyager 2 (I still wonder to this day where the schoolyard tyrant got hold of the original as these creatures are not known for their intellectual thirst, but he was certainly an excellent business man as this poor copy cost me a whole month of hard won pocket money. The investment was however worth every penny.)

The title was ‘The Blue Planet, A Close encounter with Neptune’ an article in which Newsweek depicted the triumphant flyby of the Ice giant Neptune by the Voyager 2 Space Probe in late August 1989. Everything concerning Voyager 2 was extraordinary from its early conception to the last picture show of Neptune which signed off a too brief interview of the giant world. I was not born when US Astronauts landed on the Moon and I cannot remember the early forays of Pioneer 10 and 11 when they set sail for the outer solar system in the early 70’s. However, when Voyager 2 hit the bow shock of Saturn, I was already awoken to the vast Solar System surrounding our home Planet. Then the long wait started and when in 1986, Voyager 2 arrived in the vicinity of Uranus, the public had a bit forgotten about her but millions like me were waiting and three years later, during the last encounter with Neptune, I was proud that unlike billions of others, I had not missed the arrival of Columbus in the New World. The Odyssey of the Voyagers has been countlessly told, less so was part of the story that Newsweek revealed to its readers. The Magazine reported that after the encounter with Saturn in 1981, NASA was pressured to shut down the space probe and if not for the intervention of top officials like Vice President George H.W Bush (George Bush Senior was the 41st president of the US but he also served as Vice President under Ronald Reagan from 1981 to 1989), the history of planetary exploration of the solar system would have differed dramatically. Would NASA have approved another Mission to Uranus or Neptune? Would we have known about the tormented geological features of Miranda, a satellite of Uranus? If Voyager 2 did not reveal the surprisingly geologically active Triton with its cryogenic geysers shooting nitrogen gas in the atmosphere and if the spacecraft did not fire the imagination by showing compelling evidence that Triton was a captured object of the Edgeworth Kuiper belt, the same region in which lies Pluto, would the space probe New Horizons even have visited Pluto? In the following years, I would not always be in agreement with the politics of President Bush but when I think about him, I will always remember that he had been instrumental in saving the skin of Voyager 2.

A few days ago I was alerted by a colleague about a tweet of Alan Stern who was deeply disappointed by plans of NASA

Just saw this, worthy reading! Re-posts please. #Science #NASA #Space https://t.co/9Hicdgu8wz
— Alan Stern (@AlanStern) August 26, 2023

to shift the focus of the mission of the space probe New Horizons, from an the exploration and the study of the Edgeworth Kuiper Belt objects to a research probe dedicated to Heliophysics science.

In the public’s imagination, New Horizons and the Voyagers belong to the same category of missions, the ones that appeal to all of us, the great voyages of discovery revealing worlds that have never been seen before by the human eye, the kind of missions that really counts. Getting New Horizons literally off the ground to Pluto was not a walk in the park and we relate extensively on this fascinating story in our article ‘The Case for Pluto Lives’. For those who are not familiar with the story, the name of a man, Alan Stern will always be associated with the New Horizons saga. Dr. Alan Stern was an early advocate of a mission to Pluto soon after the encounter of Voyager 2 with Neptune in 1989. With other scientists he founded an advocacy group to promote such an endeavor. For decades, he championed different concepts to explore the small worlds; each of these concepts was cancelled at different stages of completion due to technical or financial concerns. Undeterred, Stern believed that Pluto was a key celestial body for the comprehension of our solar system and should not stay unchallenged. However enormous boulders paved the way of the man even when success was almost certain. The officially funded New Horizons was effectively cancelled and not included in Nasa’s budget of 2003. What followed was a new round of lobbying for the mission spearheaded by Stern and his colleagues. Finally when the decadal survey topped New Horizons as a high priority in its recommendations for the period of 2003 to 2013, everyone knew that the mission would survive but more trouble was lurking, all which Alan Stern describes masterly in his book ‘Chasing new Horizons’ which he coauthored with David Grinspoon. The drama that was unfolding next was not one of a technical or financial nature; it was more one of human stupidity.

On the 24th of August 2006 while New Horizons was cruising somewhere between Mars and Jupiter, Pluto was demoted from its status of Planet. A controversial decision which triggered an international outburst in the international community of Astronomers and still divides planetary scientists to this day. With the passing of years, the passion around the question faded to reignite spectacularly when New Horizons finally flew by Pluto in 2015. Pluto undoubtedly baffled planetary scientists and enthusiasts around the world justifying every dollar in the billion invested to make the mission possible. Geologically active with volcanoes, mountain ranges and a unique feature in the shape of an heart which was immediately adopted worldwide by a stunned public. This geological oddity named Sputnik Planitia is a basin filled with Nitrogen ice, devoid of craters and covers an area of 1050 kilometers by 850 kilometers. What other denomination could one offer better than the one of Planet in front of the dynamism of Pluto and its Binary companion, Charon, a body half the size of its parent world? Charon lays a mere 19,640 kilometers distance from a point situated some 960 kilometers above the surface of Pluto where the barycenter of Charon is found. This makes the planetary couple more of a twin world than a system dominated by Pluto, a cosmic arrangement that is unique in the solar system as far as our knowledge is concerned. With Pluto’s encounter, a new generation proved their worth; they have had an odyssey comparable to a certain extent to the Voyagers. This apotheosis was however not a final one.

If one discounts Triton which also shares the characteristics of Pluto, it is the latter which is considered to be the inner edge and effectively the first object lying in the Edgeworth Kuiper Belt. Not unlike the asteroid belt which is situated between Mars and Jupiter, the Edgeworth Kuiper Belt contains the remnants or the building blocks of our Solar System. Contrary to the inner asteroid belt which is mainly constituted of rocks and metals, the outer Solar System belt mainly contains elements composed of frozen volatiles, Water Ice, Methane and Ammonia. The asteroid belt is poor in planetary mass objects and the only celestial body which deserves the distinction is Ceres with a diameter of 939 Km. Vesta, the other ‘Titan’ of the belt sporting 525 kilometers in diameter could have been considered in the past to meet the conditions to be a planetary size object. In short, a dwarf planet like Ceres or Pluto but however, Vesta is no longer in hydrostatic equilibrium.( A savant terminology which means that Vesta is not round in shape anymore, an essential criteria for any creature of the celestial bestiary destinedto be qualified as a planet). The explanation for the uneven shape of Vesta is that she had been battered in the past by asteroid impacts which literally send pieces of the proto planet into the heavens. There are other examples of planetary size objects in the solar system which could fit into the category of Dwarf Planets or ‘former Dwarf Planets’ and our Solar System also hosts several planetary sized moons which fit the definition but as their categorization as planets is not widely accepted, I will not mention them here.

In Contrast with the asteroid belt, the Edgeworth Kuiper Belt, the region of the Solar System which the New Horizons space probe is crossing is populated with several planetary mass objects, at least a hundred of them with their cortege of moons. The general public barely know about them and their exotic names like, Gonggong, Makemake, Quaoar, Orcus and Salacia. Some Dwarf Planets like Eris or Sedna belong to yet other regions of the Solar System, the Scattered Disc or in the case of Sedna, it belongs to the dynamical class of detached objects. For people like Alan Stern (Who by the way coined the term Dwarf Planet) and those who follow his reasoning, a Dwarf planet is a fully fledged planet just smaller. In fact our Solar System contains multiple categories of Planets. You have the classical 8 ‘Uber Planets’. The rocky worlds, Mercury, Venus, Earth and Mars followed by the Gas Giants Jupiter and Saturn and Uranus and Neptune are considered to be Ice Giants. That is not however the position of the IAU for which Dwarf Planets are not ‘real’ planets but missing ‘something’ to be the true deal. This ‘something missing’ or more prosaically, the reasons given by the IAU being highly unscientific, I will not debate it here having done so extensively in the past. But the Edgeworth Kuiper Belt contains other denizens too. Comets categorized as periodic with an orbit of less than two centuries were originally thought to reside in the region but since the 1990’s, studies have shown that the periodic comets seem likely to originate from the scattered disk in which dwells Eris, the most massive and second largest known Dwarf Planet. The Belt also contains the so called Classical Kuiper belt objects some poetically named (33001)1997 CU29, (55636)2002 TX300 or (55565) 2002 AW197. The first quoted measures 289 kilometers in diameter and the last one with a diameter of 700 KM is probably the largest known unnamed object in this region. Such an object is less barbarically named 486958 Arrokoth (barbaric refers to the insane numbering, not the name), discovered by the Hubble Space Telescope less than a year before New Horizons had its now historical encounter with Pluto. Once again, it was a complete success when Arrokoth became the farthest and most primitive object to have been visited by a space probe. Following on the plans of the extended mission, ground based assets assisted by artificial intelligence continued to search for another target for the spacecraft and everything seemed perfect until this announcement of NASA which provoked the indignation of Alan Stern and could irrevocably change the nature of the mission.

So if the spacecraft is in excellent condition and perfectly able to complete its planetary exploration, what then explains a decision of that nature from NASA? A Science Mission directorate suggestion would turn the planetary mission into one under the control of their Heliophysics division and refocus the mission in that sphere of science. (The Heliophysics Science Division of the Goddard Space Flight Center conducts research on the Sun and the Heliosphere). This new orientation is a direct result of a senior review considering the multi-disciplinary approach of the mission in the field of Planetary Science, astrophysics and heliophysics. Assessing the review and its fallout in a question answer session on the 6th of April, Lori Glaze, Planetary Science Division Director, said that the review noted that the probability of additional science return in the field of planetary science is rapidly diminishing with future additional gain in this sphere being very little. Glaze also added that having evaluated the same review, the Astrophysics and heliophysics divisions found that valuable heliophysics could be done from this unique location in the solar system. That last statement is certainly true, the twin Voyagers have undoubtedly contributed to heliophysics science and even while being operated to this day by the Jet Propulsion Laboratory (JPL), they are also part of NASA’s Heliophysics System Observatory and have since the end of their planetary mission, added a considerable amount of data along with key discoveries on the subject. What is disturbing is the way Glaze put it, if the review effectively said that the proposed Kuiper Belt Objects(KBO) studies are unlikely to dramatically improve the state of Knowledge, it never actually said that there that there was very little planetary science to be gained.

Each and every time that a respectable astronomer (Even less respectable for that matter) said that there will be no surprise in exploring an object or a region of the Solar System, he was revealed later with the insight of time to have been completely foolish. And contrary to what one may assume, it is so recurrent that one wonders how it is that no one ever learns. Today Mars is one if not the most thought of destinations of the space agencies whether it be for human or robotic exploration. After the images of the first flyby arrived, some said what was the point as this was a world covered with dust storms that appeared to be hopelessly barren, sterile and deserted. Some others were quick to say that the moons of the outer planets would be boring dead places covered with ice, frozen in time. The deep space probes proved the absolute contrary, revealing the most active world in the Solar System like the intensely volcanic Io, a Jovian satellite. Other Moons of the outer Solar System were hiding beneath their icy surfaces salty oceans containing individually more water than in all the oceans of Earth combined. All of this came as a surprise with other unexpected discoveries like the Geyser of Enceladus, the cryo volcanoes of Triton or the dynamic exchange of material between Pluto and Charon. I remember that soon after the encounter of Voyager 2 with Uranus, many observed that the planet was rather ‘placid with a lack of observable features ’ and again prematurely predicted that Neptune located further out would be even colder than Uranus and so by extension, even less interesting. Stating the exact contrary would have been more adequate as Neptune was found to have a dynamic atmosphere with giant storms and the most violent winds in the Solar System. The planet was also surprisingly warmer than it’s then supposed alter ego Uranus, which orbits at a closer distance to the sun while its only giant moon is most mysterious and fascinating.

The exact phraseology used in the review quoted by Lori Glaze was ‘A Notable primary conclusion of the panel was that the proposed studies of the Kuiper Belt Objects are unlikely to markedly improve knowledge because the spacecraft lack resources for long term, high cadence observations… ‘

Let’s say straight that one may be in disagreement for good reason with the conclusion of the senior review, but it is a not a nonsense one aimed at deliberately hurting the planetary science team identifying the strength of the mission and going on to say that, ‘All the instruments of New Horizons are still functioning and the spacecraft has sufficient propellant and power resources (RTG) to perform the K2 proposed Science goals‘. The power source will last sufficiently up to the 2028 horizon (beyond K2), after which output will be insufficient to power the instruments. The review says that the panel identified one minor weakness in the scientific merit of the planetary mission as well as one major strength. Opposed to that, the panel identified five major strengths and no weakness in the scientific merit of heliophysics and astrophysics investigation. At first view, the conclusion of the panel could appear to make sense to an independent observer, let’s see what the opposition counter argument is.

If originally New Horizons has been conceived to explore Pluto and its moon system, it has however been used from the beginning to perform heliophysics and astrophysics science and continues to do so proving that both are not incompatible. But turning and shifting the probe’s focus for the benefit of an artificially competitive division, makes it feel like a highjack or a grab. In an open letter to NASA, some unhappy scientists including preeminent heliophysicists wrote that “New Horizons has enabled uninterrupted heliophysics measurements throughout the heliosphere for over a decade, alongside its ground-breaking Kuiper Belt and other planetary observation.. The conduct of the mission’s heliophysics observations is both synoptic and in no way in competition with its planetary observations of the Kuiper Belt and Kuiper Belt Objects.” In May of this year, Alan Stern Principal Investigator on the mission commented that his team was in contact with NASA but that the communication had not been effective. He also added that in doing heliophysics observations everyday, there was no reason to make a battle between the two as they coexisted.

What about the ‘Unlikely’ future science results of New Horizons or like Lori Glaze put it the probable ‘Very little additional gain’. An announcement that the Subaru Telescope has found a new target for New Horizons would throw in the dustbin the finds of the review or the comments of Glaze but it is not so simple as Stern explains, “We’re twice as far out From Earth as when we found Arrokoth, which makes the targets we search for sixteen times farther. So the search is much harder.” Adding that the opportunity to explore the Kuiper belt will not arise again before decades have passed and that the team needs time to find another target’.

The New Horizons team would have certainly made do without this additional pressure. But what if after all they do not find a suitable target in time? The best answer may have been given by the Planetary Science Institute Director and CEO Mark Sykes, “ There might not be a target close enough to New Horizons’ flight path. But, the very high payback and the marginal cost of the effort are tiny compared to the billion dollars that has already been invested by taxpayers in this mission.” Speaking about the unique planetary, astrophysical and heliophysical observations that can be made by New Horizons, Sykes commented, “To not make these observations, to not make an effort in planetary, as well as astrophysics, and heliophysics with everything this spacecraft can do, to me is a crime”. Indeed a very powerful reaction but can we blame him? The plot seems to thicken when we learn that NASA will also replace the whole team operating the spacecraft by a fresh new one from the Heliophysics Division. No one needed a crystal ball to know that this one decision would not have been popular among the original team who have been operating the probe for almost 18 years. It is not a question of fairness when we speak about sums exceeding a billion dollars, what is humane and fair makes it rarely to the equation; it is actually a case of pure old common sense.

One can compare the rationality of NASA’s decision to change the team to the wisdom of replacing the whole logistic and mechanics of a Formula 1 team in the middle of a race. I said higher up in the text that the Planetary Senior Review does not aim at hurting any particular group. The section concerning New Horizon is barely more than one page and contains five paragraphs, it resembles all reviews of this kind, something written by a computer to be read by another machine. The last paragraph reads quote ‘KEY Finding/recommendation : K2 can be a model for long-lived probes with funding from multiple SMD divisions, if successful. The New Horizons Spacecraft and instruments are healthy and located at a never-before-explored sector of the outer solar system which presents an extraordinary opportunity to observe, measure, and collect data. Meritorious science can be achieved in heliophysics, astrophysics and planetary science but science optimization will require creative problem solving and cross-divisional leadership ‘ end quote.

For a man who was listed as among the 100 most influential people in the world by Time magazine in 2007, Alan Stern knew probably the greatest challenge of his career fighting to get New Horizons off the ground, a challenge he won against overwhelming odds. The odds are no less overwhelming in the fight he has engaged to rehabilitate the planet status of Pluto but as a scientist, he probably knows that in the case of the Dwarf Worlds, logic will prevail and that fight is mainly of time, dedication and patience. Unfortunately for this third challenge, time is not playing in his favour. He is certainly not alone ,Bill Nye CEO of The Planetary Society, Bill Diamond of The SETI institute, Sir Brian May Lead Guitar of Queen and Astrophysicist have joined forces with 22 other Scientists to sign a letter protesting the New Horizons mission changes. Many of the same people were vocal in the past to save the project during dire moments. Will the public react positively and in time to change the balance of the situation?

The letter of Bill Nye and the other scientists speaks about the mission cost to the US taxpayers but also reminds the public that New Horizons is a jewel in the Nation’s and NASA’s portfolio. Alan Stern makes almost the same remark but compares New Horizons to a national treasure. Of course they are both right but missions like New Horizons or the Voyagers, have literally a planetary scope. Adopted by a fascinated public worldwide, these little probes are the emissaries of humanity in its voyage of discovery, something appealing to a race whose origins are nomadic and hunter gathering. Since the dawn of time, the next target has been either this mythical mountain barring the view or this unattainable Horizon hiding new lands pleading to be discovered. Supporting New Horizons and its team in the last leg of this formidable cosmic Odyssey is just doing the right thing.