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Starts With A Bang

Should NASA Send New Horizons To A Nearby Star For Its Final Mission?

It’s one of only five spacecraft that will exit the Solar System, and the only one we have a chance to aim at another star.

Of all the spacecraft ever launched, only five will ever exit the Solar System.

The schematics of the Voyager spacecraft include a plutonium-238-powered Radioisotope Thermoelectric Generator, which is why Voyager 1 and 2 can still communicate with us today. New Horizons also has one attached, which should provide fuel and power for it throughout the next decade at least. (NASA / JPL-CALTECH)

Voyager 1 and 2, Pioneer 10 and 11, and New Horizons are the only ones to achieve escape velocity from our Sun.

A logarithmic chart of distances, showing the Voyager spacecraft, our Solar System and our nearest star, for comparison. We may not be well-positioned to traverse interstellar distances on human timescales just yet, but over the coming millennia, the five spacecraft leaving our Solar System will pass close by numerous stars. (NASA / JPL-CALTECH)

Although it takes 10,000+ years for each to traverse even 1 light-year, they’re all destined for interstellar space.

This image is a single projection of Gaia’s all-sky view of our Milky Way Galaxy and neighboring galaxies, based on measurements of nearly 1.7 billion stars. The map shows the total brightness and color of stars observed by the ESA satellite in each portion of the sky between July 2014 and May 2016. These stars have now had their positions and trajectories better determined than ever before. (ESA/GAIA/DPAC)

With data from ESA’s Gaia mapping the Milky Way’s stars, the trajectories of all nearby stellar neighbors can be determined.

The positions of the stars relative to our own Sun will change dramatically on timescales of thousands of years, with the nearest stars to us changing in rapid fashion over the prior 20,000 and next 80,000 years, as illustrated here. (WIKIMEDIA COMMONS / FRANCESCOA)

Over the next million years, the Voyagers and Pioneers will approach numerous stars, but only at relatively large separations.

In December of 2019, a paper was published using Gaia data to track the positions, telemetries, and velocities of more than 7 million stars, drawing the conclusion of which stars will be encountered by which spacecraft, with HIP 117795 coming within 0.75 light-years of Pioneer 10 as the closest. (C.A.L. BAILER-JONES AND D. FARNOCCHIA (2019), ARXIV:1912.03503)

The closest will be Pioneer 10, encountering HIP 117795 in ~90,000 years from 0.75 light-years away.

Illustration of objects in the outer solar system, including Pluto and 2014 MU69/Arrokoth, and the trajectory of New Horizons (yellow). The orbits of the planets are illustrated with cyan rings, and both asteroids and Kuiper Belt objects illustrated as points. Cold Classical Kuiper Belt objects are drawn in red. New Horizons will continue its travels beyond the Kuiper belt, wherever it heads next. (ALEX PARKER)

But New Horizons, unlike the others, still has significant fuel remaining.

Pluto and its moon Charon; image composite stitched together from many New Horizons images. New Horizons has been the most successful mission ever sent into the Kuiper belt, and will travel beyond it entirely at some point in the next decade or two. (NASA / NEW HORIZONS / LORRI)

After encountering Pluto and Arrokoth, it may yet target another object in the outer Kuiper belt.

The first color image constructed (via a composite from New Horizons data) of 2014 MU69: Arrokoth. The reddish color is likely due to tholins: the same reddish color visibly present on the surface of Charon. Only New Horizons has ever taught us this kind of information about Kuiper belt objects. (NASA/JHUAPL/SWRI)

Subsequently, it will eventually enter interstellar space, but can be boosted to approach future stellar targets.

The distances between the Sun and many of the nearest stars shown here are accurate, but only a very small number of stars are presently located within 10 light-years of us. Over the next million years, many stars will approach and recede from our Sun as the stars continue their gravitational dance in our galaxy. (ANDREW Z. COLVIN / WIKIMEDIA COMMONS)

Ideally, an exoplanet survey could find a suitable star with a potentially inhabited Earth-like world.

Artist’s impression of the Extremely Large Telescope (ELT) in its enclosure on Cerro Armazones, a 3046-metre mountaintop in Chile’s Atacama Desert. The 39-meter ELT will be the largest optical/infrared telescope in the world, and could perform direct searches for exoplanets if we became aware of an appropriate stellar target for New Horizons. (ESO/L. CALÇADA)

Unlike the other spacecraft, New Horizons could approach such a target within just a few Astronomical Units.

The ideal exoplanet for alien life will be an Earth-sized, Earth-mass planet at a similar Earth-Sun distance from a star that’s very much like our own. We have yet to find such a world, but are working hard to estimate how many such planets might be out there in our galaxy. If we can find one within the reach of New Horizons, we should absolutely alter its trajectory to facilitate a future encounter. (NASA AMES/JPL-CALTECH/T. PYLE)

With proper planning, New Horizons could mark humanity’s first encounter with a foreign planetary system.

An animation showing the path of the interstellar interloper now known as ʻOumuamua. The combination of speed, angle, trajectory, and physical properties all add up to the conclusion that this came from beyond our Solar System. Although none of the interstellar objects we found are of alien origin, we could send one that may become the galaxy’s first. (NASA / JPL — CALTECH)

Mostly Mute Monday tells an astronomical story in images, visuals and no more than 200 words. Talk less; smile more.

Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.


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