Five reasons why astronomy is important to our future in space.

One of the great privileges of my role in external relations at the European Organisation for Astronomical Research in the Southern Hemisphere (also known as ESO) is to represent the Organisation at the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS). The Committee was established as a permanent body of the UN General Assembly in 1959 and developed the Outer Space Treaty, adopted by the UN General Assembly in 1967. COPUOS is the only global policy forum at the highest political levels of the UN at which space science, and therefore astronomy, is discussed. One of my goals in attending the Committee is to champion the broader role of astronomy—and particularly ground-based astronomy—in space exploration.

There are many exciting things happening now in the space domain from SpaceX's and other companies' efforts to build large constellations of communications satellites, to NASA's reinvigorated plans to return humans to the Moon. These developments are attracting greater attention from governments and funding agencies, resulting in a boost and possibly reallocation of funding to support space exploration and development. While personally I believe that astronomy and other fundamental sciences are justified and important to society on their own merits, it's nevertheless important to define and translate these benefits for those policymakers focusing on the immediate goals of developing a space economy. The basic conclusion of this article is that astronomy's critical role in space exploration and space issues can be considered as an important "spin-off benefit" from investment in fundamental astronomy research. Here are five reasons why space agencies and industry should care about astronomy.

1. Astronomy facilities support many critical functions of space exploration and space science.

Did you know that many aspects of space exploration and space capabilities are dependent upon the role of ground-based astronomical observatories? Certain space assets require their three-dimensional position to be known to very high precision. The European Space Agency’s (ESA) Gaia satellite, launched in 2013, is observing over one billion stars in the Milky Way to determine their proper motions and positions. To achieve this astrometry data for target stars requires Gaia’s velocity to be known to within 2.5 millimetres per second, and its position in the sky to within 150 m – a significant challenge given that it operates at 1.5 Million kilometres from Earth! To overcome this challenge, the mission concept included a regular observing campaign by a network of optical ground-based telescopes, including ESO’s VLT Survey Telescope (VST) to determine with high precision Gaia’s location against background stars.

Essential data for spacecraft positions and trajectories are also obtained from optical and radio ground-based observatories to determine ephemerides—the positions of solar system bodies. This involves dedicated observing campaigns of solar system bodies over long periods of time. Similarly, star tracker guidance systems for satellites rely on high precision locations for background stars, which are provided by data from both ground and space observatories. Just recently, ESA announced the launch contract for its Jupiter Icy Moons Explorer (JUICE), which includes a further test of the Planetary Radio Interferometry and Doppler Experiments (PRIDE). This experiment uses Very Long Baseline Interferometry (VLBI): a network of radio telescopes to measure the difference in Doppler shift and signal arrival time from a distance spacecraft to the Earth in order to determine its position very precisely. This gives important information about the trajectory of spacecraft which can be used in turn to inform us about the gravitational field and composition of a planetary body. VLBI is also used here on Earth to measure the motions of tectonic plates and provide important validation to satellite global positioning systems.

Another important role of ground-based observatories is to allow detailed characterisation of solar system objects to support space mission design and also to provide complimentary scientific findings. Saturn’s moon, Titan, was extensively studied using ground-based telescopes prior to and during ESA’s Huygens probe landing on the surface. ESO’s Very Large Telescope and many others were used to characterise Comet 67P/Churyumov–Gerasimenko before the Rosetta probe arrived with its Philae lander. In addition to this preparatory work, the contribution of ground-based telescopes is crucial to give the context to spacecraft observations. For instance, ground-based observations were able to observe the full coma of comet 67P while Rosetta was deep within its cloud, collecting exquisitely detailed images of the comet's surface.

As the rate of space missions in our solar systems increases, the requirements for ground-based astronavigation and observation will substantially increase. We need a pool of astronomers skilled in the required observational techniques and instrumentation, both to conduct the work of space exploration but also to innovate in the sector. We know that often innovations result from solving challenging observational problems in fundamental astronomical science.

2. The best science requires both space and ground astronomy facilities.

Space and ground assets operate in a synergistic manner, based on each capability’s complementary strengths. In terms of astronomy and planetary science, space-based observatories are free from the optical disturbances and absorbing properties of Earth’s atmosphere and can view all wavelengths of light, yet it is usually either impossible or very costly to repair or change instrumentation once they are launched. Consequently, space observatories are generally higher cost and are subject to more stringent design-mission trade-offs. On the other hand, ground-based observatories rely on computer-controlled and laser-assisted adaptive optics systems to mitigate for the atmospheric turbulence, and cannot see all wavelengths, but their instrumentation packages can be rapidly and flexibly adjusted and maintained to meet new scientific requirements.

Astronomical observations are coordinated between ground and space observatories to provide maximum scientific return by monitoring faint and/or time-sensitive objects, and allowing more rapid deployment of specialist instruments. NASA’s Kepler space mission launched in 2009 observed thousands of stars to detect drops in brightness due to transiting planets orbiting around the star. Each “planet candidate” required detailed follow-up observation from ground-based telescopes using specialised instruments to determine whether the light curves may be due to another factor such as a binary star system or variable stellar activity. Similarly, the scientific goals of many other planned "exoplanet" space missions depend strongly on the supply of a wide range of ground-based facilities at different wavelengths.

3.Astronomy is an important source of technology and capacity development for a global space economy.

The first way in which many potential scientists and explorers in developing countries experience exploration of the cosmos is through ground-based astronomy, often by using small commercially available telescopes, building and operating small ground-based observing facilities, or using publicly available archive data. This builds capacity, increases the visibility of space as a vehicle for development and often acts as a gateway to develop a national capability in space science. The International Astronomical Union’s Office for Development plays a key role in facilitating this goal. Many of the national delegates from developing countries sitting at the United Nations COPUOS are former astronomers, and the astronomy sector in the country is often one of the driving forces for establishing a space sector.

Astronomy has traditionally been at the forefront of providing open-access data, developing techniques and policies adopted now by other scientific fields. Many observatories provide their data to the public. After a proprietary period for the principal investigators, ESO provides all data taken on its telescope through its publicly-accessibly ESO Science Archive. The ESASky initiative is an amazing facility catering to both generalist and specialist uses. With right skill set, anyone in the world can access data and perform research. The UN Office of Outer Space Affairs recently sponsored the Open Universe initiative, which raises awareness of the critical role of publicly and globally available data sources for astronomical science.

The development of sensitive astronomical instruments for satellite- and ground-based observatories relies on common technologies in optics, detectors, and cryogenics, and draws from the same pool of technical and scientific expertise. Astronomy capacity is not only relevant to space exploration. The quest to expand our knowledge continually pushes the technical limits of scientific instruments to higher precision, sensitivity and efficiency. This requires a large pool of technological expertise that both feeds and draws from industrial needs. In the case of astronomy, scientific and technical needs generate many industry-relevant and transferable skills in data science, data visualisation, computer programming, mathematics, optics, electronics, mechanics, control systems and energy production and conservation. The need, and ability, to coherently integrate so many different and diverse disciplines is a particular hallmark of astro-technology. Universities are now supporting this synergy through the inclusion of industry skills units in astronomy curricula.

Science and innovation have a beginning: a spark of curiosity about the natural world, or a pressing problem that drives the creation of innovative solutions. Yet science and innovation cannot occur without a technically and scientifically competent mind, and this begins with education. Astronomy and space sciences are important because they attract the attention of, and stimulate interest in, young people all over the world. They are a key driver for student uptake in academic and industrial science, technology, engineering and mathematics (STEM) fields. Astronomy may be the only scientific field with its own category of public outreach centre — the planetarium — which takes advantage of the awe-inspiring imagery from the cosmos. Under the guidance of professional scientists, astronomy projects have involved millions of amateurs and a worldwide community, which engages in ambitious and fruitful citizen science projects.

4. Astronomers may one day save humanity on Earth, and then the Moon.

From climate change to nuclear war, humankind faces many mostly self-inflicted threats, yet one from which we are completely free from blame is that posed by asteroids or comets, collectively termed near-earth objects (NEO). One only has to look at the highly cratered surface the Moon, which lacks the protective envelope of the atmosphere, to understand the problem. Earth will likely be impacted by at least one rocky / iron asteroid of 100 metres in size on the timescale of 10 millennia, causing devastating regional effects or global tsunamis. Yet given the incomplete knowledge about the local population of NEOs, we don't know exactly when such an impact could occur. Thankfully, due to the work of astronomers we can rest safely.

As a result of the scientific interest about understanding how our solar system formed, planetary scientists and astronomers have studied asteroids and comets. The practical benefit of this study is that we know a great deal about the composition of such objects. Many high profile space missions have visited asteroids and comets. A number of agencies and observatories participate in the UN-mandated International Asteroid Warning Network (IAWN) to detect, track, and physically characterise NEOs to determine which are potentially dangerous to Earth. Another international body, the Space Missions Planning Advisory Group (SMPAG) works with IAWN but focuses on the planning and future coordination of an international response to a threatening asteroid.

A recent exercise led by the NASA Planetary Defence Office took advantage of the close approach of the binary asteroid 1999 KW4 to rehearse the global response to the discovery of a threatening asteroid. A wide variety of optical, infrared, millimetre wave and radio telescopes were used to track and refine the orbit and determine object's chemical and physical composition, including ESO's Very Large Telescope. This exercise and others before it have shown the ability of the world's astronomy community to collaborate and rapidly characterise a potentially threatening object, providing vital information to space agencies who would be charged with designing a mission to redirect the object. This work is not only important on Earth. If humankind is to create large-scale, permanent settlements on the Moon and then Mars, asteroid monitoring and defence must be a component of these plans, especially as the Moon (and to some extent, Mars) lacks the relatively thick and protective atmosphere of our home planet.

5. Astronomy has played—and continues to play—a foundational role in driving humankind’s passion for space exploration.

Humankind has looked to the heavens for millennia in search of meaning and understanding about how the Universe works. The endless frontier of the cosmos has spurred our curiosity to explore and to develop scientific methods to do so, with wide-ranging impacts on our society. Astronomy has given us essential knowledge about the fundamental forces of the Universe in addition to multiple technology spin-offs and a large body of skills and technologies in optics, detectors, radio receivers and communications, which are essential to space travel. There is no reason to doubt that further discoveries from the nature of the solar system's rocky bodies to a fundamental understanding of gravity, will contribute to further possibilities in exploring space. In turn, improved capabilities in space exploration will open the door to new possibilities in astronomical research. A robust human presence on the Moon, for example, would allow for amazing astronomy projects.

After the great astronomer, planetary scientist, and public communicator, Carl Sagan, convinced the operators of the Voyager 1 probe to take a photograph of Earth from six billion kilometres, he distilled the ultimate message of astronomical science in his book, The Pale Blue Dot [1]:

“It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known. "

As humankind expands throughout the solar system, astronomy will continue to give us a collective knowledge of where we fit in the vastness of the cosmos. Astronomical discoveries have taught us that we are not the centre of the world, that the laws of physics are the same throughout the Universe, that the Universe had a beginning and started with the Big Bang, that our current understanding can only explain approximately 5% of the matter in the Universe, and that there are other planetary systems, some of which include habitable planets. Our notions of time, seasons, nature, navigation, and agriculture originated from close study of celestial objects. Astronomical knowledge about our place in the cosmos has yielded several transformational paradigm shifts, with sometimes dramatic societal consequences, by giving us an objective picture of our existence, location, and importance.

Building from thousands of years of observations of the heavens from scholars around the world, Galileo, Kepler, Newton, and others developed the first physical explanations underlying the movement of planetary objects, thus laying the foundations for exploration of space. The modern era of astronomy and space science is now culminating with the exploration of worlds outside our own solar system. In the near future, ground and space observatories will be built that allow direct imaging of exoplanets, and detailed analysis of the chemical make up of exoplanet atmospheres, which could yield the answer to the ultimate question – are we alone?

As humanity takes its first tentative steps from the comfortable boundary of Earth’s atmosphere, it is paramount that the global vision for space exploration remains founded in its peaceful scientific origins – to understand our surroundings for the purpose of knowledge for all.

[1] Sagan, Carl (1994). Pale Blue Dot: A Vision of the Human Future in Space (1st ed.). New York: Random House. ISBN 0-679-43841-6.

Author's note: I am indebted to multiple colleagues from ESO and many other astronomy organisations who provided comments and suggestions. Parts of this work began life as a document I wrote for ASTRONET and also an ESO statement for the UNISPACE+50 event.