NASA imagines a space telescope orbiting beyond Pluto

NASA imagines a space telescope orbiting beyond Pluto

A space telescope, at a distance that exceeds 500 times that which separates the Earth and the Sun (a unit of measurement conventionally called the astronomical unit, or Ua), will allow in the future to observe in detail an exoplanet using the gravitational lens produced by our star. , to hunt for the bio-signature that would demonstrate the presence of alien life forms. A project that has some science fiction, given that the Voyager 1 probe, the man-made object currently located farthest from Earth, took 44 years to travel a distance equal to just 156 AU. But NASA seriously believes in it: it is in fact one of the five programs under study that have reached phase 3 of development within the Nasa Institute for Advanced Concepts (Niac), the incubator of space innovations with which the agency spacecraft funds the craziest, most ambitious and promising technologies. Let's see what the project is, and what other oddities are currently in the pipeline at Niac.

A telescope for exoplanets The research program for the development of a space telescope with a gravitational lens of the sun is entitled “Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravitational Lens Mission ”, and was promoted to phase 3 in 2020. A milestone that brought the researchers about two million dollars in funding, with which they continued their project. The latest developments are described in a paper deposited in preprint in recent weeks, and are starting to get quite interesting.

In general, the goal is to exploit the Sun to obtain a sharper and more accurate image of an object placed at a great distance from the Earth. This is possible by relying on a method called solar gravitational lens, thanks to which the effects of the space-time distortion produced by the mass of our star allow us to magnify the images collected by a telescope placed exactly on the opposite side of the Sun with respect to the goal that you want to observe. For the technique to work, the telescope must be positioned at the focal point where the rays of light deviated from the mass of the star converge, and in our case, as calculated by Einstein himself, it means reaching a portion of space 542 AU distant from the Sun.

How to do? First, the researchers plan to use not a single large spaceship, but many small cubesats capable of self-assembling to form the telescope once the objective is reached. To accelerate the satellites properly it is necessary to exploit once again the mass of the Sun, using the gravitational slingshot effect to increase their speed at each close passage with the star, up to then propel them in the desired direction in a journey that the researchers calculate. could last as little as 25 years.

Many of the mission's technical specifications, such as the type of propulsion to use (solar sails would be the obvious choice, but with current technologies they would have trouble getting through the close pass in near the Sun), and the shielding technologies needed to go that far into open space, have yet to be thoroughly researched. But the calculations made in recent years have convinced researchers that the efforts would be more than rewarded by the result. Such a telescope could in fact provide the most accurate mapping of an exoplanet obtainable without going directly to the place: an image of the planet with a spatial resolution of about 25 kilometers, enough - they assure - to map the characteristics of the surface and identify traces of shapes of life.

What else is cooking? As we said, there are just five Niac research programs that have reached the third phase of development since the institute was refounded by NASA in 2011. The first was the Mini Bee project, in 2019, which aims to realize and to test a new technology for extracting water and other volatile compounds present in asteroids, to be used to refuel during future space missions. The technique is called optical extraction, because it involves concentrating the rays of sunlight, and exploiting them to destroy the rocks of the asteroids and thus obtain the materials kept inside them.

A second research program, which has entered the third development phase in the same year, instead foresees the realization of “Skylight”, a demonstration mission for the realization of autonomous robots able to explore the pits present on the lunar surface. Places - explain its creators - of strategic importance for the future colonization of the satellite, of which very little is currently known.

Following, in 2021, the third phase was reached by the "Cube-Sat Space Flight Test of a Neutrino Detector ”, a project that wants to send a neutrino detector into space with which to hunt down dark matter. Also in this case, the goal is to exploit the gravitational lens of the Sun to study the neutrinos coming from the galactic nucleus, deviated from the mass of the star, and those emitted directly by the Sun. In this case, being particles with mass the the focal point to be reached would be much closer than that necessary for electromagnetic radiation: a point located between 20 and 50 astronomical units, more or less between Uranus and Pluto.

Last arrival, finally, is the project that reached its third phase this year: "Diffractive Solar Sailing", a research program that aims to revolutionize the concept of solar sail, passing from the traditional one, based on materials that reflect light, to a new design that exploits metamaterials capable of using diffraction to harness the propulsive power of electromagnetic radiation from the Sun, and obtain greater power and maneuverability. The technology is still under development, but the project already involves the construction of a fleet of diffraction solar sails that should circumnavigate the Sun, to study it closely, and provide real-time data for space weather forecasts. >

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