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Does Future Space Science require Formation Flying?
Alain LgerInstitut d'Astrophysique Spatial (IAS), bat 121, Univ. Paris-uSd, F-91405 Orsay,
Abstract:I consider the different domains where FF is essential for future Space Science,including single mirror very long focal telescopes, e.g. f = 40 m for very high accuracyAstrometry (for detecting and measuring the mass of telluric planets around nearby stars),long base interferometry, e.g. 300 m, for thermal IR (Darwin-like observatories searchingfor biosignatures on Habitable Exoplanets), far-IR interferometers, and for X-rayobservatories. But also all-weather Earth observations at IR and radio wavelengths.
Keywords: Exobiology, Astrometry, IR interferometry, Earth observation
1. A special epoch
We are living a special epoch. For the first time in Humanity's history we have thepossibility to obtain the first objective responses to questions raised for over 20centuries,including by the Greek philosophers and scientists as Democritos of Abdera (460-371 BC), Epicurus of Samos (341-270 BC, Fig.1), and the medieval philosopher andtheologian Giordano Bruno (1548-1600 AD): "Are we alone in the Universe?". We havethe technical capabilities to build the instruments that can provide the first scientificanswers.
Therefore, Exo-biology should be a major scientific subject for the 21st century. "When
there is liquid water at the surface of a planet, is emergence of life a frequent, orexceptional event?" Today this question is fully open. Some responses have been
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proposed, e.g. by Jacques Monod, or Christian De Duve, two Nobel prices, but they areonly personal intuitions. By the way, they are diametrically opposite...
In the mid-future, space missions as Darwin(= TPF-I), TPF-C, or NWO should be able toanswer this first question.
We show in this paper that Formation Flying is a prior requirement for interferometry in the
IR, for the needed angular resolution.
2. A Roadmap for Exobiology
It could be:
- Q: Are there exoplanets favorable to be potentially inhabited (size, distance to star)?
A: The Keplermission is doing that, nicely [space mission searching for transits]
- Q: Which are they, nominally, around the nearest stars (the only possible telluric planetsfor direct detection and spectroscopic analysis)?
A: A space mission of extreme accuracy (0.05 micro-as) differential astrometry, e.g. Neat,could do it [requiring FF]
- Q: can we search for biosignatures made of planetary atmospheric compositions ?
A: Yes by performing spectroscopy of their atmosphere/surface, either in the visual(coronography), or in the thermal Infra-Red (space interferometer, requiring FF)