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Optical frequency standards and femtosecond comb measurement capabilities now rival and in some cases exceed those of microwave devices, with further improvements anticipated. Opportunities are emerging for the application of highly stable and accurate optical frequency devices to fundamental physics space science activities, and the European Space Agency (ESA) has recently commissioned studies on different aspects of optical clocks in space. This paper highlights some examples, including the difficulty of comparing very accurate terrestrial clocks at different locations due to fluctuations of the geoid; by locating a primary frequency standard in space, one could avoid geoid-related gravitational redshifts.

The constant of gravitation, G, is the least well-known of the physical constants. A new, independent method of measurement, estimated as having a potential uncertainty at least as small as that achieved by existing methods, would be useful for an improvement in G determination. This experiment is based on the measurement of the relative motion of two freely falling test bodies (discs), caused by their gravitational attraction. The uncertainties are analyzed for two parallel tungsten discs with masses of about 30 kg. The use of test bodies with an incorporated optical system of multipass two-beam interferometers, as well as of multibeam interferometers, is proposed to measure their relative displacement. The estimations were made for laboratory experiment with free fall duration of 0.714 s. In this case, the relative displacement to be measured is about 0.1 μm. These estimates show that relative uncertainties lower than 5 × 10^-5 can be obtained in G measurement in a single drop of the test bodies. The proposed experiment can be made in outer space. In space a lower uncertainty can be achieved because the time interval of the measurement of relative motion of the test bodies can be increased.

One could call 2006 as the year of cosmology since in that year two US scientists were awarded the Nobel prize for their studies of the Cosmic Microwave Background (CMB) spectrum and anisotropy. Here I recall earlier studies of the CMB anisotropy done with the Soviet spacecraft Prognoz-9 by the Relikt-1 team. Problems of modern cosmology are outlined. We discuss conformal cosmology parameters from supernovae data in brief. Two approaches to solve the basic problems of cosmology, such as dark matter and dark energy, are discussed, the first (standard) possibility is to introduce new particles, fields etc; the second possibility is to try to change the law of gravity to fit observational data. We discuss advantages and disadvantages of the second choice.

We explore the possibility of measuring the γ parameter of the Parameterized Post-Newtonian (PPN) formalism with an Earth-orbiting satellite and looking as close as possible to the solar limb. The technique is inspired to that used during the solar eclipse of 1919, when the gravitational bending of the light was measured for the first time. Simple estimations suggest that even a low-cost satellite could reach the 10^-6 level of accuracy with ~ 10⁶ observations of relatively bright stars at about 2° from the Sun. Further simulations with different magnitude limited star samples, uniformly distributed on the ecliptic plane, show that this result could be reached with only 20+20 days of measurements. A quick look at the real star densities suggest that this result could be greatly improved by observing particularly crowded regions near the galactic center.

The constant of gravitation, G, is the least well-known of the physical constants. A new, independent method of measurement, estimated as having a potential uncertainty at least as small as that achieved by existing methods, would be useful for an improvement in G determination. This experiment is based on the measurement of the relative motion of two freely falling test bodies (discs), caused by their gravitational attraction. The uncertainties are analyzed for two parallel tungsten discs with masses of about 30 kg. The use of test bodies with an incorporated optical system of multipass two-beam interferometers, as well as of multibeam interferometers, is proposed to measure their relative displacement. The estimations were made for laboratory experiment with free fall duration of 0.714 s. In this case, the relative displacement to be measured is about 0.1 μm. These estimates show that relative uncertainties lower than 5 × 10⁻⁵ can be obtained in G measurement in a single drop of the test bodies. The proposed experiment can be made in outer space. In space a lower uncertainty can be achieved because the time interval of the measurement of relative motion of the test bodies can be increased.

Optical frequency standards and femtosecond comb measurement capabilities now rival and in some cases exceed those of microwave devices, with further improvements anticipated. Opportunities are emerging for the application of highly stable and accurate optical frequency devices to fundamental physics space science activities, and the European Space Agency (ESA) has recently commissioned studies on different aspects of optical clocks in space. This paper highlights some examples, including the difficulty of comparing very accurate terrestrial clocks at different locations due to fluctuations of the geoid; by locating a primary frequency standard in space, one could avoid geoid-related gravitational redshifts.

The SAGACE experiment consists of a mm/sub-mm telescope with a 3-m diameter primary mirror, coupled to a cryogenic multi-beam differential spectrometer. SAGACE explores the sky in the 100-760 GHz frequency range, using four diffraction-limited bolometer arrays. The instrument is designed to perform spectroscopic surveys of the Sunyaev-Zeldovich effects of thousands of galaxy clusters, of the spectral energy distribution of active galactic nuclei, and of the [CII] line of a thousand galaxies in the redshift desert. In 2008 a full phase-A study for a national small mission was completed and delivered to the Italian Space Agency (ASI). We have shown that taking advantage of the differential operation of the Fourier Transform Spectrometer, this ambitious instrument can operate from a Molniya orbit, and can be built and operated within the tight budget of a small mission.

The ESA Planck satellite, launched on May 14^th, 2009, is the third generation space mission dedicated to the measurement of the Cosmic Microwave Background (CMB), the first light in the Universe. Planck observes the full sky in nine frequency bands from 30 to 857 GHz and is designed to measure the CMB anisotropies with an unprecedented combination of sensitivity, angular resolution and control of systematic effects. In this presentation we summarise the Planck instruments performance and discuss the main scientific results obtained after one year of operations in the fields of galactic and extragalactic astrophysics.

According to General Relativity, as distinct from Newtonian gravity, motion under gravity is treated by a theory that deals, initially, only with test particles. At the same time, satellite measurements deal with extended bodies. We discuss the correspondence between geodesic motion in General Relativity and the motion of an extended body by means of the Ehlers-Geroch theorem, and in the context of the recently launched LAser RElativity Satellite (LARES). Being possibly the highest mean density orbiting body in the Solar system, this satellite provides the best realization of a test particle ever reached experimentally and provides a unique possibility for testing the predictions of General Relativity.

GAMMA-400 is a new space experiment which will study gamma rays and cosmic rays from about 100 MeV up to some TeVs. The proposed instrument has an angular resolution ∼ 0.1 degrees at 10 GeV and better than ∼ 0.02 degrees above 100 GeV, and an energy resolution ∼ 1% at E > 100 GeV for gamma rays. With these characteristics the experiment will be able to contribute to the search for signatures of Dark Matter, and to the study of Galactic and ex-tragalactic gamma sources and diffuse emission. A large segmented calorimeter more than 25 X₀ deep will allow the study of high-energy electrons, and the measurement of the flux of protons and nuclei up to the “knee” region.

Planck is the most sensitive space mission to date dedicated to accurate measurements of the Cosmic Microwave Background. Its μK sensitivity calls for a comparable level of control of systematic effects, that represents the primary challenge to fully extract the wealth of scientific information encoded in the data. Planck has been designed and built to ensure, as much as possible, “in-hardware” rejection to spurious signals. Residual effects, however, need to be detected in the data and removed during data processing. In this talk we present a review of the main systematic effects in Planck, and of the design solutions adopted in the satellite and instruments to keep them under control. We then discuss the impact of the residual effects after data processing on the main scientific products.