Related papers: Pioneer's Final Riddle
In the last two decades an anomalous variation in the asymptotic velocity of spacecraft performing a flyby manoeuvre around Earth has been discovered through careful Doppler tracking and orbital analysis. No viable hypothesis for a…
After decades of dismissal and secrecy, it has become clear that a significant number of the world's governments take Unidentified Aerospace-Undersea Phenomena (UAP), formerly known as Unidentified Flying Objects (UFOs), seriously -- yet…
In the framework of the emergent gravity scenario by Verlinde, it was recently observed by Liu and Prokopec that, among other things, an anomalous pericenter precession would affect the orbital motion of a test particle orbiting an isolated…
The Kepler spacecraft is currently unable to hold a steady pointing and it is slowly drifting during observations. We believe that if one has to deal with targets that drift across the CCDs, one should at least be able to track the targets…
Possible models of modified gravity are being extensively studied now, with most phenomenological motivations coming from puzzles and tensions in cosmology due to a natural desire to better fit the known and newly coming data. At the same…
Planet 9 is an hypothetical object in the outer Solar system, which is as yet undiscovered. It has been speculated that it may be a terrestrial planet or gas/ice giant, or perhaps even a primordial black hole (or dark matter condensate).…
We illustrate the energy transfer during planetary flybys as a function of time using a number of flight mission examples. The energy transfer process is rather more complicated than a monotonic increase (or decrease) of energy with time.…
Relativistic rigid motion suggests a new version for the so-called `twin paradox', comparing the ages of two astronauts on a very long spaceship. Although there is always an instantaneous inertial frame in which the whole spaceship, being…
We review Fermi's paradox (or the "Great Silence" problem), not only arguably the oldest and crucial problem for the Search for ExtraTerrestrial Intelligence (SETI), but also a conundrum of profound scientific, philosophical and cultural…
In a reference frame fixed to the solar system's center of mass, a satellite's energy will change as it is deflected by a planet. But a number of satellites flying by Earth have also experienced energy changes in the Earth-centered frame --…
We investigate whether one or many companions are orbiting the extremely intermittent pulsar PSR B1931+24. We constrained our analysis on previous observations of eight fundamental properties of PSR B1931+24. The most puzzling properties…
Experimental tests of gravity performed in the solar system show a good agreement with general relativity. The latter is however challenged by the Pioneer anomaly which might be pointing at some modification of gravity law at ranges of the…
Hubble's law, which states a linear increase in velocities with distances, can physically be understood in terms of an acceleration cH. This work proposes a connection between this "universal" acceleration seen in the solar system and the…
With the 1998 announcement of new evidence for muon neutrino disappearance observed by the Super-Kamiokande experiment, the more than a decade old atmospheric neutrino anomaly moved from a possible indication for neutrino oscillations to an…
In this paper it is shown that dynamics based on a variation of the gravitational constant $G$ with time solves several puzzling and anomalous features observed, for example the rotation curves of galaxies (attributed to as yet undetected…
Solar system object P/2010 A2 is the first-noticed example of the aftermath of a recently disrupted asteroid, probably resulting from a collision. Nearly a year elapsed between its inferred initiation in early 2009 and its eventual…
The accelerated expansion of the universe is the most debatable cosmological scenario in the last two decades. Looking for the proper explanation of this scenario, researchers have presented a lot of proposals to discuss it. However,…
The meeting of two spacecraft in orbit around a planet or moon involves a delicate dance that must carefully the balance the gravitational, Coriolis, and centrifugal forces acting on the spacecraft. The intricacy of the relative motion…
Comet 157P is a faint object with a history of being prone to unfortunate situations, circumstances, and/or coincidences. Several weeks after its 1978 discovery the comet disappeared and remained lost nonstop for twenty five years.…
In the last few decades, reading the literature, we realized that we Astronomers have a strong preference to undertake very ambitious projects, and search for answers to the most fundamental questions in the history of the entire Universe.…