Normal service will be resumed tomorrow, when PCC(E) is back in action and recovered from his trip.
Meanwhile, in Dobrzyn, Hili suspects she is being short changed over her meal:
A: What are you deliberating about?
Hili: I have the impression that there is ham in the fridge.
Ja: Nad czym się zastanawiasz?
Hili: Mam wrażenie, że w lodówce jest szynka.
The orbits of the planets around the Sun have been the source for many a scientific debate. Their current orbital properties are well understood but the planetary orbits have evolved and changed since the formation of the Solar System. Planetary migrations have been the most prominent idea of recent decades suggesting that planetary interactions caused the young planets to migrate inwards or outwards from their original positions. Now a new theory suggests 2-50 Jupiter mass object passing through the Solar System could be the cause.
The evolution of the orbits of the planets is a complex process. Initially the planets formed out of a rotating disk of gas and dust around the young hot Sun. The phenomenon of the conservation of angular momentum caused the material to form a plane leading to orbits that were circular and in the same plane.
The latest view of Saturn from NASA’s Hubble Space Telescope captures exquisite details of the ring system — which looks like a phonograph record with grooves that represent detailed structure within the rings — and atmospheric details that once could only be captured by spacecraft visiting the distant world. Hubble’s Wide Field Camera 3 observed Saturn on June 20, 2019, as the planet made its closest approach to Earth, at about 845 million miles away. This image is the second in a yearly series of snapshots taken as part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets. In Saturn’s case, astronomers will be able to track shifting weather patterns and other changes to identify trends. Credits: NASA, ESA, A. Simon (GSFC), M.H. Wong (University of California, Berkeley) and the OPAL TeamAs the planets grew, interactions within the protoplanetary disk led to orbital migrations with planets moving inwards or outwards. There were gravitational interactions too that led to significant changes in the eccentricity and inclination, sometimes causing protoplanets to be ejected out of the solar system. Tidal forces from the Sun could also have altered the orbits.
While protoplanet ejections are thought to have been fairly common as the Solar System was forming, on occasions celestial objects visited us. These objects seem to have been rare and provide a valuable insight into distant planetary systems. Oumuamua, was discovered in 2017 and was the first confirmed interstellar visitor. It exhibited an elongated shape and unusual acceleration, probably caused by outgassing or other non-gravitational forces. A paper recently published has suggested such an interstellar visitor could have driven changes in the orbits of our planetary cousins.
An artist’s depiction of the interstellar comet ‘Oumuamua, as it warmed up in its approach to the sun and outgassed hydrogen (white mist), which slightly altered its orbit. The comet, which is most likely pancake-shaped, is the first known object other than dust grains to visit our solar system from another star. (Image credit: NASA, ESA and Joseph Olmsted and Frank Summers of STScI)The paper was authored by a team of scientists led by Garett Brown University of Toronto. They explore the nature of the eccentricity of the gas giants suggesting it is unlikely the current theories can explain observations. Instead they demonstrate that an object with between 2 to 50 times the mass of Jupiter passing through the Solar System was a more likely cause. Their paper explains that an object passing through with a perihelion distance (closest distance from Sun) of less than 20 astronomical units and a hyperbolic excess velocity less than 6km/s-1 could explain observations.
Their calculations suggest there is a 1 in 100 chance that an interstellar visitor could produce the orbits we see today, chances that are far better than other theories. Using simulations and approximate values for the properties of the visitor, the team conclude that the theory is the most plausible to date.
Source : A substellar flyby that shaped the orbits of the giant planets
The post An Interstellar Visitor Helped Shape the Orbits of the Planets. appeared first on Universe Today.
Propulsion technologies are the key to exploring the outer solar system, and many organizations have been working on novel ones. One with a long track record is the Ad Astra Rocket Company, which has been developing its Variable Specific Impulse Magnetoplasma Rocket (VASIMR) system for decades. However, this type of electric propulsion system requires a lot of energy, so the company has opted for a unique tie-up for a power plant that could solve that problem – a nuclear reactor. Ad Astra has recently entered into a strategic alliance with the Space Nuclear Power Corporation, or SpaceNukes, responsible for developing the Kilopower reactor, a 1kW nuclear reactor for use in space missions.
There are plenty of synergies to justify such a tie-up between the companies, but let’s look at each of their technologies, in turn, to understand why. VASIMR, the propulsion system Ad Astra has been working on for more than 20 years, is a magnetoplasma rocket, a type of electric propulsion system. Ion drives are the most commonly known form of electric propulsion and are known for being exceptionally fuel efficient. They aren’t powerful enough to lift a craft out of a planet’s gravity well, but once in space with little gravitational pull, they shine at long bursts of slow acceleration that translate into massive speeds when engaged for long enough.
The problem is they need lots of power to do so. They must ionize their fuel, which requires a significant amount of energy, and that energy is hard to come by when not connected to a power grid. Current solutions utilize either solar panels, which would require a massive area to provide enough power to something like VASIMR, or a radioisotope thermal generator (RTG), which has been in common use for years to power the systems of different spacecraft, including Voyager and Perseverance, but isn’t capable of providing enough power for a viable electric propulsion system.
Fraser describes how ion engines, a type of electric propulsion system, work.Enter another form of nuclear energy—the traditional kind. SpaceNukes has been working on its Kilopower reactor in various guises for more than 10 years and has proven a functional system at 1kW of power on a ground-based system back in 2018. It’s now working with the US Space Force under a project named JETSON to develop a 12kW design that could be used in a flight demonstration.
VASIMR scales well with larger power outputs – on the order of 100kW or more could significantly increase the rocket’s efficiency. The only viable option for such power in space is nuclear reactors, so the tie-up between the two companies seems apt. However, there is still a long way to go before a 100kW system would be flight tested – the press release announcing the company’s memorandum of understanding says they hope to have a flight demonstration done “by the end of the decades” and to commercialize the technology “in the 2030s”.
If they manage to pull that timeline off—and that is still a big if—a combined VASIMR and Kilopower-driven spacecraft would achieve the dream of Nuclear Electric Propulsion that excites many space propulsion enthusiasts. It could cut down the round-trip travel times to Mars from over a year to a few months and allow for more and better missions to the outer solar system, including interesting moons like Enceladus and Titan.
Fraser describes KRUSTY, one of the experiments leading up to the Kilopower reactor.Given both companies’ track records of slow and steady improvement, it seems likely that eventually t, the technologies will see the light of day and enable a revolution in space propulsion. They have to keep pushing – like the engines they hope to fly someday.
Learn More:
Space Nuclear Power Corporation – Ad Astra Rocket Company and The Space Nuclear Power Corporation Forge Strategic Alliance to Pioneer High-Power Nuclear Electric Propulsion
UT – New Nuclear Rocket Design to Send Missions to Mars in Just 45 Days
UT – What Future Propulsion Technologies Should NASA Invest In?
UT – Exploring the Universe with Nuclear Power
Lead Image:
Rendering of VASIMR in flight around Mars.
Credit – Ad Astra Rocket Company
The post A Commercial Tie-Up Bring High-Energy Nuclear Electric Propulsion Closer to Reality appeared first on Universe Today.