NASA: Lucy, Psyche to Explore the Early Solar System

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NASA: Lucy, Psyche to Explore the Early Solar System

Postby bystander » Wed Jan 04, 2017 7:47 pm

NASA Selects Two Missions to Explore the Early Solar System
NASA | Discovery Program | 2017 Jan 04

NASA has selected two missions that have the potential to open new windows on one of the earliest eras in the history of our solar system – a time less than 10 million years after the birth of our sun. The missions, known as Lucy and Psyche, were chosen from five finalists and will proceed to mission formulation, with the goal of launching in 2021 and 2023, respectively. ...

Lucy, a robotic spacecraft, is scheduled to launch in October 2021. It’s slated to arrive at its first destination, a main belt asteroid, in 2025. From 2027 to 2033, Lucy will explore six Jupiter Trojan asteroids. These asteroids are trapped by Jupiter’s gravity in two swarms that share the planet’s orbit, one leading and one trailing Jupiter in its 12-year circuit around the sun. The Trojans are thought to be relics of a much earlier era in the history of the solar system, and may have formed far beyond Jupiter’s current orbit. ...

The Psyche mission will explore one of the most intriguing targets in the main asteroid belt – a giant metal asteroid, known as 16 Psyche, about three times farther away from the sun than is the Earth. This asteroid measures about 130 miles (210 kilometers) in diameter and, unlike most other asteroids that are rocky or icy bodies, is thought to be comprised mostly of metallic iron and nickel, similar to Earth’s core. Scientists wonder whether Psyche could be an exposed core of an early planet that could have been as large as Mars, but which lost its rocky outer layers due to a number of violent collisions billions of years ago. ...

NASA Selects Two Discovery Missions to Explore Solar System History
Planetary Science Institute | 2017 Jan 05
Last edited by bystander on Thu Jan 05, 2017 7:42 pm, edited 1 time in total.
Reason: added PSI article
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Re: NASA: Lucy, Psyche to Explore the Early Solar System

Postby neufer » Wed Jan 04, 2017 9:01 pm

https://en.wikipedia.org/wiki/Lucy_van_Pelt wrote:
<<Lucille "Lucy" van Pelt is a character in the syndicated comic strip Peanuts, written and drawn by Charles Schulz. She is the older sister of Linus and Rerun. Lucy is characterized as a crabby, bossy and opinionated girl who bullies other characters in the strip, particularly Linus and Charlie Brown.

While she is not cold-hearted, and technically one of the main protagonists of the series, she can be quite antagonistic, often playing the villain role in a number of stories. She is also characterized as vain, as she believes she is beautiful and thinks she is perfect (though she once admitted complaining is the only thing she can do).

Lucy also has a PSYCHiatric booth where she pretends to be a PSYCHiatrist and tells her opinions on problems for five cents to the other characters in the strip, most frequently an anxious Charlie Brown; this "advice" is usually completely useless and nonsensical. A sign on the front of the booth declares that "The Doctor is" in or out, depending on which side of the "In/Out" placard is displayed.>>
https://en.wikipedia.org/wiki/Cupid_and_PSYCHe wrote:
Click to play embedded YouTube video.
<<The last trial Venus imposes on PSYCHe is a quest to the underworld itself. She is to take a box (pyxis) and obtain in it a dose of the beauty of Proserpina, queen of the underworld. Venus claims her own beauty has faded and she needs this remedy in order to attend the theatre of the gods (theatrum deorum).

Once again despairing of her task, PSYCHe climbs a tower, planning to throw herself off. The tower, however, suddenly breaks into speech, and advises her to travel to Lacedaemon, Greece, and to seek out the place called Taenarus, where she will find the entrance to the underworld. The tower offers instructions for navigating the underworld: The speaking tower warns her to maintain silence as she passes by several ominous figures: a lame man driving a mule loaded with sticks, a dead man swimming in the river that separates the world of the living from the world of the dead, and old women weaving. These, the tower warns, will seek to divert her by pleading for her help: she must ignore them. The cakes are treats for distracting Cerberus, the three-headed watchdog of Orcus, and the two coins for Charon the ferryman, so she can make a return trip.

Everything comes to pass according to plan, and Proserpina grants PSYCHe's humble entreaty. As soon as she reenters the light of day, however, PSYCHe is overcome by a bold curiosity, and can't resist opening the box in the hope of enhancing her own beauty. She finds nothing inside but an "infernal and Stygian sleep," which sends her into a deep and unmoving torpor.>>
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Re: NASA: Lucy, Psyche to Explore the Early Solar System

Postby bystander » Thu Jan 05, 2017 4:29 pm

SwRI to lead NASA’s Lucy mission to Jupiter’s Trojans
Southwest Research Institute | 2017 Jan 04

Lucy includes ASU-designed, -built thermal emission spectrometer
Arizona State University | 2017 Jan 04

ASU to Lead NASA Space Exploration Mission (Psyche) for First Time
Arizona State University | 2017 Jan 04

JHU APL Provides Key Instruments for NASA's New Discovery Missions
Johns Hopkins University Applied Physics Laboratory | 2017 Jan 06
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NASA Moves Up Launch of Psyche Mission to a Metal Asteroid

Postby bystander » Thu May 25, 2017 3:10 pm

NASA Moves Up Launch of Psyche Mission to a Metal Asteroid
NASA | JPL-Caltech | Psyche | 2017 May 24

Psyche, NASA’s Discovery mission to a unique metal asteroid, has been moved up one year with launch in the summer of 2022, and with a planned arrival at the main belt asteroid in 2026 -- four years earlier than the original timeline. ...

The Discovery program announcement of opportunity had directed teams to propose missions for launch in either 2021 or 2023. The Lucy mission was selected for the first launch opportunity in 2021, and Psyche was to follow in 2023. Shortly after selection in January, NASA gave the direction to the Psyche team to research earlier opportunities. ...

The revised trajectory is more efficient, as it eliminates the need for an Earth gravity assist, which ultimately shortens the cruise time. In addition, the new trajectory stays farther from the Sun, reducing the amount of heat protection needed for the spacecraft. The trajectory will still include a Mars gravity assist in 2023. ...
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NASA Glenn Tests Thruster Bound for Metal World

Postby bystander » Fri Sep 29, 2017 3:48 pm

NASA Glenn Tests Thruster Bound for Metal World
NASA | JPL-Caltech | Glenn Research Center | Psyche | 2017 Sep 28

Click to play embedded YouTube video.
We are using our vacuum chamber to test the Hall Effect Rocket with Magnetic
Shielding (HERMeS) thruster, which could propel NASA’s future vehicles to deep
space. It operates at 12.5 kW; three times greater power than existing systems.
Credits: NASA, Rami Daud, Alcyon Technical Services

As NASA looks to explore deeper into our solar system, one of the key areas of interest is studying worlds that can help researchers better understand our solar system and the universe around us. One of the next destinations in this knowledge-gathering campaign is a rare world called Psyche, located in the asteroid belt.

Psyche is different from millions of other asteroids because it appears to have an exposed nickel-iron surface. Researchers at Arizona State University, Tempe, in partnership with NASA's Jet Propulsion Laboratory in Pasadena, California, believe the asteroid could actually be the leftover core of an early planet. And, since we can't directly explore any planet's core, including our own, Psyche offers a rare look into the violent history of our solar system. ...

But getting to Psyche won't be easy. It requires a cutting-edge propulsion system with exceptional performance, which is also safe, reliable and cost-effective. That's why the mission team has turned to NASA Glenn Research Center in Cleveland, which has been advancing solar electric propulsion (SEP) for decades. ...
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Re: NASA: Lucy, Psyche to Explore the Early Solar System

Postby neufer » Sat Sep 30, 2017 3:36 am

https://en.wikipedia.org/wiki/Hall-effect_thruster wrote:
<<In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters trap electrons in a magnetic field and then use the electrons to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume. Hall-effect thrusters (based on the discovery by Edwin Hall) are sometimes referred to as Hall thrusters or Hall-current thrusters. Hall thrusters are often regarded as a moderate specific impulse (1,600 s = 15.69 km/s) space propulsion technology. Hall thrusters were studied independently in the United States and the Soviet Union. They were first described publicly in the US in the early 1960s. However, the Hall thruster was first developed into an efficient propulsion device in the Soviet Union. In the US, scientists focused instead on developing gridded ion thrusters.

The essential working principle of the Hall thruster is that it uses an electrostatic potential to accelerate ions up to high speeds. In a Hall thruster, the attractive negative charge is provided by an electron plasma at the open end of the thruster instead of a grid. A radial magnetic field of about 100–300 G (0.01–0.03 T) is used to confine the electrons, where the combination of the radial magnetic field and axial electric field cause the electrons to drift in azimuth thus forming the Hall current from which the device gets its name.

Compared to chemical rockets, the thrust is very small, on the order of 83 mN for a typical thruster operating at 300 V, 1.5 kW. For comparison, the weight of a coin like the U.S. quarter or a 20-cent Euro coin is approximately 60 mN. As with all forms of electrically powered spacecraft propulsion, thrust is limited by available power, efficiency, and specific impulse.

However, Hall thrusters operate at the high specific impulses that is typical for electric propulsion. One particular advantage of Hall thrusters, as compared to a gridded ion thruster, is that the generation and acceleration of the ions takes place in a quasi-neutral plasma, so there is no Child-Langmuir charge (space charge) saturated current limitation on the thrust density. This allows much smaller thrusters compared to gridded ion thrusters.

Another advantage is that these thrusters can use a wider variety of propellants supplied to the anode, even oxygen, although something easily ionized is needed at the cathode. Hall thrusters operate on a variety of propellants, the most common being xenon. Other propellants of interest include krypton, argon, bismuth, iodine, magnesium, and zinc.

Hall thrusters are able to accelerate their exhaust to speeds between 10 and 80 km/s (1,000–8,000 s specific impulse), with most models operating between 15 and 30 km/s (1,500–3,000 s specific impulse). The thrust produced by a Hall thruster varies depending on the power level. Devices operating at 1.35 kW produce about 83 mN of thrust. High-power models have demonstrated up to 3 N in the laboratory. Power levels up to 100 kW have been demonstrated by xenon Hall thrusters.

Two types of Hall thrusters were developed in the Soviet Union:
    thrusters with wide acceleration zone, SPT (Russian: СПД, стационарный плазменный двигатель; English: SPT, Stationary Plasma Thruster) at Design Bureau Fakel
    thrusters with narrow acceleration zone, DAS (Russian: ДАС, двигатель с анодным слоем; English: TAL, Thruster with Anode Layer), at the Central Research Institute for Machine Building (TsNIIMASH).
Soviet-built thrusters were introduced to the West in 1992 after a team of electric propulsion specialists from NASA's Jet Propulsion Laboratory, Glenn Research Center, and the Air Force Research Laboratory, under the support of the Ballistic Missile Defense Organization, visited Russian laboratories and experimentally evaluated the SPT-100 (i.e., a 100 mm diameter SPT thruster). Over 200 Hall thrusters have been flown on Soviet/Russian satellites in the past thirty years. No failures have ever occurred on orbit. Hall thrusters continue to be used on Russian spacecraft and have also flown on European and American spacecraft. Space Systems/Loral, an American commercial satellite manufacturer, now flies Fakel SPT-100's on their GEO communications spacecraft.

Since their introduction to the west in the early 1990s, Hall thrusters have been the subject of a large number of research efforts throughout the United States, France, Italy, Japan, and Russia (with many smaller efforts scattered in various countries across the globe). The first use of Hall thrusters on lunar orbit was the European Space Agency (ESA) lunar mission SMART-1 in 2003.

On a western satellite Hall thrusters were first demonstrated on the Naval Research Laboratory (NRL) STEX spacecraft, which flew the Russian D-55. The first American Hall thruster to fly in space was the Busek BHT-200 on TacSat-2 technology demonstration spacecraft. The first flight of an American Hall thruster on an operational mission, was the Aerojet BPT-4000, which launched August 2010 on the military Advanced Extremely High Frequency GEO communications satellite. At 4.5 kW, the BPT-4000 is also the highest power Hall thruster ever flown in space. Besides the usual stationkeeping tasks, the BPT-4000 is also providing orbit raising capability to the spacecraft. Several countries worldwide continue efforts to qualify Hall thruster technology for commercial uses.>>
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Re: NASA: Lucy, Psyche to Explore the Early Solar System

Postby neufer » Sun Oct 01, 2017 10:08 pm

https://en.wikipedia.org/wiki/Edwin_Hall wrote:
<<Edwin Herbert Hall (November 7, 1855 – November 20, 1938) was an American physicist from Maine. The Hall effect was discovered by Hall in 1879, while working on his doctoral thesis in Physics at the Johns Hopkins University. Hall's experiments consisted of exposing thin gold leaf on a glass plate and tapping off the gold leaf at points down its length. The effect is a potential difference (Hall voltage) on opposite sides of a thin sheet of conducting or semiconducting material (the Hall element) through which an electric current is flowing. This was created by a magnetic field applied perpendicular to the Hall element. The ratio of the voltage created to the amount of current is known as the Hall resistance, and is a characteristic of the material in the element. In the presence of large magnetic field strength and low temperature, one can observe the quantum Hall effect, which is the quantization of the Hall resistance. This is now the official standard for electrical resistance.

Hall was appointed as Harvard's professor of physics in 1895. Hall retired in 1921 and died in Cambridge, Massachusetts, U.S. in 1938.>>
https://en.wikipedia.org/wiki/Monty_Hall wrote:
<<Monte Hall (August 25, 1921 – September 30, 2017) was a Canadian-American game show host and producer, best known as the long-running host of Let's Make a Deal.

The Monty Hall problem is a brain teaser, in the form of a probability puzzle loosely based on the American television game show Let's Make a Deal and named after its original host, Monty Hall. The problem was originally posed (and solved) in a letter by Steve Selvin to the American Statistician in 1975 (Selvin 1975a), (Selvin 1975b). It became famous as a question from a reader's letter quoted in Marilyn vos Savant's "Ask Marilyn" column in Parade magazine in 1990 (vos Savant 1990a):

Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. He then says to you, "Do you want to pick door No. 2?" Is it to your advantage to switch your choice?

Vos Savant's response was that the contestant should switch to the other door (vos Savant 1990a). Under the standard assumptions, contestants who switch have a 2/3 chance of winning the car, while contestants who stick to their initial choice have only a 1/3 chance.

The given probabilities depend on specific assumptions about how the host and contestant choose their doors. A key insight is that, under these standard conditions, there is more information about doors 2 and 3 that was not available at the beginning of the game, when the door 1 was chosen by the player: the host's deliberate action adds value to the door he did not choose to eliminate, but not to the one chosen by the contestant originally.

Many readers of vos Savant's column refused to believe switching is beneficial despite her explanation. After the problem appeared in Parade, approximately 10,000 readers, including nearly 1,000 with PhDs, wrote to the magazine, most of them claiming vos Savant was wrong (Tierney 1991). Even when given explanations, simulations, and formal mathematical proofs, many people still do not accept that switching is the best strategy (vos Savant 1991a). Paul Erdős, one of the most prolific mathematicians in history, remained unconvinced until he was shown a computer simulation demonstrating the predicted result (Vazsonyi 1999).>>
https://en.wikipedia.org/wiki/Erd%C5%91s_number wrote:
<<The Erdős number describes the "collaborative distance" between mathematician Paul Erdős (26 March 1913 – 20 September 1996) and another person, as measured by authorship of mathematical papers. Several studies have shown that leading mathematicians tend to have particularly low Erdős numbers. The median Erdős number of Fields Medalists is 3. Only 7,097 (about 5% of mathematicians with a collaboration path) have an Erdős number of 2 or lower. As time passes, the smallest Erdős number that can still be achieved will necessarily increase, as mathematicians with low Erdős numbers die and become unavailable for collaboration. Still, historical figures can have low Erdős numbers. For example, renowned Indian mathematician Srinivasa Ramanujan has an Erdős number of only 3 (through G.H. Hardy, Erdős number 2), even though Paul Erdős was only 7 years old when Ramanujan died.>>
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