Blog – Page 4 – WinStars 3

New version 3.072 online

With the latest update (3.072), the program now features new functionalities that improve the management of artificial satellites.

A dialog box now allows users to choose the satellites to display in WinStars.

And here is the result in the “3D navigation” mode:

The transit of satellites is also visible in the planetarium mode:

The program also calculates when a satellite exits Earth’s shadow (here, the ISS).

Finally, the Moon is displayed in high resolution with the names of geological formations when zooming in on it from the planetarium mode.

Server outage!

A failure on the server has made impossible the consultation of the site and the running of the software since Thursday. The situation is gradually returning to normal. Thank you for your understanding.

Juno: a deep dive into Jupiter

Juno is a NASA space probe orbiting the planet Jupiter. It was built by Lockheed Martin and is operated by NASA‘s Jet Propulsion Laboratory. The spacecraft was launched from Cape Canaveral Air Force Station on August 5, 2011 (UTC), as part of the New Frontiers program, and entered a polar orbit of Jupiter on July 5, 2016 (UTC), (July 4, US time) to begin a scientific investigation of the planet. After completing its mission, Juno will be intentionally deorbited into Jupiter’s atmosphere.

Juno‘s mission is to measure Jupiter’s composition, gravity field, magnetic field, and polar magnetosphere. It will also search for clues about how the planet formed, including whether it has a rocky core, the amount of water present within the deep atmosphere, mass distribution, and its deep winds, which can reach speeds up to 618 kilometers per hour (384 mph).

Juno is the second spacecraft to orbit Jupiter, after the nuclear powered Galileo orbiter, which orbited from 1995 to 2003. Unlike all earlier spacecraft sent to the outer planets, Juno is powered by solar arrays, commonly used by satellites orbiting Earth and working in the inner Solar System, whereas radioisotope thermoelectric generators are commonly used for missions to the outer Solar System and beyond. For Juno, however, the three largest solar array wings ever deployed on a planetary probe play an integral role in stabilizing the spacecraft as well as generating power.

Juno was selected on June 9th 2005 as the next New Frontiers mission after New Horizons. The desire for a Jupiter probe was strong in the years prior to this, but there had not been any approved missions. The Discovery Program had passed over the somewhat similar but more limited Interior Structure and Internal Dynamical Evolution of Jupiter (INSIDE Jupiter) proposal, and the turn-of-the-century era Europa Orbiter was cancelled in 2002. The flagship-level Europa Jupiter System Mission was in the works in the early 2000s, but funding issues resulted in it evolving into ESA’s Jupiter Icy Moons Explorer.

Juno completed a five-year cruise to Jupiter, arriving on July 5, 2016. The spacecraft traveled a total distance of roughly 2.8 billion kilometers (18.7 astronomical units; 1.74 billion miles) to reach Jupiter. The spacecraft was designed to orbit Jupiter 37 times over the course of its mission. This was originally planned to take 20 months. Juno‘s trajectory used a gravity assist speed boost from Earth, accomplished by an Earth flyby in October 2013, two years after its launch on August 5, 2011. The spacecraft performed an orbit insertion burn to slow it enough to allow capture. It was expected to make three 53-day orbits before performing another burn on December 11, 2016 that would bring it into a 14-day polar orbit called the Science Orbit. Because of a suspected problem in Juno‘s main engine, the burn of December 11 was canceled, and Juno will remain in its 53-day orbit for its remaining orbits of Jupiter.

During the science mission, infrared and microwave instruments will measure the thermal radiation emanating from deep within Jupiter’s atmosphere. These observations will complement previous studies of its composition by assessing the abundance and distribution of water, and therefore oxygen. This data will provide insight into Jupiter’s origins. Juno will also investigate the convection that drives natural circulation patterns in Jupiter’s atmosphere. Other instruments aboard Juno will gather data about its gravitational field and polar magnetosphere. The Juno mission was planned to conclude in February 2018, after completing 37 orbits of Jupiter. The probe was then intended to be de-orbited and burn up in Jupiter’s outer atmosphere, to avoid any possibility of impact and biological contamination of one of its moons.

 

Flight trajectory

Launch

Juno was launched atop the Atlas V at Cape Canaveral Air Force Station, Florida. The Atlas V (AV-029) used a Russian-built RD-180 main engine, powered by kerosene and liquid oxygen. At ignition it underwent checkout 3.8 seconds prior to the ignition of five strap-on solid rocket boosters (SRBs). Following the SRB burnout, about 93 seconds into the flight, two of the spent boosters fell away from the vehicle, followed 1.5 seconds later by the remaining three. When heating levels had dropped below predetermined limits, the payload fairing that protected Juno during launch and transit through the thickest part of the atmosphere separated, about 3 minutes 24 seconds into the flight. The Atlas V main engine cut off 4 minutes 26 seconds after liftoff. Sixteen seconds later, the Centaur second stage ignited, and it burned for about 6 minutes, putting the satellite into an initial parking orbit. The vehicle coasted for about 30 minutes, and then the Centaur was reignited for a second firing of 9 minutes, placing the spacecraft on an Earth escape trajectory in a heliocentric orbit. Prior to separation, the Centaur stage used onboard reaction engines to spin Juno up to 1.4 r.p.m.. About 54 minutes after launch, the spacecraft separated from the Centaur and began to extend its solar panels. Following the full deployment and locking of the solar panels, Juno’s batteries began to recharge. Deployment of the solar panels reduced Juno’s spin rate by two-thirds. The probe is spun to ensure stability during the voyage and so that all instruments on the probe are able to observe Jupiter. The voyage to Jupiter took five years, and included an orbital manoeuvre in 2012 and a flyby of the Earth on October 10, 2013. When it reached the Jovian system, Juno had traveled approximately 19 AU, almost two billion miles.

Flyby of the Earth

After traveling for about a year in an elliptical heliocentric orbit, Juno fired its engine in 2012 near aphelion (beyond the orbit of Mars) to change its orbit and return to pass by the Earth in October 2013. It used Earth’s gravity to help slingshot itself toward the Jovian system in a maneuver called a gravity assist. The spacecraft received a boost in speed of more than 3.9 km/s (8,800 mph), and it was set on a course to Jupiter. The flyby was also used as a rehearsal for the Juno science team to test some instruments and practice certain procedures before the arrival at Jupiter.

 
 
South America as seen by JunoCam on its October 2013 Earth flyby
 
 
 
 
 
 
 

Insertion into jovian orbit

Jupiter’s gravity accelerated the approaching spacecraft to around 210,000 km/h (130,000 mph). On July 5, 2016, between 03:18 and 03:53 UTC Earth-received time, an insertion burn lasting 2,102 seconds decelerated Juno by 542 m/s (1,780 ft/s) and changed its trajectory from a hyperbolic flyby to an elliptical, polar orbit with a period of about 53.5 days. The spacecraft successfully entered Jupiter orbit on July 5 at 03:53 UTC.

 
 
Animation of Juno‘s trajectory around Jupiter from 1 June 2016 to 31 July 2021
 
 
 
 
 
 
 

Orbit and environment

Juno’s highly elliptical initial polar orbit takes it within 4,200 kilometers (2,600 mi) of the planet and out to 8.1 million km (5.0 million mi), far beyond Callisto’s orbit. An eccentricity-reducing burn, called the Period Reduction Maneuver, was planned that would drop the probe into a much shorter 14 day science orbit. Originally, Juno was expected to complete 37 orbits over 20 months before the end of its mission. Due to problems with helium valves that are important during main engine burns, mission managers announced on February 17, 2017, that Juno would remain in its original 53-day orbit, since the chance of an engine misfire putting the spacecraft into a bad orbit was too high. Juno will now complete only 12 science orbits before the end of its budgeted mission plan, ending July 2018.

The orbits were carefully planned in order to minimize contact with Jupiter’s dense radiation belts, which can damage spacecraft electronics and solar panels, by exploiting a gap in the radiation envelope near the planet, passing through a region of minimal radiation. The “Juno Radiation Vault”, with 1-centimeter-thick titanium walls, also aids in protecting Juno’s electronics. Despite the intense radiation, JunoCam and the Jovian Infrared Auroral Mapper (JIRAM) are expected to endure at least eight orbits, while the Microwave Radiometer (MWR) should endure at least eleven orbits. Juno will receive much lower levels of radiation in its polar orbit than the Galileo orbiter received in its equatorial orbit. Galileo’s subsystems were damaged by radiation during its mission, including an LED in its data recording system. Orbital operations The spacecraft completed its first flyby of Jupiter (perijove 1) on August 27, 2016, and captured the first images of the planet’s north pole. On October 14, 2016, days prior to perijove 2 and the planned Period Reduction Maneuver, telemetry showed that some of Juno’s helium valves were not opening properly. On October 18, 2016, some 13 hours before its second close approach to Jupiter, Juno entered into safe mode, an operational mode engaged when its onboard computer encounters unexpected conditions. The spacecraft powered down all non-critical systems and reoriented itself to face the Sun to gather the most power. Due to this, no science operations were conducted during perijove 2. On December 11, 2016, the spacecraft completed perijove 3, with all but one instrument operating and returning data. One instrument, JIRAM, was off pending a flight software update. Perijove 4 occurred on February 2, with all instruments operating. Perijove 5 occurred on March 27, 2017. Perijove 6 took place on May 19, 2017. Although the mission’s lifetime is inherently limited by radiation exposure, almost all of this dose was planned to be acquired during the perijoves. As of 2017, the 53.4 day orbit was planned to be maintained through July 2018 for a total of twelve science-gathering perijoves. At the end of this prime mission, the project was planned to go through a science review process by NASA’s Planetary Science Division to determine if it will receive funding for an extended mission. In June 2018, NASA extended the mission operations plan to July 2021. When Juno reaches the end of the mission, it will perform a controlled deorbit and disintegrate into Jupiter’s atmosphere. During the mission, the spacecraft will be exposed to high levels of radiation from Jupiter’s magnetosphere, which may cause future failure of certain instruments and risk collision with Jupiter’s moons.

 

Jupiter imaged using the VISIR instrument on the VLT. These observations will inform the work to be undertaken by Juno.

 

 

 

Planned deorbit and disintegration

NASA plans to eventually deorbit the spacecraft into the atmosphere of Jupiter after 2021. The controlled deorbit is intended to eliminate space debris and risks of contamination in accordance with NASA’s Planetary Protection Guidelines.

Team

Scott Bolton of the Southwest Research Institute in San Antonio, Texas is the principal investigator and is responsible for all aspects of the mission. The Jet Propulsion Laboratory in California manages the mission and the Lockheed Martin Corporation was responsible for the spacecraft development and construction. The mission is being carried out with the participation of several institutional partners. Coinvestigators include Toby Owen of the University of Hawaii, Andrew Ingersoll of California Institute of Technology, Frances Bagenal of the University of Colorado at Boulder, and Candy Hansen of the Planetary Science Institute. Jack Connerney of the Goddard Space Flight Center served as instrument lead.

Cost

Juno was originally proposed at a cost of approximately US$700 million (fiscal year 2003) for a launch in June 2009. NASA budgetary restrictions resulted in postponement until August 2011, and a launch on board an Atlas V rocket in the 551 configuration. As of June 2011, the mission was projected to cost US$1.1 billion over its life.

Scientific objectives

The Juno spacecraft’s suite of science instruments will:

  • Determine the ratio of oxygen to hydrogen, effectively measuring the abundance of water in Jupiter, which will help distinguish among prevailing theories linking Jupiter’s formation to the Solar System.
  • Obtain a better estimate of Jupiter’s core mass, which will also help distinguish among prevailing theories linking Jupiter’s formation to the Solar System.
  • Precisely map Jupiter’s gravitational field to assess the distribution of mass in Jupiter’s interior, including properties of its structure and dynamics.
  • Precisely map Jupiter’s magnetic field to assess the origin and structure of the field and how deep in Jupiter the magnetic field is created. This experiment will also help scientists understand the fundamental physics of dynamo theory.
  • Map the variation in atmospheric composition, temperature, structure, cloud opacity and dynamics to pressures far greater than 100 bars (10 MPa; 1,450 psi) at all latitudes.
  • Characterize and explore the three-dimensional structure of Jupiter’s polar magnetosphere and auroras.
  • Measure the orbital frame-dragging, known also as Lense–Thirring precession caused by the angular momentum of Jupiter, and possibly a new test of general relativity effects connected with the Jovian rotation.

Among early results, Juno gathered information about Jovian lightning that revised earlier theories.

Read the full article on Wikipedia


If you want to view the Juno mission in WinStars, please download the latest version of the program (3.0.56) and activate the Juno module .

 

 

 

The version 3.0.52 is online

After weeks of effort, a new version is now online, aiming to significantly improve the graphical quality of the program. The textures of the objects in the solar system have been updated, but it is especially the rendering of the Moon’s surface that has received special attention.

The images used to recreate the lunar surface come from the Lunar Reconnaissance Orbiter Camera (LROC), an instrument installed on the Lunar Reconnaissance Orbiter mission that has been mapping our satellite in high resolution since June 2009.

To create a 3D effect, I use the Parallax Occlusion Mapping technique, which allows for the simulation of cast shadows on the relief, depending on the position of the Sun and the observer. Thus, even though it currently only involves flat textures applied to a simple sphere, the result is often impressive and gives the impression of being able to walk between mountains and craters.

Highlighting of cast shadows in red

In a future version, the surfaces of several objects in the solar system will be truly recreated in 3D, but it will be necessary to have a sufficiently powerful configuration to take advantage of this feature (i.e., having a graphics card compatible with DirectX 11 or OpenGL 4.0 at a minimum, capable of applying hardware tessellation).

New details that were already present in version 2 are back with this revision 3.0.52, such as the reflection of the Sun on Earth’s oceans.

Finally, the program now displays the names of the main geological formations visible on the surface of planets and their satellites (as well as the capitals for Earth and the landing sites of the main space missions for other objects).

It’s up to you to try and find the Apollo mission landing sites!

The version 3.0.26 beta is online

Version 3.0.26 offers new features like the support of eyepieces whose field can be represented on maps.

Under Android, it is also possible to activate a video mode allowing to overlay the images generated by WinStars with those coming from the camera located at the back of the device.

The icon system has also been revised for the Android mobile version.

Oumuamua, the Strange Interstellar Asteroid

Oumuamua is the first known interstellar object to pass through the Solar System. Formally designated 1I/2017 U1, it was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakala Observatory, Hawaii, on 19 October 2017, 40 days after it passed its closest point to the Sun. When first seen, it was about 33,000,000 km (21,000,000 mi; 0.22 AU) from Earth (about 85 times as far away as the Moon), and already heading away from the Sun. Initially assumed to be a comet, it was reclassified as an asteroid a week later, and finally (6 November 2017) as the first of the new class of interstellar object.

Oumuamua is a small object, estimated to be about 230 by 35 meters (800 ft × 100 ft) in size. It has a dark red color, similar to objects in the outer Solar System. ʻOumuamua showed no signs of a comet tail despite its close approach to the Sun, and has significant elongation and rotation rate, so it is thought to be a metal-rich rock with a relatively high density. ʻOumuamua is tumbling rather than smoothly rotating, and it is moving so fast relative to the Sun that there is no chance it originated in the Solar System. It also means that ʻOumuamua cannot be captured into a solar orbit, so it will eventually leave the Solar System and resume traveling in interstellar space. ʻOumuamua’s system of origin and the amount of time it has spent traveling amongst the stars are unknown.

Oumuamua in WinStars 3

As the first known object of its type, ʻOumuamua presented a unique case for the International Astronomical Union, which assigns designations for astronomical objects. Before its true nature was known it was classified as comet C/2017 U1 and later as asteroid A/2017 U1. Once it was unambiguously identified as coming from outside the Solar System a new designation was created: I for Interstellar object. ʻOumuamua, as the first object so identified, was designated 1I, with rules on the eligibility of objects for I-numbers and the names to be assigned to these interstellar objects yet to be codified. The object may be referred to as 1I; 1I/2017 U1; 1I/ʻOumuamua; or 1I/2017 U1 (ʻOumuamua).

The name comes from Hawaiianʻoumuamua, meaning ‘scout’, (from ʻou, meaning ‘reach out for’, and mua, reduplicated for emphasis, meaning ‘first, in advance of) and reflects the way this object is like a scout or messenger sent from the distant past to reach out to us. The first character is a Hawaiian ʻokina, not an apostrophe, and is represented by a single quotation mark and pronounced as a glottal stop; the name was chosen by the Pan-STARRS team in consultation with Kaʻiu Kimura and Larry Kimura of the University of Hawaii at Hilo.

Before the official name was decided upon, the name Rama was suggested, the name given to an alien spacecraft discovered under similar circumstances in the science fiction novel Rendezvous with Rama (1973) by Arthur C. Clarke.

ʻOumuamua is the first known interstellar object to visit the Solar System and it appears to come from roughly the direction of the star Vega in the constellation Lyra. The incoming direction of motion of ʻOumuamua is 6° from the solar apex (the direction of the Sun’s movement relative to local stars), which is the most likely direction for approaches from objects outside the Solar System. On 26 October, two precovery observations from the Catalina Sky Survey were found dated 14 and 17 October. A two-week observation arc had verified a strongly hyperbolic trajectory. It has a hyperbolic excess velocity (velocity at infinity) of 26.33 km/s (58,900 mph), its speed relative to the Sun when in interstellar space.

By mid November, astronomers were certain that it was an interstellar object. Based on observations spanning 34 days, ʻOumuamua’s orbital eccentricity is 1.20, the highest ever observed. An eccentricity above 1.0 means an object exceeds the Sun’s escape velocity, is not bound to the Solar System, and may escape to interstellar space. While an eccentricity slightly above 1.0 can be obtained by encounters with planets, as happened with the previous record holder C/1980 E1, ʻOumuamua’s eccentricity is so high it could not have been obtained through an encounter with any of the Sun’s planets, known or unknown. Even undiscovered planets, if any exist, could not account for ʻOumuamua’s trajectory – any undiscovered planet must be far from the Sun and hence moving slowly according to Kepler’s laws of planetary motion. Encounters with such a planet could not boost ʻOumuamua’s speed to the observed value, and therefore ʻOumuamua can only be of interstellar origin. ʻOumuamua entered the Solar System from above the plane of the ecliptic. The pull of the Sun’s gravity caused it to speed up until it reached its maximum speed of 87.71 km/s (196,200 mph) as it passed below the ecliptic on 6 September and made a sharp turn upward at its closest approach to the Sun (perihelion) on 9 September at a distance of 0.255 AU (38,100,000 km; 23,700,000 mi) from the Sun, i.e., about 17% closer than Mercury’s closest approach to the Sun. The object is now heading away from the Sun (towards Pegasus) at an angle of 66° from the direction of its approach.

On the outward leg of its journey through the Solar System, ʻOumuamua passed below the orbit of Earth on 14 October at a distance of approximately 0.1616 AU (24,180,000 km; 15,020,000 mi) from Earth, and went back above the ecliptic on 16 October and passed above the orbit of Mars on 1 November. It will pass above Jupiter’s orbit in May 2018, Saturn’s orbit in January 2019, and Neptune’s orbit in 2022. As it leaves the Solar System it will be approximately right ascension (RA) 23h51m and declination +24°45′, in Pegasus. It will continue to slow down until it reaches a speed of 26.33 km/s relative to the Sun, the same speed it had before its approach to the Solar System. It will take the object roughly 20,000 years to leave the Solar System completely.

Accounting for Vega’s proper motion, it would have taken ʻOumuamua 600,000 years to reach the Solar System from Vega. But as a nearby star, Vega was not in the same part of the sky at that time. Astronomers calculate that one hundred years ago, the asteroid was 561 AU (83.9 billion km; 52.1 billion mi) from the Sun and traveling at 26.33 km/s with respect to the Sun. This interstellar speed is very close to the mean motion of material in the Milky Way in the neighborhood of the Sun, also known as the local standard of rest (LSR), and especially close to the mean motion of a relatively close group of M dwarf stars. This velocity profile also indicates an extrasolar origin, but appears to rule out the closest dozen of stars. In fact, the strong correlation between ʻOumuamua’s velocity and the local standard of rest, might mean that it has circulated the galaxy several times and thus may have originated from an entirely different part of the Milky Way.

It is unknown how long the object has been traveling among the stars. The Solar System is likely the first star system that ʻOumuamua has closely encountered since being ejected from its birth star system, potentially several billion years ago. It has been speculated that the object may have been ejected from a stellar system in one of the local kinematic associations of young stars (Carina or Columba specifically), within a range of about 100 parsecs, some 45 million years ago. The Carina and Columba associations are now very far in the sky from the Lyra constellation, the direction from which ʻOumuamua came when it entered the Solar System. Others have speculated that it was ejected from a white dwarf system and that its volatiles were lost when its star became a red giant. About 1.3 million years ago the object may have passed within a distance of 0.16 parsecs (0.52 light-years) to the nearby star TYC 4742-1027-1, but its velocity is too high to have originated from that star system, and it probably just passed through the system’s Oort cloud at a speed of 103 km/s (230,000 mph).

According to one hypothesis, ʻOumuamua could be a fragment from a tidally disrupted planet.

Source : Wikipedia

If you want to view Oumuamua’s position in WinStars, please download the latest version of the program (3.0.22 beta) and activate the Oumuamua module .