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This page contains examples of ORSA at work, i.e. some of the tasks that can be performed using ORSA.

Visualization of the spin state of asteroid (99942) Apophis Aug 16 2005

The asteroid (99942) Apophis, previously known as 2004 MN4, will experience a very close approach to Earth in 2029. Professor D.J. Scheeres and colleagues have simulated the effect of this close approach on the spin state of this asteroid, and their simulation has been imported into ORSA to fully visualize the evolution of the spin state of this asteroid during its 2029 Earth flyby. An animation [GIF, 1150 kb], realized by P. Tricarico using ORSA, illustrates the results of this simulation.
Importing and visualizing this simulation has been possible thanks to the ongoing development of the ORSA software, that will soon allow to simulate asteroids with arbitrary 3D shape and complex gravitational models. Some of the features used are not yet present in the public version of ORSA, but are now under development and will be made available in future releases.

The Rosetta's Close Approach with Earth Feb 28 2005

The Rosetta space mission has scheduled a close approach to the Earth on March 4 2005. ESA provides a flash animation of this encounter, showing how the Earth will look like if observed from the Rosetta spacecraft. This kind of animation can be easily generated using ORSA, providing an accurate representation of the Earth-Rosetta econunter. The Rosetta's orbit can be retrieved from the JPL's HORIZONS System using the telnet service (command: "telnet ssd.jpl.nasa.gov 6775"), and the commands sequece:

2005 Feb 28
2005 Mar 10
generates the following orbital elements:
2453429.500000000 = A.D. 2005-Feb-28 00:00:00.0000 (CT)
 EC= 1.155133635742327E-01 QR= 8.839937540598229E-01 IN= 4.226330880146734E-01
 OM= 1.643258833664068E+02 W = 9.313908635480863E+01 Tp=  2453515.376420700457
 N = 9.864320913061125E-01 MA= 2.752887427347696E+02 TA= 2.620495075361020E+02
 A = 9.994427475264792E-01 AD= 1.114891740993136E+00 PR= 3.649516303989381E+02
This orbit can be used to integrate Rosetta, using the JPL ephemeris file for the planets' data and using multipole perturbations for the numerical integration of the Rosetta spacecraft. We have generated five animations, using always the same numerical integration, time interval, and changing only the observer position. The first animation shows the Earth observed from Rosetta, like the ESA's animation. As usual, there are no stars or atmosphere, but the orbit of the planets is visible. An orthographic representation of the close encounter is also available in this animation, observing from the positive vertical to the ecliptic plane, centered on the Earth, with the Sun far on the top side of the animation, and the Moon visible while orbiting the Earth on the right. Using a bigger scale, it is possible to observe the spacecraft's orbit change during the encounter: the encouner puts Rosetta on an orbit with a greater semi-major axis. The encounter can also be observed from the Moon or from the Sun.

Distributed Computing and Near Earth Objects Hazard Monitoring Nov 14 2004

A Distributed Computing system is under development, based on the ORSA framework and on the BOINC platform. The basic idea is that the computations needed to monitor the impact hazard posed by Near Earth Objects can be distributed over a big number of clients. ORSA provides the numerical library needed to propagate the orbit of the NEOs, while BOINC provides the system to distribute work units, collect the results and perform many other tasks.
This poster [PDF, A0 paper, 314 kb] describes the system. The poster is also available in A4 or letter paper format.

Close Encounters with Earth and Moon Oct 5 2004

We have compiled a list of close encounters between all the Near Earth Asteroids and the Earth-Moon system. The orbital elements of the asteroids are taken from the NEODyS catalog. The period monitored includes 150 years, from 1950 to 2100, and the distance threshold is set to 10 lunar distances (LD). We provide two separate files, one for the Earth and one for the Moon. Each file is available in three different versions, as it can be sorted by asteroid ID, epoch or distance.

We plan to update these lists every month. Please contact us for any problem or error.
[UPDATE (Nov 22 2004): these lists represent a very preliminary work, because only the nominal orbits of the asteroids are propagated. A deeper analysis, using the error on the orbital elements for each asteroid and covering a longer period, is now in progress.]

The Glanerbrug meteorite by Marco Langbroek Sep 27 2004

An animation [MPEG, 2.7 Mb] of the Glanerbrug meteorite hitting the Earth is available. This animation has been realized by Marco Langbroek. Please visit this page for more details.

2004 ST26 close approach with the Moon Sep 24 2004

In this animation we show the path of the asteroid 2004 ST26 into the Earth/Moon system (using the orbit published on MPEC 2004-S55). The point of view is that of the asteroid, i.e. all the animation is recorded from a camera that is attached to the asteroid while traversing the system, and the camera is always centered on the Moon. The minimum distance between the asteroid and the Moon is of 0.000196 AU = 0.076 LD = 16.9 MR = 4.6 ER only, around Tuesday 2004 Sep 22 00:01 UTC. Many thanks to Bill Allen from Asteroid/Comet Connection for pointing out the passage of this object.

ORSA demo movie Sep 3 2004

If you really want to see ORSA at work, probably this is the best way to do it! We have a ORSA demo movie [MPEG, 30.5 Mb, 13 min.] that shows how to start using ORSA, perform a numerical simulation, visualize it in the 3D OpenGL window or using the 2D plotting tools, and save it on a file. If you downloaded ORSA but you don't know how to use it, maybe watching this movie is a good start.

2004 FU162 close approach with Earth Aug 24 2004

In this animation, we show the path of the asteroid 2004 FU162 into the Earth/Moon/satellites system. The point of view is that of the asteroid, i.e. all the animation is recorded from a camera that is attached to the asteroid while traversing the system. Some artificial satellites are visible, showing that the object passed inside the outermost shell (geostationary satellites, goes-*) and also inside the GPS constellation, while the shell of low-orbit satellites is still closer to the Earth than the asteroids' path. In background, the inner Solar System is visible.
We want to thank Bill Allen from Asteroid/Comet Connection for his suggestions, his stimulating questions, and his continuous work in the Minor Planets News world, helping professionals and amateurs to keep up-to-date with the latest events in the field.

2004 FH close approach with Earth Mar 20 2004

The recent flyby of the asteroid 2004 FH into the Earth/Moon system has been followed using ORSA. The numerical results and some animations have been published by Asteroid/Comet Connection, in the days 17, 18, and 19 March 2004.

2002 GO9 the first Uranus Trojan? Mar 10 2004

As pointed out March 9, 2004 by Denis Denissenko on the Minor Planet Mailing List (Yahoo! Groups page), the asteroid 2002 GO9 has a "quasi-Uranian" Trojan orbit. As no Uranus Trojans are known to date, it is important to check whether or not 2002 GO9 is the first one.
We have generated 32 virtual asteroids using the latest 2002 GO9 orbital elements and covariance matrix, available at the AstDyS 2002 GO9 page. Using ORSA, we have integrated for 50000 years the system composed by the Sun, Jupiter, Saturn, Uranus and Neptune, and the 32 massless virtual asteroids. The first 10000 years of this integration are available on this animated gif [933 kb], where the system is showed in the rotating frame, keeping Uranus always on the negative X axis. Essentially, all the 2002 GO9's clones have close approaches with Uranus around the years 5000 and 9000, and in particular the effect of the last one is to put every clone on a quite different orbit, so that it is not possible to state what will be the fate of the real one. It is important to note that none of the clones shows a Trojan-like orbit or even an horse-shoe like orbit.
When more observations of this object will be available, it will be possible to check with more precision if 2002 GO9 is an Uranus Trojan. With the present data, such an orbit type can be excluded.

Relativistic Effects added in ORSA 0.5.0-rc2 Feb 18 2004

A new interaction, called [Newton + Relativistic Effects], has been added in the latest ORSA release. This interaction takes into account the main corrections to the Newton interaction due to the General Theory of Relativity. Using this interaction it is possible to compute correctly the precession of the perihelion of Mercury, as well as correctly integrate the orbit of very eccentric objects.
In particular, the relativistic contribution to the precession of the perihelion of Mercury has been computed, obtaining 43.03 arcsec/century in perfect agreement with the literature. To check this result it is sufficient to integrate two times the Solar System for a century, starting i.e. at Jan 1 2000, using the Radau integrator with an accuracy of 1.0e-12. The first integration is performed using the [Newton] interaction, the second using the [Newton + Relativistic Effects] interaction. Using the 2D widget it is then possible to plot the pericenter of Mercury with respect to the Sun for each integration, and using the [save] button it is possible to save the data on a different file for each plot. By comparing the final value of the two integrations, we obtain the Relativistic contribution in degrees, and by multiplying it by 3600.0 we obtain the result in arcseconds.

The Quadrantids and 2003 EH1 Dec 16 2003

As pointed out by P. Jenniskens at NASA Ames Research Center (PDF paper, IAU Circular), 2003 EH1 "would seem to be a very strong candidate for the parent of the Quadrantid meteor stream". With xorsa we have studied this object using the most up to date orbit from MPC, obtaining the recent close approaches with Jupiter, and the behavior of the perihelion distance, in particular in the vicinity of 1 AU. In this animation it is showed the passage of the perihelion from below to above 1 AU, in coincidence with a close approach with Jupiter. The MOID with the Earth is showed, and the flip is evident. (unfortunately Earth and Moon labels are overlapped)

2003 WT42 on Asteroid/Comet Connection Dec 1 2003

Another hit on A/CC news. In this case, the peculiar object 2003 WT42 has been analyzed and the animation, realized with xorsa, is available at the A/CC news page.

2003 WT153 on Asteroid/Comet Connection Nov 30 2003

The ORSA software has been used to study the newly discovered asteroid 2003 WT153 and its close encounter with the Earth, and the results have been published on the news page of Asteroid/Comet Connection. In particular, using xorsa we have measured the minimum approach distance between the object and the Moon, only about 0.87 LD. An animation obtained with xorsa and showing the close approach between 2003 WT153 and the Earth-Moon system is available at the A/CC news page.

Earth-Mars Close Encounter Aug 4 2003

The close encounter with the Red Planet can be simuated using xorsa. We have simulated the Solar System, studying the period 1st July - 30th September 2003, and we have created this animation showing the two planets and their orbits relative to the Sun. It is also visible the MOID (Minimal Orbital Intersection Distance) or the two orbits. The animation is available in animated GIF [244 kb] and MPEG [175 kb] formats.

Website last updated: May 12 2008
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