#Movement data in #QGIS 7: animated trajectories with TimeManager
▻https://anitagraser.com/2017/08/14/movement-data-in-gis-7-animated-trajectories-with-timemanager
In this post, we use TimeManager to visualize the position of a moving object over #time along a #trajectory. This is another example of what is possible thanks to QGIS’ geometry generator feature. The result can look like this:
#map
#Rosetta’s complete journey – #animation
▻http://blogs.esa.int/rosetta/2016/12/23/rosettas-complete-journey-animation
Now in one complete animation: #rosetta’s #trajectory around #Comet_67P/Churyumov–Gerasimenko, from arrival to mission end. The animation begins on 31 July 2014, during Rosetta’s final approach to the comet after its ten-year journey through space. The spacecraft arrived at a distance of 100 km on 6 August, from where it gradually approached the comet and entered initial mapping orbits that were needed to select a #Landing site for Philae. These observations also enabled the first comet science of the mission. The manoeuvres in the lead up to, during and after Philae’s release on 12 November are seen, before Rosetta settled into longer-term science orbits. In February and March 2015 the spacecraft made several flybys. One of the closest triggered a ‘safe mode’ that forced it to retreat (...)
#Fun_stuff #Operations #video ##CometLanding #flyby #manoeuvre
Movement data in GIS part 3: visualizing massive trajectory datasets | Free and Open Source GIS Ramblings
►https://anitagraser.com/2016/11/07/movement-data-in-gis-3-visualizing-massive-trajectory-datasets
While visualizing individual trajectories is important, the real challenge is trying to visualize massive trajectory datasets in a way that enables further analysis.
1) Extracting characteristic points from the trajectories
2) Grouping the extracted points by spatial proximity
3) Computing group centroids and corresponding Voronoi cells
4) Deviding trajectories into segments according to the Voronoi cells
Counting transitions from one cell to another
La suite...
Movement data in GIS extra : trajectory generalization code and sample data
▻https://anitagraser.com/2017/10/13/movement-data-in-gis-extra-trajectory-generalization-code-and-sample-da
https://underdark.files.wordpress.com/2017/10/trajectory_generalization_start1.png 
https://underdark.files.wordpress.com/2017/10/trajectory_generalization_final1.png Today’s post is a follow-up of #Movement data in GIS 3: visualizing massive trajectory datasets. In that post, I summarized a concept for #trajectory #generalization. Now, I have published the scripts and sample data in my QGIS-Processing-tools repository on Github.
▻https://github.com/anitagraser/QGIS-Processing-tools/tree/master/2.12/trajectory_generalization
Visualising #Rosetta’s descent
▻http://blogs.esa.int/rosetta/2016/09/26/visualising-rosettas-descent
Imagine how #rosetta's descent might look if you were an observer at Comet 67P/C-G! This new animation visualises the final stages of Rosetta’s descent to Comet 67P/Churyumov–Gerasimenko on 30 September 2016. The sequence is speeded up to show the relative motion of Rosetta and the rotating comet below. Earlier today, Rosetta completed a small manoeuvre as planned that puts it on the start of a 16 x 23 km #orbit needed in preparation for the collision manoeuvre on 29 September. Recap the final trajectories in the below animation:
#Landing #Operations ##CometLanding #ocm #thruster #trajectory
#Rosetta’s final orbits – animation
▻http://blogs.esa.int/rosetta/2016/09/22/rosettas-final-orbits-animation
This new animation visualises Rosetta’s last two months of trajectories around Comet 67P/Churyumov-Gerasimenko. The animation begins in early August, when the spacecraft started flying elliptical orbits that brought it progressively closer to the comet at its closest approach. On 24 September, #rosetta will leave its current close, flyover orbits and transfer into the start of a 16 x 23 km orbit that will be used to prepare and line up for the final descent. On the evening of 29 September (20:50 GMT) Rosetta will #manoeuvre onto a collision course with the comet, beginning the descent from an altitude of 19 km. The spacecraft will fall freely, without further manoeuvres, collecting scientific data during the descent. The animation below highlights this final set of manoeuvres and the (...)
ESA Hangout : Preparing for #Rosetta’s grand finale
▻http://blogs.esa.int/rosetta/2016/09/15/esa-hangout-preparing-for-rosettas-grand-finale
ESA’s #rosetta spacecraft is set to complete its incredible mission in a controlled descent to the surface of Comet 67P/C-G on 30 September. Join mission experts on 19 September, 1200 GMT / 1400 CEST to discuss Rosetta’s final days and hours of operation, including expectations for the images and other scientific data that will be collected as the spacecraft gets closer and closer to the surface. We’ll also discuss the exciting discovery of Philae that was made earlier this month. Watch it live here:
Guests: Andrea Accomazzo, Flight #Operations director Sylvain Lodiot, Rosetta spacecraft operations manager Claire Vallet or Richard Moissl (TBC), Rosetta #Science ground segment liaison scientist Laurence O’Rourke, Rosetta downlink #science operations (...) #Rosetta’s descent towards region of active pits
▻http://blogs.esa.int/rosetta/2016/09/09/rosettas-descent-towards-region-of-active-pits
Squeezing out unique scientific observations until the very end, #rosetta’s thrilling mission will culminate with a descent on 30 September towards a region of active pits on the #comet’s ‘head’. The region, known as Ma’at, lies on the smaller of the two lobes of #Comet_67P/Churyumov–Gerasimenko. It is home to several active pits more than 100 m in diameter and 50–60 m in depth – where a number of the comet’s dust jets originate. The walls of the pits also exhibit intriguing metre-sized lumpy structures called ‘goosebumps’, which scientists believe could be the signatures of early ‘cometesimals’ that assembled to create the comet in the early phases of Solar System formation. Rosetta will get its closest look yet at these fascinating structures on 30 September: the spacecraft will target a point (...)
#Comets #Instruments #Landing #Operations #Science ##CometLanding #instruments #science #trajectory
Rosetta will get its closest look yet at these fascinating structures on 30 September: the spacecraft will target a point adjacent to a 130 m-wide, well-defined pit that the mission team has informally named Deir el-Medina, after a structure with a similar appearance in an ancient Egyptian town of the same name.
Like the archaeological artefacts found inside the Egyptian pit that tell historians about life in that town, the comet’s pit contains clues to the geological history of the region.
Rosetta will target a point very close to Deir el-Medina, within an ellipse about 700 x 500 m.
Video report : the end is in sight
▻http://blogs.esa.int/rosetta/2016/09/02/video-report-the-end-is-in-sight
Post-perihelion changes, close flybys, and preparing for end of mission!
#Comet_67P #Comets #Images #Instruments #Landing #Operations #Rosetta #Science ##CometLanding ##perihelion2015 #navcam #osiris #rosetta #science #trajectory
La fin est proche ! Repentez-vous !
(euh, non, il s’agit de Rosetta… ce sera le 30 septembre)
▻https://www.youtube.com/watch?v=UobzGZH2VnE
Celebrating two years at the comet
▻http://blogs.esa.int/rosetta/2016/08/05/celebrating-two-years-at-the-comet
We’re celebrating #Rosetta’s two year anniversary at #Comet_67P/C-G (tomorrow!) with a new animation visualising the spacecraft’s incredible adventure flying alongside the comet. The animation begins on 31 July 2014, during #rosetta’s final approach to the comet after its ten-year journey through space. The spacecraft arrived at a distance of 100 km on 6 August whereupon it gradually approached the comet and entered initial mapping orbits that were needed to select a #Landing site for #philae. These observations also enabled the first comet #Science of the mission. The manoeuvres in the lead up to, during and after Philae’s deployment on 12 November are seen, before Rosetta settled into longer-term science orbits. In February and March 2015 the spacecraft made several flybys. One of the closest (...)
#Arrival #Operations ##CometLanding ##LivingWithAComet ##perihelion2015 ##WakeUpRosetta #orbit #timeline #trajectory
#Rosetta finale set for 30 September
▻http://blogs.esa.int/rosetta/2016/06/30/rosetta-finale-set-for-30-september
This article is mirrored from the ESA Web Portal. #rosetta is set to complete its mission in a controlled descent to the surface of its comet on 30 September. The mission is coming to an end as a result of the spacecraft’s ever-increasing distance from the Sun and Earth. It is heading out towards the orbit of Jupiter, resulting in significantly reduced solar power to operate the craft and its #Instruments, and a reduction in bandwidth available to downlink scientific data. Combined with an ageing spacecraft and payload that have endured the harsh environment of space for over 12 years – not least two years close to a dusty comet – this means that Rosetta is reaching the end of its natural life. Unlike in 2011, when Rosetta was put into a 31-month hibernation for the most distant part of (...)
#Comet_67P #Images #Landing #Operations #Science ##CometLanding #esoc #instruments #landing #manoeuvre #science #trajectory
Rosetta’s operators will begin changing the trajectory in August ahead of the grand finale such that a series of elliptical orbits will take it progressively nearer to the comet at its closest point.
“Planning this phase is in fact far more complex than it was for Philae’s landing,” says Sylvain Lodiot, ESA Rosetta spacecraft operations manager. “The last six weeks will be particularly challenging as we fly eccentric orbits around the comet – in many ways this will be even riskier than the final descent itself.”
“The closer we get to the comet, the more influence its non-uniform gravity will have, requiring us to have more control on the trajectory, and therefore more manoeuvres – our planning cycles will have to be executed on much shorter timescales.”
A number of dedicated manoeuvres in the closing days of the mission will conclude with one final trajectory change at a distance of around 20 km about 12 hours before impact, to put the spacecraft on its final descent.
The region to be targeted for Rosetta’s impact is still under discussion, as spacecraft operators and scientists examine the various trade-offs involved, with several different trajectories being examined.
Broadly speaking, however, it is expected that impact will take place at about 50 cm/s, roughly half the landing speed of Philae in November 2014.
#Rosetta safe mode 5 km from #comet
▻http://blogs.esa.int/rosetta/2016/05/30/rosetta-safe-mode-5-km-from-comet
Over the weekend, #rosetta experienced a ‘safe mode’ event 5 km from the surface of Comet 67P/Churyumov-Gerasimenko. Contact with the spacecraft has since been recovered and the mission teams are working to resume normal #Operations. “We lost contact with the spacecraft on Saturday evening for nearly 24 hours,” says Patrick Martin, ESA’s Rosetta mission manager. “Preliminary analysis by our flight dynamics team suggests that the star trackers locked on to a false star – that is, they were confused by comet #dust close to the comet, as has been experienced before in the mission.” This led to spacecraft pointing errors, which triggered the safe mode. Unfortunately the star trackers then got hung in a particular sub mode requiring specific action from Earth to recover the spacecraft. “It was an (...)
“It was an extremely dramatic weekend,” says Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager.
“After we lost contact, we sent commands ‘in the blind’, which successfully tackled the hung star tracker issue and brought the spacecraft back into three-axis stabilised safe mode, and we now have contact with the spacecraft again. However, we are still trying to confirm the spacecraft’s exact position along its orbit around the comet – we only received images for navigation this morning, the first since Saturday.”
[…]
Operating close to the comet means that the spacecraft is surrounded by a lot of dust. Even though the comet’s activity has diminished significantly since passing through its closest point to the Sun along its orbit last August, the environment is still dusty enough that the star trackers can occasionally mistake comet debris in its field of view for stars.
[…]
Details of Rosetta’s final descent will be provided soon. The provisional plan is to target the small lobe close to Philae’s original planned landing site at Agilkia, most likely on 30 September.
Tchourioumov-Guérassimenko à 1 pixel = 13 cm
#Philae status update
▻http://blogs.esa.int/rosetta/2015/12/09/philae-status-update
Short video update from the #lander Control Center at DLR: #Videoupdate: the quest to re-establish contact with @Philae2014 continues... #lifeonacomet pic.twitter.com/0fp7Jrl8g2 — DLR - English (@DLR_en) December 9, 2015
#Landing #Operations #Rosetta ##CometLanding #philae #rosetta #trajectory
#Rosetta and #Philae : one year since #Landing on a #comet
▻http://blogs.esa.int/rosetta/2015/11/12/rosetta-and-philae-one-year-since-landing-on-a-comet
One year since #philae made its historic landing on a comet, mission teams remain hopeful for renewed contact with the #lander, while also looking ahead to next year’s grand finale: making a controlled impact of the #rosetta orbiter on the comet. This article is mirrored from the main ESA web portal. Rosetta arrived at #Comet_67P/Churyumov–Gerasimenko on 6 August 2014, and after an initial survey and selection of a landing site, Philae was delivered to the surface on 12 November. After touching down in the Agilkia region as planned, Philae did not secure itself to the comet, and it bounced to a new location in Abydos. Its flight across the surface is depicted in a new animation, using data collected by Rosetta and Philae to reconstruct the lander’s rotation and attitude (Ed’s note: more (...)
#Images #Instruments #Operations #Science ##CometLanding #instruments #science #trajectory
From one comet #Landing to another: planning #Rosetta’s grand finale
▻http://blogs.esa.int/rosetta/2015/11/12/from-one-comet-landing-to-another-planning-rosettas-grand-finale
As announced in June along with confirmation of the mission’s extension, #rosetta teams are planning to end the operational phase of the mission in a controlled impact of the orbiter on the surface of Comet 67P/Churyumov-Gerasimenko at the end of September 2016. While the specific details of the trajectories and impact site are still under discussion, ESA’s Rosetta Spacecraft #Operations Manager Sylvain Lodiot, Project Scientist Matt Taylor, and mission manager Patrick Martin, share some background information on the planning of this dramatic mission finale. Why will the mission come to an end? Following perihelion in August, Comet 67P/C-G and Rosetta are now moving away from the Sun and back out towards the orbit of Jupiter. This creates a number of challenges: Reduced solar power As the (...)
#Instruments ##CometLanding #manoeuvre #timeline #trajectory
Understanding #Philae’s #wake-up: behind the scenes with the Philae team
▻http://blogs.esa.int/rosetta/2015/09/11/understanding-philaes-wake-up-behind-the-scenes-with-the-philae-team
Since #Rosetta’s #lander Philae first woke up from hibernation and called ‘home’ on 13 June, the teams at the Lander Control Center (LCC – DLR), the Science #Operations and Navigation Center (SONC – CNES), the Max-Planck Institute (MPS – Göttingen) and the Institute for Particle and Nuclear Physics (Wigner Research Centre for Physics – Budapest) have been working with ESA’s #rosetta Mission Operations Centre (RMOC – ESOC) and the Rosetta Science Ground Segment (RSGS – ESAC), and in close cooperation with the Philae and Rosetta scientists, to establish regular and predictable contacts with Philae, and to resume scientific measurements. This blog post has been written by Koen Geurts, Philae technical manager, and Cinzia Fantinati, Philae operations manager (both from the LCC at DLR), and gives a (...)
#Comet_67P #Instruments #Landing ##CometLanding #instruments #trajectory
Long (et passionnant) billet détaillant les communications avec Philae et le puzzle à reconstituer pour resituer les informations reçues et mettre en place une stratégie visant à optimiser les chances d’échange entre Rosetta et Philae.
Par exemple, puissance reçue par les panneaux solaires au cours de 3 « jours cométaires »…
Position de Philae et survols de Rosetta, carrés verts et triangles violets indiquant les instants d’échanges (2 types différents)
À venir, le 23 septembre, départ d’une excursion lointaine (à 1500km de la comète).
à suivre, …
Celebrating a year at the #comet
▻http://blogs.esa.int/rosetta/2015/08/06/celebrating-a-year-at-the-comet
This article is mirrored from the main ESA Web Portal ESA’s #Rosetta mission today celebrates one year at #Comet_67P/Churyumov–Gerasimenko, with its closest approach to the Sun now just one week away. It’s been a long but exciting journey for #rosetta since its launch in 2004, featuring Earth, Mars and two asteroid flybys before arriving at its ultimate destination on 6 August 2014. Over the following months, the mission became the first ever to orbit a comet and the first to soft land a probe – #Philae – on its surface. The mission teams have had to overcome many challenges in learning to fly in an unpredictable and sometimes inhospitable environment, and the spacecraft has returned a wealth of outstanding scientific data from this intriguing comet, spanning its interior, the dramatic surface (...)
#Arrival #Comets #CometWatch #Images #Instruments #media #On_this_day #Operations #Science ##CometLanding ##CometWatch ##RosettaAreWeThereYet ##WakeUpRosetta #flyby #instruments #lander #landing_day #philae #science #trajectory #wake-up
Video update from #lander Control Centre
▻http://blogs.esa.int/rosetta/2015/07/01/video-update-from-lander-control-centre
As tweeted by the German Aerospace Center (DLR) yesterday, a mini status update direct from the Lander Control Center in Cologne. In short, the teams are still working hard on trying to re-establish contact with the lander. Update on status of @Philae2014 on #67P directly from #LCC in Cologne (video) #lifeonacomet (FW) pic.twitter.com/sEuNeFL7l3 — DLR - English (@DLR_en) June 30, 2015
#Landing #Philae #Rosetta ##CometLanding #rosetta #trajectory
#Philae wake-up triggers intense planning
▻http://blogs.esa.int/rosetta/2015/06/15/philae-wake-up-triggers-intense-planning
The receipt of signals from #Rosetta’s #philae #lander on 13 June after 211 days of hibernation marked the start of intense activity. In coordination with its mission partners, ESA teams are working to juggle #rosetta’s flight plan to help with renewed lander science investigations. Philae has woken up after seven months in hibernation on Comet 67P/Churyumov–Gerasimenko. Hidden by shadows, Philae shut down on 15 November 2014 at 00:36 GMT after completing its main science #Operations sequence on the comet when the primary battery expired as expected after about 60 hours. Since March 2015, when Philae’s environmental conditions started to improve with higher surface temperatures and better illumination, the orbiter’s receiver had been turned on periodically to listen for signals from the lander (...)
#Rosetta and #Philae find #comet not magnetised
▻http://blogs.esa.int/rosetta/2015/04/14/rosetta-and-philae-find-comet-not-magnetised
This new result was just presented at EGU2015 and is published in #Science Express today. The text is mirrored from our news story on the main ESA web portal. Measurements made by #rosetta and #philae during the probe’s multiple landings on Comet 67P/Churyumov-Gerasimenko show that the comet’s nucleus is not magnetised. Studying the properties of a comet can provide clues to the role that magnetic fields played in the formation of Solar System bodies almost 4.6 billion years ago. The infant Solar System was once nothing more than a swirling disc of gas and dust but, within a few million years, the Sun burst into life in the centre of this turbulent disc, with the leftover material going into forming the asteroids, #Comets, moons and planets. The dust contained an appreciable fraction of iron, (...)
#Comet_67P #Instruments #Landing ##CometLanding #instruments #lander #science #trajectory
New trajectories for #Rosetta
▻http://blogs.esa.int/rosetta/2015/04/10/new-trajectories-for-rosetta
Rosetta continues to recover well from the problems experienced during the close flyby over the weekend of 28 March that resulted in the spacecraft entering safe mode. Some of the #science #Instruments are now switched back on again, and more will follow in the coming week. As a result of the safe mode, #rosetta moved onto an ‘escape #trajectory’ taking it approximately 400 km from #Comet_67P/C-G. An orbital correction #manoeuvre was executed on 1 April to start to bring the spacecraft back again, and with a second manoeuvre executed on 4 April, the target distance of 140 km was reached on 8 April. But the previous difficulties in navigation mean that the #Operations team needs to be cautious while bringing the spacecraft even closer. In particular, they will need to assess the behaviour of (...)
But the previous difficulties in navigation mean that the operations team needs to be cautious while bringing the spacecraft even closer. In particular, they will need to assess the behaviour of the spacecraft’s star trackers in the environment of the increasingly active comet, since the previous navigation issues resulted from the star trackers becoming confused by comet particles.
#Rosetta status report : close #flyby navigation issues
▻http://blogs.esa.int/rosetta/2015/04/01/rosetta-status-report-close-flyby-navigation-issues
During its most recent close flyby last Saturday, where #rosetta flew within 14 km of the surface of the #comet, the spacecraft experienced significant difficulties in navigation. This resulted in its high gain antenna starting to drift away from pointing at the Earth, impacting communications, and was subsequently followed by a ‘safe mode’ event. The spacecraft has now been successfully recovered, but it will take a little longer to resume normal scientific #Operations. Here is the full report from the mission team: Rosetta has been flying a series of flyby trajectories around #Comet_67P/C-G since February, allowing the spacecraft to collect scientific data from a range of distances. Its closest flyby to date took it just 6 km from the surface of the comet – over the Imhotep region on the (...)
#Rosetta #Science Working Team meeting report
▻http://blogs.esa.int/rosetta/2015/03/18/rosetta-science-working-team-meeting-report
US #rosetta Project Scientist Claudia Alexander and ESA’s Rosetta Project Scientist Matt Taylor report on the discussions held at the recent Rosetta #science Working Team meeting. The Rosetta Science Working Team (SWT) met for the 40th time earlier this month, this time at ESTEC in Noordwijk, Netherlands. This meeting was attended by principal investigators and co-investigators of the #Instruments and other researchers but also science #Operations personnel and staff from the mission operations team. This week the main topics discussed were the science of the mission so far, science operations and new trajectories going forward, and updates on the state of the health of the experiments and the spacecraft. Compared to our predictions and expectations, the activity of the comet is slightly (...)
Observing 67P/C-G from Earth
As part of the SWT week, splinter workshops included that of the ground-based observing campaign, let by Colin Snodgrass, a UK cometary scientist at the Open University who leads (along with colleagues at ESO) the professional ground based campaign group (▻http://www.rosetta-campaign.net). Both amateurs and professionals are welcome to the meeting. The comet is currently behind the Sun, and will not be visible to professional ground-based observers until about June 2015 (just before perihelion). It is the hope that amateur astronomers will be able to observe the comet starting in the April-May timeframe. The US Rosetta Project manages the amateur ground-based observing program on behalf of the project. A new website is being designed, with a welcome page for amateur astronomers who are interested in participating in this exciting campaign. Web pages will soon be introduced at the JPL Rosetta web site, and a form for amateurs to fill out to register for the program. Instructions for how amateurs can upload (FITS Format) pictures will be included in a hand-book at that time.
#CometWatch 14 February – flyby special
▻http://blogs.esa.int/rosetta/2015/02/16/cometwatch-14-february-flyby-special
On Saturday, #Rosetta passed within just 6 km of the surface of #Comet_67P/Churyumov-Gerasimenko in the first dedicated close flyby of the mission. The closest approach took place at 12:41 UT over the Imhotep region on the comet’s large lobe. Four sets of #navcam #Images taken on 14 February were downlinked from the spacecraft yesterday and we are delighted to be able to share all four with you here today. As usual, we present either a mosaic of montage of each image, noting that at the closest distances the combined effect of the rotation of the comet and the movement of the spacecraft between the first and last image being taken is particularly large, resulting in difficulties in creating an accurate mosaic. The montages/mosaics have been tweaked in Lightroom for global (...)
Where is #Philae? When will it wake up?
▻http://blogs.esa.int/rosetta/2015/01/30/where-is-philae-when-will-it-wake-up
These are the two most popular questions currently being asked of the mission – especially on our social media channels – and ones that we will try to answer in this post, including inputs from the OSIRIS team, and from the Lander Control Centre at the German Aerospace Center (DLR). Where is #philae? Ever since Philae touched down on #Comet_67P/Churyumov-Gerasimenko for the final time on 12 November – it is thought to have come into contact with the #comet’s surface a total of four times including the final #Landing – the search has been on to identify it in images. While the CONSERT instrument has helped to narrow down a 350 x 30 m ‘landing strip’ on Comet 67P/C-G’s smaller lobe, a dedicated search in OSIRIS images has so far not been able to confirm the little lander’s final location. Philae’s (...)
#Instruments #Rosetta ##CometLanding #rosetta #trajectory #wake-up
L’historique des orbites de Rosetta au moment de l’atterrissage de Philae
▻http://wpc.50e6.edgecastcdn.net/8050E6/mmedia-http/download/public/videos/2014/10/013/1410_013_AR_EN.mp4
#Rosetta in 2015
▻http://blogs.esa.int/rosetta/2015/01/06/rosetta-in-2015
Before the Christmas break we left you with a bounty of #comet #Images to create a movie – if you took on the challenge, do post links to your videos on the relevant post: #CometWatch – the movie. We are looking forward to seeing your mosaics and movies! We were also keeping our ear to the ground for an update on the whereabouts of #Philae, but attempts to identify the lander in high-resolution OSIRIS images acquired from a distance of 20 km have reportedly not yet been successful. (Note, the link is to a German news story in which OSIRIS PI Holger Sierks told the Göttinger Tageblatt “We have still not discovered the lander.”) The scientists continue to scour the images for confirmation of the landing site. #rosetta is now orbiting #Comet_67P/C-G at a distance of about 30 km. The images included (...)
#Operations #Science #manoeuvre #navcam #philae #science #trajectory