Daily Archives: April 30, 2017

Space Sunday: Saturn, spacesuits and printing a base on the Moon

An artist’s impression of NASA’s Cassini passing Titan, Saturn’s largest moon, on its way to the first of its Grand Finale dives between the planet and its ring system

NASA’s Cassini mission has completed the first of its final 22 “dives” through the gap between  Saturn its ring system. In the process, the craft came to its closest past so far over the planet’s cloud tops.

As I noted in my previous Space Sunday update, after 20 years in service and with manoeuvring fuel running out, the mission is set to end on September 15th, 2017, when the veteran spacecraft will enter the upper reaches of Saturn’s atmosphere and burn up, preventing any risk of the vehicle colliding with one of Saturn’s moons and risk contaminating it with the radiation from its plutonium power cells.

Two images of a vast hurricane-like vortex at Saturn’s north pole. Left: the raw image captured by Cassini as it passed over the planet on April 27th, 2017 (UT). Right; a colour enhanced image (from a slightly different angle) showing the complex mechanics of the atmosphere around the vortex. Credit: NASA/JPL / Jason Major. Click for full size

This first pass between planet and rings was a complete dive into the unknown – so much so, that the spacecraft was out of contact for 20 hours during the critical part of the pass. This was because prior to making the pass, the vehicle had to be oriented so that its 4-metre (13 ft) diameter communications dish was facing away from Earth and into the direction of flight, so it could act as a shield to prevent any dust particles within gap impacting more sensitive parts of the vehicle.

NASA’s Deep Space Communications network lost contact with the vehicle at 09:00 UT, on April 26th, as Cassini cross Saturn’s ring plane. The signal was successfully re-acquired at 06:56 UT on April 27th, after the vehicle had cleared the gap and could re-orient itself and point its communications dish back towards Earth. The transfer of data gathered during the pass commenced a few minutes later.

A dramatic image from April 27th (UT) showing the darkened limb of Saturn with a thin band of the upper atmosphere catching the sunlight. Above the planet are the hazy, sunlight reflecting major rings of the planet with the bright wedding ring of the G-ring brightly catching the Sun’s light. Credit: NASA/JPL / Jason Major

“No spacecraft has ever been this close to Saturn before. We could only rely on predictions, based on our experience with Saturn’s other rings, of what we thought this gap between the rings and Saturn would be like,” said Cassini Project Manager Earl Maize at NASA’s Jet Propulsion Laboratory, California, as the data from the spacecraft started flowing. “I am delighted to report that Cassini shot through the gap just as we planned and has come out the other side in excellent shape.”

The gap between the rings and the top of Saturn’s atmosphere is about 2,000 km (1500 mi) wide, and Cassini came within 3,000 km (1900 mi) of Saturn’s cloud tops, in an area where there was a risk of smoke particle sized motes of dust being encountered. Small as they might be, the fact that the probe was travelling at some 124,000 km/h (77,000 mph) relative to Saturn meant that any dust striking an unprotected part of the vehicle could have been catastrophic, hence using the communications antenna (which could suffer some damage without serve loss of capability) as a shield.

Tipped on its side, this true colour image of Saturn shows the planet’s north polar region and vortex (just visible, bottom right), caught in sunlight, together with the planet’s ring system. Credit: NASA/JPL / Sophia Nasr

“In the grandest tradition of exploration, NASA’s Cassini spacecraft has once again blazed a trail, showing us new wonders and demonstrating where our curiosity can take us if we dare,” said Jim Green, director of the Planetary Science Division at NASA Headquarters.

The data from Cassini is already being analysed and revealing more about Saturn and it’s atmosphere, but it has been the images that were released following the pass which have stunned observers on Social media – although some needed to have their perspective adjusted as the first of the raw images appeared.

“Hey, it’s a GIF of something you think’s gonna be cool, but it’s Cassini proving it’s no better at camera s*** than somebody getting shot at,” one commentator chose to Tweet. This prompted a quick response from fellow space enthusiast, Jason Major (whose images are used in this article); “Cute. Now realise Cassini is taking these pics w/a camera built in 1996 while travelling 65,000 mph where sunlight is 100x dimmer than here.”

Cassini’s second ring-dive will occur on Tuesday, May 2nd.

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Artefacts, adventures, archives and ransoms

It’s time to kick-off another week of storytelling in Voice by the staff and volunteers at the Seanchai Library. As always, all times SLT, and events are held at the Library’s Second Life home at Bradley University, unless otherwise indicated.

Monday, May 1st 19:00: Architects of Hyperspace

Humour, hard science and speculative science fiction all combine in this novel by Thomas R. McDonough, who has worked with both the SETI Institute and The Planetary society.

A trio driven by personal ambitions comes together after a dying man’s last words send them in search of the secrets of a lost alien civilisation.

A wonderful tongue in cheek story backed by great speculative science. The combination of the sometimes screwball comedy with the specifics of how hyperspace could work and the details of the time lags of space communication, etc, made for a believable and well-formed diegesis. There were times reading this book that I just had to stop to laugh. The book reminds me a great deal of Red Dwarf. 

Join Gyro Muggins as he reads this unusual story.

Tuesday, May 2nd 19:00: Wild at Heart

Aoife Lorenfield continues Clare Alexander’s 2017 novel.

At 26 and unmarried, Nora Nicholson believes she has little choice but to follow her brother Edward away from England to West Africa. So it was that, having never set foot outside of the village where she had been born, she found herself boarding a Royal Navy frigate about to set sail for those exotic, distant lands.

Little did she know that she would find work illustrating birds for the naturalist and ship’s surgeon, John Sharples, or form the unlikeliest of friendships with Senhora Morena – or that she would meet Hugh Beaumont, naturalist and explorer, late of the 95th Rifles.

Once he led men in war, many of whom died in the field of battle. Now he desires to explore the rivers and forest of West Africa. But for Hugh Beaumont, leaving duty behind does not come easy. So it is he finds himself bringing criminals to justice and protecting Miss Nicholson, who is sorely in need of help. Then love enters the picture.

Wednesday, May 3rd 19:00 The Atrocity Archives Part 2

atrocity-archivesBob Howard is a low-level techie working for The Laundry, a super-secret government agency. While his colleagues are out saving the world, Bob’s under a desk restoring lost data. None of them receive any thanks for the jobs they do, but at least a techie doesn’t risk getting shot or eaten in the line of duty. Bob’s world is dull but safe, and that’s the way it should have stayed; but then he went and got Noticed.

Now, Bob Howard is up to his neck in spycraft, alternative universes, dimension-hopping Nazis, Middle Eastern terrorists, damsels in distress, ancient Lovecraftian horror and the end of the world.

Only one thing is certain: it will take more than control-alt-delete to sort this mess out…

Join Corwyn Allen as he resumes relating stories involving Charles Stross’ unlikely hero, Bob Howard.

Thursday, May 4th 19:00, Night of the Wolf

Robert E. Howard is perhaps best known as the creator of Conan the Barbarian and Solomon Kane. However, he also wrote a plethora of short stories involving a range of characters and settings. This story involves Cormac Mac Art, an outlawed Gael, a pirate and a Reiver.

Set on the island of Golara, North of the Scottish mainland, near the Shetlands. Here is a mix of native Picts, ostensibly under the “protection” of a Norse raiding group who are using the island as their base of operations – and their bitter enemies, the Danes, are using as a target.

Into this wades Irish legend Cormac Mac Art (and opponent of Danes and Norsemen), trying to operate in disguise to win the freedom of someone captured by the Norse raiding party who is not all he appears to be. Problem is, the leader of the Norse is not for a moment fooled by Cormac’s disguise…

Read by Shandon Loring and also presented in Kitely grid.kitely.com:8002:EXPLORESeanchai).


Please check with the Seanchai Library’s blog for updates and for additions or changes to the week’s schedule.

The featured charity for March April is Project Children, building peace in Ireland one child at a time.

SL project updates 17/2: server, viewer Content Creation UG

Patankar – blog post

Server Deployments

As always, please refer to the server deployment thread for the latest information  / updates.

  • There was no deployment to, or restart of, the Main (SLS) channel on Tuesday, April 25th
  • Depending on the outcome of late QA testing, the three RC channels may be updated on Wednesday, April 26th as follows:

DRTSIM-343: Allow Public Access Region / Parcel Settings Changes

This is the update to region / parcel access that will mean that if a region is explicitly set to Allow Public Access, parcel holders on the region will no longer be able to override the setting at the parcel level (see my update here). It had been deployed to the three RC channels a couple of weeks ago, but was then withdrawn. This may now be reappearing on an RC in week #18 (commencing Monday, May 1st, 2017), with Rider linden noting:

There were a number of suggestions about additions to the project. I just finished getting the code in that will send a notification to the parcel owner if their access settings are changed out from under them. Rider Linden: I’ve also fixed it so that the previous settings are stored in the simstate and restored if the override is reverted.

SL Viewer

The AssetHTTP project viewer, which shifts remaining asset types to delivery over HTTP via the Content Delivery Network(s) leveraged by the Lab, was updated to version 5.0.5.325825 on Thursday, April 27th. This is primarily a bug-fix release, aimed at reducing the high crash rate exhibited by the previous version.

Content Creation User Group Meeting

The following notes are taken from the Content Creation User Group meeting, held on  Thursday April 27th, 2017 at 1:00pm SLT at the the Hippotropolis Camp Fire Circle. The meeting is chaired by Vir Linden, and agenda notes, etc, are available on the Content Creation User Group wiki page.

The meeting was more of a general Q&A session, live streamed / recorded by Medhue Simoni, and that video is embedded at the end of this update, my thanks to him for providing it. Timestamps in the text below will take readers directly to the relevant point in the video (in a separate tab) where topics are discussed. Note that there was a lot of discussion via text, with topics overlapping. The notes here, together with the time stamps and audio extracts from my own recording refer to the key topics where Vir Linden provided input / feedback.

Attachments Using non-Hand Bones Following Hand Movements

[5:31] Medhue Simoni has been trying to work out a way to have attachments used by the hand (such as a gun, or nunchuk system, for example) rigged to non-hand bones in the skeleton correctly track with the hands. This would, for example allow someone perform a set of nunchuk exercises without the weapons massively separating from the hands, or allow a gun to be drawn, fired, twirled on a trigger finger, etc, and then be returned to the holster in a fluid, hand-following movement.

The problem here is that s non-hand bones which might be used for this aren’t actually connected to the hands, they have no way of knowing where the hand might be placed. However, Medhue believes that given time, he might be able to solve the problem.

“Layering” Meshes using Alpha Textures

[9:20] Some content creators have been taking advantage of placing two meshes in the same location and using an alpha texture as an overlay, thereby forcing one mesh to always be on top.  This can add a certain level of realism to objects such as plants without the need for additional textures / baking.

However, how meshes with alphas are “sorted” at present appears to be more a factor of how the rendering pipeline is working at present, rather than being an intentional feature, therefore using layered meshes and alphas in this way is not recommended, as it cannot be guaranteed that a future update to the rendering system won’t change the behaviour.

Advanced Lighting Model and Lower-End Systems

[20:38] A question was asked if Advanced Lighting Model (ALM) “be made to work on lower spec computers”, so that more people have the opportunity to see materials in use.

ALM has tended to be a controversial subject, as it is often blamed for causing significant performance hits. However, on medium-to-high end systems, this is perhaps a case of people confusing enabling ALM with enabling ALM together with enabling shadow rendering (which does cause a performance hit); enabling ALM by itself shouldn’t result in any significant hit.

Lower specification systems and older GPU systems, however, are different. Some are not capable of handling ALM, regardless as to whether shadows are disabled, and a performance hit is noticed simply by turning it on. This, coupled with a number of other factors, means that trying to adjust ALM so be of use to lower specification systems isn’t really something that the Lab could realistically engineer.

Note that the above discussion continues for a large part of the meeting, mostly in text chat.

JIRA Feature Acceptance & Action

[26:38] Feature requests submitted via the JIRA can go in one of several ways. If a request proposes something that the Lab believes cannot reasonably be done, or which cannot be done, or which offer what is thought to be a small return for the amount of investment in terms of effort, which tend to get rejected.

Where a request is accepted by the Lab and pulled into their internal JIRA, this doesn’t mean it will definitely result in it being implemented. Again, this doesn’t automatically mean the idea will be implemented; it simply means the Lab is considering the idea. Again, it comes down to matters of overall benefit, resource requirements and availability, etc., as to whether it is actually implemented.

Supplemental Animations and Animated Mesh

[41:32] Both are still under consideration at the Lab, but no news on actual projects being on the horizon. Concerns about performance with animated meshes has been raised internally where people to fill there region / space with lots of animated meshes (NPS, trees with branches swaying in the wind, animals, etc.).

Next Meeting

The next content Creation User Group meeting will be on Thursday, May 11th.