SOS is a collection of hardware that integrates computers and video projectors
to display animated images onto the surface of a large sphere. Taken in pieces,
the system consists of a sphere situated in a room, surrounded by four video
projectors, numbered one to four starting with number one closest to the
computer and then going counterclockwise.
The video projectors are connected and driven by the primary computer. Each
projector is responsible for its own quadrant of the sphere. The computer has
one six output graphics card to support the four projectors and a second
graphics card to run the user interface. The computer pulls in content, usually
some type of planetary imagery, renders it to an Earth projection, subsets it,
and upon command displays it onto the sphere. The computer is responsible for
many things, namely among them: running the main user interface to the system,
real time data collection, and providing the interface to the automation
control protocol. All of the computers use the Linux operating system Ubuntu
(currently version 16.04). Most sites buy a “hot” spare that is identical to
the primary computer in terms of hardware, as a backup system. All of the
software that drives and controls the SOS system is written and maintained by
The computer in the SOS system is a standard computer system with mid- to
high-end graphics cards.The system is generally specified so that both the
primary and spare computers are identical from a hardware perspective to allow
easy swapping of components (in case of system failures).
Projectors are usually specified so that they work well in high duty hour
environments. Mostly, projectors classified as “board room” projectors meet
this requirement. These projectors typically have multiple fans to provide
adequate cooling during the day. The projectors are also specified so that they
produce a high light output (lumens), mostly in the range of 3500 to 5000
lumens. The supported resolution for the projectors should be at least
1024x768, though higher resolutions are recommended.
An audio system is part of a standard SOS exhibit. A typical setup includes a
mixer, microphones, and four speakers. Some of the content that comes with
Science On a Sphere® includes a narration track with background music,
requiring the use of the audio system. Also, presenters often use the
microphones, if available, during large presentations. Each site is responsible
for designing their audio system to meet their needs.
Each site is configured differently in regards to projector height, distance
and resolution. All of this information is stored in
/home/sos/sos_stream_control.config if you’re using a SOS version 5.4 and
below, or held in /shared/sos/site-config/local_sos_config.json if you’re on
version 5.5 or above. The parameters in this file are set during installation
and normally should only be changed if the exhibit is reconfigured. Details on
what is in this file and a few options you can modify are discussed in
Appendix A: SOS Stream Control Configuration File.
Every site also has individual alignment files that are stored in
/shared/sos/site-config. In this directory you will find the alignment files.
All of these files are included in those that are backed up and synced daily.
Cron is a time-based job scheduler that is used to automate processes on the
computer. The crontab is the file that contains all the information about the
jobs that are scheduled. The SOS computers come with a default crontab that can
be edited by each site. Included in the default crontab are hourly real-time
data downloads, daily data syncs and backups, and weekly downloads of new
datasets. The crontab can also be configured to include the automatic power up
and down of the projectors if desired. In a terminal, entering crontab –l will
display everything that is included in the cron. For more information about the
cron, watch the “How to Edit the Crontab” video tutorials in our tutorials.
The computers are connected via a gigabit network to enable high speed
communication and data transport.The primary and spare computers reside in a
private, non-routable network space (usually in the 10.x.x.x network range).
The primary computer, however, also usually sits on the border between the
private SOS network and the sites local Intranet. The primary computer sits at
the border of the network to enable outside access for remote systems
administration, software updates,and download of real time data from the NOAA
servers. While the local, private SOS network is gigabit, the external
connection can be whatever the local site supports in their network
infrastructure. If supported by the projector infrastructure, the projectors
can also be connected to the private network to allow for remote power on/off.
In many cases a Wi-Fi network is also set up to allow use of the iPad SOS
Remote App. An existing Wi-Fi infrastructure can be used, or a dedicated Wi-Fi
network can be set up for use with SOS. A dedicated Wi-Fi network provides the
most responsive control of your SOS system by the app. Doing this in a secure
way requires some network expertise. You may need to select a Wi-Fi channel
that doesn’t conflict with other Wi-Fi networks, for example. Using the minimum
transmitter power that you need is always a good idea. And WPA2 encryption is
probably the minimum level of encryption you will want to use. You might want
to turn off the beacon identifier for your Wi-Fi router to make it less obvious
to casual visitors at your site. You might also consider limiting access to the
specific MAC addresses of your portable devices. SOS personnel work with the
site staff to determine the best options for each individual site.
Administrators of Linux sometimes need access to the super user account
(similar to the Windows “administrator” privileges). The super user account in
Linux is called “root”. The password is set at machine installation and can be
changed locally at the site. It is generally considered safer, or at least a
better practice, to not use root directly, but rather use the sudo command that
temporarily raises a normal users privilege to root for the duration of a
single command. Only the sos user has sudo privileges.
sos is an administrative account that has the ability to download new data,
run the alignment software, install updates and manage the real-time data
sosdemo is used for day-to-day system operation and running the SOS
software. The user sosdemo does not have permission to delete data,
edit the software or run alignment. This user is intended to serve as a
“safe” mode, where the computer operator will be able to do very little
damage to the software or the data
Every process that runs under Linux must have a user id. The SOS system uses
two user ids: sos and sosdemo.
The computers are set to run backup scripts early every morning to push data
from the primary computer to the spare computer. In general, all of the data
that comes with the system can be retrieved from NOAA, however, there are some
data files that are customized to be site specific. Examples of site specific
data include the custom playlist data in the SOS home directory, the alignment
configuration files that are in the home directory, and any custom or local
site content that was developed and installed on the system.
All of the media files and playlist files are synced from the primary to the
spare computer so that there is a backup copy on the spare computer. Backup
copies of the playlist and alignment files are stored on the spare computer in
/shared/sos/site-backup.hostname. In case of failure, the spare computer has a
duplicate copy of everything needed, though the alignment files will have to be
moved from the backup folder to /shared/sos/site-config. Sites are still
encouraged to backup data on a separate system as well. Generally, the playlist
and alignment data are just a few megabytes (usually much less). In terms of
content, only the content developed by the site needs to be backed up on a
separate system. All of the content that comes preloaded on the system is
always available from NOAA. The custom content can sometimes be many gigabytes,
but is definitely worth backing up.
In addition to syncing the computers, backups are also stored on the local
computer in /shared/sos/site-backup.hostname. In this directory, you will find
dated files for every day that contain all of the same files that are synced to
the other computer (excluding the media tree), including configuration files
and playlists. In addition, backups of the playlist files are tarred and stored
every time the playlist editor is opened. Those files are in the home folder
for each users in a directory called sosrc-backups: /home/sos/sosrc-backups and
We have increased our software security measures starting in SOS version 5.3.
SOS now requires a new licensed Wibu CodeMeter security USB dongle before you
can do the software upgrade. You can request one using an online SOS Version
5.3.0 Upgrade Request form. Once SOS
Support has received your request, a dongle will be mailed to your site. If you
run into any problems using the request form you can
firstname.lastname@example.org. We will provide instructions on how to
upgrade your system to 5.3 once we have mailed out your new CodeMeter device.
Note that unlike the previous Bluetooth USB devices used in earlier versions of
SOS, you will have only one CodeMeter dongle that will be required to be
plugged into the computer that is running SOS. This means if you switch to
using your backup system, you will also need to physically move the CodeMeter
dongle to that machine before you can run SOS. Also, if your site is using
Bluetooth to connect your iPad to SOS, you will still need to keep the current
dongle keys in place as the Bluetooth software depends on them.