Expanse privacy policy
Last updated: October 8, 2026
Publisher: Stratos Digital LLC
Contact: stratosdigitalllc@gmail.com
Application support: Contact Stratos Digital
This policy describes Expanse's iOS and Android apps, with separate notes below for desktop and web builds.
Overview
Expanse has no user accounts, advertising, analytics SDKs or tracking SDKs. Saved games and settings are stored on your device, subject to your operating system's backup settings. The app does not upload saved games to Stratos Digital LLC.
Some image features connect to external astronomy services. Selecting a relevant object or opening an image or telescope view can start a download automatically; there is not a separate permission prompt for every image. The receiving service sees connection information, including an IP address and a generic software identifier. These connections are different from app analytics, but they are not a guarantee that no information leaves your device.
Saved games, settings and image caches
The app stores saved games, settings, bookmarks and navigation history locally. Your operating system may include local game files in backups under your own account and settings. Stratos Digital LLC does not operate those backups.
On iOS, game files may be accessible through Files or computer file sharing. Desktop and Android builds also offer file export and import where supported. Copies you export or back up remain under your control.
Downloaded astronomy images are cached locally. On iOS and Android, these image caches use the operating system's cache location when available, separating re-downloadable images from intended game-file backup data. Desktop builds, and mobile builds when no OS cache location is available, keep these caches in the app's local user-data storage. Actual backup behavior depends on your operating system and settings. The telescope cache has a nominal limit of 512 MB on mobile and 1 GB on desktop; downloaded release pictures use a separate image cache. These are implementation limits, not a promise about your device's total storage use.
Desktop, Android and iOS builds can also keep telescope pictures for offline use (Telescope archive → Download for offline, or Menu → Settings). Only the packs you choose are downloaded, after their estimated size is shown, and they are stored in separate folders beside those caches that the size limits above do not trim; on iOS and Android those folders are also in the operating system's cache location when available, so the system may still clear them when storage runs low. "Remove downloads" in the same panel deletes them. The web build offers no such download.
The Android and iOS apps do not include the high-detail 3D model set (about 530 MB) in the install. The same panel offers it as a download, one file per model category, from the project's own content bucket over HTTPS (https://expanse-tiles.stratosdigitalllc.com, the bucket named in "Hubble, Webb, ESO and NOIRLab pictures" below, under hd/<app version>/). The request names the app version and the category, nothing else; the bucket's provider sees ordinary connection information such as the source IP address and software identifier. The files are stored with the offline packs above and removed the same way. Without them the app draws its standard models.
Removing the app can remove its local storage. It does not necessarily remove exported files, operating-system backups or records retained by external services. Manage those copies through the relevant device, backup or service controls.
Astronomy image requests
Telescope survey images
Telescope views request images over HTTPS from alasky.cds.unistra.fr, operated by CDS in Strasbourg, France. Requests specify the survey, sky coordinates, field of view, image dimensions and related image parameters. The desktop and mobile apps mostly fetch the surveys' static HiPS tile files from the same host (a survey name, a tile order and a tile number) and draw the views on the device. Sky coordinates identify an astronomical target, not your device's geographic location.
Selecting a galaxy on the map that the app has no bundled picture of requests one small survey image of it from the same host (the same kinds of requests: tiles on desktop and mobile, one hips2fits image on the web), kept in the app's cache.
The Observatory's sky requests its survey tiles from the same host (and one from skies.esac.esa.int for Webb's MIRI images). Zooming in on the Observatory's sky also requests star-catalogue tiles (Gaia DR3) from hipscat.cds.unistra.fr, also operated by CDS: each request names a tile order and number (a patch of sky), nothing else; the desktop and mobile apps keep the tiles on the device. "Download for offline" sends the same kinds of requests to the same hosts, many at once while it runs (up to about six at a time, until the chosen packs are complete or you pause it): the views of the telescopes' famous targets, their full-resolution tiles, and Planck's whole-sky tiles.
The receiving infrastructure also sees ordinary connection information, such as the source IP address and the engine's software identifier. The app does not add your name, saved game, account identifier or device GPS location to these requests.
Service information: CDS legal information.
Hubble, Webb, ESO and NOIRLab pictures
Selecting an object with an ESA/Hubble, ESA/Webb, ESO or NOIRLab picture, opening that picture, or using a related telescope view can request higher-resolution images from cdn.esahubble.org, cdn.esawebb.org, cdn.eso.org or storage.noirlab.edu over HTTPS (ESO's and NOIRLab's from the desktop and phone apps only: the web version doesn't carry those pictures). The desktop and phone apps carry each picture's 1280-px copy inside the app, so they ask only for the full-size picture (when one is opened full screen or the eyepiece zooms in); the web version also fetches the 1280-px copy when an object is selected. The request identifies the public picture and resolution. "Download for offline" requests every release picture's full-size copy in one go when you choose that pack (the web version has no offline downloads). The receiving infrastructure sees ordinary connection information such as the source IP address and software identifier; the app does not add saved games or personal profile information.
Chandra's own releases work the same way from chandra.harvard.edu (the picture's ~900-px or full-size JPEG, in Chandra's eyepiece or the Target panel). NASA's own Hubble and Webb releases (the Space Telescope Media Assets of science.nasa.gov, hosted by STScI) work the same way: selecting an object with one of those pictures, opening it or using a related telescope view requests its 1280-px or full-size copy from assets.science.nasa.gov over HTTPS (desktop and phone apps only; the web version doesn't carry those pictures), identifying only the public picture and size. The app never contacts science.nasa.gov itself: the pictures' pages are linked in the credits for you to open.
Provider information: ESA/Hubble, ESA/Webb, ESO, NOIRLab and NASA Science (NASA's Media Usage Guidelines).
Zooming the Observatory's sky or a telescope view in past a release picture's full-size copy (desktop and phone apps) can request tiles of that picture's original from the project's own picture-tile bucket over HTTPS (https://expanse-tiles.stratosdigitalllc.com, set in PressPhotos.TILES_BASE: a Cloudflare R2 bucket on the project's own domain). The request names the picture and a tile number, nothing else; the bucket's provider (an S3-compatible store such as Cloudflare R2) sees ordinary connection information such as the source IP address and software identifier.
Opening an amateur astronomer's picture (an object's Target panel, the Backyard telescope's eyepiece, the full-screen viewer) requests its 1280-px or 4000-px copy from upload.wikimedia.org over HTTPS, operated by the Wikimedia Foundation. The request identifies the public picture and size; the receiving infrastructure sees ordinary connection information such as the source IP address and software identifier. Provider information: Wikimedia Commons.
Opening a picture taken at a landing site full screen (a real landing site's Target panel: Apollo, Viking, Curiosity, Perseverance, Huygens; desktop and phone apps only) requests its original from images-assets.nasa.gov over HTTPS, operated by NASA. The request identifies the public picture; the receiving infrastructure sees ordinary connection information such as the source IP address and software identifier. The smaller copies are inside the app (or, on the web, fetched from the same site as the game). Provider information: NASA Image and Video Library.
The site viewer's "Today on Mars ▸" only connects when the player presses it, at Curiosity's or Perseverance's site. It asks mars.nasa.gov over HTTPS, operated by NASA/JPL, for the rover's newest raw pictures: /rss/api/?feed=raw_images or /api/v1/raw_image_items/. On desktop and phone apps it also asks for the rover's current position (/mmgis-maps/…/…_waypoints_current.json) and downloads the pictures shown (/mars2020-raw-images/…, /msl-raw-images/…). On the web it reads only the list. "At NASA ▸" opens the picture's page on NASA's site in the browser. The requests name public data and nothing about the player. The receiving infrastructure sees ordinary connection information such as the source IP address and software identifier. Provider information: NASA Mars raw images.
Today's Sun and space weather
Zooming the Observatory's sky in on the Sun, or selecting the Sun there, asks for today's picture of it and the current space weather. The desktop and phone apps request the time of the latest Solar Dynamics Observatory image and then a rendered picture of it from api.helioviewer.org (the Helioviewer Project, operated for NASA and ESA); the request names the SDO channel, the image time and the picture's size. The web version doesn't request these pictures (Helioviewer serves its own site only). Every version requests five small public JSON files from services.swpc.noaa.gov (NOAA's Space Weather Prediction Center): the latest X-ray flare, the NOAA scales, the planetary K index and the solar wind's speed and magnetic field. These are requested again at most every 15 minutes (pictures) and 5 minutes (weather) while the Sun is zoomed in or selected, kept in memory only and never saved. The receiving infrastructure sees ordinary connection information such as the source IP address and software identifier; the app adds nothing else. Provider information: Helioviewer, NOAA SWPC.
External-service handling
External service and hosting operators may retain request or security logs under their own practices. We have not independently established every service or CDN's retention period or use of those logs. This policy does not promise that their processing is limited to the instant an image is delivered, that remote logs disappear when you uninstall Expanse, or that public images imply an absence of logging.
The app's core simulation and built-in images can be used without these downloads. Online views and higher-resolution images may be unavailable without a connection or when a provider is unavailable.
Features not used by the mobile app
Expanse does not include an account system, advertising identifiers, in-app purchases, an integrated analytics or crash-reporting service, or access to your contacts, camera, microphone or device location. It does not provide human-to-human messaging or a public user-content feed. Messages and conversations in the game are part of its fiction.
These statements describe the app's integrations. They do not describe every service your operating system, app store, network provider or an external image host may operate independently.
Desktop and web builds
The web build requests additional game files from the website serving it, including catalogues, images, music, selected model resources and the illustrative surface maps of other stars' planets and moons (fetched when a star system that uses them is opened). The website and its hosting infrastructure receive ordinary web request information. Native builds bundle these resources instead of using the web build's ordinary same-origin download path (the phone apps' optional high-detail model download is described above).
Some desktop builds support an optional, user-configured external language-model service for fictional dialogue. If you enable it with your own provider credentials, generated game context and dialogue are sent to that provider under its terms. This feature is disabled in the iOS, Android and web builds. Expanse does not require you to configure it.
Audience and content
Expanse includes fictional conflict and mature science-fiction story themes alongside its astronomical material. Its scientific subject matter should not be treated as an all-ages content classification. Consult the applicable distribution platform for its published content rating. The app does not ask for your date of birth or create age-based accounts.
Contact and changes
For privacy questions or application support, email stratosdigitalllc@gmail.com. If you contact us, we receive the information you choose to send through email. Do not send passwords, private signing keys or other credentials. Share only the details needed to explain your question; screenshots or logs can contain personal information.
We will update this policy when the app's relevant data practices change. The date above identifies this policy revision; it is not a statement that a store release or privacy questionnaire has been approved.