satellites is critical, but observers use more than just the V band. To allow forecasting models to accurately predict changes in satellite reflectivity as a function of time, operators should provide relevant metadata such as reflectivity and BRDF measurements in the optical to infrared (at least ~ 0.3–20 microns) range. This will better enable observers to assess the potential impact on their observations and/or detectors and take the appropriate action while observing or preparing to observe.
For radio astronomy, additional information is required from operators to allow for radio frequency interference analyses to be done. This includes EIRP, transmission bandpasses, and nominal flux density at different frequencies. Information about a satellite's beaming strategy would further help radio astronomers in planning observations to protect sensitive equipment. Radio astronomers also need to know satellite altitudes, as well as whether transmissions from LEOsats to ground stations are pointed “straight down” or if they are somehow inclined to advance or retard the transmission beam.
3.3. Improving and standardizing TLE and ephemerides formats
As discussed in Section 3.1, general perturbation orbital solutions (commonly in TLE format) need to be shared along with uncertainties. We propose adopting the Orbit Mean-Elements Message (OMM) format from CCSDS 502.0-B-2[1], as suggested by Celestrak, which contains the same information as a TLE but with an optional covariance matrix at the end of the file. Sharing general perturbation orbital solutions in this format, and requiring accompanying uncertainties, will accomplish the goal of adding error bars to general perturbation data.
In addition to general perturbation orbital solutions, which are time-averaged Keplerian elements, operator ephemeris files contain state vectors, which record satellite positions and velocities. However, at present, this information is shared publicly on a voluntary basis and there are different formats available. Presently, SpaceX provides Starlink orbital ephemerides to Space-Track, and it is freely available to everyone who creates an account at that website. However, while OneWeb provides orbital ephemerides to Space-Track, these are only accessible by the owner/operators, not by the public or astronomers. We seek to simplify the situation by requiring all operators to use the same format, such as the plain text NASA modified ITC ephemeris format, which is currently used by SpaceX in their publicly released ephemeris files. If everyone uses the same format, ephemeris software can ingest data from all operators and avoid having to write code to handle each operator separately.
3.4. A central web portal for sharing and retrieving orbital solutions
To improve community collaboration among myriad stakeholders, especially satellite operators, we propose the Orbital Solution Portal aspect of SatHub (see Figure 1) to simplify how orbital solution data are collected and shared.
- ↑ Orbit Data Messages Recommended Standard, Blue Book, November 2009.
