This discussion exposes the fact that we don't all have to work in the same reference frame or time system - as long as we understand what we are using and make it clear to users. Orbit data transfer standards developed by CCSDS and others require sufficient metadata that users can reproduce your results with the same outcome and transform your data into the time system and reference frame they wish to use. Metadata also includes characteristics of the geopotential model. There is no point in propagating to high order and degree initial information that was created at low order or degree, for example. Unfortunately, some operators don't know what is inside the black box. We accommodate this by requiring the fields but not the real content. If geopotential info fields are filled with default characters, we know that this idiot doesn't even know what he did and discount his input. Lying is another story. However, there are institutional sanctions for providing false information. Like, you get cut off from everyone else's data.
These lessons came hard. For example, lack of gravitational metadata led to low perigee events in Superbird 6, a Comsat. The launch provider included lunar gravitation and the on-orbit operator did not. The handover state provided by the launch agency did not lead to the desired final orbit for the operator. With regard to what is significant and what is not. If someone raised the issue, then it must be significant to him. If the others don't care or it doesn't matter to them, it won't matter if they have the additional information or greater precision. I've said this before, "We don't create standards for people who don't need them. We create standards for those who do need them." The "don't cares" usually don't get a vote. GRACE mission data is available in near real time for those who worry about Earth tides and millimeters of ocean height! (The units are cm/sec^2, which are now called Gals -- for Galileo.) Dave Finkleman Senior Scientist Center for Space Standards and Innovation Analytical Graphics, Inc. 7150 Campus Drive Colorado Springs, CO 80920 Phone: 719-510-8282 or 719-321-4780 Fax: 719-573-9079 Discover CSSI data downloads, technical webinars, publications, and outreach events at www.CenterForSpace.com. _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
