7

You're right; these objects aren't lost. However, Space-Track doesn't actually track a lot of higher-orbiting objects. They just don't seem particularly interested in anything with a multi-day orbit; I don't know why. Of the four objects you mention, TESS and IBEX are tracked by the people operating those missions. I know of no public data for IBEX, ...


5

On May 30 there had been a meeting concerning the status of Spektr-R. Afterwards Roscosmos published a statement at https://www.roscosmos.ru/26397/ Here a machine translated version using www.DeepL.com (if any Russian speaker is around and would like to provide a real translation, I'll be happy delete this answer): Spectrum R: Mission accomplished, data ...


4

I found a 2008 citation of space-based VLBI 'by using a radio antenna in earth orbit. This has indeed been accomplished with the Japanese satellite "HALCA" (Highly Advanced Laboratory for Communications and Astronomy, Hirabayashi et al. 2000)'. There were two papers cited for this instance: SUB-MILLIARCSECOND IMAGING OF QUASARS AND ACTIVE GALACTIC NUCLEI by ...


3

KRT-10 radiotelescope in July 1978 The world's first VLBI-experiment was conducted with a KRT-10 space-based radiotelescope and a RT-70 radiotelescope in Evpatoria, Crimea. https://ru.wikipedia.org/wiki/КРТ-10 (in Russian) See also Space VLBI The first space VLBI experiment was on Salyut-6 orbital station with KRT-10 (ru:КРТ-10), a 10-meter radio ...


2

JAXA had a radio telescope mission named HALCA: HALCA was launched by M-V-1 on February 12, 1997. As a radio astronomy satellite, it conducted various engineering experiments including deployment of large antenna and VLBI interference experiments before successfully making VLBI observation. It is now a mainstay of the VSOP program, a large-scale ...


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