A Gremlin crept into Bill Wheaton’s excellent SIRTF article in the October issue of Canopus. About 3 paragraphs of data went missing from within the sentence that began: "the current baseline is for a …" This has been corrected on the web-site but we are publishing the missing data here for your records.

The current baseline is for a <1000kg spacecraft with just 360l of LHe (less than needed for IRAS, the first IR astronomy satellite in 1982), to be launched on a Delta for a total cost of $450 million.

One key efficiency has been to move from Earth orbit to an orbit around the Sun. The spacecraft will be launched on a slow escape trajectory that will drift away from Earth at about 0.1 AU (15 000 000 km) per year. The removal of the Earth and Moon as heat sources, which need to be excluded from the telescope field of view, resulted in an enormous simplification in the thermal design, and in operational complexity.

It now appears that the original goal of a 5 year LHe lifetime can be nearly met.

Sorry Bill – we’ll try to be more observant and careful in the future.