sirtf mission is still alive from the jpl universe april sirtf is still very much in business by mark whalen in these times of extra tight nasa budgets the very survival of a number of missions has been uncertain but thanks to major design refinements implemented in recent months jpl s space infrared telescope facility sirtf a major project considered to be in trouble a couple of years ago is alive and well according to project scientist michael werner a lighter spacecraft revised orbit and shorter mission have added up to a less expensive project with tremendous scientific power and a bright future said werner designed as a follow up to the highly successful infrared astronomical satellite iras and cosmic background explorer cobe missions sirtf a cryogenically cooled observatory for infrared astronomy from space is scheduled for launch in or if plans proceed as scheduled iras pioneering work in space based infrared astronomy years ago allowed astronomers to view the milky way as never before and revealed among other things galaxies and comets it provided a sky survey times more sensitive than any previously available from ground based observations cobe has measured the infrared and microwave background radiation on large angular scales and revealed new facts about the early universe but to illuminate sirtf s potential jim evans jpl s manager of astrophysics and fundamental physics pre projects recently said that the project is to million times more capable than iras based on technological advances in infrared detector arrays however despite the enormous strides in infrared exploration sirtf promised and the fact that it was cited as the highest priority new initiative for all of astronomy in the s by the national academy of sciences it took a diet or die directive from nasa headquarters last year to keep the project going according to werner the project is now known as atlas sirtf based on the key factor in its new design the satellite will orbit the sun instead of the earth permitting the use of an atlas rocket launch instead of the formerly proposed and heavier titan the main advantage of the solar orbit is that you can use all of your launch capability for boosting the payload you don t have to carry up a second rocket to circularize the orbit werner said the other advantage to a solar orbit he said is that it s in a better thermal environment away from the heat of the earth additional major changes in sirtf s redesign include shortening the mission from five to three years and building a spacecraft that is less than half as heavy as in the original plan atlas sirtf will weigh kilograms pounds compared to titan sirtf s kilograms pounds all of that adds up to a less stressful launch environment werner said and a cost savings of more than million for the launch in addition to increased savings in the design of the smaller less massive spacecraft werner said sirtf s redesign came as a result of congress telling nasa you re trying to do too many things if you want us to support sirtf which is a good project develop a plan to see how it fits into nasa s overall strategy shortly thereafter sirtf was named as nasa s highest priority flagship scientific mission by the interdisciplinary space sciences advisory committee in addition to the blessing from the national academy of sciences while the spacecraft and its instruments required descoping to keep the project alive sirtf s major scientific contribution always promised to come about from its advanced infrared detector arrays which will allow images to be developed tens of thousands of times faster than before according to evans up until a couple of years ago werner said all infrared astronomy was done with single detectors or very small arrays of individually assembled detectors since then the department of defense has developed a program to produce arrays of tens or hundreds of thousands of detectors rather than just a few and those are very well suited for use on sirtf werner noted that in addition to dealing with budget pressures congress is currently watching nasa projects with an eye out for any technological spinoff on that question i think we have some things to say he said because the detectors we re using are straight off various military developments also sirtf will be built by the u s aerospace industry and it s a real technological and engineering challenge in addition to being a tremendous scientific project sirtf will be used by the entire astronomical community werner added but the revised three year mission puts a premium on observing time we have to educate the user community and develop a program that involves early surveys and quick turnaround of the data werner said the downsizing of the project required a reduction in scope and complexity of sirtf s three instruments the infrared spectrograph infrared array camera and multiband imaging photometer however these reductions will only result in losses of efficiency rather than capability he said the project hopes to start a phase b activity in which will provide a detailed concept for development and design building the hardware would begin about two years later projected cost estimates evans said are million million i am very optimistic about sirtf he said it will provide a tremendous return for the investment werner added that an additional benefit from the project will be the enrichment of our intellectual and cultural environment people on the street are very interested in astronomy black holes the possibility of life on other planets the origin of the universe and those are the kind of questions sirtf will help answer ron baalke baalke kelvin jpl nasa gov jet propulsion lab m s telos the aweto from new zealand pasadena ca is part caterpillar and part vegetable
