Most people reading this story will probably know that a SpaceX Falcon 9 rocket with a NASA spacecraft was launched into orbit on Wednesday – the Transit Exoplanet Survey Satellite – to fuel the space agency's search for exoplanets ,
Less well known is the smart orbit of the TESS spacecraft, which enables a cost-effective yet robust scientific mission to search for planets that cross from nearby stars. This "moon-resonant" orbit, which has never been used by a spaceship, will allow TESS to observe nearby stars and transmit data back to Earth with minimal energy. (The useful life of a spacecraft is often determined by the amount of fuel on board.)
Moon Resonance Railway
Scientific missions often require uninterrupted and unobstructed views of their targets, and TESS is no different as it monitors 200,000 relatively close Stars for tiny changes in their brightness. NASA's previous planet hunter, who was looking for similar transits, the Kepler mission, observed his targets from a heliocentric orbit in the Earth, about 10 million kilometers from our planet. Such a train has high energy costs to reach them, stationing and data restrictions.
will bring it within 108,000 km of the Earth's surface (or about three times the height of the geostationary orbit) and up to 373,000 km from the Earth, which is just inside the Moon's orbit. During a three hour period of closest approach, TESS will aim to send robust data to the planet (full screen images) while spending the rest of its time during the 13.7-day orbital observation of stars.  Science in 60 Days
After this week's launch, TESS will take a few weeks to reach this stable orbit as the spacecraft carries out half a dozen bow thrusters and uses gravity support from the moon to reach its desired orbit , After that, it will go through about two months of check-outs before it starts its scientific operation.
The TESS spacecraft, costing $ 200 million, costs about one-third the cost of the Kepler spacecraft, which has a primary mirror diameter of 0.95 meters. The TESS apertures are much smaller: 10 cm for four identical cameras. Its advantage is that while Kepler observes a small area of the sky, TESS will see much more, about 85 percent overall.
Because of its small cameras, the telescope will most likely find nearby stars (and accordingly, exoplanets), probably those within 30 and 300 light-years and, according to NASA, 30 to 100 times brighter than Kepler's targets. If successful (and because of its stable orbit), TESS could well exceed its design life of two years.
Listing image by Trevor Mahlmann