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posted by chromas on Wednesday April 18 2018, @09:22PM   Printer-friendly
from the guarding-tess dept.

Update: SpaceX: All systems and weather are go for Falcon 9's launch of @NASA_TESS today at 6:51 p.m. EDT, or 22:51 UTC.

Update 2: SpaceX's live coverage starts at 6:36 PM EDT (22:36 UTC).

Update 3: TESS successfully separated from Falcon 9 and was deployed into a highly elliptical orbit.

NASA's Transiting Exoplanet Survey Satellite (TESS) mission is set to launch on April 16 at 6:32 PM ET (22:32 UTC) aboard a Falcon 9 rocket from SLC-40, Cape Canaveral Air Force Station, Florida. The spacecraft was developed by MIT with seed funding in Google back in 2008. The spacecraft will perform an all-sky survey using four 24° × 24° wide field-of-view cameras that can image a total of 24° × 96° (2,304 square degrees) of sky every 30 minutes (the Sun and Moon are only about 0.2 deg2 to Earth-based observers).

TESS will use a unique "P/2" 2:1 lunar resonant orbit to image stars in both the Northern and Southern hemispheres. The survey will image 26 observation sectors of 24° × 96° each, with some overlap at the ecliptic poles. The total survey area will be about 400 times larger than the area searched by the Kepler mission.

TESS will study about 500,000 stars, including the nearest 1,000 red dwarfs, with the goal of finding at least 3,000 new transiting exoplanet candidates. The spacecraft will study F, G, K and M type stars (spanning from F5 to M5), some of which are 30-100 times brighter than stars surveyed by the Kepler spacecraft. Many of the stars will be much closer to Earth than stars surveyed by Kepler, allowing for easier confirmation and follow-up measurements of exoplanets. 30-minute full-frame exposures will be used to search for transient events such as supernovae, star flares, and gamma-ray bursts.

Each observation sector will only be viewed for 27 days (at least in the initial phase of the mission), which will limit the exoplanets seen to those with shorter orbital periods. Potentially habitable exoplanet candidates will likely be found around red dwarfs rather than Sun-like stars. However, TESS's own orbit should remain stable for decades, which could mean that its mission will be extended to allow for a greater variety of exoplanets to be found.

NASA's Kepler spacecraft is running out of fuel and may not be operational beyond 2018, leaving TESS to be Earth's premier exoplanet hunter in space. The European Space Agency's (ESA) CHaracterising ExOPlanets Satellite (CHEOPS) will launch in late 2018. It will provide precise radii for exoplanets with known masses, and can follow-up on TESS observations to provide suitable targets for the James Webb Space Telescope. In 2026, ESA will launch the PLAnetary Transits and Oscillations of stars (PLATO) space observatory, which will search for planetary transits around 300,000 to 1 million stars. PLATO will study bright stars of magnitudes between 4 and 11, and will be rotated by 90 degrees every 3 months, allowing it to continuously survey a patch of sky and discover exoplanets with longer orbital periods than TESS will.

There is no direct link available yet, but live footage of the launch should be available through SpaceX's YouTube channel.

Also at NYT, The Verge, MIT News, and EarthSky.

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  • (Score: 2) by Runaway1956 on Friday April 13 2018, @01:46AM (4 children)

    by Runaway1956 (2926) Subscriber Badge on Friday April 13 2018, @01:46AM (#666292) Journal

    TESS's own orbit should remain stable for decades

    As I was reading, I wondered why the mission was so limited. Apparently, those goals listed are merely initial goals. If the satellite is even worth launching, it should be capable of much, much more than those initial goals. We'll see how much value it has, as time passes.

    ‘Never trust a man whose uncle was eaten by cannibals’
    • (Score: 5, Interesting) by takyon on Friday April 13 2018, @02:46AM (2 children)

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Friday April 13 2018, @02:46AM (#666310) Journal

      They start out with a 2 year mission duration. A little less than a month looking at each of the 26 observation sectors. That will allow them to find many of the planets that orbit very close to their stars. These might not be the most interesting targets because they are generally scorched worlds, or possibly irradiated/flared worlds in the case of red dwarf stars. But it would be valuable to get a sense of how a star system's planets are typically configured. It seems that Jupiter or something else pulled back the inner planets, allowing Earth (and Venus and Mars) to get into our Sun's habitable zone. Some star systems have multiple planets orbiting within the orbit of Mercury (~0.4 AU).

      This satellite seems worth it just for the 2 year mission alone. It looks like it cost $75 million to build, and $87 million for the SpaceX launch contract. We should be launching missions like this annually. When BFR starts launching, massive payloads could be sent for even less. IIRC, TESS was designed to use a smaller launch vehicle but got switched to Falcon 9, and barely takes up any of the Falcon 9's payload capacity (TESS is 350 kg).

      After the first 2 years, they should be able to focus on sections of sky for longer than 27 days. Boost it to 3-6 months and we may see some more "relevant" exoplanets.

      TESS is estimated to discover 3,000 exoplanet candidates, 500 of which will be Earth/Super-Earth sized, and 20 of those in a habitable zone (probably around a red dwarf). Those estimates are presumably for the 2 year initial mission, and given the huge amount of stars it will be looking at, they could be conservative estimates. Either way, it will be an exciting mission.

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      • (Score: 0) by Anonymous Coward on Friday April 20 2018, @04:35PM (1 child)

        by Anonymous Coward on Friday April 20 2018, @04:35PM (#669697)

        While the 2 year initial mission is the first goal, the orbit is designed to be stable for 15 years [], with essentially no propellant use during that time.

        --Some guy on the interwebs

        • (Score: 2) by takyon on Friday April 20 2018, @04:55PM

          by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Friday April 20 2018, @04:55PM (#669710) Journal

          I know that the orbit will remain stable long after 2 years. Your source actually says "expected to be stable for at least 20 years", and I heard "decades" elsewhere. It's just that a lot could get done in just those first 2 years alone. Hopefully, by the time TESS experiences issues, we will be capable enough to cheaply send a robot to fix it.

          It seems like the observation sectors were chosen to avoid the area already covered by Kepler. I think that for the extended mission(s), they should do the same thing they are doing for the first 2 years, but rotate the spacecraft to point the "poles" so that a different region of sky gets the 108-351 days of continuous viewing. For example, they could rotate it by 45-90 degrees on the y-axis (see illustration []).

          This story is the first I've heard of the "JWST continuous viewing zone" though. If JWST is pointing at that region often or continuously, they may choose to do a repeat of the first campaign in order to get great coverage of that region. They could find exoplanets orbiting further than 1 AU from their star, increasing the haul of potentially habitable Earth-like exoplanets not orbiting a red dwarf.

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    • (Score: 5, Informative) by takyon on Friday April 13 2018, @01:00PM

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Friday April 13 2018, @01:00PM (#666441) Journal

      The overlap at the poles might be enough to find exoplanets with longer orbital periods: []

      Because of those tight observing windows, the spacecraft won’t be able to pick up planets with longer Earth-sized orbits, as Kepler could. But since the 13 observation strips in each hemisphere overlap at the poles, TESS will have eyes on both the northern and southern polar skies for nearly a year at a time. In a few years — if TESS’s two-year mission is extended long enough — it could eventually find the kinds of rocky, habitable-zone planets that Kepler could.

      You can get a sense of how that looks from this image: [] [] (alt)

      So there is a not insubstantial region that will get 351 days of coverage during the ~2 year campaign. A ring getting 189 days. Small bits getting 108 days, and larger portions getting 54 and 81 days.

      I assume you'd want to see at least 2 transits to get an exoplanet candidate, 3 preferred. So TESS could find some exoplanets with 100-150 day orbital periods, which could be in the habitable zone of stars that are dimmer than the Sun but much brighter than red dwarfs.

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  • (Score: 2) by takyon on Thursday April 19 2018, @11:44AM

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday April 19 2018, @11:44AM (#669015) Journal []

    SpaceX and NASA officials said the Falcon 9 rocket achieved an on-target orbit before deploying TESS less than 50 minutes after liftoff, while the spacecraft soared over the Indian Ocean west of Australia.

    A few minutes later, engineers confirmed TESS extended its power-generating solar panels to a span of 12.8 feet (3.9 meters) tip-to-tip. The satellite started charging its batteries as designed, while ground controllers at Orbital ATK, which built the TESS spacecraft, ran it through a post-launch health check.

    Officials said TESS was performing as expected late Wednesday evening.

    [...] After a five-day checkout of the spacecraft, ground controllers will kick off procedures to switch on TESS’s cameras, with “first light” from the observatory expected next week.

    [...] The compact spacecraft’s on-board propulsion system will raise TESS’s orbit in the coming weeks to set up for a flyby of the moon May 17.

    [...] The collection of science data is scheduled to begin in July, with the first year of TESS’s two-year campaign aimed at stars in the southern sky. In 2019, TESS will start looking at stars in the northern sky.

    If they look at each month's batch of data as it comes in, maybe we'll have the first exoplanet candidates by September or so.

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