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Thread: Active Interplanetary Missions

  1. #16
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    Venus Express is down to about 132 km pericentric distance from Venus btw, slamming through the atmosphere at Mach 30 on every pass. One concern currently is that during the passes, the solar panels of the satellite heat up significantly; Venus Express therefore cools the panels during each orbit before entering atmosphere by pointing them away from the sun. The other is that the upper atmosphere of Venus is pretty unpredictable, with atmospheric drag varying by up two 30% between two passes. So far, atmospheric drag has lowered orbit time by 20 minutes.

  2. #17
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    Venus Express will do a final dip down to 129.1 km pericentric distance today. Earlier this week it went down to 130.2 km during its 3000th orbit of Venus. Recorded atmospheric density at 130 km was 1000 times as dense as at 165 km, and similar to that at equivalent altitude in the lower Thermosphere within a few dozen km above the Mesopause over Earth.

    Afterwards, starting with the next orbit today, it will attempt to reraise its altitude to 460 km in a series of 15 thruster burns between today and July 26th. ESA is not yet sure whether fuel reserves are enough to complete all 15 burns. If the probe achieves its 460 km planned pericentric distance it will then be allowed to naturally decline back to the atmosphere, in which it will burn up in December 2014.

  3. #18
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    Planned Japanese missions, "below Jupiter" and "in the neighborhood". Seriously though, finding anything on JAXA missions is like pulling teeth.


    Hayabusa 2

    - JAXA
    - asteroid sample return mission
    - planned approach to asteroid (162173) 1999 JU 3; 1.5 years survey operations, then return to Earth
    - like Hayabusa, will land on asteroid and retrieve sample for return to Earth
    - technology for the probe itself mostly identical to Hayabusa-1 with improvements primarily to landing system (which failed in Hayabusa-1)
    - mass: ~600 kg wet
    - planned launch Dec 5th 2014, arrival planned 2018, return planned 2020/21

    Hayabusa 2 will carry six detaching subsystems, four of which will land on the asteroid (separately from Hayabusa-2's landing):

    - MASCOT
    - MINERVA II-1A
    - MINERVA II-1B
    - MINERVA II-2
    - SCI
    - DCAM3

    Mascot is German-/French-designed. At 10 kg the heaviest of the detachable systems. 30x30x20 cm box-shaped drone for geological survey using four instruments. Will operate for 16 hours, hopping by itself over distances of up to 200m per jump to at least three separate sites on the surface. The four instruments used are CIVA/MI, ROMAP, ROLIS and MUPUS-TM all carried over from Philae (which with its larger size carries six more instruments).

    Minerva II is the followon to the singular Minerva I drone carried and unsuccessfully deployed by the first Hayabusa mission. Hayabusa-2 will carry three of these instead of one. The drones are supposed to be rather similar to Minerva I, which was a 5-inch diameter, 4-inch length can of 600g weight that could move using a flywheel and as primary sensor carried a camera for cartography. Unlike the other detachable systems, Minerva is powered by solar power and hence capable of longer operations.

    SCI is, for lack of a better word, a heavy anti-tank mine by operation (not propelled). It will fire a shaped charge of 6.5 kg explosives to send a 2.5 kg explosively-formed penetrator at the asteroid from a distance of about 100 meters in order to artificially create a crater. SCI by itself is free-flying being released by Hayabusa-2 from 500 m above the surface, after which Hayabusa-2 rapidly moves to its "home position" about 20 km away before sending the firing signal.

    DCAM3 is a detachable free-flying camera (not propelled) that will observe while Hayabusa-2 deploys SCI. The drone is basically a small coffee-cup-sized can 6cm long and 6cm in diameter weighing 500g. DCAM has been used with the IKAROS mission, with DCAM1 and DCAM2 used to observe the proper unfolding of that probe's solar sail. DCAM3 will additionally carry a high-resolution camera. It will operate for several hours to observe ejecta thrown up by SCI.

    Procyon

    - JAXA
    - asteroid flyby mission
    - planned to visit three NEO asteroids, will take photos
    - mostly testing micronized space probe equipment - demonstrating a 50 kg deep space probe bus
    - mass: ~60 kg
    - planned launch Dec 5th 2014 (with Hayabusa-2)

    Shin'en 2

    - Kagoshima University
    - interplanetary amateur radio transponder/beacon
    - will assume a heliocentric elliptic orbit with a perihelion of 0.7 AU (near Venus) and aphelion of 1.3 AU (halfway between Earth and Mars)
    - mass: 2.85 kg (!)
    - planned launch Dec 5th 2014 (with Hayabusa-2)

    DESPATCH/ARTSAT-2

    - Tama Art University
    - art satellite, fully 3D-printed.
    - 7 days of operations as a amateur radio beacon from a position about 3 million km / 0.02 AU from Earth.
    - mass: ~30 kg
    - planned launch Dec 5th 2014 (with Hayabusa-2)
    Last edited by kato; 20 Jul 14, at 16:31.

  4. #19
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    Quote Originally Posted by kato View Post
    Afterwards, starting with the next orbit today, it will attempt to reraise its altitude to 460 km in a series of 15 thruster burns between today and July 26th.
    As of last friday, Venus Express completed eight out of those fifteen burns, and has raised its orbit to about 300 km pericentric distance; VEX runs one burn on every orbit of Venus. Tests of the spacecraft have so far shown no degradation of system performance due to the aerobraking campaign, and current estimates based on flight dynamics say there will even be fuel left-over after the rising campaign is completed.

    Venus Express passed the 3,000-orbit mark during the aerobraking campaign, and if successful in the rising will likely exceed 1,000 earth days in Venus orbit; it should exceed 4 Venusian siderial days by December this year. The original requirements called for two Venusian sideral days (486 earth days) and 500 orbits.

    If we're lucky, the next orbiter to visit Venus will be Akatsuki, which will reattempt orbital insertion when it flies by Venus again in November 2015. Akatsuki was originally planned to work together with Venus Express, but missed its orbital insertion and has since been orbiting the sun. The second insertion assempt will be more complicated since JAXA, to lighten the aircraft, vented the oxidizer for the orbital thrust engine a while ago and relies entirely on Akatsuki's monopropellant RCS thrusters now. There's an alternative insertion possibility for the flyby after that one, in June 2016.
    Last edited by kato; 20 Jul 14, at 20:29.

  5. #20
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    Currently still active, Below Earth section:

    IKAROS

    - on permanent heliocentric orbit at ca 0.6 AU from the sun after successful Venus flyby
    - hibernates 7 months out of every 10-month sun orbit; last active period was mid-April to mid-June 2014
    - only solar-sail-propelled interplanetary probe
    - mass: 315 kg
    - active since 2010

    Primary mission of the craft is to examine how to sail in space - and how to move the sail in the solar wind pressure without using any kind of own propellant. The sail of the craft is a large square with a side length of 14.1m; it has solar cells embedded in it that provide limited electric supply to the craft. The sail is spinning in a circle, used both at high-spin initially to rig it open and now at low-spin to more easily tilt it into any direction wanted in the solar wind. The probe is located within a center cut-out in the sail which is tethered to it, not directly connected.
    The "tilting" of the sail used for attitude control is actually a modification of how the sail reacts to the wind pressing on it: the sail has 80 small LCD displays embedded at its outer edges that can be set to either diffuse light or reflect it. Setting the LCDs on one side of the sail to diffuse and on the other to reflect will result in higher solar wind pressure upon the "reflect side", and thus the sail tilting towards the "diffuse side". It's not a particularly fast process - changing the movement direction of the craft relative to the the sun takes about 40 hours per degree of angle. It's also not a precise geometric equation - like the wind on Earth, the solar wind is finicky and not necessarily blowing exactly like you want it. For attitude control, this means that the craft riding the wind does not move at precisely only one angle, it tilts to the left and right with slight changes of pressure in the wind. Rather fascinating.

    JAXA was planning to launch an upscaled version - 35 meter side length - later this decade and sail it to Jupiter, but budget cuts since then have made this rather unlikely.

  6. #21
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    Gaia, located at SEL2, completed its commissioning phase on July 18th and is now fully operational. The first scan routine - each lasting 4 weeks - began July 25th.

    Gaia is the largest (man-made) digital camera in the universe, combining 100+ CCDs into a camera with over one gigapixel. Due to limitations in downlink datarate, the system will automatically determine the interesting regions of objects observed, basically cut them out of the picture and only send those down. Uncompressed resulting data volume from the 5-year mission will still be about 200 TB.

    Gaia's mission during this time is to observe one billion stars in the Milkyway (1% of the population) with about 70 observations per target on average, determining exact position, chemical composition of the atmosphere. She will also - by expectations - find about half a million new quasars, and closely observe supernovae in our or other galaxies. For our local neighborhood, Gaia will examine several 100,000 stars* within 500 ly for exoplanets, with expectations of her finding up to several 10,000 new planets of Jupiter size or larger. Within the solar system, Gaia will map the positions of about 200,000 known asteroids and comets, and is expected to find several 10,000 new objects of this size class.

    * Some 6000 stars were originally thought to be too bright for Gaia to image. During commissioning, this has been reduced to 230 stars for which a special imaging mode has been designed.

  7. #22
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    cuz Spitzer just popped up on DSN as downlinking data, here's two more for the list...

    Inner Solar System: Below Jupiter

    Spitzer Space Telescope
    - NASA
    - infrared space observatory
    - since 2009 on "warm" mission (ran out of cryogen)
    - trailing earth in same orbit since 2003, moving about 0.10 AU away per year
    - heliocentric orbit, currently approximately at SEL5 (moving towards SEL3)
    - mass: 950 kg wet

    Kepler Space Telescope
    - NASA
    - visual-spectrum space observatory
    - sole instrument is a photometer observing occultation by exoplanets of 145,000 stars in its field of view
    - mostly collecting exoplanets (about 1000 confirmed and 3000 unconfirmed found so far)
    - trailing earth in same orbit since 2009, moving about 0.25 AU away per year
    - heliocentric orbit, currently approximately at SEL5 (moving towards SEL3)
    - mass: 1050 kg wet

  8. #23
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    Voyager 2 is currently sending data via DSN to antenna DSS45 in Canberra. From 15.67 billion km (about 105 AU), at a phenomenal 159 Bytes/second with received power of 3.5*10^-23 KW. Voyager 1 and 2 are the only two still actively communicating probes out there where a data roundtrip back and forth takes more than a day. DSS43 is talking to New Horizons at the same time right now, about one quarter as far away enroute to Pluto.

    DSN Now can be seen here: DSN Now

    Basically that page just shows which Deep Space Network antenna is talking to which probe out there at this exact moment.
    Last edited by kato; 04 Aug 14, at 18:49.

  9. #24
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    Article on a potential first ever mission with the sole purpose to study Uranus. (Cue Jokes).

    BBC - Future - Uranus: Why we should visit the most unloved planet

    Uranus has always been left out when it comes to missions to our near neighbours. But now there are serious attempts to visit this toxic gas giant, writes Richard Hollingham.
    Uranus has only ever qualified for the planetary equivalent of a presidential brush-by, when Voyager 2 sped past on its way to the edge of the solar system in 1986.
    The scientists have until January 2015 to submit a detailed mission proposal to ESA. “There’s a tremendous amount of work involved – we need to work out everything from what sort of rocket we launch to what orbit we go into and what instruments we take with us,” says Arridge. “However, there’s a growing global momentum and a real sense of excitement.”

  10. #25
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    That mission concept was originally called ODINUS, and would explore both Neptune and Uranus. Was submitted for the ESA Cosmic Vision L2/L3 mission, but not selected. The team had the prospect that they might have a chance for spot L4, with launch around 2043, or L5 with launch in 2056.

    Apparently they've downscaled the mission majorly (budget of €300 million instead of €650 million), since they're now trying to go for the M4 spot - the Jan '15 call is for that one:
    ESA Science & Technology: Call for a Medium-size mission opportunity in ESA's Science Programme for a launch in 2025 (M4)

  11. #26
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    The original proposals for ESA's Cosmic Vision L2/L3 missions can be found here: http://sci.esa.int/science-e/www/obj...objectid=52029

    The 587-page document has the mission outlines for about 40 or so entries each described in about 15 pages, including among others:
    - the obligatory Mars sample return mission
    - several Venus missions with orbiters, one or more balloon probes or UAVs and zero or more landers
    - Titan orbiters and landers
    - a Neptune orbiter
    - a Uranus orbiter and entry probe
    - an asteroid belt explorer orbiting 3-5 planetesimals (a primordial asteroid of at least 100 km diameter)
    - a similar explorer orbiting a planetesimal and a main-belt comet (an asteroid exhibiting comet behaviour)
    - a Saturn entry probe
    - various SEL2-based observatories for planetary, exoplanetary, stellar or cosmological science
    - a probe to the interstellar medium (with 25-30 years flight time to 200 AU...)
    - a solar corona observer
    - some lunar missions incl. one or multiple landers
    - missions involving up to 100,000 (!) nanosatellites forming a sensor network over an area of several Km to Mm for radioastronomy or as a hypertelescope
    - a sample return mission intercepting multiple meteoroid swarms

    Odinus (last post) can also be found in there, as well as the two ultimately chosen (Athena+ and eLISA/NGO).
    Last edited by kato; 16 Sep 14, at 20:24.

  12. #27
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    NASA's MAVEN (Mars Atmosphere and Volatile Evolution) will arrive in Mars orbit on sunday, ISRO's MOM (Mars Orbiter Mission) will do so three days later.

    MAVEN is a 2.4-ton wet / 800-kg dry orbiter with 65 kg scientific payload, MOM is a 1.35-ton wet / 500-kg dry orbiter with 15 kg scientific payload.

    These values can't be directly compared though (the fuel ratios look similar at first glance) since the 1.6 tons of fuel for MAVEN do not include the trans-Mars-injection burn carried out by a Centaur stage - while MOM did that kick burn itself. MAVEN carries way more fuel since NASA has plans on mission extensions for up to 41 months scientific (minimum 12 months) and beyond that an additional 72 months as a communications platform, supplanting MRO and Odyssey as a backup relay asset. MOM in comparison has a planned operations time in Mars orbit of 6 months.

    Both spacecraft aren't particularly large or ambitious in their mission layout; the ISRO mission is more proof-of-concept - being able to put a spacecraft, a modification based off their lunar orbiters, out there - while the NASA mission is the last remainder of a discontinued "budget" program.

  13. #28
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    Quote Originally Posted by kato View Post
    She will also - by expectations - find about half a million new quasars, and closely observe supernovae in our or other galaxies.
    Five days into the second scan routine, Gaia observed a rather large Type Ia supernova in another galaxy, located about 500 million ly away. The event has been named Gaia14aaa, and, using Gaia's resolution and comparison to ground-based sky surveys could be traced to the outer areas of its host galaxy. Automatic detection and downlink worked well enough that two ground-based telescopes could zoom in on the event location and verify it as well as adding additional data to the picture.

    Detection software routines aboard Gaia are being continuously trained in automatically detecting events such as this. By early next year, the oversight team expects Gaia to detect about three supernovae per day.

  14. #29
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    Hayabusa 2, Procyon, Shin'en-2 and DESPATCH (see post 18 above) have had their launch date fixed down and publically released now: Nov 30th '14, at around 0425 GMT, i.e. in about 2 months.

  15. #30
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    The launch of DSCOVR in early FY2015, i.e. sometime in the next couple weeks to months has been confirmed.

    What they aren't really saying when talking about DSCOVR though is that the spacecraft is actually the one whose launch has been delayed for the longest time; DSCOVR was originally named Triana and ready built for launch on a Space Shuttle in 2002. The flight was scrapped due to lack of priority - NASA could barely do its required ISS flights - and Triana placed in storage in a cleanroom in November 2001, with its mission completely cancelled from NASA's board in 2005. Both France and Ukraine had offered to launch the satellite for NASA during the last decade, with Ukraine even offering a free launch, but NASA declined both since it would have to bear operational costs and because US law prohibits foreign carriers from competing with United Launch Alliance (wonder if that'd still be the case once we get TTIP...).

    Triana's original mission would have been earth surveillance with a secondary space weather observation function. DSCOVR has that changed to a primary space weather station as a replacement for ACE (which has been operating 10 years past its due date...). The launch is effectively made possible by cofunding from the USAF which is gonna buy a ride on a SpaceX Falcon 9 for it, as well as NOAA now taking over all operational duties and costs. NASA's role is limited to refurbishing Triana and handing it over.

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