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    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MDRCUA4KX6V4UUG3SBSKAAFZRNI2M3BF/?format=api",
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    "message_id": "CAGX_=kd4RADoPzqLZzpYs4mmi+16yF3MF+PgeHHjVxyJs2sn5g@mail.gmail.com",
    "message_id_hash": "MDRCUA4KX6V4UUG3SBSKAAFZRNI2M3BF",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/MDRCUA4KX6V4UUG3SBSKAAFZRNI2M3BF/?format=api",
    "sender": {
        "address": "ericrosenberg.dc (a) gmail.com",
        "mailman_id": "92a52370fffc4b8a950eb1fe31daeea5",
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    },
    "sender_name": "Eric Rosenberg",
    "subject": "[amsat-bb] Space Hackers Prepare to Reboot 35-Year-Old Spacecraft\t(Long)",
    "date": "2014-05-21T14:03:58Z",
    "parent": null,
    "children": [],
    "votes": {
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        "status": "neutral"
    },
    "content": "This long piece comes from IEEE Spectrum\nhttp://spectrum.ieee.org/tech-talk/aerospace/satellites/space-hackers-prepare-to-reboot-35-year-old-spacecraft\n\nAMSAT-DL is mentioned throughout this piece. Dennis Wingo is KD4ETA. He has\na blog http://denniswingo.wordpress.com/\n\nEnjoy!\n\n73,\nEric W3DQ\n--------------------\n\nSpace Hackers Prepare to Reboot 35-Year-Old Spacecraft\n\nBy Rachel Courtland\n\nPosted 15 May 2014 | 17:00 GMT\n\n\n\nEarly next week, a team of volunteers will use the Arecibo Observatory in\nPuerto Rico to see if they can make contact with a spacecraft that hasn't\nfired its thrusters since 1987. If all goes well, the effort could bring\nthe 35-year-old spacecraft, the International Sun-Earth Explorer\n3<http://solarsystem.nasa.gov/missions/profile.cfm?MCode=ISEEICE>\n(ISEE-3),\nback into position near the Earth, where it could once again study the\neffect of solar weather on Earth's magnetosphere.\n\n\n\nIt will be a race against time. ISEE-3, which is transmitting two carrier\nsignals, only came into hearing range a couple of months\nago<http://amsat-uk.org/2014/03/09/radio-amateurs-receive-nasa-isee-3ice-spacecraft/>.\nDennis Wingo, CEO of California-based Skycorp\nIncorporated<http://www.skycorpinc.com/Skycorp/Home.html>, and\nhis colleagues reckon ISEE-3 still has enough fuel to make it back to its\noriginal orbit at the Lagrangian point\nL1<http://www.esa.int/Our_Activities/Operations/What_are_Lagrange_points>,\nat a spot between the sun and the Earth where a spacecraft can stay in sync\nwith Earth's orbit. But to make it, Wingo says, the spacecraft must\nbe commanded to fire its thrusters by mid-June.\n\n\n\nAnd that's far easier said than done. NASA no longer has the hardware to\ncommunicate with the ISEE-3. So in April, Wingo and Keith Cowing, a former\nNASA employee and editor of the websites NASAWatch <http://nasawatch.com/>and\nSpaceRef <http://www.spaceref.com/>, started a (still-running) crowdfunding\ncampaign <http://www.rockethub.com/42228> on RocketHub to develop what they\nneed to communicate and control the spacecraft: signal modulators and\ndemodulators, transmitters, and a software-based mission control console to\nmonitor the spacecraft's propulsion and attitude control systems.\n\n\n\nBuilding all of this even 10 years ago \"would have been impossible,\" Wingo\nsays. But with the advance of embedded systems technology, the team can\nconstruct radio components in software and debug them on aggressive\ntimescales without breaking the bank.\n\n\n\nWith no time to wait, the team has already purchased software-defined radio\nperipherals <https://www.ettus.com/product/details/UN210-KIT> built by\nEttus Research, which can be used to implement modulator and demodulator\nprograms that would once have had to be built in hardware.\n\n\n\nEttus has volunteered to help with the programming, and one member of the\ncompany will join Wingo in Arecibo. They'll set to work there on 19 May,\nusing a 400-watt transmitter shipped in from Germany to try to make contact\nwith the spacecraft. One of the first things they'll do is command the\nspacecraft into engineering telemetry mode, where it's hoped it will send\nsignals that will give the team a better sense of the condition of the\nspacecraft.\n\n\n\nAssuming ISEE-3 is in good health, Wingo says, the next big challenge will\nbe to assess its trajectory for a proper thruster firing. The team will use\ntransmitters and antennas at Arecibo, Morehead State University in\nKentucky, the Bochum Observatory in Germany, and, potentially, the Allen\nTelescope Array in California, to ping the spacecraft. The hope is that the\nteam will not only be able to measure Doppler shifts in frequency to get a\nfix on the spacecraft's velocity, but also signal time of flight to\ntriangulate its position. This will be difficult, so even though the\nproject met its fundraising goal on Wednesday, Wingo says the team is still\nseeking funds in case they must pay NASA to do the ranging for them.\n\n\nThe reboot project schedule is aggressive. \"We're in panic mode every day,\"\nWingo says. \"But I think we have a reasonable chance of making this work if\nthe spacecraft is healthy.\"\n\n\n If the effort succeeds, it won't be the first time that ISEE-3 has had a\nchange of course. After its launch in 1978, the spacecraft was repurposed\n(and renamed the International Cometary Explorer) in the early 1980s to\nchase Halley's Comet, then tasked again with performing solar observations\nin 1991 before mission cancellation in 1997.\n\n\n\nAlthough more capable spacecraft have since launched, recapturing ISEE-3\ncould give researchers access to a consistent set of instruments with which\nto compare old measurements of the Earth environment, Wingo says. The peak\nof this solar cycle is about half as\nactive<http://www.solen.info/solar/images/comparison_recent_cycles.png>as\nthe peak of solar cycle 21, which ISEE-3 observed.\n\n\n\n\"[We can use the] same set of instruments to look and see what the\ndifferences are in Earth's magnetosphere,\" Wingo says. Most of ISEE-3's\nscience instruments could still be in good working order, Wingo says, as\nwell as the core command components of the spacecraft, which has no\nmicroprocessor and hence no memory to corrupt.\n\n\n\nIf the team can get ISEE-3 to fire its thrusters by mid-June, the\nspacecraft will swing past the moon at an altitude of less than 50\nkilometers on August 10. A few more engine firings could place it back at\nL1, where the spacecraft could potentially start collecting data by\nmid-September. If the plan works, Wingo says, the team hopes to have a\nwebsite up where people can see the spacecraft's engineering telemetry and\nscience data for themselves.\n",
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