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ISEE-3: The Challenge of Long Duration Flight

Some mission concepts for interstellar flight demand equipment that can stay functional not just for decades but for centuries. Do we know how to build such things? Missions like Voyager are encouraging in that we have two spacecraft that were never built for the kind of longevity we’ve demanded of them, and we’re still tracking their signals. But as Robert Forward once speculated, the problem may not be just in building the spacecraft, but in how we handle them.

Forward’s issue involved the changes on Earth that might occur over a long-duration spaceflight like the one he envisioned in Rocheworld (1984, first published as Flight of the Dragonfly). A crewed starship is actually on the way to Barnard’s Star, dependent on the massive laser installations in the Solar System whose beam will allow it to decelerate (through ‘staging’ the sail) into the destination star system. But there is a movement afoot on Earth to shut down the beam, motivated by money, politics and the usual cast of miscreants. The technology, in other words, works, but the question is whether the humans behind it will make the right decision.


Much goes on in Rocheworld and the question of shutting down the laser is but a minor theme, but the question Forward raises is intriguing. Consider what’s happening with the International Sun-Earth Explorer-3 (ISEE-3), a spacecraft launched in 1978 to make observations of the solar wind’s interactions with Earth’s magnetosphere. Back in 1983, ISEE-3 turned into ICE, the International Cometary Explorer, and in that guise studied comet Giacobini-Zinner and later Halley’s comet. NASA even turned the craft loose after that to study coronal mass ejections before decommissioning the probe and closing down its systems.

This August, as the Planetary Society’s Emily Lakdawalla has noted, the spacecraft in its heliocentric orbit will be catching up with the Earth from behind, which creates an interesting issue of its own. Although officially out of service, ISEE-3 has been broadcasting a carrier signal that was detected in 2008. It’s also known that as of last check — this was some time in the 1990s — twelve of its thirteen instruments were still working. Could we get the 36-year old spacecraft back in service? It’s a compelling thought, but a tough task to accomplish.

Image: The ISEE-3/ICE spacecraft. Can it be returned to use? Credit: NASA.

The problem isn’t with the data from the spacecraft, which can be accessed by the Deep Space Network. The issue is our ability to talk to the probe. The Goddard Space Flight Center team responsible for the craft maintains a Facebook page, from which Lakdawalla quotes:

The transmitters of the Deep Space Network, the hardware to send signals out to the fleet of NASA spacecraft in deep space, no longer includes the equipment needed to talk to ISEE-3. These old-fashioned transmitters were removed in 1999. Could new transmitters be built? Yes, but it would be at a price no one is willing to spend. And we need to use the DSN because no other network of antennas in the US has the sensitivity to detect and transmit signals to the spacecraft at such a distance.

However, all hope is not lost. ISEE-3’s signal has been detected by the Allen Telescope Array as well as by radio amateurs, and scientists at the Applied Physics Laboratory are studying potential new, lower-power ways of contacting the probe, as Lakdawalla reports in a later update. If the craft’s engines can be commanded to fire, it could be recaptured into a halo orbit at the L1 Lagrangian point and returned to service. The odds are long and time is short — the engine firing needs to be accomplished no later than early June — but the fact that the APL team is actively working on this inspires me to keep an eye on the ISEE3returns Facebook page.

ISEE-3 is not, obviously, a manned mission, so the question of reactivating it has none of the life-or-death drama of the Forward novel. But it’s an interesting commentary on how our technology can sometimes expose our weaknesses. In this case, we have a functioning spacecraft that could conceivably come back into use, one that is for now rendered impotent until we can pull the resources together to use it. The cost factor speaks for itself, and it’s understandable. But I’m reminded of our problems reading old data from the Pioneer days because the equipment has become obsolete. Truly long-term thinking involves planning for changing formats and technological upgrades, a subject about which we’ll be learning much more as we contemplate deeper and longer missions into the dark between the stars.


Comments on this entry are closed.

  • Marc Millis April 9, 2014, 13:00

    In a discussion with a spacecraft designer at John Hopkins, who asked not to be quoted with these estimates, the maximum lifespan of a spacecraft, based on the best of what we have now, might be a century. With dedicated reliability improvements, this might be pushed to two centuries.

    Therefore, unless your spacecraft plans include amazing reliability innovations, we should probably limit mission duration planning to two centuries… for now.

    More importantly, if any of you have solid information on this situation, please share the citation for that reference!


  • JoeP April 9, 2014, 13:37

    Modern humans are also now living in a society that provides a lot of instant gratification. Psychologically, this cannot help the commitment challenges covered in your article.

  • CharlesJQuarra April 9, 2014, 13:56
  • Randy Chung April 9, 2014, 15:28

    Well, I’ve designed computer chips for about 25 years (although I do software now), so I’ll give my $.02. For really long trips (many centuries), in addition to lots of redundancy and reconfigurable logic, I’d include an IC fab. This sounds crazy, but if you don’t have to worry about maintaining a high vacuum or don’t require high volume production, the manufacturing processes such as ion etch, chemical vapor deposition, molecular beam epitaxy, ion implantation, etc. would be much simplified. To avoid wet chemical processing, you’d avoid masks and use electron or ion beams to define the geometries (that’s how you’d make and repair the masks in the first place). You could put a lot of logic and memory onto a single wafer with a 20 nm diameter beam. When the wafer got damaged enough by high energy particles, it could be taken out of service, the active surface ground off and new logic could be laid down. I’d imagine there wouldn’t be too much neutron activation, or the whole space ship would be in trouble.

    As far as communication protocols and modulation schemes, they should be open sourced and standards based. There is an issue with dissemination of encryption keys, though. You wouldn’t want just anyone to control or communicate with your starship, right? I’d guess you’d want some escrow service, maybe more than one, to hold the keys.

  • Andrew Higgins April 9, 2014, 22:18

    Book plug (hopefully, on topic, but still a plug):


  • Lionel April 10, 2014, 0:45

    @Randy Chung, I think IC fabs in space are a fascinating proposal both for very long mission ships and for achieving semi- or fully- self-replicating probes or asteroid miners. I’d like to hear your opinion on what electronics / IC production processes could be achieved first in space. NASA is taking a 3D printer to the ISS later this year – how long do you think it will be before they can take some IC producing machines to the ISS, and what processes do you think these will be?

    Last year Keith Cooper posted on this website (https://centauri-dreams.org/?p=27362) about 3D printers enabling us to make self-replicators / von-Neumann probes possible, however I think that 3D printers are limited to mechanical parts and for making our electronics in space we will need some of the the ones you mentioned

    With 3D printers and IC fabs in space, are we then able to mass produce probes for colonising NEOs?

  • NS April 10, 2014, 4:19

    Even if we overcome the technological hurdles and create a probe that can return data after centuries, there’s still the issue of whether that data will be useful to anyone. Five hundred years ago was the time of Copernicus. Is any information gathered at that time still useful now? Science will change even more drastically in the next 500 years than it did in the last 500. Can we even guess what data our descendants then will be interested in?

    I suggest hedging our bets. Build probes that will last for as long as we can manage, but have them return data that will be useful to us and hopefully our immediate successors. If later generations decide a probe is still useful they can monitor it for as long as they like. If not they’ll shut it down. The choice will be theirs, not ours.

  • Michael April 10, 2014, 9:33

    @Lionel April 10, 2014 at 0:45

    ‘…however I think that 3D printers are limited to mechanical parts and for making our electronics in space we will need some of the the ones you mentioned’

    We are currently or are in the advanced process of using 3D printers that use cells as the ink, we should be able to ‘print’ organisms/organs using a collection of cells eventually. This is by no means a small feat with many obstacles to overcome.

  • Randy Chung April 10, 2014, 11:19

    Lionel, the quickest approach to a demo or proof of concept would be to modify a Focused Ion Beam (FIB) machine. Here’s a good article on FIB: “Focused Ion Beam Microscopy and Micromachining”, http://www.nanolab.ucla.edu/pdf/mrs_bulletin_2007_fib_machining.pdf

    I’m totally in favor of asteroid mining and in-space manufacturing using asteroid material, since it can significantly change the economics of building starships and energy beamers, but in *this* solar system, it will be easier to ship IC’s up from Earth, they don’t weigh much.

  • Paul W April 10, 2014, 12:59

    If I was part of a “crewed starship” heading for the deep, I would not be comfy about having to rely on the good folks back on earth for needed braking, or much else, for that matter.
    If the earthlings stay on the line, great. But let’s not stake anyone’s life on flaky earth types being there for them in a pinch.

  • Mark April 10, 2014, 13:48

    I see two problems here to be addressed:

    1) Repair of systems in space far from human hands
    2) Maintenance of working “legacy” space computer/radio systems and data here on Earth.

    For repair of systems in space, you need to carry a supply of raw materials to effect repairs and some dedicated onboard robotics (nanobotics?) to perform the repair. The IC fab is a start, but how to repair the components of the IC fab itself should it fail? Nano-bots swarming in tandem and operating at the molecular level might be the way to go to perform repairs of degraded ICs. The nanobot swarm would have to be self-repairing, autonomous, and incapable of redirecting the course of the space ship for the purposes of perpetrating mayhem against their creators.

    For the maintenance of legacy systems on earth, I would propose for example that the U.S. National Archives should establish a legacy space technology branch, (dotted line reporting to NASA) and be tasked with maintaining the software, data, computer hardware, and comms/radio systems of obsolete space systems in fully functioning condition. Had such a technology archive been in existence during the Apollo program we would not have misplaced the original (clear) TV signal from Armstrong’s first footfalls on the moon’s surface, nor would we have lost or scattered the Pioneer data. We would also not have mislaid the engineering drawings to make the Saturn V. It is incumbent on us to preserve the functioning history of our space achievements.

  • ljk April 10, 2014, 15:03

    Historical information is of great value to historians for one things. Records of times long past are useful to those doing such thing as long-term astronomical work and climate change. The advantage of that old data is that it is collected at a time too remote for current and future researchers. Most researchers would give their left arms for access to the Library of Alexandria, as one big example.

    The Saturn 5 blueprints are not lost, that is an old legend. But I agree that better archiving of historical space data needs to be done. Engineers need to look beyond focusing on fixing the problem of the moment. All disciplines need to do better at understanding and appreciating the other side of C. P. Snow’s Two Cultures.

  • Randy Chung April 10, 2014, 17:04

    Mark, redundant systems (multiple IC fabs, multiple 3D printers, multiple robot arms) would be necessary to keep the whole system running while repairs are being made. As long as any part of the IC fab could be manufactured by the 3D printer, and any part could be assembled by a robot arm, and at least one of the critical subsytems is still working (and there’s spare material of course), you could rebuild back to full redundancy.
    On thinking about nanobots, an IC fab could be used to build nanobots using MEMS technology. The hard part would be building batteries. (Or maybe it sounds hard because I don’t know how to build good batteries.)

  • Lionel April 10, 2014, 22:45

    @Randy Chung
    Delighted to hear you mention FIB – I spent 8 months working with a gallium FIB for my graduate thesis, making nanoscale Josephson Junctions from high Tc superconductor thin films using vertical and horizontal milling :) I haven’t worked with them since though and I’m taking a bit of a different direction from nano at the moment. The circuits we made just had a few components to demonstrate the properties of the devices we were testing. Have FIBs also been used to make whole ICs, a computer’s CPU for instance?

  • NS April 11, 2014, 0:04

    You’re right, ljk, I should have asked different questions. Are there any devices from 500 years ago that (if operating as built today) would provide information that is scientifically useful to us? Not information about the science and technology of 500 years ago, but data that would be helpful in problems that science is addressing now. The answers to these questions would give us some guidance on whether it is worthwhile for us to create devices for our descendants of 500 years from now. This is essentially what we would be doing in building probes that last that long.

  • ljk April 11, 2014, 10:43

    But do we just sit and wait for things to advance? If we do not try now, the chances are the skills and technology needed for those presumed later advancements may be delayed or never even happen at all. Yes our cars and airplanes are much better than those made a century ago, but without those early efforts we might still be using the horse and buggy. We are the results of the efforts from our past.

    I recall reading a book about the Apollo Lunar Module. One engineer said sure, they could have waited until the technology was more sophisticated, but then they might not have put men on the Moon until 1990. Or perhaps never, due to the major attitude shift that happened between JFK’s pronouncement in 1962 and by the time Apollo really did deliver astronauts to the lunar surface.

    The late 1960s and early 1970s saw a major cultural shift that included rejecting many established ideas and traditions: Some changes were good like civil rights, but the space program got caught up in that as well and that is one reason why we have not put another human on the Moon since 1972.

    And sometimes the ancients knew and did things we still cannot duplicate. Certain kinds of stained glass windows are one example off the top of my head. Did you know Leonardo da Vinci determined one aspect of how the human heart works that was not confirmed by modern medicine until about 20 years ago? Imagine if someone in the medical field had paid attention to da Vinci’s notes much earlier.

    This is why I am wary when people assume both that the ancient ideas and tools are obsolete and that residents of the future will automatically be better and smarter and have that FTL drive ready to go when we finally get there. As Arthur C. Clarke once wryly said, what has posterity ever done for me?

  • Randy Chung April 11, 2014, 20:23

    Lionel, I don’t think there are any existing FIB machines that would be suitable for an entire IC, because there’s no business case for it.
    In the future, I think the “open source hardware” movement, similar to the way open source software is developed and improved by teams of volunteer developers connected only by the Internet, is the way to create custom machines for a hundred year project.

  • NS April 12, 2014, 3:12

    No, we don’t sit and wait. We build now to solve the problems we have now. Some of the things we build now may be useful in the far future, but we can’t anticipate which things. If we try to build things that will only be useful at some distant time (if ever) chances are they will never be useful at all.

  • Michael April 12, 2014, 14:05

    A possible geometric way to protect the ‘brain’ of the probe is to have it designed in layers perpendicular to flight, each layer able to control the craft on its own. When one layer is disrupted say from completing a simple algorithm another layer takes over that can complete this simple algorithm. This should give a great deal of protection against catastrophic failure.

    @Randy Chung April 10, 2014 at 17:04

    ‘On thinking about nanobots, an IC fab could be used to build nanobots using MEMS technology. The hard part would be building batteries. (Or maybe it sounds hard because I don’t know how to build good batteries.)’

    Instead of using batteries super-capacitors could be made, IC tech is already available.


  • Randy Chung April 13, 2014, 1:41

    Michael, you’re right, supercapacitors would work much better. Supercaps don’t have much capacity compared to batteries today, but that will probably change in the future. There are already reports about wafer sized graphene films.

  • Michael April 14, 2014, 13:09

    @Randy Chung April 13, 2014 at 1:41

    ‘Supercaps don’t have much capacity compared to batteries today, but that will probably change in the future. There are already reports about wafer sized graphene films.’

    As reasons stated by yourself earlier, the vacuum of space has immense advantages for manufacturing. In the very high vacuum of space I.C manufacture becomes a lot easier and so does thin film technology by default. One of our first steps into space should be securing a manufacturing base-in-space.

  • Dennis Wingo April 14, 2014, 15:40


    We have just official tossed our hat in the ring to recover this amazing spacecraft.


    Please visit http://www.rockethub.com/projects/42228-isee-3-reboot-project-by-space-college-skycorp-and-spaceref

    and help us out.

    Our goal is to if possible make a May 15, 2014 date to fire the thrusters to do a course correction. The last date we can do this and still reserve some fuel is June 20th.

    This is going to be a very tough goal to hit but with your financial support I think we can do it.

    We have already completed tasks associated with recovering data from the Lunar Orbiter spacecraft, and from the Nimbus II weather satellite so we understand these old birds.

    I have also built several Shuttle payloads, and my own small AMSAT (SEDSAT-1/OSCAR-33.

    Please check Rockethub for daily updates! I will try and answer questions here as well.

    Dennis Wingo
    ISEE-3 Reboot Project.

  • ljk April 18, 2014, 9:33

    The folks who are restoring the Lunar Orbiter images are also looking for the original data telemetry tapes from ISEE-3. Can you help them? See here:




    ISEE-3 reboot project update:


  • ljk April 18, 2014, 9:45

    The ISEE PDF Document Library online here:


    ICE encounter operations from 1985:


    ISEE-3/ICE Telecommunications Summary:


  • ljk April 24, 2014, 10:14

    A new video on recovering ISEE-3/ICE into an orbit for redirecting to a new space mission here:


  • ljk April 30, 2014, 8:58

    The latest news on the ISEE-3 Reboot project, which includes a link to a story about it on NPR here:


  • ljk May 15, 2014, 14:21

    ISEE-3 Reboot Project Status and Schedule for First Contact

    By Keith Cowing on May 15, 2014 11:37 AM

    Dennis Wingo: Today’s update regards the progress of the ISEE-3 Reboot Project team in our preparations to contact the spacecraft. We started this effort 32 days ago on on April 12, 2014. Below is what we have accomplished in that time – and the challenges that lie ahead.

    Full article here:


  • ljk May 21, 2014, 10:15

    ISEE-3 Reboot Project Hardware Detects ISEE-3 at Arecibo

    By Keith Cowing on May 19, 2014 11:19 PM

    The following are screenshots of data from the live receive session we did with our Ettus Research Software Defined Radio unit attached to the Arecibo antenna today (19 May). “Waterfalls” were generated by post-processing the recorded data. There are four recordings of various lengths as we were testing the setup, and this is the very, very initial result.

    The first and second screenshot images were taken during the live capture. You can see the faint diagonal line of the carrier. This is a simple flowgraph Balint Seeber put together in GNU Radio that receives samples from the USRP (which is in turn connected to the IF output from their existing S-band receiver), records the samples to disk and also displays the FFT and waterfall plots of a selectable narrow-band portion of the spectrum.

    Figures 1 and 2 (images 3 and 4) are the output of a Python script Balint wrote quickly after the data capture to perform a large FFT on the data (256K points) and produce the waterfalls with numpy & matplotlib (this one capture is ~14.5 min). Figure 1 is the entire baseband spectrum captured from the USRP (250 kHz BW). You can see the carrier left of center (log color scale). Figure 2 is zoomed into that area and you can see the Doppler shift (~977 Hz BW, linear color scale). Scales on both are just the FFT bin indices.

    Unfortunately the signal is a little weaker than we expected, and it’s also odd that it fades out toward the end of this capture (it returns and fades in subsequent ones too). Again, this is all very preliminary data done tonight on a rush basis. Much more detail to follow.


  • zq June 4, 2014, 11:25

    ISEE-3 Reboot has successfully commanded the spacecraft to provide basic telemetry and has decoded spacecraft attitude and magnetometer data.

    Signal issues above were due to errors in predicting spacecraft location.

    They may just pull this off. http://spacecollege.org/isee3/ for status.

  • Tiens van Greuning August 4, 2014, 21:55

    OK so it seems ISEE-3 has run out of nitrogen propellant.

    Just wondering, since the ISEE-3 Reboot project was and still is successfully funded through Kickstarter, how difficult would it be to try and fund a type of solar sail through Kickstarter, which if successfully launched and deployed, could go and “dock” with ISEE-3 and be used to move it?