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.
The Learning Curve
Perhaps the toughest part of doing something like this in a very limited timespan is to climb the learning curve - and to do so with a spacecraft you knew very little about. Early on we did a preliminary evaluation of the spacecraft and its systems so as to better understand it. This was a long jump into deep water. As we did with our Lunar Orbiter Image Recovery Project (concerns the 1960s era Lunar Orbiter spacecraft) the search for ISEE-3 documents has been intense and not without failure.
Most of the best information that we have been able to find has been from the people who worked on the project in the 1980's when the spacecraft was fully operational. After its baseline mission, ISEE-3 was repurposed and rechristened as the International Cometary Explorer (ICE). This image shows the trajectory of ISEE-3/ICE during that period:
Figure 1: ISEE-3/ICE Trajectory through 1986
We have also obtained several documents from NASA as part of the development of our Space Act Agreement. Yet many holes still remain in our knowledge of the spacecraft that we have to deal with. For example, we don't really know the last state of the spacecraft. In digging through documents and consulting with those who should know we have yet to find a record of the last commands sent to ISEE-3. We know that both transmitters (2270.4 Mhz and 2217.6 Mhz) are fully operational but they are not sending telemetry. Clarity is finally coming to us as our team (Austin, Cameron, Marco, and Tim) have diligently gone through the documents we have. They are coming up with a series of commands that we will need to send to the spacecraft to set up its engineering telemetry mode.
Since there is no computer on board the ISEE-3 spacecraft our task is actually much easier since we are going to be directly commanding various subsystems. Our team has made a lot of progress in this area. We are going to be ready to head off to Arecibo this weekend to attempt the first commanding of the spacecraft using their 305 meter dish, the largest in the world.
We now have our Ettus Research Software Radio's inhouse at ISEE-3 Mission Control. Figure 2 shows the spectrum of our signal at a ISEE-3/ICE receiver frequency of 2090.66 Mhz:
Figure 2: Ettus Research USRP N210 Output at ISEE-3/ICE Receiver B Frequency
We have a baseline configuration completed by the engineering team at Ettus to modulate (using GNU Radio) the waveforms required by the ISEE-3/ICE spacecraft. We expect to be ready for receiving and debugging the demodulated stream if we are able to command the engineering telemetry mode to "on" aboard ISEE-3. We have a couple of questions related to parity generation and convolutional coding that we hope that we have right. However, since things are all in software, we can play around with parameters while we are in a window waiting to see the spacecraft.
Command Generation Console and Telemetry Screens
Tim Reyes in Mountain View, California and Matt Sachs from Huntsville, Alabama have been working together to develop the consoles for commanding the spacecraft. Figure 3 shows a mockup of the screens without the commands present (ITAR caution):
Figure 3: ISEE-3/ICE Command Console Screen (Tim Reyes and Matt Sachs)
We are ready to go with the commanding structure butwe are still working on exactly what commands to send. Since we don't completely know the current state of the ISEE-3 spacecraft we are going to make some assumptions and then work from there with a contingency plan of multiple commands, being extremely careful!
The telemetry screens are coming along as well. Our team has been focusing on climbing the steep learning curve for understanding the telemetry system. In this effort details are everything. We have to understand the calibrations required for things such as temperature and pressure sensors, solar array voltages and currents, attitude determination sensors, etc.. This is an ongoing process and we have, as usual, dug some of the pertinent information out of 35 year old IEEE or AIAA papers that are publicly available. Figure 4 is from the old 1978 Mission Operation Plan that we obtained from Bob Farquhar:
Figure 4: Original Telemetry Screen from the ISEE-3 Mission
Depending on how much time we have, we will do a very quick and dirty system that Austin Epps will build. Ideally we will use a Labview version, provided to us by Eddie Rodriquez from National Instruments. The people that make Labview have been incredibly supportive of our efforts and long term we will use Labview for our operational support of the spacecraft for engineering and science. Another issue we have is that we have no idea what has failed on the spacecraft since telemetry was last obtained. There are no surviving records that we can find of what was working the last time the spacecraft was operated. This makes things more difficult in that we have to debug not only our telemetry system, our modulator and demodulator, but we also have to determine whether or not to believe what is coming back from ISEE-3's telemetry indicators. This makes things more complicated, but not impossible.
We are not going to use exactly the conventions that you see above for the telemetry system. We may start out that way but we want something that is much more in keeping with modern graphical systems. Keep in mind that all of this is being done on a rapid basis, and much of the work is being done by volunteers. All of the folks working on this, whether they are volunteers, NASA folks helping us with the Space Act Agreement, or our own internal team, have done a marvelous job in getting rapidly up to speed on what is necessary to pull this off. The next miracles that need to occur are related to transmitting to- and then commanding the spacecraft.
Ground Station Transmitters
We have two ground station power amplifiers that we are currently working with. These amplifiers are being sent to our ground station partners. One amplifier is from AR RF/Microwave Instrumentation of Souderton, Pennsylvania. This unit is a 700 watt transmitter (Model 700S1G4) that AR is loaning the project to be used on the big dish at the Morehead State University Space Science Center (MSU-SSC). The Model 700S1G4 is a portable, self-contained, air-cooled, broadband, completely solid-state amplifier designed for applications where instantaneous bandwidth, high gain and linearity are required. The model 700S1G4 is a 700 watt minimum output power amplifier at S Band frequencies (188.8.131.52 GHz for our application). The folks at AR RF/Microwave have graciously loaned us the transmitter for when the spacecraft is close enough to the Earth (around mid July) for a link to close for commanding ISEE-3/ICE. The power amplifier will be driven by a Ettus Research USRP N210 software radio transceiver.
The second power amplifier is coming from Dirk Fischer Electronics in Senifurt, Germany. This power amplifier is being built specifically for us and will be shipped to Arecibo to be installed next week. Figure 5 shows parts of this transmitter under construction:
Figure 5: DK2FD Power Amplifiers Ready for Testing The power amplifier as well as the Ettus Research Radio's and other equipment has been purchased with the Rockethub-provided funding (well we are borrowing against it right now).
We have purchased a laptop onto which we are loading GNU Radio software and Linux operating system. As soon as we get our Labview developer software we will start working with it as well and integrating the work that Eddie and Mike have done for us in that area. We may not have everything working by next week but we will have the critical parameters loaded. There will probably be more hardware to buy but for now and for next week this will work.
Space Act Agreement With NASA
All the T's are crossed and the I's have been dotted for the Space Act Agreement (SAA) with NASA. The document has been put into the SAA formatter and (in theory) it will be forwarded to the lawyers for a final review before signing sometime in the next day or two. NASA has already provided us with the documentation from Goddard Space Flight Center and did it early so as to help foster our success in the effort.
The spacecraft is traveling at a quarter million miles per day, and with this in mind everyone is working together to fulfill the terms of the agreement as if it was already signed. Since what we are doing is setting a precedent for future activities of this type we are sure that they are just making sure that they have assured themselves that everything is done just right.
Our first official attempt to contact the spacecraft will be at the Arecibo antenna in Puerto Rico the week of the May 19.. The folks down there are working to fit us into their busy schedule of radar observations of Near Earth Objects. That kind of stuff is interesting to me as well so it will be a lot of fun to see a place that I've seen on TV and in movies for most of my life. We are working out an arrangement whereby to where the ISEE-3 Reboot Project will donate the power amplifier that we are getting from Germany to Arecibo in consideration for their support of our project.
Morehead State University
The Morehead State University Space Science Center 21 meter dish is going to be our primary ground station for the activities leading up to and including everything required to put the spacecraft into its final science operating state. However, until the spacecraft is within about 2-3 million kilometers of Earth, which will be in mid to late July, it does not have the wherewithal to close the link with the spacecraft so as to allow two way communications. During our time at Arecibo we will be commanding the spacecraft from there. If we are successful in putting the spacecraft into engineering telemetry mode, one of the USRP N210 radios and our software will be there to process and store the telemetry received. We will be shipping a radio there on Thursday to be ready for next week.
Bochum Observatory and AMSAT-DL
The Bochum Observatory, located in Bochum, Nordrhein-Westfalen, Germany is a private institution set up in 1946 by professor Heinz Kaminski. The observatory has a 20 meter dish that is used for radio science, amateur radio operations, and as a science receiver to receive data from many different satellites. The Amateur Radio Satellite Organization in Germany (AMSAT-DL) works closely with the Bochum observatory. It was this group that in early March of this year detected the signals from ISEE-3/ICE which first generated our interest in communicating with the spacecraft.
The group there with Achim Vollhardt and Mario Lorenz have been working with us and providing signal strength readings from the spacecraft. Independently of our effort they have developed a demodulator for the signals from ISEE-3/ICE. Due to ITAR limitations we have been careful in developing their site for commanding the spacecraft but we are working out a way to do so without compromising our requirements in the ITAR regime. What we hope to do is to have them receive the signals from the spacecraft, demodulate, store, and forward them to us after we command the spacecraft into engineering telemetry mode. With sites in Germany, Kentucky, and Arecibo we will have pretty good coverage, though the Arecibo dish only sees the satellite until the Earth turns away from it.
Other Ground Stations
We are working to get on other ground stations. The SETI Institutein California has been tracking the signal as a means to calibrate and troubleshoot the Allen Array. We are working with them and hope to be able to provide them with a radio and or software so that they can demodulate the signal.
We have a another station here in California that we are talking to in order to get their support. Can't report anything until we close that effort but things are in negotiation now.
Surprise! Google Creative Labs and the ISEE-3 Reboot Project
Some folks had mentioned and recommended to us to get a film crew to go with us to Arecibo as this will be a very noteworthy event. We were recently contacted by the folks at Google Creative Labs about our project and we have worked out a collaboration for them to film us in operation at Arecibo! We have created a Google + page as well and are working to turn this into a longer term means of better communicating and disseminating our educational and scientific product for the ISEE-3 Reboot project.
We hope to be able to do a live stream from Arecibo with the Google Creative Lab folks for our attempt to command the spacecraft. It looks like we are also going to be there when the transmitter arrives from Germany so we will work with the Arecibo folks to get it installed as soon as possible.
On the evening of May 14, 2014 we reached our fundraising goal for the project! First of all a hearty thanks to everyone for your support and as soon as the funding gets to us we will start putting together the goodies to everyone. When we started this we only had a very vague idea of how much we would need to do this. We have spent about $35,000 so far with more spending coming as we go to Puerto Rico to Arecibo to attempt the first contact. We had to borrow and get terms to pay for some items that we will have to pay for when the funds arrive.
In all probability we will need more funds so we would like to ask for folks to continue to give as you can until the funding window ends on Saturday morning 17t May, at just about the time we get on an airplane to Puerto Rico. We will take a hiatus for fund raising but there is a strong possibility that we may have to pay for the Deep Space Network to do a ranging to the spacecraft for us. If so we will definitely have to do more fund raising. I still marvel at the technical ability of the DSN and how it does interplanetary spacecraft ranging. It is absolutely a non-trivial task!
Next Week's Activities
Next week is crucial to the success of our project. Using the dish at Arecibo gives us the best chance of being able to command the spacecraft in the very near term. Every day is exceedingly important to us right now. The spacecraft gets about the distance from the Earth to the Moon closer each day and now every day the amount of propulsion burn it takes to make the trajectory correction grows.
The ISEE-3/ICE spacecraft was never really designed to be an interplanetary cruiser and thus the thrusters on board are very small. We estimate that if we wait until mid-June to do the course correction that it will take 17 hours of thrusting to get the course change of about 40 meters/second that we will need at that time. As such, everyday we wait, the risk increases. You see, as we have to continually command the spacecraft to fire for every 512 pulses, thus increasing the chance that something will go wrong.
Figure 6 shows the track of the spacecraft against the sky right now and the distance that it travels per day shown as the tick marks. It is pretty much impossible to see it now, but at least you can get an idea of its track in the sky as it approaches the Earth:
Figure 6: Track of the ISEE-3/ICE Spacecraft The Sky Mid May 2014 (Time Reyes)
Our flight operations engineer Tim Reyes put this graphic together. Our team has done a marvelous job getting everything together and climbing an incredibly steep learning curve. We have another new person Cameron Woodman, who has also done just a stellar job in helping everyone else get up to speed and to help with the back and forth engineering thought process related to getting the telemetry system going. Marco Colleluori is putting in an incredible amount of effort to get Matlab to do what the old ICEMAN program did 35 years ago. We have a great group of other people as well from our artist Mark Maxwell, who put together our logo, the folks at the ground stations, the team of ISEE-3/ICE alumni, without whom this would have been impossible to do!
And of course without my project co-lead Keith Cowing, we would have never generated the immense public interest that the project has developed or collected donations from so many intersted supporters that is going to translate our plans into reality. This is a very interesting spacecraft and I think that this process has been a great learning experience for our team and we look forward to the possibility of being able to return this truly historic spacecraft to science operations.
The following links are the best way to stay up to date with our progress: