The ISEE-3 has been detected, but can they get it to talk back in the next month?
When F. Scott Fitzgerald wrote that there were “no second acts in American lives,” obviously he didn't know about our space program. The International Sun-Earth Explorer (ISEE-3) was already reborn once as the Earth's foremost comet hunter and the probe is set to be revived again, 17 years after its mission was terminated.
As NASA didn't have the funding to wake up its 36-year-old spacecraft, a couple of space nerds got the space agency's blessing and took to the internet, where they reached their crowdfunding goals and then some. On May 15, a month and three days after their Rockethub page went up, the ISEE-3 Reboot Project passed its initial goal of $125,000.
The team is now going for a flex goal, in order to pay for some time on NASA's Deep Space Network to do some ranging, which is the quickest and most precise means of estimating the location of the spacecraft. They're approaching $136,000 as this is being written, and the wheels are already in motion. Yesterday the ISEE-3 was detected via their Ettus Research Software Defined Radio unit that they attached to the world's largest single-dish radio telescope.
“As we speak the team is in Arecibo; we posted photos today,” Keith Cowing told me over the phone. Cowing is an editor at NASAWatch.com, SpaceRef.com, Astrobiology.com, and was also immensely jealous of the team that was down in Puerto Rico. But someone had to be in the US posting the results to Space College and answering my questions, the first of which was: Where to now?
“Sending it a tone, and if the spacecraft responds with that tone, then we know at that basic level that the spacecraft can send and receive information,” Cowing said. “If we can't get that, it's game over. But after that we'll repeat that a number of times and get more complex so we make sure we have that worked out.”
Even though the ISEE-3's transmitter has stayed on, and was detected as recently as 2008 by NASA's DSN, that's all that we really know. So the first step is getting the vitals back from the spacecraft—where it is, how fast it's going, and how fast it's spinning—some of which is an opportunity to keep their army of interested investors invested and interested.
“One thing we're toying with doing is, if we get enough good data back, we're going to put the information up on the website and crowdsource—ask folks if they can help us figure out what the spin rate is for the spacecraft,” Cowing said.
"Your toaster is smarter than this thing."
Then a software team has to figure out how to use new computers to talk to a spacecraft that Cowing told me didn't really have a computer. “It has a processor, which is hardwired to do certain things,” he said. “It doesn't remember anything. You just tell to do a task and that's it. Your toaster is smarter than this thing.”
Based on NASA documentation of how they spoke to the spacecraft back when they launched it in 1978, software engineers are writing a sort of emulator. “The user interface will be similar to the VW Beetle you can buy today. It might look like the '60s but under the hood it runs a bit differently, but it does the same thing,” Cowing explained.
The immense outpouring of generosity has taken some of the monetary pressures off the team, and NASA signed the Space Act Agreement papers, taking the legal pressure off . The only pressure left is pressing time. The laws of physics dictate that the sooner they fire the engines, the less fuel it will take to steer the ISEE-3 into a position where, after coming around the moon in August, it can be steered back into position to monitor space weather, as it was originally designed to do.
“There is sort of an asymptotic deadline—the further out you get the more fuel it takes to do the same thing,” Cowing said. “And we're getting into very late June and early July it starts to get really close. So we need to fire this in June.”
August 10, when ISEE-3 reemerges from the shadow of the moon, is what Cowing calls “nail-biting time.” The spacecraft will be out of the Sun and, as a result, shut down for about 20-25 minutes.
“It's got to come around the moon and come on again and hopefully in a position where we can fire the engines,” Cowing said, which would be the fine-tuning the spacecraft's trajectory to get it into position where it can again can monitor the Sun as it did before it was reborn as a comet hunter.
There's still a lot of questions that need to be answered before the ISEE-3 is put in position, including where in space this position will be exactly and what it will be doing once it's there. But the successful crowdfunding has reinforced the ISEE-3 reboot team's commitment to making sure the journey there, and whatever it then does is as open as possible to everyone.
“This is just the beginning of a long dance,” Cowing said. “We're approaching 1,900 donors, and they take this personally. Whether they've given us $5, $10, $1,500, they have an investment in us and they feel they've help make something cool happen, and we want to take everyone along for the ride. We want people to be able to use it.”