Tensions High After Second Failed Cable At Arecibo

November 11, 2020 by Tom Nardi 45 Comments

Today we’re sad to report that one of the primary support cables at the Arecibo Observatory has snapped, nudging the troubled radio telescope closer to a potential disaster. The Observatory’s 300 meter reflector dish was already badly in need of repairs after spending 60 years exposed to the elements in Puerto Rico, but dwindling funds have made it difficult for engineers to keep up. Damage from 2017’s Hurricane Maria was still being repaired when a secondary support cable broke free and smashed through the dish back in August, leading to grave concerns over how much more abuse the structure can take before a catastrophic failure is inevitable.

The situation is particularly dire because both of the failed cables were attached to the same tower. Each of the remaining cables is now supporting more weight than ever before, increasing the likelihood of another failure. Unless engineers can support the dish and ease the stress on these cables, the entire structure could be brought down by a domino effect; with each cable snapping in succession as the demands on them become too great.

Workers installing the reflector’s mesh panels in 1963.

As a precaution the site has been closed to all non-essential personnel, and to limit the risk to workers, drones are being used to evaluate the dish and cabling as engineers formulate plans to stabilize the structure until replacement cables arrive. Fortunately, they have something of a head start.

Back in September the University of Central Florida, which manages the Arecibo Observatory, contacted several firms to strategize ways they could address the previously failed cable and the damage it caused. Those plans have now been pushed up in response to this latest setback.

Unfortunately, there’s still a question of funding. There were fears that the Observatory would have to be shuttered after Hurricane Maria hit simply because there wasn’t enough money in the budget to perform the relatively minor repairs necessary. The University of Central Florida stepped in and provided the funding necessary to keep the Observatory online in 2018, but they may need to lean on their partner the National Science Foundation to help cover the repair bill they’ve run up since then.

The Arecibo Observatory is a unique installation, and its destruction would be an incredible blow for the scientific community. Researchers were already struggling with the prospect of repairs putting the powerful radio telescope out of commission for a year or more, but now it seems there’s a very real possibility the Observatory may be lost. Here’s hoping that teams on the ground can safely stabilize the iconic instrument so it can continue exploring deep space for years to come.

Damage To Arecibo Leaves Gaping Hole In Astronomy

August 24, 2020 by Tom Nardi 69 Comments

In the early morning hours of August 10th, a support cable at the Arecibo Observatory pulled lose from its mount and crashed through the face of the primary reflector below. Images taken from below the iconic 305 meter dish, made famous by films such as Contact and GoldenEye, show an incredible amount of damage. The section of thick cable, estimated to weigh in at around 6,000 kilograms (13,000 pounds), had little difficulty tearing through the reflector’s thin mesh construction.

Worse still, the cable also struck the so-called “Gregorian dome”, the structure suspended over the dish where the sensitive instruments are mounted. At the time of this writing it’s still unclear as to whether or not any of that instrumentation has been damaged, though NASA at least has said that the equipment they operate inside the dome appears to have survived unscathed. At the very least, the damage to the dome structure itself will need to be addressed before the Observatory can resume normal operations.

The Arecibo Observatory by JidoBG [CC-BY-SA 4.0]

But how long will the repairs take, and who’s going to pay for them? It’s no secret that funding for the 60 year old telescope has been difficult to come by since at least the early 2000s. The cost of repairing the relatively minor damage to the telescope sustained during Hurricane Maria in 2017 may have been enough to shutter the installation permanently if it hadn’t been for a consortium led by the University of Central Florida. They agreed to share the burden of operating the Observatory with the National Science Foundation and put up several million dollars of additional funding.

It’s far too early to know how much time and money it will take to get Arecibo Observatory back up to operational status, but with the current world situation, it seems likely the telescope will be out of commission for at least the rest of the year. Given the fact that repairs from the 2017 damage still haven’t been completed, perhaps even longer than that. In the meantime, astronomers around the globe are left without this wholly unique resource.

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ISEE-3: On Track To Come Home

June 8, 2014 by Brian Benchoff 15 Comments

map — Intended trajectory from ICE team in 1986 (blue), 2001 ephemeris of ISEE-3 (white) and current ephemeris (red/green). Click to embiggen.

When last we heard of the progress of commanding the derelict ISEE-3 satellite into stable orbit between the Earth and the sun, the team had just made contact with the probe using the giant dish in Arecibo, sent a few commands, and started gathering data to plot where the spacecraft is and where it will be. A lot has happened in a week, and the team is now happy to report the spacecraft is alive and well, and much, much closer to the intended trajectory than initially believed.

Before last week, the best data on where ISEE-3 was heading was from a 13-year-old data set, leaving the project coordinators to believe a maneuver of about 50-60 m/s was necessary to put the spacecraft into the correct orbit between the Earth and the sun. With new data from Arecibo, that figure has been reduced to about 5.8 m/s, putting it extremely close to where the original ICE navigation team intended it to go, all the way back in 1986. This also gives the team a bit of breathing room; the original planned maneuver to capture the spacecraft required nearly a third of the available fuel on board. The new plan only requires the spacecraft expend about 5% of its fuel stores. This, of course, brings up the idea of continuing the planned mission of the rebooted ISEE-3 beyond the Earth-Sun L1 point, but that is very much putting the cart before the horse.

Of course, getting ranging data of the spacecraft is only a small part of what has happened with the ISEE-3 part this week. Thanks to the ‘away team’ sent to Arecibo to install hardware and attempt to make contact with the satellite, both transceivers are working, telemetry is being downloaded from the probe, and work has begun on refining the exact position of ISEE-3 to compute where and when the spacecraft needs to make its maneuver.

Regular Hackaday feature and software defined radio god [Balint] was on hand with the away team at Arecibo to install his company’s SDR unit on the largest dish on the planet. His happy dance of the first data from ISEE-3 made the blog rounds, but the presentation (PDF) and photo gallery tell the story of working on the largest dish on the planet much better.

There’s still a lot of work to be done by the ISEE-3 team as they figure out how best to capture the spacecraft and prepare for the burn in the following week. They should have the exact orbit of ISEE-3 nailed down early this week, and after that, ISEE-3 could on a path back home in less than two weeks.

Talking To ISEE-3

May 29, 2014 by Brian Benchoff 18 Comments

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ISEE-3, the plucky interplanetary spacecraft fueled by the dreams of thousands of crowdfunding backers and hydrazine is now transmitting data to Earth.

Where all radio contact with ISEE-3 this year has only been a carrier frequency, the folks at the reboot project have successfully commanded ISSE via the huge Arecibo telescope to transmit data back to Earth. Usable data are now being received at 512 bits/second at ground stations in Germany, Kentucky, and California, surely being looked over by the ISEE reboot project engineers.

Simply transmitting the commands to put the data multiplexers into their engineering telemetry mode was no small task; a power amplifier needed to be built, shipped to Arecibo, and installed in the giant dome hanging over the Arecibo dish. The amplifier was only installed in the last day, during an earthquake, no less.

There’s still a lot of work to be done before the project can go any further; the team will need to check the status of the spacecraft from the data received, more systems will be checked out, and eventually the spacecraft will be commanded to perform a 17-hour long burn with its small thrusters, putting it on course to be captured by Earth some time in August.

It’s an amazing achievement to do any sort of communication on this scale, and now events in the ISEE-3 mission timeline will be coming rather quickly. We’re trying to organize a video/blog/cast thing with the team from NASA Ames or Morehead State, but the team is, understandably, a little busy right now.

ISEE-3: Ready To Come Home

May 16, 2014 by Brian Benchoff 31 Comments

The team working to reboot the ISEE-3 satellite hurtling towards an August encounter with Earth is hard at work. They’ve put up a crowdfunding page, and now that they’re completely funded (don’t stop donating, btw), they’re starting to go deeper into the waters that will allow them to capture a forgotten satellite.

The project put up a status report going over what they’ve accomplished so far, and what work has yet to be done. For a few months now, they knew both transmitters aboard the craft were operational, but they were not sending telemetry. The team has gone through the documentation, came up with a set of commands, and are currently en route to Arecibo to transmit those commands.

Two ground station transmitters are being constructed, one specifically built to be installed at Arecibo for this application. The other is a portable, self-contained 700 watt transmitter that will be used at the official ISEE-3 ground station in Morehead State University in Kentucky.

With transmitters taken care of and receiving handled by an SDR from Ettus Research, a lot of work has focused on the command and telemetry systems. In 1978, the user interface for commands and telemetry was primitive to say the least. The team is now working on a system built-in Labview that’s much easier on the eyes than the vintage text terminal screens.

So far, signals from ISEE-3 are planned to be received at Arecibo, Morehead State, and Bochum observatory in Germany. This will give the team extremely good coverage for most of a day, and there are other ground stations in California that will extend the time the team is able to communicate with ISSE-3 each day by a few hours.

There’s still a lot of work to be done; the team really doesn’t know what systems are still operating, although most of them did make it 20 years with only one fault. In the next few days, we’ll all get to see if this satellite will be up to the task of coming back home to Earth. If everything goes to plan, ISEE-3 will be on track towards a 17 hour burn to put it on the correct trajectory some time in mid June.