How Does The James Webb Telescope Phone Home?

When it comes to an engineering marvel like the James Webb Space Telescope, the technology involved is so specialized that there’s precious little the average person can truly relate to. We’re talking about an infrared observatory that cost $10 billion to build and operates at a temperature of 50 K (−223 °C; −370 °F), 1.5 million kilometers (930,000 mi) from Earth — you wouldn’t exactly expect it to share any parts with your run-of-the-mill laptop.

But it would be a lot easier for the public to understand if it did. So it’s really no surprise that this week we saw several tech sites running headlines about the “tiny solid state drive” inside the James Webb Space Telescope. They marveled at the observatory’s ability to deliver such incredible images with only 68 gigabytes of onboard storage, a figure below what you’d expect to see on a mid-tier smartphone these days. Focusing on the solid state drive (SSD) and its relatively meager capacity gave these articles a touchstone that was easy to grasp by a mainstream audience. Even if it was a flawed comparison, readers came away with a fun fact for the water cooler — “My computer’s got a bigger drive than the James Webb.”

Of course, we know that NASA didn’t hit up eBay for an outdated Samsung EVO SSD to slap into their next-generation space observatory. The reality is that the solid state drive, known officially as the Solid State Recorder (SSR), was custom built to meet the exact requirements of the JWST’s mission; just like every other component on the spacecraft. Likewise, its somewhat unusual 68 GB capacity isn’t just some arbitrary number, it was precisely calculated given the needs of the scientific instruments onboard.

With so much buzz about the James Webb Space Telescope’s storage capacity, or lack thereof, in the news, it seemed like an excellent time to dive a bit deeper into this particular subsystem of the observatory. How is the SSR utilized, how did engineers land on that specific capacity, and how does its design compare to previous space telescopes such as the Hubble?

Continue reading “How Does The James Webb Telescope Phone Home?”

NASA’s Flying Telescope Is Winding Down Operations

NASA’s Hubble Space Telescope is arguably the best known and most successful observatory in history, delivering unprecedented images that have tantalized the public and astronomers alike for more than 30 years. But even so, there’s nothing particularly special about Hubble. Ultimately it’s just a large optical telescope which has the benefit of being in space rather than on Earth’s surface. In fact, it’s long been believed that Hubble is not dissimilar from contemporary spy satellites operated by the National Reconnaissance Office — it’s just pointed in a different direction.

There are however some truly unique instruments in NASA’s observational arsenal, and though they might not have the name recognition of the Hubble or James Webb Space Telescopes, they still represent incredible feats of engineering. This is perhaps best exemplified by the Stratospheric Observatory for Infrared Astronomy (SOFIA), an airborne infrared telescope built into a retired airliner that is truly one-of-a-kind.

Unfortunately this unique aerial telescope also happens to be exceptionally expensive to operate; with an annual operating cost of approximately $85 million, it’s one of the agency’s most expensive ongoing astrophysics missions. After twelve years of observations, NASA and their partners at the German Aerospace Center have decided to end the SOFIA program after its current mission concludes in September.

With the telescope so close to making its final observations, it seems a good time to look back at this incredible program and why the US and German space centers decided it was time to put SOFIA back in the hangar.

Continue reading “NASA’s Flying Telescope Is Winding Down Operations”

More Than Just Hubble: The Space Observatories Filling The Skies Today And Tomorrow

Amidst the recent news about the Hubble Space Telescope’s troubles (and triumphant resurrection), it is sometimes easy to forget that although Hubble is a pretty unique telescope, it is just one of many space-based observatories that are currently zipping overhead right now or perched in a heliocentric orbit. So what is it that makes these observatories less known than the iconic Hubble telescope?

Hubble is one of the longest-lived space telescopes so far, and it is also the only space telescope that was both launched and serviced by the Space Shuttle. None of the other telescopes have this legacy, the high-profile, or troubled history of Hubble’s intended successor: the James Web Space Telescope (JWST).

Even so, the mission profiles of these myriad other observatories are no less interesting, least of the many firsts accomplished recently such as a long-term moon-based telescope (Chang’e 3’s LUT) and those of the many upcoming and proposed missions. Let’s take a look at the space observatories many of us have never heard of.

Continue reading “More Than Just Hubble: The Space Observatories Filling The Skies Today And Tomorrow”

The Fix Is In: Hubble’s Troubles Appear Over For Now

Good news this morning from low Earth orbit, where the Hubble Space Telescope is back online after a long and worrisome month of inactivity following a glitch with the observatory’s payload computer.

We recently covered the Hubble payload computer in some depth; at the time, NASA was still very much in the diagnosis phase of the recovery, and had yet to determine a root cause. But the investigation was pointing to one of two possible culprits: the Command Unit/Science Data Formatter (CU/SDF), the module that interfaces the various science instruments, or the Power Control Unit (PCU), which provides regulated power for everything in the payload computer, more verbosely known as the SI C&DH, or Scientific Instrument Command and Data Handling Unit.

In the two weeks since that report, NASA made slow but steady progress, methodically testing every aspect of the SI C&DH. It wasn’t until just two days ago, on July 14, that NASA made a solid determination on root cause: the Power Control Unit, or more specifically, the power supply protection circuit on the PCU’s 5-volt rail. The circuit is designed to monitor the rail for undervoltage or overvoltage conditions, and to order the SI C&DH to shut down if the voltage is out of spec. It’s not entirely clear whether the PCU is actually putting out something other than 5 volts, or if the protection circuit has perhaps degraded since the entire SI C&DH was replaced in the last service mission in 2009. But either way, the fix is the same: switch to the backup PCU, a step that was carefully planned out and executed on July 15th.

To their credit, the agency took pains that everyone involved would be free from any sense of pressure to rush a fix — the 30-year-old spacecraft was stable, its instruments were all safely shut down, and so the imperative was to fix the problem without causing any collateral damage, or taking a step that couldn’t be undone. And further kudos go to NASA for transparency — the web page detailing their efforts to save Hubble reads almost like a build log on one of our projects.

There’s still quite a bit of work to be done to get Hubble back into business — the science instruments have to be woken up and checked out, for instance — but if all goes well, we should see science data start flowing back from the space telescope soon. It’s a relief that NASA was able to pull this fix off, but the fact that Hubble is down to its last backup is a reminder Hubble’s days are numbered, and that the best way to honor the feats of engineering derring-do that saved Hubble this time and many times before is to keep doing great science for as long as possible.