ed | A Not-so-final Hubble Servicing Mission

The Hubble House Telescope is likely one of the best instruments ever designed for science. It has studied questions far past the attain of another instrument. With its three deep discipline exposures alone, it has seen farther at extra wavelengths than any ground-based telescope, and it revolutionized our understanding of the early universe. For many years, some scientists have predicted that adaptive optics would “quickly” render it out of date. Hubble has proved them unsuitable each time.

Twenty-five years after launch, the queue of scientists hoping for a shot of Hubble telescope time extends across the proverbial block. These on the finish of the road could also be dissatisfied. The ultimate Hubble servicing mission was launched in Could 2009 and, absent the area shuttle, we’re instructed Hubble can’t be repaired once more.

With out one other servicing mission, Hubble will inevitably fail, most certainly early within the subsequent decade. However is the shuttle actually essential to mount a restore mission?

Scientists had hoped to function Hubble similtaneously the James Webb House Telescope, presently deliberate for launch in late 2018. Regardless of its big 6.5-meter major mirror, and its being marketed as a “successor” to Hubble, it’s not a successor. Webb is optimized for infrared wavelengths extending simply into the seen vary (orange), whereas Hubble operates at ultraviolet and visual wavelengths, extending simply into the near-infrared. The 2 devices are complementary, with a slight overlap. There isn’t any successor to Hubble; no comparably massive area telescope designed to look at at seen or ultraviolet wavelengths is anyplace close to launch.

Persevering with technological and administration issues with the JWST could properly delay that instrument’s debut past Hubble’s skill to outlive with out additional upkeep. If that’s the case, a tremendously priceless but low-cost scientific alternative to concurrently look at the identical objects at excessive decision throughout a particularly broad vary of optical and infrared frequencies will slip away.

Hubble was designed for servicing in orbit, and 5 restore flights have been carried out by area shuttle astronauts, together with the preliminary one to put in further lenses to compensate for a flawed major mirror. (Confusingly, NASA counts 4 upkeep missions, as a result of mission three was cut up into two flights, servicing missions 3A and 3B.)

Any future restore mission will most certainly want to switch failed gyroscopes and reboost the telescope into a better orbit. The gyroscopes spin at 19,200 revolutions per minute on gasoline bearings to measure and counter telescope drift, offering a particularly nonetheless platform for observations. In keeping with the European House Company, they’re the very best obtainable, however having shifting elements they’re liable to failure.

Hubble’s orbit is low sufficient to come across odd particles of air on the high of the environment. Friction with these causes the orbit to slowly decay. And not using a increase, it is going to re-enter early within the 2020s. Changing devices with extra up-to-date cameras could be good, however shouldn’t be important to maintaining Hubble in enterprise and productive.

When it comes to sources, the flexibility to hold cargo and to conduct spacewalks is crucial. Extra propellant or a propulsion module is required for the reboost. We are going to quickly have a minimum of one spacecraft with all of those traits.

The SpaceX Falcon 9-launched Dragon v2, or “Crew Dragon,” is a NASA-subsidized, privately owned, human-rated capsule in superior growth. If the remainder of its growth goes properly, it may fly as early as 2016 and be operational in late 2017. It’ll have each one of many required traits. Crucially, it has what quantities to a miniature model of the area shuttle’s payload bay — an unpressurized “trunk.”

SpaceX Crew Dragon. Credit score: SpaceX artist’s idea

The trunk is the cylindrical adapter between the spacecraft and its Falcon 9 launch automobile, which stays with the Dragon capsule till simply earlier than re-entry. The freighter model of the Dragon has already carried quite a lot of massive experiments in its trunk for mounting on the outside of the Worldwide House Station. If the business crew trunk is used the identical means, it ought to be capable to simply carry a number of 11-kilogram Hubble price sensor items, every concerning the dimension of a breadbox and carrying two gyroscopes. The telescope has a complete of six gyroscopes; three are required for regular observations.

The Crew Dragon additionally has highly effective rocket engines mounted round its perimeter to flee an exploding rocket. If these engines are usually not wanted in an emergency, their gasoline is offered to be used in orbit.

SpaceX, producer of each the Dragon and the Falcon 9, did a really preliminary, casual research of utilizing Crew Dragon with a robotic arm to deorbit Hubble, or to restore and reboost the telescope. This was a part of a wider SpaceX PowerPoint presentation on utilizing Crew Dragon to service satellites, publicly launched in March 2010 simply earlier than the primary Falcon 9 launch.

On the time, the Crew Dragon design was envisioned as being nearer to that of the Dragon business cargo spacecraft than is the case at the moment, however its gross traits have been just like at the moment’s specs.

The research envisioned three crew members (versus the seven astronauts Crew Dragon is theoretically able to carrying) with an undetermined variety of spacesuits. Gear for extravehicular exercise could be saved within the trunk, together with a small propulsion module. The module would connect to the docking gadget that was mounted on Hubble through the ultimate shuttle servicing mission. Below one situation, the propulsion module could be used to securely deorbit Hubble right into a terrestrial ocean — and that may be that.

A extra attention-grabbing situation would use the robotic arm and/or spacesuited astronauts to alter out failed tools, and presumably to put in a brand new instrument or two. The propulsion module would then increase Hubble into a better orbit, the place it will proceed operations. With common servicing flights, Hubble may conceivably stay lively and productive indefinitely.

In December 2014, David L. Akin of the College of Maryland’s House Methods Laboratory introduced the outcomes of his research of sustaining Hubble utilizing the Crew Dragon or Sierra Nevada Corp.’s Dream Chaser business crew spaceplane. He thought-about mounting an inflatable airlock within the nostril cap of Dragon to enhance the effectivity of spacewalks, though this may make it unattainable to kind a inflexible dock to Hubble. The trunk may maintain comparatively lengthy and sturdy robotic arms — with extra joints, one design may be as succesful because the shuttle’s Canadarm. If two smaller arms have been carried, one may kind a “comfortable dock” and create a path for astronauts to make use of to get to the telescope, whereas the opposite manipulated cargo and instruments.

SpaceX doesn’t present a lot data to the general public about its plans, and even particulars of practically operational automobiles. Nevertheless, Akin instructed me, “As I perceive it, the avionics on Dragon are able to working in a vacuum,” that means the capsule could possibly be evacuated to permit spacewalks with out the inflatable airlock. He added, “SpaceX can be growing their very own spacesuit in home.”

Akin stated he didn’t have sufficient particulars concerning the different winner of NASA’s business crew competitors, Boeing’s CST-100, to judge it for a Hubble upkeep mission. It’s not clear that the CST-100 would be capable to carry the required cargo, though that may be launched on a separate flight. Akin concluded that the loser in NASA’s business crew competitors, Sierra Nevada’s Dream Chaser mini-shuttle, would provide some benefits over Dragon. At a March 17 press convention to disclose the automated cargo model of Dream Chaser, meant to win a business cargo contract to produce the Worldwide House Station, Sierra Nevada talked about utilizing a crewed model to keep up Hubble. Sadly, that concept stays a political and technical lengthy shot. Dream Chaser must win a cargo contract over the incumbent business cargo contractors (SpaceX and Orbital ATK) and discover the monetary wherewithal to adapt that to the crewed model — all earlier than Hubble succumbs to the environment. Nevertheless, Akin concludes that Hubble servicing is “undoubtedly possible” from both Dream Chaser or Dragon.

Lockheed Martin has proposed a spacecraft referred to as Jupiter for the following spherical of area station business cargo contracts. In keeping with the corporate, “The Jupiter spacecraft builds upon the design of MAVEN, now in orbit round Mars, and OSIRIS-REx, presently underneath building for an asteroid pattern return mission,” with the addition of a robotic arm. After its first launch with an hooked up cargo module, Jupiter could be left in orbit to dock with new, individually launched modules, which might ship cargo to the area station — reasonably like standardized transport containers are loaded aboard seagoing freighters — or to conduct satellite tv for pc upkeep missions. This automobile, with its robotic arm, pressurized module and talent to hold cargo, could be an excellent companion to one of many business crew automobiles in supporting a Hubble restore.

Neither NASA nor SpaceX has unambiguously revealed the price of a Crew Dragon mission, however it’s clear {that a} Dragon Hubble upkeep flight would value a lot lower than an area shuttle servicing mission. Science author Govert Schilling final yr urged a crowdfunding marketing campaign to boost among the cash, a method he stated some on the House Telescope Science Institute have been contemplating. House analyst Tim Kyger urged SpaceX ought to negotiate doing it “on their very own dime. “It may be salvage,” he stated, after which SpaceX may personal Hubble outright and lease it out to scientists.

With two business crew automobiles being ready for flight, along with NASA’s Orion spacecraft, we’re coming into a interval when human spaceflight will probably be comparatively routine and low-cost.

There isn’t any longer any excuse to wastefully abandon main property — constructed and positioned in orbit at nice expense — and allow them to fall into the ocean. After refurbishing Hubble, NASA must also think about using Orion to keep up the JWST, using a docking ring that was added to the telescope for simply such a contingency.

As we strategy Hubble’s twenty fifth anniversary on April 25, it’s time to begin planning for the observatory’s subsequent 25 years.

Donald F. Robertson is a contract area business journalist primarily based in San Francisco. He’s a shareholder of Orbital ATK, an organization talked about on this article. For additional examples of his work, see www.DonaldFRobertson.com. Observe him on Twitter: @DonaldFR

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