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SLS liquid hydrogen tank test article placed on test stand

The structural test article for the Space Launch System's liquid hydrogen tank is loaded onto Test Stand 4693 at NASA's Marshall Space Flight Center in Huntsville, Alabama. Photo Credit: Tyler Martin / NASA

The structural test article for the Space Launch System’s liquid hydrogen tank is loaded onto Test Stand 4693 at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Photo Credit: Tyler Martin / NASA

Even though much of the U.S. space agency is currently furloughed due to the ongoing partial U.S. government shutdown, some work is still being done on NASA’s most important programs, including the Space Launch System, which could fly as early as 2020.

According to the U.S. space agency, the largest piece of structural test hardware for the SLS — the 149-foot (45-meter) tall liquid hydrogen tank for the core stage — was loaded onto the 215-foot (66-meter) tall Test Stand 4693 at NASA’s Marshall Space Flight Center in Huntsville, Alabama, on Jan. 14, 2019.

“The liquid hydrogen tank test article is structurally identical to the flight version of the tank that will comprise two-thirds of the core stage and hold 537,000 gallons of supercooled liquid hydrogen at minus 423 degrees Fahrenheit,” a NASA news release reads.

The full core stage of SLS, which includes a liquid oxygen tank, will measure 212 feet (65 meters) tall and have a diameter of 27.6 feet (8.4 meters). Together they will feed four RS-25 engines at the base of the rocket to produce 1.6 million pounds (7,440 kilonewtons) of thrust.

Combine that with two five-segment solid rocket boosters, the SLS is expected to have a total liftoff thrust of about 8.8 million pounds (39,400 kilonewtons).

NASA said dozens of hydraulic cylinders in Test Stand 4693 will “push and pull the tank,” to subject it to stresses the core stage is expected to see during launch.

As of right now, the first test flight — the uncrewed Exploration Mission 1 — is expected sometime in mid-2020. It will see an Orion spacecraft fly around the moon before coming back to Earth for a splashdown in the Ocean.

Photo Credit: Tyler Martin / NASA

Photo Credit: Tyler Martin / NASA



Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity.

Reader Comments

Once this single flight takes place NASA can abandon SLS and move on to using Falcon Heavy.

Curiously, SpaceX Starship may even proceed this single SLS launch event and return to land at the launch pad for reuse versus being discarded like SLS.

A reusable spaceship, built with private funds and at a small fraction of SLS costs. An easy choice.

“Most important programs…”

You’re kidding, right?

James Lunar Miner

The SLS is far more important than the grossly propellant inefficient and CO2 spewing fossil fueled SpaceX Starship/space bomber.


The SLS will be used to launch reusable 130 metric ton propellant efficient 900+ Isp Nuclear Thermal Rocket upper stages that will have far greater and more useful delta-v capabilities than the overweight and low 380 Isp and limited delta-v of the Starship/space bomber.
‘Space Dominance’ and Lunar mining missions require high performance Nuclear Thermal Rocket propellant efficiency that is far beyond the inherently limited capabilities of the propellant inefficient Starship/space bomber.

James Lunar Miner

Why do the confused folks expect everyone to respect the propellant inefficient, slow, space radiation riskier, and overweight fossil fueled cult starship/spaceship when NASA experts want far more propellant efficient, faster, and safer nuclear thermal rocket powered spacecraft?


“Nuclear thermal propulsion is ‘the most effective’ way of sending humans to Mars.”

And, “That’s according to Nasa administrator and former astronaut, Charles Bolden, who made the statement when speaking to Congress this week.”

And, “‘We are on a journey to Mars and most people believe that, in the end, nuclear thermal propulsion will be the most effective form of propulsion to get there,’ he said.”

And, “Nasa is betting on nuclear propulsion because it weighs almost half as much as a chemical rocket without reducing thrust.”

And, “This means larger payloads of cargo can be carried on the spacecraft and they can also be made to travel far faster.”

From: “Nasa wants to use nuclear rockets to get to Mars: Space agency claims the technique is ‘most effective way’ of reaching red planet”
By Ellie Zolfagharifard March 18, 2016

SLS will fly once and the entire system will be discarded.

Not to worry, SpaceX will be there to actually get us out of the gravity well with real technology. Not some fantasy power point system which will never be more than a pretty drawing.

James Lunar Miner

Both Russia and China have made plans to benefit from the excellent propellant efficiency and cost reductions that are offered by nuclear-powered spacecraft.

Russians built and tested the 900+ Isp RD-0410 nuclear thermal rocket engine more than three decades ago and yet today we have a neo luddite Mars colonies soon cult trying to sell America on a grossly propellant inefficient 380 Isp SpaceX starship/space bomber.


“Neo-Luddism is a leaderless movement of non-affiliated groups who resist modern technologies and dictate a return of some or all technologies to a more primitive level.[3] Neo-Luddites are characterized by one or more of the following practices: passively abandoning the use of technology, harming those who produce technology, advocating smple living, or sabotaging technology.”

From: “Neo-Luddism” Wikipedia

The SLS will be used to launch the international Orion spacecraft and reusable 130 metric ton solar or nuclear electric propulsion powered space tugs that will have 6 to 36+ times the propellant efficiency of the fossil fueled Falcon Heavy’s and Starship/space bomber’s respective upper stages.

Do we Americans want to haul mainly useful cargo into LEO and to the Moon, asteroids, and Mars and win our Cold War II or do we instead foolishly want to mainly haul the massive amounts of low energy fossil fuel propellants that are needed for grossly propellant inefficient fossil fueled rocket propulsion systems and thus become losers in our Cold War II?

James Lunar Miner

The cult folks of the grossly propellant inefficient (and low 380 Isp) SpaceX starship/space bomber powered by energy weak fossil fuel rocket engines may remain confused and lost in space, but the experts at the European Space Agency (ESA) understand the critical importance of advanced space propulsion technology and highly propellant efficient solar powered electric propulsion systems to enable cost effective Lunar missions for both large and small spacecraft.

Note concerning the ESA’s 367 kg SMART-1:

“SMART-1 was about one metre across (3.3 ft), and lightweight in comparison to other probes.”

And, “It was propelled by a solar-powered Hall effect thruster (Snecma PPS-1350-G) using xenon propellant, of which there was 82 kg (50 litres by volume at a pressure of 150 bar) at launch. The thrusters used an electrostatic field to ionize the xenon and accelerate the ions to a high speed. This ion engine setup achieved a specific impulse of 16.1 kN·s/kg (1,640 seconds), more than three times the maximum for chemical rockets.”

And, “Total ΔV: 3.9 km/s”

And, “Xenon throughput: 82 kg”

And, “SMART-1 was launched September 27, 2003 together with Insat 3E and eBird 1, by an Ariane 5 rocket from the Guiana Space Centre in French Guiana. After 42 minutes it was released into a geostationary transfer orbit of 7,035 × 42,223 km. From there it used its Solar Electric Primary Propulsion (SEPP) to gradually spiral out during thirteen months.”

From: “SMART-1” Wikipedia

James Lunar Miner

The SLS can launch huge, reusable, 130 metric ton, 1,600 to 14,000+ Isp (and thus super propellant efficient and highly mission capable) nuclear or solar electric propulsion space tugs.

The confused Neo-Luddite folks have babbled on about Mars colonies supported by the grossly propellant inefficient (and low 380 Isp) fossil fueled BFR/Starship/space bomber, while smart engineers in the world of commercial spacecraft building have bought into the high Isp and large propellant efficiency driven cost reductions that are gained by using various high Isp solar electric propulsion systems.

“The SSL 1300, previously the LS-1300 and the FS-1300, is a satellite bus produced by SSL (company). Total broadcast power ranges from 5 to 25 kW, and the platform can accommodate from 12 to 150 transponders.”

And, “SSL stated that they would use electric propulsion for North-South station keeping for the first time on the MBSat in 2004. The subsystem was supplied by International Space Technologies Inc and used Fakel’s Hall thrusters and American and European propellant supply and electronics.”

And, “There are more SSL 1300’s currently providing service on orbit than any other model communications satellite.[6]”

And, “The 1300 was the first Western satellite to use electric propulsion, which reduces mass allowing for more payload power or a less costly launch. Today there are 18 1300s with electric propulsion on orbit.[6]”

From: “SSL 1300” Wikipedia

James Lunar Miner

Concerning the above noted “Fakel’s Hall thrusters” produced by an important electric propulsion company:

“OKB Fakel (Russian ОКБ ‘Факел’) is a Russian electric propulsion system development company. It is located in Neman in Kaliningrad Oblast.[2][3] It was founded in 1955 as a Propulsion laboratory of the Soviet Academy of Sciences; in 1962 it obtained status of Design Bureau, OKB. [4]”

And, “Fakel specializes in spacecraft attitude control thrusters, ion engines and plasma sources.[2] It is a world leader in the field of Hall thruster development and a leading Russian developer and manufacturer of electric propulsion systems.[5]”

And, “The company’s third-generation electric propulsion system SPT-100 has been certified in accordance with western standards and the company is actively marketing the system to foreign customers.[2]”

And, “Many companies have used Fakel electrically powered spacecraft propulsion systems on their hardware flown in space. Company’s hardware were used on SESAT 1, Alphasat, SMART-1, LS-1300, Meteor spacecraft, USP bus, Amos-6, MobaHo!, Inmarsat-4 F3, Astra 1K, Luch, and many others as well.”

From: “OKB Fakel” Wikipedia

Currently, Russia is working on a super high Isp (and thus super propellant efficient) nuclear powered electric propulsion system which could help to implement Russian commercial and military dominance in LEO, Cislunar Space, and on the Moon and asteroids.

See: “Russia ‘tests’ key piece of nuclear space engine to revolutionize long-range missions”
October 29, 2018

” SLS can launch huge, reusable, 130 metric ton”
Nope. It can’t launch anything. It’s never flown and will likely fly only once.

James Lunar Miner

Boeing understands the commercial benefits of the cost effective and propellant efficient electric propulsion system on its 702SP satellite.

Someday, the SLS might launch huge, reusable, 130 metric ton electric propulsion Boeing spacecraft that could efficiently haul far more cargo than the grossly propellant inefficient fossil fueled SpaceX Starship/space bomber.

“The Eutelsat and ABS satellites will launch without a supply of conventional liquid hydrazine fuel, relying entirely on electric ion engines to reshape their orbits and maintain their positions for up to two decades.”

“‘Going to an all-electric system, you’re able to reduce the fuel load by almost a factor of 10,’ Connelly said. ‘That fuel load reduction allowed us to stack the satellites on top of each other, and give the customers a two-for-one deal on the launch costs.’

From: “Boeing’s first two all-electric satellites ready for launch” By Stephen Clark 3/1/2015

NASA also understands the benefits of highly propellant efficient electric propulsion systems!

“But getting to Psyche won’t be easy. It requires a cutting-edge propulsion system with exceptional performance, which is also safe, reliable and cost-effective. That’s why the mission team has turned to NASA Glenn Research Center in Cleveland, which has been advancing solar electric propulsion (SEP) for decades.”

From: “NASA Glenn Tests Thruster Bound for Metal World”
September 28, 2017

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