Why was the James Webb telescope launched by Ariane instead of a US company Like SpaceX or the ULA?

[RV_]

It is a US project. So why the European agency? Because the launch was free! I found this article with all the FAQs about the telescope. Read why it was free.

Excerpt:

"Why was the Ariane 5 chosen to launch Webb? Why did NASA not change to Space X?

We chose Ariane in the early 2000's for a combination of reliability (it was the only launch vehicle that met NASA's requirements for launching a mission like Webb) and for the value it brings via our international partnership.

By "value" we mean that the European Space Agency provides us a launch vehicle and associated services on a no exchange of funds basis. In exchange, NASA guarantees European scientists a fraction of observing time on Webb (roughly 15%). Since architectural realities of Webb and international technology restrictions (plus industrial capabilities and strategic technology interests) meant we couldn't have a spacecraft bus or a sunshield or telescope parts from Europe, we asked for the launch vehicle, launch services and science instruments instead.

Another reason not to change launch vehicles midway through a project is because each vehicle has its own environmental characteristics. Rockets are all similar to an extent, but they do have significant differences in their major vibro-acoustic modes. Designing something to encompass any/all environmental specifications is pretty tough, adds cost and mass, and reduces capability. Knowing your launch vehicle early helps you design for it. Also, launch programs (ascent profiles) are specific not only to the vehicle but are even quasi-specific to the day of the year and time of day. This means you need to know not only your launch vehicle but your launch location.

Agreements with Ariane were made to ensure the use of the Ariane 5 for our launch in 2021."

Here are the links to each FAQ:

• General Questions about Webb

   

  • What is the James Webb Space Telescope?
  • What was the Webb called before it was named after James Webb?
  • Who was James E. Webb?
  • How will Webb be better than the Hubble Space Telescope?
  • When was Webb launched?
  • How did Webb's launch windows work?
  • How was Webb launched?
  • Why was the Ariane 5 been chosen to launch Webb? Why did NASA not change to Space X?
  • What happens after Webb is launched?
  • Was there flexibility built into the planned deployments?
  • Why do we have to go to space at all? Can we not get these data with large telescopes on the ground, using adaptive optics?
  • How long will the Webb mission last?
  • Why is Webb not serviceable like Hubble?
  • Why did we not assemble Webb in orbit?
  • How was testing different for Hubble and Webb's mirrors? What did Hubble teach us?
  • Will Webb use gyroscopes for pointing?
  • How is Webb pointed?
  • How big is Webb?
  • Why does the sunshield have five layers rather than one thick one?
  • How will Webb communicate with scientists at Earth?

   

• Webb's Orbit

   

  • How long will it take Webb to reach its orbit?
  • Why does Webb have to go so much farther away from Earth than Hubble? What is the second Lagrange point orbit?
  • Is Webb’s view limited because of its orientation and is its sunshield blocking out part of the sky?

   

• Webb's Mirrors

   

  • How can Webb's primary mirror be six times the size of Hubble's but be less massive?
  • The primary mirror on Webb is made of beryllium. What is beryllium?
  • How did you protect Webb from the violent forces involved in the Ariane rocket launch? Isn't beryllium brittle?
  • Will micrometeoroids damage the beryllium mirror?
  • Why is the mirror gold-coated and how much gold is used?
  • Why does Webb have a segmented, unfolding primary mirror?
  • What is Webb's angular resolution, and how will its images compare to Hubble's? Will they be as beautiful?

   

• Webb's Instruments & Technology

   

  • What kind of instruments does Webb have?
  • What kind of detectors does Webb have?
  • What is the operating temperature of the telescope and the instruments?
  • Can Webb take selfies?

   

• Webb Science

   

  • Why is Webb optimized for near- and mid-infrared light?
  • What about visible light?
  • At which wavelengths will Webb observe?
  • How faint can Webb see?
  • What are the main science goals of Webb?
  • How far will Webb look?
  • Will Webb see planets around other stars?
  • Can Webb observe planets in our own solar system?
  • What will Webb's first targets be?
  • Will Webb contribute to the dark matter research?
  • What about dark energy?
  • Will Webb be able to tell us more about the Big Bang?

   

• Building and Using Webb

   

  • Who are the partners in the Webb project?
  • Which states are involved?
  • Which countries are involved?
  • Who will be able to use Webb and how is this decided?

   

• Webb and the Public

   

  • Will I be able to see Webb pictures?
  • Will Webb images look as good as Hubble's?
  • Where did Webb launch?

   

• Basic Science

   

  • What will the first galaxies that formed after the Big Bang look like?
  • What is redshift and how do you measure it?
  • What is a light-year? And what is a parsec?
  • What is a micrometer? What is a micron?
  • What is an arc-minute? What is an arc-second?
  • What is infrared radiation?
  • What is the electromagnetic spectrum?
  • How does our atmosphere block infrared radiation from space?

   

• More Information

   

  • How can I find out more about Webb?
  • Do you have anything for kids?
  • I'm a professional astronomer - how can I find out more about Webb?

[Darryl&Rita]

Thanks, RV. That's an impressive collection of links that need exploring.

[RV_]

YW Darryl! I like them because they have something for the lay person, the engineers and the US taxpayers.