John Mather, Nobel Laureate and Webb Telescope project scientist answers "Tweet Chats" questions on Reddit.


Question & Answer

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    Fact sheet on the Webb Mission.

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    The most popular questions about Webb. (General Public)

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    All the major aspects of the Webb Mission are covered here. (General Public)

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    Technical FAQ on a variety of mission issues, aspects and capabilities. (Science/Technical)

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    Technical FAQ specifically on Solar System observations. (Science/Technical)

Tweet Chat #1
with John Mather

These are the answers Dr. John Mather (Nobel Laureate and James Webb Space Telescope project scientist) gave to questions asked on Twitter during our first Tweet Chat. The answers are very succint due to Twitter's 140 character limit (and we also added the #JWSTscience hashtag to each answer). Often the questions are rephrased in the answers so that our Twitter followers would know what we were giving the answer to.

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Out of the 5 lagrangian points....why L2 is chosen? (asked by @Aghori_thinks)

Why L2? It's close to Earth and the sunshield protects the spacecraft from both Sun and Earth at the same time.

How will JWST help in the search for habitable planets ? (asked by @arundeepkohali)

How will JWST find habitable planets? It will observe planetary atmospheres through the transit technique.

Will JWST be able to measure what the planets around other stars atmospheres are made of? (asked by @HarryBostock1)

Yes, #JWST will be able to measure what exoplanets' atmopsheres are made of.

If the CMB is the border between IR and MW, how close to it will an object be resolved? Or, How far back can we see? (asked by @BillTheScribe) How far back will you be able to see? Close to the big bang?(asked by @gemmaloubryan)

How far back will #JWST see? We can see the first objects that formed 200 millions years after the Big Bang.

Will it have the resolution to detect atmospheres in Exo-planets? Specifically signs of pollution to indicate industry. (asked by @BillTheScribe)

Can JWST detect pollution in exoplanet atmospheres? We're not expecting to find it, but JWST could detect chlorofluorocarbons - CFCs.

Not JWST exactly, but blackbody. Can something be so cold it emits radio instead of IR? (asked by @BillTheScribe)

Can something be so cold it emits radio instead of IR? Yes! The Cosmic Microwave Background emits at millimeter & microwave.

Is there any possiblity of capturing the FIRST Light in near future by JWST or any other future devices? (asked by @Aghori_thinks)

We will look for the first luminous objects but the very first light was the Big Bang itself. The heat of the Big Bang has been seen already - it is the Cosmic Microwave Background.

Any plans or provisions to image objects in our own solar system? (asked by @BillTheScribe)

We will absolutely image objects in our solar system. Except for those between the spacecraft and the Sun!

Do you anticipate JWST being used to further characterize Type 1a SNs from diff. sources? (asked by @raphaelperrino)

We will be able to see them further back towards the beginning of time when we think conditions were different. More detailed SN1a info here:

Do you think that thr JWST will be able to look expand our understanding of dark matter and dark energy? (asked by @HarryBostock1)

JWST will be able to measure the gravitational effects of dark matter on galaxies & will measure dark energy more precisely!

What are the odds that the JWST will pull a Hubble and continue to deliver years after the primary mission ends? (asked by @BillTheScribe)

Will JWST continue like HST? We expect to continue doing wonderful science as long as the observatory is alive!

Why is JWST specifically designed to work in IR over the other regions of electromagnetic spectrum? (asked by @Aghori_thinks)

Why IR? It's almost unexplored, you can see the highly-redshifted earliest galaxies, & see stars form inside dust clouds.

Is JWST capable of taking direct pictures of exoplanets? (asked by @arundeepkohali)

Can JWST take direct pictures of expolanets? Yes, if they are big and bright and far from the star. #JWSTscience

What is the ultimate goal of james webb? (asked by @BeccaWinkert)

Our goal - to help understand the history of the universe, from the beginning to the future and our place in it. Another goal of #JWST is to help understand the conditions leading to human life.

Oh, speaking of first light, any idea of the first few targets once the science starts? (asked by @BillTheScribe)

First targets? We haven't decided, but we'll start with the easy ones! (Nearby objects.)

What rocket will you be using to send it up? (asked by @HarryBostock1)

We will launch on an Ariane 5 rocket.

How far back in time will the #JWST be able to peer? What do you expect to discover? (asked by @CyaeghaUK)

We'll see back to 200 million years after the Big Bang, and hope to discover whether the first objects were stars or blackholes.

What/how measurements were taken to conclude that dark matter,energy accounts for 96%? (asked by @Aghori_thinks)

Great WMAP page on dark matter/dark energy: JWST will add to our knowlegde of dark energy.

If exoplanets are as far as our Earth is from sun. Can they be captured by JWST's camera? (asked by @arundeepkohali)

If Earth were an exoplanet it would be too close to the Sun for JWST to see it. Would need to be brighter/more distant.

What are the parameters that determine the life span of JWST? Rocket propellent to reposition? etc (asked by @JGuirreri)

Rocket propellant is the only life span limiter for JWST. We are carrying at least 10 years supply.

What about in-space refueling the telescope? Would it be possible to extend the mission lifespan this way? (asked by @hrissan)

In-space refueling of #JWST? Logically possible but difficult. It would require robots!

Will HST be phased out of commission as JWST matures? (asked by @vyresince)

It's so magnificent we can't imagine turning it off! As long as it stays alive, we suspect it will continue to do great science!

Since the resolution is no better than Hubble will we be able to tell anything more about the structure of early galaxies? (asked by @Michael_RA)

Our resolution is better than Hubble and we will see early galaxies when they were young by using infrared. Also, Hubble can't see the very first galaxies but we will be able to.

Not related to JWST but with the presence of dark mater/energy, how come Andromeda, Milky way collide? (asked by @Aghori_thinks)

Why are the MilkyWay and Andromeda colliding? They are pulling towards each other with their own gravity! #JWSTscience

I thought it was still 0.1 arc sec like Hubble. The mirror is bigger but the infrared lowers effective resolution. (asked by @Michael_RA)

Our pixels are .032 arc seconds.

Do you look better the planets of solar system with JWST or with the Hubble? (asked by @SaganDawkins)

Is JWST or Hubble better for looking at our planets? Each does different science. IR gives a different view!

What if the dark ages weren't really dark. (asked by @WimVO)

What if the dark ages weren't really dark? I guess that's something that will need some light shed on it!

Would it ever be possible to service it once it's in position? (Pretty sure "no" but someone I know sees that as a flaw.) (asked by @BillTheScribe)

JWST wasn't designed for servicing (would be very expensive to build it that way) and it is also very delicate.