Questions tagged [space-telescope]

Questions regarding telescopes in orbit around Earth, such as the Hubble Space Telescope.

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What is the gravitational lensing focal distance of a white dwarf star?

I tried looking this up, but I couldn't find any formula on gravitational lensing distance. I know that our Sun's is about 550 AU, though further distances work too, as it's not a single focus due ...
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8 votes
4 answers
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Where exactly is the modification that first corrected the spherical aberration in Hubble's primary mirror?

The April 2015 CBS News article How NASA fixed Hubble's flawed vision - and reputation describes the modification taken to the Hubble Space Telescopes by the Space Shuttle that was used to correct for ...
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5 votes
2 answers
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What's still needed before we can observe orbits of exomoons thereby weighing exoplanets?

Comments below this answer to How do we weigh a planet? point out that we currently cannot (or at least have not) detect moons around exoplanets, much less measure the sizes and periods of their ...
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5 votes
1 answer
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Which space telescope is the most distant?

From the earth, and from the sun. Only interested in active, operational ones.
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3 votes
1 answer
205 views

How are space telescopes stabilised to a perfect standstill?

I assume that for space telescopes to get good images, they must be put in perfect standstill, as even the slightest deviation in the viewing angle is amplified by the distance of observed objects, ...
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2 votes
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What would "the next GAIA"-like instrument be like? Could it simply be a 3 to 5x scaled-up version of the same beautiful system?

This excellent, thorough and well-sourced answer to Has a gravitational microlensing event ever been predicted? If so, has it been observed? mentions several works where hundreds to thousands of ...
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5 votes
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Why didn't we see those campfires on the Sun until now?

What is it about its optics and instrumentation (aperture, sensors, filters), being in space and distance from the Sun on 30 May 2020 that allowed Solar Orbiter's HRIEUV telescope to see something ...
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4 votes
1 answer
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Has GAIA learned anything about General Relativity looking near Jupiter? (Gerry Gilmore: "oblate rotating mass moving in a deeper (Solar) potential")

From Gerry Gilmore (2018) Gaia: 3-dimensional census of the Milky Way Galaxy 4.4 Fundamental physics Relativistic effects are highly significant for Gaia measurement accuracy, with tests of General ...
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11 votes
1 answer
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What are the next planned space telescopes?

We've had hubble for two decades. Its become the most famous space telescope, and lately Kepler seems to be running for the second place. Are there any more powerful, better telescopes planned for ...
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7 votes
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Which JWST instrument modes are compatible with observations of the bright trans-Earth planets Mars, Jupiter, and Saturn? Which aren't?

My comment says: ...answers to the Space SE question Can James Webb take pictures of our solar system? In what ways will they differ from/compliment those from Hubble? suggest that at some point JWST ...
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6 votes
4 answers
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Why not use only one support vane for the secondary mirror, to avoid multiple diffraction spikes?

Each vane holding the secondary mirror in front of the primary causes a diffraction spike. Couldn't the secondary mirror be held with only one vane? If stability is the issue, couldn't it be ...
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What (if any) capabilities of Hubble are unique and irreplaceable? What can it do that can't be done by any other ground or space-based telescope?

It's impossible to summarize in an SE post the depth and breadth of the contributions to science made using the Hubble Space Telescope. Above the atmosphere it has access to an extremely dark and ...
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4 votes
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Deciding optical factors between a refractive and reflective space telescope optics as a function of aperture? (visible light)

Reading Yale News' Lighting a path to Planet Nine: To detect objects that are otherwise undetectable, Rice and Laughlin employ a method called “shifting and stacking.” They “shift” images from a ...
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4 votes
1 answer
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How will microshutter arrays be used in the James Webb and future space telescopes?

Question: How will microshutter arrays be used in the James Webb and future space telescopes? Are they acting as a sort of moving pinhole or slit, or is the pattern more complicated, like a coded ...
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2 votes
1 answer
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Can the WISE telescope detect black holes?

Black holes are hot, aren't they? With its infrared scan, could the WISE telescope also detect a black hole? The hypothetical planet beyond the Kuiper belt could actually be a primordial black hole. ...
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1 answer
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When thermal infrared space telescopes spot asteroids, are they seeing the body's own thermal emission, or reflected TIR from the Sun?

From the Space SE question Why has the Earth-Sun libration point L1 been chosen over L2 for NEOCam to detect new NEOs?: above: Profoundly not-to-scale illustration of NEOCam in an orbit around the ...
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Did the Spectr-R space-based radio telescope use on-board accelerometer to measure non-gravitational acceleration for baseline correction?

This answer to Why is space-based VLBI scattering sub-structure "Hopefully, a new promising tool to reconstruct the true image of observed background target(s)"? summarizes the contribution ...
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41 votes
4 answers
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Why are we building larger land-based telescopes instead of launching larger ones into space?

This question is a follow-up to Do bigger telescopes equal better results? How much bigger does a ground-based mirror have to be to match what a space-based one can do? I guess I'm asking primarily ...
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10 votes
3 answers
392 views

Why are telescopes positioned in Lagrange points?

In this Wikipedia article about the list of space telescopes to be launched (which I assume is exhaustive), of the 11 telescopes yet to be launched, 6 will be positioned at the Sun-Earth L2 Lagrange ...
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7 votes
2 answers
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Can the Gaia telescope detect small temporarily captured asteroids near its Lagrange orbit?

The Gaia space telescope is in a Lissajous orbit around the Sun-Earth Lagrange point 2. The orbit period is about 180 days and the size of the orbit is 263,000 x 707,000 x 370,000 km. It has been ...
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7 votes
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Why (the heck) is the basic angle of GAIA 106.5°?

This answer to Why does the Gaia space telescope have two main mirrors says: According to the GAIA FAQs which does an excellent job: http://www.cosmos.esa.int/web/gaia/faqs: Why is there an angle of ...
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22 votes
4 answers
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Why is Starlink polluting the night sky a big concern if we have space telescopes?

There's a lot of concern in the Astronomy community over the deployment of Starlink satellites. For a good discussion, see the related question How will Starlink affect observational astronomy? But ...
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21 votes
2 answers
2k views

Parking a telescope at a Lagrange point: is this a good idea from a debris point of view?

The James Webb space telescope is supposed to be located at the Earth-Sun L2 Lagrange point. Do we expect the region around that point to have a higher concentration of space debris, asteroids, dust,...
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3 votes
1 answer
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Are X-ray telescopes with glancing angle surfaces basically "funny-looking" Cassegrain telescopes mathematically?

In this answer I included the image below of a reflective X-ray telescope. It is made from two elements; the first is concentric shells of glancing (high incidence) angle paraboloidal surfaces, and ...
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14 votes
3 answers
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Is the measurement of distance and position of remote celestial bodies accurate?

Considering that light is affected by gravity, how accurate are measurements of distant stars and galaxies? When light passes through objects with great mass, such as Jupiter size planets, stars, or ...
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11 votes
1 answer
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Will James Webb see Population III stars?

I have heard that James Webb will see the first stars that our universe produced. Can I assume that we may see galaxies that are so young that all of the stars in them are population III?
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8 votes
1 answer
347 views

Is there a cosmic, rather than technological, upper limit to what a telescope can resolve?

Space radio interferometers could have a baseline of millions of kilometers, but is there a point where a larger baseline doesn't improve the resolution anymore because the photons observed are ...
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7 votes
1 answer
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How could a 20 inch space telescope "be able to make out Earth-size planets" orbiting Alpha Centauri?

The NY Times article Telescope to Seek Earthlike Planet in Alpha Centauri System describes a proposed effort to put a telescope into orbit fairly quickly with a narrowly defined purpose - to look for ...
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4 votes
1 answer
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Why does Nancy Grace Roman = 100 × Hubble? Why is the new space telescopes wide field camera so much wider than the old one's?

The title of the WFIRST project description (before it was named the Nancy Grace Roman Space Telescope) is The Wide Field Infrared Survey Telescope: 100 Hubbles for the 2020s. Question: Why does Nancy ...
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3 votes
1 answer
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Why is the Nancy Grace Roman Space Telescope's field of view shaped like a PacMan "ghost"?

The Curious Droid YouTube video NASA's Mega Hubble - The Roman Space Telescope illustrates the shape of the telescope's field of view and the outline has a smile or frown shape. For whatever reason it ...
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3 votes
1 answer
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What does the celestial sphere look like in thermal IR?

The Space SE question JWST detector heat load asks ...what is the heat load from the collected radiation of the main mirrors on the detector, and how does that vary depending on what objects or ...
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3 votes
1 answer
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Why wasn't CHEOPS data taken during passage through the South Atlantic Anomaly downlinked in this case, resulting in gaps in photometry?

Section 4.1.2. CHEOPS in Six transiting planets and a chain of Laplace resonances in TOI-178 says Due to the low-Earth orbit of CHEOPS, the spacecraft-target line of sight was interrupted by Earth ...
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2 votes
1 answer
66 views

Limits of space telescope?

Watching this video describing the "next generation" space telescope, it seems like the biggest mirror will be ~6 meters in diameter. Theoretically, if a telescope was built in space instead ...
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2 votes
0 answers
35 views

How do HabEx's internal coronagraph and external starshade work together and complement each other? What is it that each can do that the other can't?

Limits of space telescope? links to the video 4 Future Space Telescopes NASA wants to build and that page links to The New Great Observatories. These cover the four space-based instruments proposed by ...
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2 votes
1 answer
114 views

Why would a tidally-locked rocky planet have a first-order spherical harmonic surface temperature distribution?

The new Letter to Nature Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b (also ArXiv) analyzes the thermal infrared light curve from the system (about 4.5 to 5.5 um). The planet ...
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2 votes
1 answer
611 views

What are the differences between TESS and PLATO exoplanet telescopes?

Within a year now it has been decided to launch TESS in 2017 and PLATO in 2024, space telecopes of NASA and ESA. They seem to have very similar science goals, both searching for transiting Earth sized ...
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1 vote
1 answer
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How far above the galactic plane would a telescope array need to be in order to image the whole galaxy?

I hope this isn't a stupid question, but Google searches are turning up nothing relevant. I was just thinking about how it's difficult for us to determine the true shape and composition of the Milky ...
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1 vote
0 answers
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What kind of space telescope could best take advantage of orbiting far from the Sun?

While Hubble has provided an astounding amount of science from low Earth orbit, one of the reasons it was put in LEO was to be readily accessible for service and upgrades by the Space Shuttle. JWST ...
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1 vote
1 answer
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Why do space telescopes have GRISMS? Why a grating AND a prism for cross-dispersion in slitless spectroscopy?

https://hst-docs.stsci.edu/wfc3ihb lists the page 8.2 Slitless Spectroscopy with the UVIS G280 Grism which contains details of one of the GRISMs of the Hubble Space Telescope (GRISM = Grating + Prism)....
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1 vote
1 answer
175 views

How are "parallel fields" implemented on the Hubble Space Telescope?

The Phys.org news item Hubble is the ultimate multitasker: Discovering asteroids while it's doing other observations mentions the Hubble Space Telescope's use of parallel fields: A couple years ago, ...
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1 vote
0 answers
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What is an "Off Rowland-circle Telescope"? Are there "On Rowland-circle Telescope" as well?

The NASA Goddard news item NASA to Demonstrate New Star-Watching Technology with Thousands of Tiny Shutters says: The technology, called the Next-Generation Microshutter Array (NGMSA), will fly for ...
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1 vote
1 answer
186 views

Does this CHEOPS first light image imply bad astronomy?

@KeithMcClary's comment under lousy mirror corrected by software links to Bad Astronomy's First Light for the Exoplanet Hunter Mission CHEOPS Goes Tetrahedral which shows the image below. I understand ...
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