Proposed NASA space telescope
Lynx X-ray Observatory
The Lynx X-ray Observatory
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Names
| Lynx X-ray Surveyor (previous name)
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Mission type
| Space telescope
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Operator
| NASA
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Website
| www
.lynxobservatory
.org
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Launch date
| 2036 (proposed)
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Reference system
| Sun?Earth L
2
orbit
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Type
| Wolter telescope
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Diameter
| 3 m (9.8 ft)
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Focal length
| 10 m (33 ft)
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Collecting area
| 2 m
2
(22 sq ft) at 1
keV
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Wavelengths
| X-ray
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Resolution
| 0.5
arcsec
across the entire field of view
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Lynx X-ray Mirror Assembly (LMA)
High Definition X-ray Imager (HDXI)
Lynx X-ray Microcalorimeter (LXM)
X-ray Grating Spectrometer (XGS)
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The Lynx X-ray Observatory Wordmark
|
The
Lynx X-ray Observatory
(
Lynx
) is a
NASA
-funded
Large Mission Concept Study
commissioned as part of the
National Academy of Sciences
2020
Astronomy and Astrophysics Decadal Survey
. The concept study phase is complete as of August 2019, and the
Lynx
final report
[1]
has been submitted to the Decadal Survey for prioritization. If launched,
Lynx
would be the most powerful
X-ray astronomy
observatory constructed to date, enabling order-of-magnitude advances in capability
[2]
over the current
Chandra X-ray Observatory
and
XMM-Newton
space telescopes.
Background
[
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]
In 2016, following recommendations laid out in the so-called
Astrophysics Roadmap
of 2013,
NASA
established four
space telescope
concept studies for future
Large strategic science missions
. In addition to
Lynx
(originally called X-ray Surveyor in the
Roadmap document
)
,
they are the
Habitable Exoplanet Imaging Mission
(HabEx), the
Large Ultraviolet Optical Infrared Surveyor
(LUVOIR), and the
Origins Space Telescope
(OST, originally called the Far-Infrared Surveyor). The four teams
completed their final reports
in August 2019, and turned them over to both NASA and the
National Academy of Sciences
, whose independent
Decadal Survey
committee advises NASA on which mission should take top priority. If it receives top prioritization and therefore funding,
Lynx
would launch in approximately 2036. It would be placed into a halo orbit around the
second Sun?Earth Lagrange point
(L2), and would carry enough
propellant
for more than twenty years of operation without servicing.
[1]
[2]
The
Lynx
concept study involved more than 200 scientists and engineers across
multiple international academic institutions
,
aerospace
, and
engineering
companies.
[3]
The
Lynx
Science and Technology Definition Team (STDT) was co-chaired by
Alexey Vikhlinin
and
Feryal Ozel
.
Jessica Gaskin
was the NASA Study Scientist, and the
Marshall Space Flight Center
managed the
Lynx
Study Office jointly with the
Smithsonian Astrophysical Observatory
, which is part of the
Center for Astrophysics | Harvard & Smithsonian
.
Scientific objectives
[
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]
According to the concept study's
Final Report
, the
Lynx
Design Reference Mission was intentionally optimized to enable major advances in the following three astrophysical discovery areas:
Collectively, these serve as three "science pillars" that set the baseline requirements for the observatory. Those requirements include greatly enhanced
sensitivity
, a
sub-arcsecond
point spread function
stable across the telescope's
field of view
, and very high
spectral resolution
for both
imaging
and gratings
spectroscopy
. These requirements, in turn, enable a broad science case with major contributions across the
astrophysical landscape
(as summarized in Chapter 4 of the
Lynx
Report
), including
multi-messenger astronomy
,
black hole
accretion
physics,
large-scale structure
,
Solar System
science, and even
exoplanets
. The
Lynx
team markets the mission's science capabilities as "transformationally powerful, flexible, and long-lived", inspired by the spirit of
NASA
's
Great Observatories program
.
Mission design and payload
[
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]
Spacecraft
[
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]
As described in Chapters 6-10 of the concept study's
Final Report
,
Lynx
is designed as an
X-ray observatory
with a
grazing incidence
X-ray telescope
and detectors that record the position, energy, and arrival time of individual X-ray
photons
. Post-facto aspect reconstruction leads to modest requirements on pointing precision and stability, while enabling accurate sky locations for detected photons. The design of the
Lynx
spacecraft
draws heavily on heritage from the
Chandra X-ray Observatory
, with few moving parts and high
technology readiness level
elements.
Lynx
will operate in a
halo orbit
around
Sun-Earth L2
, enabling high observing efficiency in a stable environment. Its maneuvers and operational procedures on-orbit are nearly identical to
Chandra'
s, and similar design approaches promote longevity. Without in-space servicing,
Lynx
will carry enough
consumables
to enable continuous operation for at least twenty years. The spacecraft and payload elements are, however, designed to be serviceable, potentially enabling an even longer lifetime.
Payload
[
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]
The major advances in sensitivity, spatial, and spectral resolution in the
Lynx
Design Reference Mission are enabled by the spacecraft's payload, namely the mirror assembly and suite of three science instruments. The
Lynx
Report notes that each of the payload elements features
state-of-the-art
technologies while also representing a natural evolution of existing instrumentation technology development over the last two decades. The key technologies are currently at
Technology Readiness Levels
(TRL) 3 or 4. The
Lynx
Report notes that, with three years of targeted pre-phase A development in early 2020s, three of four key technologies will be matured to TRL 5 and one will reach TRL 4 by start of Phase A, achieving TRL 5 shortly thereafter. The
Lynx
payload consists of the following four major elements:
- The
Lynx
X-ray Mirror Assembly
(LMA): The LMA is the central element of the observatory, enabling the major advances in sensitivity, spectroscopic throughput, survey speed, and greatly improved imaging relative to
Chandra
due to greatly improved
off-axis performance
. The
Lynx
design reference mission baselines a new technology called
Silicon Metashell Optics
(SMO), in which thousands of very thin, highly polished segments of nearly pure
silicon
are stacked into
tightly packed concentric shells
. Of the three mirror technologies considered for
Lynx
, the SMO design is currently the most advanced in terms of demonstrated performance (already approaching what is required for
Lynx
). The SMO's highly modular design lends itself to parallelized manufacturing and assembly, while also providing high fault tolerance: if some individual mirror segments or even modules are damaged, the impact to schedule and cost is minimal.
- The
High Definition X-ray Imager
(HDXI): The HDXI is the main
imager
for
Lynx
, providing high
spatial resolution
over a wide
field of view
(FOV) and high sensitivity over the 0.2?10
keV
bandpass
. Its 0.3
arcsecond
(0.3′′) pixels will adequately sample the
Lynx
mirror
point spread function
over a 22′ × 22′ FOV. The 21 individual sensors of the HDXI are laid out along the optimal focal surface to improve the off-axis PSF. The
Lynx
DRM uses
Complementary Metal Oxide Semiconductor
(CMOS) Active Pixel Sensor (APS) technology, which is projected to have the required capabilities (i.e., high readout rates, high broad-band
quantum efficiency
, sufficient
energy resolution
, minimal pixel
crosstalk
, and
radiation hardness
). The
Lynx
team has identified three options with comparable TRL ratings (TRL 3) and sound TRL advancement roadmaps: the Monolithic CMOS, Hybrid CMOS, and Digital
CCDs
with CMOS readout. All are currently funded for technology development.
- The
Lynx
X-ray Microcalorimeter
(LXM): The LXM is an
imaging spectrometer
that provides high
resolving power
(
R
~ 2,000) in both the
hard and soft X-ray bands
, combined with high spatial resolution (down to 0.5′′ scales). To meet the diverse range of
Lynx
science requirements, the LXM focal plane includes three arrays that share the same readout technology. Each array is differentiated by its absorber pixel size and thickness, and by how the absorbers are connected to thermal readouts. The total number of pixels exceeds 100,000 ? a major leap over past and currently planned X-ray microcalorimeters. This huge improvement does not entail a huge added cost: two of the LXM arrays feature a simple, already proven, “thermal” multiplexing approach where multiple absorbers are connected to a single temperature sensor. This design brings the number of sensors to read out (one of the main power and cost drivers for the X-ray microcalorimeters) to ~7,600. This is only a modest increase over what is planned for the X-IFU instrument on Athena. As of Spring 2019, prototypes of the focal plane have been made that include all three arrays at 2/3 full size. These prototypes demonstrate that arrays with the pixel form factor, size, and wiring density required by Lynx are readily achievable, with high yield. The energy resolution requirements of the different pixel types is also readily achievable. Although the LXM is technically still at TRL 3, there is a clear path for achieving TRL 4 by 2020 and TRL 5 by 2024.
- The
X-ray Grating Spectrometer
(XGS): The XGS will provide even higher spectral resolution (
R
= 5,000 with a goal of 7,500) in the soft X-ray band for
point sources
. Compared to the current state of the art (
Chandra
), the XGS provides a factor of > 5 higher spectral resolution and a factor of several hundred higher throughput. These gains are enabled by recent advances in X-ray grating technologies. Two strong technology candidates are: critical angle transmission (used for the
Lynx
DRM) and off-plane reflection gratings. Both are fully feasible, currently at TRL 4, and have demonstrated high efficiencies and resolving powers of ~ 10,000 in recent X-ray tests.
Mission Operations
[
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]
The
Chandra X-ray Observatory
experience provides the blueprint for developing the systems required to operate
Lynx
, leading to a significant cost reduction relative to starting from scratch. This starts with a single
prime contractor
for the science and operations center, staffed by a seamless, integrated team of scientists, engineers, and programmers. Many of the system designs, procedures, processes, and algorithms developed for
Chandra
will be directly applicable for
Lynx
, although all will be recast in a software/hardware environment appropriate for the 2030s and beyond.
The science impact of
Lynx
will be maximized by subjecting all of its proposed observations to peer review, including those related to the three science pillars. Time pre-allocation can be considered only for a small number of multi-purpose key programs, such as surveys in pre-selected regions of the sky. Such an open General Observer (GO) program approach has been successfully employed by large missions such as
Hubble Space Telescope
,
Chandra X-ray Observatory
, and
Spitzer Space Telescope
, and is planned for
James Webb Space Telescope
and
Nancy Grace Roman Space Telescope
. The
Lynx
GO program will have ample exposure time to achieve the objectives of its science pillars, make impacts across the astrophysical landscape, open new directions of inquiry, and produce as yet unimagined discoveries.
Estimated cost
[
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]
The cost of the
Lynx X-ray Observatory
is estimated to be between US$4.8 billion to US$6.2 billion (in
FY20
dollars
at 40% and 70%
confidence levels
, respectively). This estimated cost range includes the
launch vehicle
, cost reserves, and funding for five years of mission operations, while excluding potential foreign contributions (such as participation by the
European Space Agency
(ESA)). As described in Section 8.5 of the concept study's
Final Report
, the
Lynx
team commissioned five independent
cost estimates
, all of which arrived at similar estimates for the total mission lifecycle cost.
See also
[
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]
References
[
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]
- ^
a
b
Gaskin, Jessica A.; Ozel, Feryal; Vikhlinin, Alexey; Allen, Steven; Bautz, Mark; Brandt, W. Niel; Bregman, Joel; Donahue, Megan; Haiman, Zoltan; Hickox, Ryan; Jeltema, Tesla; Kollmeier, Juna; Kravtsov, Andrey; Lopez, Laura; Madau, Piero; Osten, Rachel; Paerels, Frits; Pooley, David; Ptak, Andrew; Quataert, Eliot; Reynolds, Christopher; Stern, Daniel (23 August 2019).
"Concept Study Report"
(PDF)
. Lynx X-ray Observatory
. Retrieved
10 January
2020
.
This article incorporates text from this source, which is in the
public domain
.
- ^
a
b
Gaskin, Jessica A.; Swartz, Douglas A. (29 May 2019).
"Lynx X-Ray Observatory: an overview"
.
Journal of Astronomical Telescopes, Instruments, and Systems
.
5
(2): 021001.
Bibcode
:
2019JATIS...5b1001G
.
doi
:
10.1117/1.JATIS.5.2.021001
.
hdl
:
10150/634656
.
ISSN
2329-4124
.
- ^
"The Lynx Team"
.
Lynx X-ray Observatory
. Retrieved
17 January
2020
.
External links
[
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Operating
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Planned
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Proposed
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Retired
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Hibernating
(Mission completed)
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Cancelled
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