Jianing in Huntsville. The spaceship is built in

Jianing Zhang

Professor Pommier

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SIO 1

25 January 2018

 

The OSIRIS-REx
Visible and Infrared Spectrometer (OVIRS): Osiris-REX – Asteroids

Fig. 0. NASA,
et al. “OSIRIS-REx Technology: OVIRS.” NASA, NASA, 25 July 2016,
svs.gsfc.nasa.gov/12309.

OSIRIS-REx is the third
mission of NASA’s New Frontiers Program conducted by NASA’s Marshall Space
Flight Center in Huntsville. The spaceship is built in Lockheed Martin Space
Systems in Denver and OSISRIS-REx sicence Processing and Operations Center are
at the University of Arizona, NASA’s Goddard Space Flight Center in Greenbelt.
The instrument, OSRIS-REx Visible and infrared Spectrometer (OVIRS) will be
discussed in this report.

Purpose
& Scientific Questions

In the mission of sending
OSRIS-REx spacecraft to an asteroid Benuu that is rich of carbon material,
scientists are hoping to find the origins of life in it. They built the
OSRIS-REx Visible and infrared Spectrometer (OVIRS) to look at asteroid Benuu’s
spectral signature to detect minerals and organics. It breaks down light into
separate individual wavelength packets in order for the scientists to analyze
from the details of spectra to tell which material they are looking for. OVIRS
will work along with another instrument, the Thermal Emission Spectrometer
(OTES). With information collected by OVIRS and OTES, scientists will also
study the Yarkovsky effect, which is how surface heating and cooling will
affect Bennu’s orbit.

 

Mechanisms
of Instruments

OVIRS is a spectrometer
equipped with a 4-mrad field of view providing wavelength range of 0.4 – 4.3
um. It has a wedged two-dimensional spectral filter (linearly variable, LVF)
that could detect varies of substances. In LVF, wavelength of the transmitted
light will wary in one dimension. The filter segments will be put on an
assembly placed over the detector. It has a spectral resolution defined as
resolving power, R.

Resolving
Power

Spectral Range(?m)

R>=
125

0.4
to 1.1

R>=
150

1.1
to 2.0

R>=
200

2.0
to 4.3

R>=
350

2.9
to 3.6

 

With this resolution,
OVIRS could provide data of many mineral and molecular components such as
sulfates, oxides, canbonates, silicates, water and many organic species. It
will provide spectral data for the asteroid, spectral maps with 20m resolution.
It will provide two spectral samples for each spectral resolution element to
make a full use of it.

Fig. 1. Reuter, D.C., et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017,
arxiv.org/abs/1703.10574.

The shape of graph was
determined for the filter focal plane assembly with multi-order grating. Thus,
it could generate a table of wavelength and resolving power. Figure 11 shows an
example of the readout of LVF segments with the output of a grating
monochromator. The three peaks matched to order of six to four of 4 ?m grating. Two lines shows the
progress of changing grating setting to pass through a spectral element…We
could see from data of the instrument and determine that the line shape is
Gaussian.

OVIRS is equipped with an
off-axis parabolic mirror(OAP) to form the image of the surface of asteroid
onto a field stop which included 4 milliradian angular region of the image.
Light passes through the first OAP to the second to re-collimates and set forth
the Focal Plane Assembly. With each detector sees the same spatial region and others
in the array see at different wavelengths, the spectrum will be got with single
measurement. It is different from other wedged filter spectral imagers whose
spectrum is built up over several different frames.

Fig. 2. Reuter, D.C., et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017,
arxiv.org/abs/1703.10574.

Figure2 is the model of
the OVIRS Optics Box exterior. This part is mainly to control temperature and
separate titanium flexures. The First stage radiator will cool down the
temperature of the second stage, then the inflight temperature of the whole
optic box will be from range 120k to 150k. While remaining in low temperature,
the thermal load on the focal plane will decrease.

Fig. 3. Reuter, D.C., et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017, arxiv.org/abs/1703.10574.

 

Figure 3 is a model of
the interior of the box. The first mirror has an 80-mm aperture and a focal
length of 350mm. Image will form on field stop from the primary aperture or
solar calibrator aperture. The field stop is a 1.4mm circular aperture that let
light pass to the second mirror from a 4 milliradian angle. Light will travel
to the focal plane which is 150 mm from field stop and eventually, the angular
spread of light will be 7 milliradian.

Also, all the equipment
on OVIRS will pass through a Calibration Test before launch and during flight.
In order to monitor the calibration during flight, OVIRS used solar calibration
aperture to access the stability of the system which is independent of other
devices onboard. The input will be point to the sun and the solar radiance will
strike the wire system near the focal plane. The mesh scatters and creates a
relatively flat illumination pattern on entire focal plane. In figure 3,
filament Calibrator and Blackbody Calibrator will monitor the calibration
frequently.

 

Data
Collected and Results

The mission is still in
progress. It will reach Bennu is 2018 and return with data in 2023. So we
haven’t got the data collected by OVIRS on Bennu yet.

But why we choose Bennu
over 500000 known asteroids in the solar system? First, for a mission like
OSIRIS-REx that investigate a near earth object, asteroids will be chosen from
1.6 AU to 0.8 AU. When OSIRIS-REx’s asteroid selection begun in 2008, there are
only 192 asteroids that meet the requirements. Second, asteroid rotates faster
if they have small diameters. If it spins too fast, the loose material will be
ejected. The target asteroid has to have a diameter larger than 200m for a
spacecraft to safely land and gather enough data on it. This limits the 192
asteroids to only 26. Third, Bennu is one of the most primitive asteroids that
are carbon rich and has stayed the same since they first form. Bennu contains a
lot of organics, volatiles and other material that have been the origins of
life on earth. Studying Bennu will benefit a lot with our understanding of the
origins of life. Only 5 asteroids of the 26 is carbon rich and primitive and
Bennu is one of it. Bennu has 500-meter diameter which is safe for spaceship to
land, and it has an orbiting period of 436.604 days and it comes close to earth
every 6 years. This gives us a high chance of discovering Bennu and that is why
Bennu became the ideal asteroid for OSIRIS-REx.

Fig. 4. “WHY
BENNU?” OSIRIS-Rex Asteroid Sample Return Mission, NASA, www.asteroidmission.org/why-bennu/.

 

 

History
and Development of OVIRS

OVIRS is designed to be
long-lasting and stable, reducing a lot of risk of malfunction. First, it has
to be at very low temperature to produce the best data, but temperature in
space varies a lot. If OVIRS is heated up, there will be more thermal radiation
and scattered light to interfere with the data. Scientists anodized the
interior coating of the spectrometer which increases resistance to corrosion of
the metal. It also reduces the scattered light to stabilize environment of
OVIRS observation.

Another big threat is
water. As OVIRS will be searching for water in the surface, any water that
comes in the instrument will damage the results. Even if the instrument avoid
direct contact with water, OSIRIS-REx may be affected by accumulating moisture
while on the launch pad in Florida. In order to solve this, scientists will
turn on heaters to eliminate water’s existence.

Conclusion

Although the mission is
still in progress, the design of OVIRS for OSIRIS-REx mission made a great
example for detecting material and organics outside earth. OVIRS has a set of
optics to feed the focal plane which gives us spectral range of 0.4 to 4.3?m. The spectral data will return to
Earth and bring scientists information of minerals, chemicals and organics,
OVIRS will give us a detailed information including composition, thermal
characteristics and so on, helping scientists learn more about the environment
in Bennu and maybe build a connection between Bennu and the primitive
development of Earth.

 

 

 

Work
Cited

D.C., Reuter, et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017, arxiv.org/abs/1703.10574.

Hille, Karl. “NASA to Map the Surface of an Asteroid.” NASA,
NASA, 25 July 2016,
www.nasa.gov/feature/goddard/2016/nasa-to-map-the-surface-of-an-asteroid.Jianing Zhang

Professor Pommier

SIO 1

25 January 2018

 

The OSIRIS-REx
Visible and Infrared Spectrometer (OVIRS): Osiris-REX – Asteroids

Fig. 0. NASA,
et al. “OSIRIS-REx Technology: OVIRS.” NASA, NASA, 25 July 2016,
svs.gsfc.nasa.gov/12309.

OSIRIS-REx is the third
mission of NASA’s New Frontiers Program conducted by NASA’s Marshall Space
Flight Center in Huntsville. The spaceship is built in Lockheed Martin Space
Systems in Denver and OSISRIS-REx sicence Processing and Operations Center are
at the University of Arizona, NASA’s Goddard Space Flight Center in Greenbelt.
The instrument, OSRIS-REx Visible and infrared Spectrometer (OVIRS) will be
discussed in this report.

Purpose
& Scientific Questions

In the mission of sending
OSRIS-REx spacecraft to an asteroid Benuu that is rich of carbon material,
scientists are hoping to find the origins of life in it. They built the
OSRIS-REx Visible and infrared Spectrometer (OVIRS) to look at asteroid Benuu’s
spectral signature to detect minerals and organics. It breaks down light into
separate individual wavelength packets in order for the scientists to analyze
from the details of spectra to tell which material they are looking for. OVIRS
will work along with another instrument, the Thermal Emission Spectrometer
(OTES). With information collected by OVIRS and OTES, scientists will also
study the Yarkovsky effect, which is how surface heating and cooling will
affect Bennu’s orbit.

 

Mechanisms
of Instruments

OVIRS is a spectrometer
equipped with a 4-mrad field of view providing wavelength range of 0.4 – 4.3
um. It has a wedged two-dimensional spectral filter (linearly variable, LVF)
that could detect varies of substances. In LVF, wavelength of the transmitted
light will wary in one dimension. The filter segments will be put on an
assembly placed over the detector. It has a spectral resolution defined as
resolving power, R.

Resolving
Power

Spectral Range(?m)

R>=
125

0.4
to 1.1

R>=
150

1.1
to 2.0

R>=
200

2.0
to 4.3

R>=
350

2.9
to 3.6

 

With this resolution,
OVIRS could provide data of many mineral and molecular components such as
sulfates, oxides, canbonates, silicates, water and many organic species. It
will provide spectral data for the asteroid, spectral maps with 20m resolution.
It will provide two spectral samples for each spectral resolution element to
make a full use of it.

Fig. 1. Reuter, D.C., et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017,
arxiv.org/abs/1703.10574.

The shape of graph was
determined for the filter focal plane assembly with multi-order grating. Thus,
it could generate a table of wavelength and resolving power. Figure 11 shows an
example of the readout of LVF segments with the output of a grating
monochromator. The three peaks matched to order of six to four of 4 ?m grating. Two lines shows the
progress of changing grating setting to pass through a spectral element…We
could see from data of the instrument and determine that the line shape is
Gaussian.

OVIRS is equipped with an
off-axis parabolic mirror(OAP) to form the image of the surface of asteroid
onto a field stop which included 4 milliradian angular region of the image.
Light passes through the first OAP to the second to re-collimates and set forth
the Focal Plane Assembly. With each detector sees the same spatial region and others
in the array see at different wavelengths, the spectrum will be got with single
measurement. It is different from other wedged filter spectral imagers whose
spectrum is built up over several different frames.

Fig. 2. Reuter, D.C., et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017,
arxiv.org/abs/1703.10574.

Figure2 is the model of
the OVIRS Optics Box exterior. This part is mainly to control temperature and
separate titanium flexures. The First stage radiator will cool down the
temperature of the second stage, then the inflight temperature of the whole
optic box will be from range 120k to 150k. While remaining in low temperature,
the thermal load on the focal plane will decrease.

Fig. 3. Reuter, D.C., et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017, arxiv.org/abs/1703.10574.

 

Figure 3 is a model of
the interior of the box. The first mirror has an 80-mm aperture and a focal
length of 350mm. Image will form on field stop from the primary aperture or
solar calibrator aperture. The field stop is a 1.4mm circular aperture that let
light pass to the second mirror from a 4 milliradian angle. Light will travel
to the focal plane which is 150 mm from field stop and eventually, the angular
spread of light will be 7 milliradian.

Also, all the equipment
on OVIRS will pass through a Calibration Test before launch and during flight.
In order to monitor the calibration during flight, OVIRS used solar calibration
aperture to access the stability of the system which is independent of other
devices onboard. The input will be point to the sun and the solar radiance will
strike the wire system near the focal plane. The mesh scatters and creates a
relatively flat illumination pattern on entire focal plane. In figure 3,
filament Calibrator and Blackbody Calibrator will monitor the calibration
frequently.

 

Data
Collected and Results

The mission is still in
progress. It will reach Bennu is 2018 and return with data in 2023. So we
haven’t got the data collected by OVIRS on Bennu yet.

But why we choose Bennu
over 500000 known asteroids in the solar system? First, for a mission like
OSIRIS-REx that investigate a near earth object, asteroids will be chosen from
1.6 AU to 0.8 AU. When OSIRIS-REx’s asteroid selection begun in 2008, there are
only 192 asteroids that meet the requirements. Second, asteroid rotates faster
if they have small diameters. If it spins too fast, the loose material will be
ejected. The target asteroid has to have a diameter larger than 200m for a
spacecraft to safely land and gather enough data on it. This limits the 192
asteroids to only 26. Third, Bennu is one of the most primitive asteroids that
are carbon rich and has stayed the same since they first form. Bennu contains a
lot of organics, volatiles and other material that have been the origins of
life on earth. Studying Bennu will benefit a lot with our understanding of the
origins of life. Only 5 asteroids of the 26 is carbon rich and primitive and
Bennu is one of it. Bennu has 500-meter diameter which is safe for spaceship to
land, and it has an orbiting period of 436.604 days and it comes close to earth
every 6 years. This gives us a high chance of discovering Bennu and that is why
Bennu became the ideal asteroid for OSIRIS-REx.

Fig. 4. “WHY
BENNU?” OSIRIS-Rex Asteroid Sample Return Mission, NASA, www.asteroidmission.org/why-bennu/.

 

 

History
and Development of OVIRS

OVIRS is designed to be
long-lasting and stable, reducing a lot of risk of malfunction. First, it has
to be at very low temperature to produce the best data, but temperature in
space varies a lot. If OVIRS is heated up, there will be more thermal radiation
and scattered light to interfere with the data. Scientists anodized the
interior coating of the spectrometer which increases resistance to corrosion of
the metal. It also reduces the scattered light to stabilize environment of
OVIRS observation.

Another big threat is
water. As OVIRS will be searching for water in the surface, any water that
comes in the instrument will damage the results. Even if the instrument avoid
direct contact with water, OSIRIS-REx may be affected by accumulating moisture
while on the launch pad in Florida. In order to solve this, scientists will
turn on heaters to eliminate water’s existence.

Conclusion

Although the mission is
still in progress, the design of OVIRS for OSIRIS-REx mission made a great
example for detecting material and organics outside earth. OVIRS has a set of
optics to feed the focal plane which gives us spectral range of 0.4 to 4.3?m. The spectral data will return to
Earth and bring scientists information of minerals, chemicals and organics,
OVIRS will give us a detailed information including composition, thermal
characteristics and so on, helping scientists learn more about the environment
in Bennu and maybe build a connection between Bennu and the primitive
development of Earth.

 

 

 

Work
Cited

D.C., Reuter, et al. “The OSIRIS-REx Visible and InfraRed
Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu.” Cornell
University Library, Cornell University Library, 30 Mar. 2017, arxiv.org/abs/1703.10574.

Hille, Karl. “NASA to Map the Surface of an Asteroid.” NASA,
NASA, 25 July 2016,
www.nasa.gov/feature/goddard/2016/nasa-to-map-the-surface-of-an-asteroid.