What is JASMINE

Nano-JASMINE

2008/05/21

Mission Objectives

Scientific Mission:
Infrared Astrometry (precise 3D mapping of positions and transverse velocities of stars with an accuracy of 1 milli-arcsecond in an infrared region)
Engineering Mission:
Demonstration of new satellite technologies including a precision mission telescope, precise attitude / thermal control (1 arecsec / 0.1 deg K), and satellite simulation

Major Characteristics

Mass 35 kg (TBC) without separation mechanism
Size 50 cm cubic (TBC)
Attitude Control Three axis stabilization
Communication S-band / 100kbps
Mission Life Two years
Orbit Sun-Synchronous Orbit, LTAN(Local Time of Acsending Node) is TBC.
Mission life 2 years
Diameter of primary mirror 5cm
Relative angle of two FOVs 99.5 °
Focal length 1.67 m
Field of view 0.5° × 0.5 °
Detector Back illuminated full depletion CCD, 1K × 1Kpixels
Pixel size 15μ×15μ, 1.8arcsec × 1.8 arcsec
Spin period 100 min(TBC in detail according to the orbit hight),(0.001047rad / sec in angular velocity)
Exposure time 8.2sec(detector transit time of each stars)
precession time 2 month(TBC) around the Sun
Spin axis direction constant angle 45°(TBC), from the Sun
Observational band 0.6μm1.0μm is also candidate.
Accuracy 3mas @ z = 7.5
Nano-JASMINE Specification

Major characteristics are shown in the table.

Schedule

technical issues

the operating principles of nano-Jasmine

Launch
at the end of 2014 ∼ from Alcantera launch site in Brazil by a Ukrainian Cyclone-4 vehicle
Initial hardware checkout
about 1 month.
Determine the satellite orbit
On board GPS data reception. Kinematic point positioning in postprocessing on ground.
Nominal observation
2 years (not guranteed).
operation
University of Tokyo 3m antenna and hopefully NAOJ Mizusawa 10m, 2 or 3 path in every 12hours.

Diameter of the primary mirror is 5cm. There are several folding mirrors in light path. Beam combiner is located in front of the primary mirror. Its angular stability (1 mas / 2 hours) is confirmed on FEM computation, and was checked in STM tests in July 2008.

Nano-JASMINE telescope observed anti Earth direction. Scanning angular velocity is determined as synchronous to the satellite orbital period.

information on the scanning law

Nano-JASMINE observes 99.5° separating two FOVs simultaneously. The spin axis is perpendicular to directions of the FOVs. Nano-JASMINE spin axis is 45°(TBC) from the Sun direction, and it rotate 2π radian per 2month(TBC) around the Sun. Using two FOVs, 3.4(TBC) times exposure is available in 2 scan phases. We will optimize these three parameters denoted as TBC, during the determining of the LTAN.

design of the focal plane

There is only one 1K×1K full-depletion detector with z-band(TBC) filter. There is no photometry detector. Colors are calculated from the existing catalogue such as GCS. Stellar images are extracted on board FPGA. The size of extracted image is 5×9 pixels with time tag in each lines. Time is calibrated by pps signal from GPS. GPS accuracy is μsecconds.

Attitude and orbit are detected with star tracker and GPS on board.

LSF centroiding accuracy

Following to GAIA, PSF fitting is used for Centroid algorithms, and charge distortion model is applied for the change of CTI by radiation damage. We already confirmed the performance of center of mass method, and achieved 1/150 pixel accuracy. Dr. F. van Leeuwen suggest us (in JASMINE case) that PSF fitting should be also considered.

Data accuracies in indivisual steps are listed in the below table.

stage 0.810.99μband 0.61.0μband
diffraction 4.51 arcsec 4.03arcsec
centroid 13.5mas7.4mas
successive 2 spin observations 7.3mas 3.0mas
2year's accuracy 2.1mas(position)0.87mas
(including parallax factor) 3.8 mas 1.55mas
accuracy

Data analysis

The core data reduction for the Nano-JASMINE mission is planned to be done with Gaia's Astrometric Global Iterative Solution(AGIS). The collaboration started at 2007 prompted by Michael Perryman's idea and Uwe Lammers' proposal. In addition to similar design and operating principles of the two missions, this is possible thanks to the encapsulation of all Gaia-specific aspects of AGIS in a Parameter Database. Nano-JASMINE will be the test bench for Gaia AGIS software. The Nano-JASMINE catalogue will be more reliable because we can use well tested data reduction software.

Science

Science working group starts at Feb. 2010. The leader is Asoc. Prof. Ryoichi Nishi at Niigata University. We now start to study what science will be available with astrometric data of Nano-JASMINE accuracy.

Development Organization

Mission Payload:
Jasmine Project Office, National Astronomical Observatory of Japan, Department of Physics, Kyoto University, etc.
Spacecraft Bus:
Intelligent Space Systems Laboratory, University of Tokyo