Running head: LOOKING OUT THE WINDOW
Looking out the Window
"The Mission"
William R. Sharp
Everglades University
Introduction to Space
ASC 4050
Professor: Michael Flynn
September, 4 2007
Looking out the Window
The process of getting a spacecraft out of earth's atmosphere takes many months if not years of planning, negotiating, and struggle. Scheduling, management of things like location, type of launch vehicle, type of rocket are all purely mathematical questions but, also financial land mines. I have never been directly involved in the process and I am on the outside looking in when it came to righting this paper.
It seems all to be a matter of the weight of the vehicle being launched as to the requirement of the size of the rocket used. Cost is always and underlying factor as a team of people progress toward a scheduled day of the launch. The launch vehicle may be made anywhere in the world and also the rocket for that matter. Several new countries in the last few years now have been launching things into space on their own without using the facilities of NASA. It is humanity and the nature of us that, is driving us to explore new places on a personal level. There is also a planetary concern driving this exploration on a national level. Resources are becoming harder to find and nation states are investing the future by prompting companies and individuals to become involved in space exploration. The potential pay back of nature resource from say one of the large gas planets could solve many of our energy needs on earth for thousands of generation here. The technologies created from the exploration of space have improved our lives. Understanding of the space environment and what it takes to get there, operate, and return was the answer to President Kennedy's famous Man on the Moon speech.
Today, we have come to the point that space flight is common and not many people even notice it anymore. I remember being glued to the TV as a child wanting to know more and I still do at times. There is little thing that pulls at each one of us to answer the question: What is really out there? Past the window the street lights and the air. As I am sitting here looking out my window looking at the stars I wonder how far away they really are.
The answers to my questions and the questions themselves are the subject of this paper.
As I was researching for information to write about I came across a satellite launch scheduled for December 2009, my birth month. This was a change from the original 10 June 2010 launch date mentioned in, May 2009 article by Jet Propulsion Laboratory. I dove in and started to notice what I feel to be an answer to my first question. The program I found is, WISE which is an acronym for: Wide-field Infrared Survey explorer. I found very little un-classified information on this project.
Figure 1, Arts sketch of WISE, (JPL, 2006)
The launch vehicle was constructed and transported from Ball Aerospace in Boulder CO. to the launch facilities at Vandenberg AFB, CA in early August 2009. The telescope and instrumentation systems were built by Space Dynamics Laboratory in Logan UT. WISE will ride on a Delta 7320-10 launch vehicle. (JPL, 2006)
The mission project manager was Mr. Ned Wright (UCLA) in 2003 and he was replaced at some point by William Irace from NASA's Jet Propulsion Laboratory located in Pasadena CA. Because of the technology of Infrared camera equipment and the size of the Telescope engineers over came cooling issue by designing the WISE in such a matter as to allow it to store solid Hydrogen on board to cool the equipment. With capabilities of WISE we should get a better answer to how far away these objects are from us. The follow is information from JPL website and covers the basics of the design of WISE.
- HgCdTe and Si: As 10242 arrays at 3.5, 4.6, 12, and 23 microns with 2.2" pixels
- Two stage solid hydrogen cryostat to cool detectors and optics
- 50 cm primary mirror and reimaging optics
- Scan mirror to stabilize line-of-sight while the spacecraft scans the sky
(JPL, 2003)
This mission has a distant predecessor; The Infrared Astronomical Satellite launched in 1983 is where we have a large vault of data. The data from that mission has promoted a return to space with better equipment. Because it matters what we are studying in space and who is paying the bill, there are two other satellite mission in orbit that could do some of WISE mission However not at designed with the same mission in mind would limit the data acquired.
WISE's mission is to look out the window of space and find as much information possible in the time she will have in operation Approximately 6 months in length. WISE is also described as a "Single instrument", with a four-channel imager that will take overlapping snapshots of entire sky (JPL, 2003). It seems the thoughts that went into this project set it up to return later after the data is analyzed to look out at point not yet seen with other telescopes in the past. The hope is that the data found with WISE will to some degree give a better understand of how things are formed in the Universe. The increase capabilities which WISE "will provide an all-sky survey from 3.5 to 23 microns up to 1OOOx more sensitive than IRAS." (JPL, 2003).
WISE will be placed into a Sun -synchronous orbit some 300 miles above the earth. The project team with undergo system checkout for approximately 30 days. Then WISE will be pointed at her Target (space) and begin mission operations i.e. one large Google Star map to go please... (JPL, 2006) The pointing of WISE and management of the Bit Stream are critical to the success of its mission.
The WISE science survey plan will be developed at UCLA; engineering operations will be conducted at the Jet Propulsion Laboratory's Earth Science Mission Operations Center. Here, science pointing from the survey plan will be integrated with the pointing required for downlink and other engineering activities. Data processing will occur at Caltech's Infrared Processing and Analysis Center (IPAC). (JPL, 2006)
As with many spacecraft the WISE has to be in a general rotation to maintain its station. With WISE though the Telescope needs to remain stationary during operation so the equipment was designed to "Freeze frame" the mirrors so the data acquired is useful and not made erroneous by vibration or turning or blurring during a scan. (JPL, 2006) In addition JPL engineers must have accurate ways to simulate the Pointing of the telescope this is accomplished through the use of software designed to estimate the changes of WISE Orbit while still acquiring the desired data.
Two software programs will be used to plan, integrate and simulate WISE pointing. The first, to be used at the WISE Science Planning Center, is the Survey Planner software. This software accepts as input the two-line element (TLE) providing orbit information for WISE and the values of several survey parameters. It calculates the projected positions of WISE, the moon and sun and produces as output a set of scan quaternions and rates. In doing so, it validates that the plan satisfies WISE's sky coverage requirements (4 or more independent exposures in each filter at each sky position over at least 95% of the sky). (sic.), (JPL, 2006)
A second software package is used to plan TDRSS pointing, integrate it with the science pointing and simulate all pointing in the final command load. This program, called PGEN, will take as input the science plan, a file containing the planned TDRSS pass schedule (where constraint-free views to TDRSS are determined by an independent program developed by WISE navigators) and the WISE and TDRS ephemerides (also projected from TLEs by independent navigational software). PGEN will insert pointing for TDRSS passes into the science pointing schedule during the times specified in the TDRSS pass schedule and return to the science pointing plan after the end of each TDRSS pass. It will output a time-tagged set of pointing commands corresponding to this integrated pointing plan. (JPL, 2006)
Some other things of interest include how and who is running the program. WISE is as state before being managed under NASA. Specifically the NASA's Science Directorate with oversight being vested to a Mr. Edward Wright as Principle Mission Investigator. The program itself was competitively bid out through the Goddard Space Flight Center, Greenbelt, MD.
Finally the goals of this mission breakdown as follows:
- Find the most luminous galaxies in the Universe
- Find the closest star brown dwarfs to the Sun
- Detect most main belt asteroids larger than 3 km
- Extend 2MASS survey into thermal IR Provide catalog for JWST
(JPL, 2003)
Overall this program seems to be on track and ready for launch. The objectives are reachable and there is a lot of sound engineering in place. We will know shortly if all the effort will pay off with useful data or dead air.
References
Fabinsky, B. (2006), A Survey of Ground Operations Tools Developed to Simulate the Pointing Of Space Telescopes and the Design for WISE, SPIE Astronomical Telescopes and Instrumentation, Orlando, Florida, May 21-24, 2006., JPL Beacon e-space website, Retrieved September 2, 2009 from hdl.handle.net/2014/39379
Mainzer, A. K.; Eisenhardt, P.; Wright, E.L.; Feng-Chuan L.; Irace, W.; Heinrichsen, I. et al. (2006), Update on the Wide-field Infrared Survey Explorer (WISE), JPL Beacon e-space website, Retrieved September 2, 2009 from hdl.handle.net/2014/39988
Mainzer, A. K. (2003), 1st Advanced Chilean School on Astrophysics: Extrasolar Planets and Brown Dwarfs Conference, Santiago, Chile, December 15-19, 2003, (sic.), Wide-field Infrared Survey Explorer (WISE), JPL Beacon e-space website, Retrieved September 2, 2009 from hdl.handle.net/2014/38703
