Why explore space

1
Why explore space?

• Science
• Commerce
• Defense
• Earth observation
• National prestige

2
Science in Space

• Initially part of scientific method
• Verify theoretical predictions of orbital theory
• Initially the hazards of getting to space and
  operating in space not well known
• Thus operational systems not supported by
  commerce of government.
• Space scientists funded by the government to
  perform one-off experiments.
• In doing so the foundations for operational use
  of space were laid.

3
Funding

• Space science falls in the category of Big
  Science a term which relates to the level of
  funding and infrastructure support need to
  perform experiments.
• If the government funds the work how is it
  decided who gets support?
• For defense related work, congress and military
  work this out often in secret for obvious
  reasons.
• For civilian research a system of proposal
  solicitation followed by peer review is used.
• In hard times this can break down because
  everybody proposes in a given area and there are
  no knowledgeable peers left in the community to
  review the proposals.
• Even with government funding the areas of study
  are restricted because of general decisions made
  on the research emphases by the government
  agencies advised by panels of scientists.
• E.g. Space science not Science in Space edict
  from NASA Office of Space Science some years ago.

4
Issues

• Should taxpayers money be used for scientific
  research with no immediate benefit to the public
  at large?
• Benefits of the advance of scientific knowledge
• Maintenance of national workforce at leading edge
  of science and technology
• Is it appropriate for government to do groundwork
  for future for-profit companies?
• What is the ultimate pay-off of the governments
  investment to individuals and to the country?
• Is it worth it?
• Where would the money be better spent?

5
A New Arena for Scientific Observation

• An orbiting or escaping spacecraft provides an
  experimental platform with unique features
• Above 99.99 or more of the atmosphere
• Located within the interaction regions of the sun
  and the earth (planets) (ionosphere,
  magnetosphere, solar wind)
• Very low gravitational forces (platform in
  free-fall)
• Normally at least 300 km above earths surface.

6
Summary of Measurement Techniques Employed in
Space.

• In-situ measurements of space environment
• Instruments to measure many properties of the
  material at location of spacecraft.
• Remote sensing without atmospheric absorption
• E.g. Hubble, Chandra, Cosmic and Gamma rays,
  Solar Radiation
• Limb scanning of planetary atmospheres
• Transport of people and instruments to surface of
  moon
• Instrument also to surfaces of some solar system
  planets
• People to planets later ???
• Earth Imaging
• Surface features, clouds, air temperatures ...
• Refection, self emission
• Optical, UV, IR, Synthetic Aperture Radar (SAR)
• Active Experiments
• Stimulation/response, use space environment as
  plasma laboratory.
• Microgravity Experiments
• Chemistry (crystals, proteins, )
• Human and plant physiology

7
Spacecraft Infrastructure

• In order to be functional and provide useful data
  to the ground, spacecraft need the following
  basic infrastructure which in general should be
  lightweight (remember /kg to orbit)
• Mechanical structure and shielding
• Launch (landing) stresses
• Operation in vacuum
• Thickness of skin depends on environment and need
  to shield electronics
• Power
• Solar energy
• Other
• Attitude control
• Spin stabilized
• 3-axis control
• Telemetry
• Radio links to send digital data stream to ground
• On-board networking to assemble data from myriad
  sources
• Telecommand
• Reliable, secure radio uplinks to adjust the
  spacecraft functions
• Life support
• Breathing, eating, excreting, sleeping in a
  comfortable temperature

8
In-situ Measurements

• Means in place and uses sensors which detect
  properties at the location of the spacecraft.
• Initially these concentrated on the upper
  atmosphere
• Local gas and plasma properties
• Incoming fluxes of energetic particles
• Electric and magnetic fields
• DC and AC (electromagnetic and plasma waves)
• Then measurements extended into the magnetosphere
  and the solar wind
• Now we have in-situ measurements from
  interplanetary space
• Note primarily in the ecliptic plane (except
  Ulysses (later))
• Two examples of an earlier and current satellites
  carrying in-situ sensors for the ionosphere and
  the magnetosphere follow.

9
Dynamics Explorer 1

• Launch Information
• Launch Date/Time 1981-08-03 at 095600 UTC
• Launch Site/Country Vandenburg AFB, United
  States
• Launch Vehicle Delta
• Orbital Information
• Orbital Period 409.00 m
• Inclination 89.90 degrees Eccentricity
  0.62000
• Perigee 567 km Apogee 23,289
  km
• DE-1 Experiments
• Magnetic Field Observations Triaxial Fluxgate
  Magnetometer (MAG-A) (PI Slavin)
• Plasma Waves Instrument (PWI) (PI Gurnett)
• Spin Scan Auroral Imager (SAI) (PI Frank)
• Retarding Ion Mass Spectrometer (RIMS) (PI
  Chappell)
• High Altitude Plasma Instrument (HAPI) (PI
  Burch)
• Energetic Ion Composition Spectrometer (EICS)
  (PI Shelley)
• Auroral Physics Theory (PI Maggs)
• Controlled and Naturally Occurring Wave Particle
  Interactions Theory (PI Helliwell)

DE-1 Spin test
10
POLAR

• Launch
• 24 Feb. 1996 Launch Site Vandenberg, Launch
  Vehicle Delta 7925 .
• Orbit
• Perigee 5,554 km. Apogee 50,423 km.
  Inclination 86.3 deg.
• Instrument Descriptions
• Plasma Waves Investigation (PWI)
• Magnetic Fields Experiment (MFE)
• Toroidal Imaging Mass-Angle Spectrograph (TIMAS)
• Electric Fields Investigation (EFI)
• Thermal Ion Dynamics Experiment (TIDE)
• Ultraviolet Imager (UVI)
• Visible Imaging System (VIS)
• Polar Ionospheric X-Ray Imaging Experiment
  (PIXIE)
• Charge and Mass Magnetosperic Ion Composition
  Experiment (CAMMICE)
• Comprehensive Energetic-Particle Pitch-Angle
  Distribution -
• Source/Loss Cone Energetic Particle Spectrometer
  (CEPPAD/SEPS)
• Hot Plasma Analyzer (HYDRA)

11
Remote Sensing

• Another class of space science observation uses
  sensors mounted on the satellite which are
  observing radiated energy from distant sources.
• The need to be in space to do this is to avoid
  the complex absorption of radiation by the
  earths atmosphere and ionosphere.
• But limb scanning utilizes atmospheric absorption
  as source sets behind a planet
• This type of satellite includes astrophysical
  measurements by the Great Observatories.
• This type of remote sensing will be addressed
  later.
• It also includes earth and planetary imaging.
• These also will be addressed later.
• In some cases the radiant energy is generated on
  the satellite and reflected from the region under
  consideration.
• Space borne ionosonde
• Space borne Lidar in planning
• Two examples of this type of scientific satellite
  follow.
• One early solar observatory and one current
  satellite with a recent launch date

12
The OSO-8 Satellite

• The 8th Orbiting Solar Observatory (OSO-8) was
  launched on 21 June 1975 by NASA. While OSO-8's
  primary objective was to observe the Sun, four
  instruments were dedicated to observations of
  other celestial X-ray sources brighter than a few
  milliCrab. OSO-8 ceased operations on 1 October
  1978.
• Mission Characteristics
• Lifetime 21 June 1975 - 1 October 1978 Energy
  Range 0.15 keV - 1 MeV
• Payload
• GSFC Cosmic X Ray Spectroscopy Experiment (GCXSE)
• High Energy Celestial X-ray Experiment
• Soft X-ray Background Radiation Experiment
• Graphite Crystal X-ray Spectrometer
• Science Highlights
• Iron-line detection in the X-ray spectra of a
  cluster of galaxies.
• Detection of Black-Body spectrum from X-ray
  bursts.
• Set upper limit on the polarization of radiation
  from several X-ray binaries.
• Archive
• Light curves and Raw data from the GCXSE

13
Image Program

• IMAGE was launched from the Western Range
  (Vandenberg AFB) in March, 2000. The Delta II
  rocket placed IMAGE in an elliptical polar orbit
  with an apogee altitude of 7 Earth radii (44,647
  km) and a perigee altitude of 1000 km. The
  initial apogee was at 40 degrees north latitude.
  IMAGE will completes one orbit every 13.5 hours.
• Instruments
• Neutral Atom Imagers (NAI)
• Low-Energy Neutral Atom (LENA) imager
• Medium-Energy Neutral Atom (MENA) imager
• High-Energy Neutral Atom (HENA) imager
• Extreme Ultraviolet Imager (EUV)
• Far Ultraviolet Imager (FUV)
• Radio Plasma Imaging (RPI)

14
Early New Result from IMAGEEUV Imager
Sharp cutoff at plasmasphere boundary
NP
NP
Earths shadow
Earths shadow
Scattered 30.4 nm sunlight from helium ions in
the earths plasmasphere
15
Planetary Missions

• Three general categories of spacecraft
• Planetary orbiter
• Planetary flyby
• Planetary lander
• Extended to digger and/or rover on some occasions
• The manned and unmanned lunar program will not be
  further addressed.
• Planetary probes normally include both in-situ
  and remote sensing instruments.
• Many missions include both orbiters and landers.
• They must operate at extreme distances from the
  earth and the sun which poses communication and
  electrical power problems.
• They must be very reliable for the long journeys
  to and between the solar system planets.

16
Planetary - Orbiters
PIONEER VENUS ORBITER Launch 1978, in orbit
1980-92 The Pioneer Venus Orbiter carried 17
experiments and 4 multiprobe landers
MAGELLAN Launch 1989 Mapping of Venus using SAR
radar
17
Galileo
Galileo has been orbiting Jupiter since late
1995, and completed its 29th orbit as it flew by
the moon Ganymede on December 28, 2000
18
IMAGES FROM GALILEO(1)
Order from planet
1
2
4
3
Ganymede
Callisto
Io
Europa
These are called the Galilean satellites after
Galileo who first observed them in 1610
Composite Image of the Four Largest Moons of
Jupiter
19
IMAGES FROM GALILEO(2)EUROPA
Hemisphere Images of Europa (true color and false
color)
Close up image of surface Showing what are
believed to be ice fields
20
Planetary Flyby
Jupiter
Saturn
21
ULYSSES FLYBY JUPITER
Launch 1990 arrived at Jupiter 1992
22
PLANETARY LANDERS
Mars Pathfinder with Mars Rover Launched 1996
Viking Mars Lander Launched 1975
23
MARS
Martian Landscape Observed from Mars Pathfinder
24
Astrophysics Missions

• These spacecraft primarily use remote sensors
  spanning a large part of the electromagnetic wave
  spectrum.
• The spacecraft must be very reliable to survive
  the long operational lifetimes planned for such
  missions.
• The spacecraft are often very large to
  accommodate large telescopes with superior
  light collecting capability.
• Reliability and complexity drives up the price of
  this category of spacecraft.
• In the last 10 years a subset of the
  astrophysicsal missions have been named the
  Great Observatories
• E.g. Compton GRO, Chandra, Hubble, Infrared Space
  Observatory (ISO)
• Operated like large ground-based telescope
  facilities
• Government supported aided by the continuing wide
  interest by the general public in astronomy and
  cosmology.

25
Spanning the Spectrum IR to X-ray
Infrared Space Observatory (ISO) Launched
1995 Operational 1995-98
Advanced X-ray facility (Chandra) Launched July
1999
26
Cosmic IR Observation by ISO

• A ring of organic molecules around HD 97300
  (ESA/ISO/ISOCAM and R. Siebenmorgen et al. )
• This image shows extended emission, an elliptical
  ring structure of size about 0.045x0.03 pc as
  well as two peaks of emission, separated by about
  3" (240 AU). One of the two peaks coincides with
  the position of HD 97300, while the other may be
  an embedded companion. The data show that the
  emission in this region is dominated by the
  infrared emission bands centered at 6.2, 7.7,
  8.7, 11.3 and 12.5 µm, with a very small
  contribution from continuum emission at longer
  wavelengths.

pc parsec , distance at which earths orbit
subtends angle of 1 sec (3.25 light years)
27
Cosmic X-ray Observations from Chandra

• E0102-72 is a supernova remnant in the Small
  Magellanic Cloud, a satellite galaxy of the Milky
  Way.
• Located in the constellation Tucana, this galaxy
  is 190,000 light years from Earth. The remnant is
  approximately a thousand years old. Stretching
  across forty light years of space, the expanding
  multi-million degree shell of gas resembles a
  flaming cosmic wheel.

28
Chandra Observes Black Hole in Andromeda

• Andromeda Galaxy (M31) Our nearest neighbor
  spiral galaxy at a distance of two million light
  years.
• This X-ray image shows the central portion of the
  Andromeda Galaxy. The blue dot in the center of
  the image is a "cool" million degree X-ray source
  where a supermassive black hole with the mass of
  30 million suns is located. The X-rays are
  produced by matter funneling toward the black
  hole. Numerous other hotter X-ray sources are
  also apparent. Most of these are probably due to
  X-ray binary systems, in which a neutron star or
  black hole is in a close orbit around a normal
  star.

29
The Hubble Space Telescope

• Launch Date April, 1990
• On-orbit dry mass 11600.00 kg
• Nominal Power Output 2400.00 W
• The Hubble Space Telescope (HST) was the first
  and flagship mission of NASA's Great
  Observatories program. Designed to complement the
  wavelength capabilities of the other spacecraft
  in the program (CGRO, AXAF, and SIRTF)
• HST has a 2.4 m, f/24 Ritchey-Chretien telescope
  capable of performing observations in the
  visible, near-ultraviolet, and near-infrared
  (1150 A to 1 mm).
• Placed into a low-earth orbit by the space
  shuttle, HST was designed to be modular so that
  on subsequent shuttle missions it could be
  recovered, have faulty or obsolete parts replaced
  with new and/or improved instruments, and be
  re-released.
• HST is roughly cylindrical in shape, 13.1 m
  end-to-end and 4.3 m in diameter at its widest
  point.

Note Service call to be launched this Thursday
30
Striking Image of Nebula by Hubble

• Image of Keyhole nebula showing very fine detail
  of the structure of the gas and dust clouds

31
Hubble images star formation

• Star formation in a distant galaxy illuminates
  the whole galaxy

32
Planetary Observations by Hubble

• Auroral light emission at the north and south
  poles of Saturn

33
Active Experiments

• Mostly related to plasma physics studies.
• Until space age these experiments were done only
  in vacuum chambers
• Problems due to wall interference with effects
  being studied.
• Limits to small size, fast responding
  experiments.
• Ionosphere forms a low pressure region with
  significant ionization present.
• Basically stimulus/response studies in which
  stimulus can be
• Solid material interactions
• Satellite wakes
• Natural vehicle charging
• Material release
• Neutral gases
• Ionized gases
• Particle beams, ions, electrons, neutral atoms
• Electric field application
• DC, currents, vehicle charging
• AC, wave plasma interactions
• Many active experiments can be related to natural
  phenomena in the atmosphere/ionosphere/magnetosphe
  re region. They have the advantage of being
  performed under controlled conditions.

34
Tethered Satellite System (TSS)

• Join NASA/Italian program.
• 1.6 m diameter satellite deployed on a 20 km
  insulated, conducting tether.
• Motion through earths magnetic field induced up
  to 5000 V bias between the satellite and the
  shuttle.
• Studied current collecting capabilities.
• Satellite instrumented to study distribution of
  charge carriers.
• Measurements aided and facilitated by additional
  instrumentation on board the Space Shuttle.
• Tether broke when almost full deployment was
  reached.

TSS-1R Space Shuttle flight STS-75 Launched Feb.
22, 1996