A detailed study of ethane and ethylene photochemistry is presented for the troposphere and stratosphere. It is demonstrated that the loss of ethane is controlled by OH in the troposphere and Cl in the stratosphere. Observations of ethane show a stratospheric behavior indicative of a free chlorine concentration below 30 km that is only 10% of the predicted value given by both our photochemical model calculations and those done by others. The inferred lower amount of chlorine cannot be explained by heterogeneous processes for concentrations of aerosols representing average background conditions, nor does current stratospheric photochemistry show agreement. Chemical destruction of ethane and ethylene within the atmosphere leads to the production of carbon monoxide, formaldehyde, and other products. Tropospheric concentrations of formaldehyde are enhanced by nearly a factor of 3 for an ethylene mixing ratio of 2 ppb. Simultaneous monitoring of formaldehyde and carbon monoxide, as well as other products, will greatly aid in determining the relative importance of different tropospheric CO sources. Peroxyacetyl nitrate (PAN) acts as a reservoir for odd‐nitrogen at the expense of HNO3, HO2NO2, NO, and NO2.

An electron accelerator was flown on an Aerobee 350 rocket from Wallops Island, Virginia, in January 1969. At altitude the accelerator put out a series of electron‐beam pulses up to 1 sec long aimed downward along the magnetic‐field line. Several electron energies up to a maximum of 9.5 kev were used. The beam current was also varied up to a maximum of 490 ma. The highest power pulses were detected on the ground by sensitive optical systems. The vehicle neutralization was accomplished by collecting an ionospheric current equal to the beam current on a large aluminized mylar foil deployed perpendicular to the magnetic field. Attempts were made to measure electromagnetic waves that might be produced by the beam and also to measure with radar the ionization trail resulting from the beam interacting with the atmosphere. The artificial auroral rays produced by the electron beams appeared at the right place and time with about the right shape and intensity. This experiment demonstrates the feasibility of propagating electron beams long distances in space with relatively small alterations resulting from plasma instabilities or beam propagation problems.

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We present measurements of electron temperature Te made by a retarding potential analyzer and a Langmuir probe (both flush‐mounted on the spin‐stabilized satellite Explorer 31) to investigate the variation of Te around the satellite. Most of the time there is a Te variation, which repeats for given ionospheric conditions. The variation is strongly controlled by the angle between the velocity vector and the probe normal, Te usually being enhanced in the near wake of the satellite. Magnetic field control of Te, if it is present, is hidden by the stronger velocity vector control. Our results indicate that the magnitude of the Te enhancement in the wake does not depend on the average ion mass M, although the electron density depletion in the wake is strongly correlated with M.

The integral spectrum for low‐energy electrons has been measured with detailed definition of temperature and number density throughout the IMP 2 orbit. Electrons are found to have a Maxwellian distribution at energies below 2.0 ev with a component of higher energy. The electron temperature typically increases from above the ionosphere as the square of the radial distance, whereas the number density decreases approximately as the inverse cube of the distance out to 5 RE. From 5 to 15.9 RE (apogee) the temperature remains between 1.0 and 2.0 ev, and the number density remains between 25 and 50 electrons/cm−3. It is verified that the observed positive ion density of 25–50 cm−3 is in agreement with the number of electrons observed per unit volume in the solar wind region. The location of the magnetopause is not evident in the low‐energy electrons; however, a small temperature increase is noted at the shock boundary. An intensity increase is noted in the energetic electron component in the magnetosheath. Data for a six‐month period covering a 180° sector of the earth's environment is reported on. These observations constitute the first integral measurements in the solar wind region of charged particle spectra in the energy range 0–45 ev. Our observations of the number density are in disagreement with presently accepted solar wind theory but are not inconsistent with previous measurements of the streaming ions.