Editing Sputnik 2 (section)

==Spacecraft==

Sputnik 2 was a {{convert|4|m|ft|adj=mid|-high}} cone-shaped capsule with a base diameter of {{convert|2|m|ft}} that weighed around {{convert|500|kg|lb}}, though it was not designed to separate from the rocket core that brought it to orbit, bringing the total mass in orbit to {{convert|7.79|tonnes|lb}}.<ref>{{Cite web|url = http://www.russianspaceweb.com/sputnik2_design.html|title = Russian Space Web}}</ref>

===Passenger===
{{main|Laika}}

''Laika'' ("Barker"), formerly ''Kudryavka'' (Little Curly), was the part-Samoyed terrier chosen to fly in Sputnik 2.<ref name=nssdcsput2/> Due to a shortness in the time frame, the candidate dog could not be trained for the mission. Again, OKB-1 borrowed from the sounding rocket program, choosing from ten candidates provided by the Air Force Institute of Aviation Medicine that were already trained for suborbital missions. Laika was chosen primarily because of her even temperament. Her backup was Albina, who had flown on two<ref name=challenge/>{{rp|173}} R-1E missions in June 1956.<ref name=rsp/>{{rp|23}} Laika weighed about {{cvt|6|kg|lb}}.<ref name=nssdcsput2/>

Both Laika and Albina had telemetry wires surgically attached to them before the flight to monitor respiration frequency, pulse, and blood pressure.<ref name=challenge/>{{rp|173}}

The pressurized cabin on Sputnik 2 was padded and allowed enough room for Laika to lie down or stand. An air regeneration system provided oxygen; food and water were dispensed in a gelatinized form. Laika was chained in place and fitted with a [[safety harness|harness]], a bag to collect waste, and [[electrode]]s to monitor vital signs. A television camera was mounted in the passenger compartment to observe Laika. The camera could transmit 100-line video frames at 10 frames/second.<ref name=nssdcsput2/>

===Experiments===

[[File:Atmospheric_electromagnetic_opacity.svg|thumb|300px|Wavelengths of light blocked by Earth's atmosphere.]]

Sputnik 2 was the first platform capable of making scientific measurements in orbit. This was potentially as significant as the biological payload. The [[Atmosphere of Earth|Earth's atmosphere]] blocks the Sun's X-ray and ultraviolet output from ground observation. Moreover, solar output is unpredictable and fluctuates rapidly, making sub-orbital [[sounding rocket]]s inadequate for the observation task. Thus a satellite is required for long-term, continuous study of the complete solar spectrum.<ref name="SP100">{{cite book |date=1966 |title=Significant Achievements in Solar Physics 1958–1964|publisher=NASA|oclc=860060668}} {{PD-notice}}</ref>{{Rp|5–6, 63–65}}<ref name=NAP>{{cite book|chapter-url=https://www.nap.edu/read/11299/chapter/8#157 |author=Committee on the Navy's Needs in Space for Providing Future Capabilities, Naval Studies Board, Division on Engineering and Physical Sciences, National Research Council of the National Academies|title=The Navy's Needs in Space for Providing Future Capabilities |chapter=Appendix A: Department of the Navy History in Space|page=157|date=2005|access-date=January 6, 2019|publisher=The National Academies Press|archive-url=https://web.archive.org/web/20190107015833/https://www.nap.edu/read/11299/chapter/8#157|archive-date=January 7, 2019|url-status=live|isbn=978-0-309-18120-4|doi=10.17226/11299}} {{PD-notice}}</ref>

Accordingly, Sputnik 2 carried two spectrophotometers, one for measuring solar ultraviolet rays and one for measuring X-rays. These instruments were provided by Professor Sergei Mandelstam of the Lebedev Institute of Physics and installed in the nose cone above the spherical PS. In addition, Sergei Vernov, who had completed a cosmic ray detector (using [[Geiger counter]]s) for Object D, demanded that the instrument his Moscow University team (including Naum Grigoriev, Alexander Chudakov, and Yuri Logachev) had built also be carried on the flight. Korolev agreed, but as there was no more room on the satellite proper, the instrument was mounted on the Blok A and given its own battery and telemetry frequency.<ref name=rsp/>{{rp|30,32}}

Engineering and biological data were transmitted using the Tral_D telemetry system, which would transmit data to Earth for 15 minutes of each orbit.<ref name=nssdcsput2/>