There's always a big flurry of interest when a new spacecraft is launched like
the SpaceX Falcon 9 and the Dragon Crew capsule a few days back but as they say
today's news is tomorrow's chip wrapper so what happens to all the old
spacecraft, do they just hang around up there in space and does the old adage of
what goes up must come down still apply.
We've been putting spacecraft into orbit and beyond since the 4th of October
1957 with the launch of Sputnik so far we've launched over 6500 but that
figure is debatable because it depends on how we count them was Apollo 11 one
spacecraft two or even three but whichever way we look at it that's still
an awful lot of things we've put into space. The vast majority of these are
satellites for communications meteorology and remote sensing the life
of a satellite can range from a few days to decades and really depends upon where
they are placed and how long they can maintain their orbit and age doesn't
necessarily mean that much when it comes to this aspect. Sputnik only stayed
operation for 22 days and in orbit for three months. America's first satellite
launched just after Sputnik Explorer 1 stayed in orbit for over 12 years but a
record for the oldest piece of space hardware still in space goes to the
USA's second satellite Vanguard 1 launched on March 17th 1958 this
grapefruit-sized satellite is still in orbit along with its launcher. It was
the first used solar cells which enabled it to transmit signals from Earth for seven
years although it is now long dead it isn't expected to return to
Earth until 2198 if that remains true it will be a 240
year long orbital lifetime. The reason why Sputnik came down after just three
months and Vanguard is expected to stay there for 240 years his due to the
distance of their orbit from Earth Sputnik was 225 kilometers above the
earth at its lowest orbital point or perigee and his apogee or the farthest
point was 939 kilometers but that was still 500 kilometers lower than where it
should have been. Vanguard on the other hand has a perigee of 657 km
and an Apogee of 3840 kilometers. The father away from you
Earth's atmosphere the longer a satellite can stay in orbit.
Even the ISS is close enough of 403 kilometers to encounter some small
amount of drag from the upper atmosphere and if it weren't for a regular
repositioning it too would end up crashing back to earth. This will be the
ultimate fate for almost everything that's orbiting the earth up to a few
thousand kilometers. Now the surface of the earth is a very large area and even
the biggest satellites like the ISS which is the size of a football field
are very small in comparison and during reentry most of those satellites will
end up burning up in the atmosphere and ending up as ash and dust but that still
leaves the biggest densest parts to fall back to earth and possibly onto
populated areas. So to avoid this an area in the South Pacific is designated as
this spacecraft cemetery the area which is also known as "Point Nemo" or the
Oceanic Point of Inaccessibility and is the farthest point from any land and located
between Easter Island, Pitcairn Island and Antarctica. Over 265 spacecraft are
somewhere in this patch of sea including the International Space Station's
predecessor Mir and six other salyut space stations as well as numerous
transfer and cargo craft used to resupply the ISS. When it comes to
finally decommission the ISS itself what's left of it will end up there too.
But this won't be the fate for the highest satellites in geosynchronous in
geostationary orbits that's things like communications and meteorological
satellites that stay over one place and orbit some 35,786 kilometres above
the earth. There they are too far away to be affected by the atmosphere instead
their orbits are influenced by the gravitational effects of the Earth Moon
and Sun and even by the solar wind and radiation pressure. The life of these
satellites is not determined by their electronic lifetime but by how much
propellant they can carry to power the small thrusters used
to keep them in their allocated positions. Once that fuel runs out their
service life has come to an end even if they are still working perfectly OK
otherwise. Now just as spacecraft that come back to
earth are directed to the spacecraft Cemetery in the Pacific there is a
corresponding place in space where the satellites were just too high to be
brought back to earth safely can be effectively dumped out of a way of other
functional craft. This is known as the graveyard orbit and is about 300
kilometres higher than the geosynchronous one. Just before they run
out of fuel they should be boosted to this higher orbit, now I say should
because not all of them have been moved though since 2002 anyone wanting a
license to operate telecommunication services in the US as to commit to
moving their satellite to the graveyard orbit at the end of its service lifetime.
Once there they will stay out of the way of a functional satellites below. In
theory they could stay there for millions of years but in reality they
will be affected by gravitational forces and even the solar wind so they may well
become a problem at some point in the future but not for the next few thousand
years or so. Some satellites pose more of a problem than others when they come
back those are ones which used nuclear reactors to power their electrical
supply systems. The Soviet Union put 33 small reactor powered radar ocean
reconnaissance satellites into orbit between 1967 and 1988. Although most of
them have ejected their radioactive cores into higher orbit, four have
through various failures come back to earth and spread radioactive material
over Canada's Northwest Territories, the Northern Pacific and the South Atlantic.
Only one U.S. craft were SNAP-10A launched in 1965 used a fission
reactor as a test but due to an electronic failure unrelated to the
nuclear reactor it shut down after just 42 days. Since then it's been in a 1,300
kilometre orbit above the but in 1979 it started shedding at least
50 large traceable pieces, maybe after a collision with other space debris though
it's 1300 kilometer orbit should keep it away from Earth for about
the next 4,000 years or so. Of course there are some spacecraft that have
ended up much farther away and like the earth are now in a heliocentric orbit
around the Sun including solar observatories like Soho and others which
have ended up there by accident. Once in orbit around the Sun they are like any
other small asteroid, they will stay there until they either collide with
something else or they are affected by the gravity of a larger body or planet.
Over millions of years the charged particles from the solar radiation will
gradually break down much of their structure until they break up into
smaller and smaller pieces. In 1959 Pioneer 4 did a lunar flyby passing
60,000 kilometers from the moon before entering an heliocentric orbit and it was
still there as of 1969. The S-IVB third stages of Apollo 8, 9, 10, 11 and 12 have
all ended up in orbit around the Sun as well as the Apollo 10 ascent stage also
known as Snoopy, the only once manned spacecraft still to be in space. Many
others were lost on route to locations like the moon Mars and Venus including
Ranger 3 and Ranger 5, Luna 1, Venera 1, Mars 1, Zond 2, Mars 4, Mars 7,
Phobos 1, Mars Observer, Nozomi, Minvera mini lander and SHIN-EN.
For some a very small corner of a foreign planet will be forever Earth,
these are the probes and Landers primarily sent to Mars but also to Venus
Saturn's moon Titan and to a couple of asteroids. As for the Martian Lander
38 attempts have been made but only 19 of succeeded but for some of those they
have lasted much longer than expected. The Mars rover Opportunity has recently
been pronounced dead fifteen years after it landed, it lost
contact with earth after being hit by a large Martian dust storm. The 15 year
lifespan is all more amazing as it was only ever built to last for three months.
Its twin the Spirit rover lasted over six years before being stuck in a sand
trap which limited its ability to recharge its battery and led to his
eventual demise in 2007. The Curiosity rover landed in 2012 and was expected to
last for two years but has been active now for 6-1/2 years and its
mission has now been extended indefinitely effectively until it ceases
to function which could be many years from now barring an unexpected event. But
the longest-lived craft are those which we have sent to the farthest planets and
beyond. Currently there are five such spacecraft
pioneer 10 and 11 Voyager 1 and 2 and New Horizons. There are also some of the
third stages of the launch vehicles and De-spin weights which were attached to
the probes that were generally traveling in the same direction as the probes
themselves. In deep space the sun's power is too weak for solar cells so all of
these use radioisotope thermoelectric generators basically the heat from a
radioactive source is turned into electrical power for the spacecraft's
electrical systems and depending upon the half-life of a radioactive material
these can last for decades. Eventually though the power from the
radioactive source and the degeneration of the bimetallic thermocouples which
convert the heat into electrical power will drop to a point where they can no
longer power the craft but it's a testament to the quality of these
spacecraft and the electronic components inside made in the 1970s with 1960s
designs in some cases that they are still working in the harsh conditions of
deep space over four decades later. Pioneer 10 launched in 1972 and stopped
transmitting due to a lack of power in 2003, it's currently about 18.1
billion kilometers from Earth and in 12 kilometers a second in the general
direction of the star Aldebaran 68 light-years away. Pioneer 11 launched in
1973 and in 1995 due to a lack of power it was shut down and its antenna moved
away from direction of Earth cutting any further communications. It's now about 15
billion kilometers from Earth traveling at 11.2 kilometers per
second and heading in the direction of the constellation of Scutum.
Voyager 1 launched in 1977 and is still in contact with earth and expected to
carry on until the mid 2020s when it's nuclear generators won't have enough
power to keep it running. It was the first man-made object to reach
interstellar space in August 2012 and is currently 21.6 billion kilometers from
Earth traveling at 16.9 kilometers per second and heading towards a star called
AC 79 388 some 17.6 light-years away. Voyager 2 launched in 1977, 16 days
before Voyager 1 but was on a slower trajectory to Jupiter and Saturn and
then on to Uranus and Neptune. It's expected to continue working until the
mid 2020s it - like Voyager 1 entered interstellar space in November 2018 and
is currently 18 billion kilometers from Earth traveling at 15.3
kilometres per second and heading roughly in the direction of the star
Sirius 8.6 light-years away. And then there's New Horizons launched in January
2006 the newest and fastest of these far-flung Wanderers, though Voyager 1 is
still faster due to be gravitational assist it gained from Jupiter and then
Saturn it's currently 6.8 billion kilometers from Earth and traveling at
about 16.2 kilometers per second providing nothing happens to it New
Horizons should reach interstellar space by 2038 which is also the estimated life
of nuclear power pack. All of these five
spacecraft barring any collision or recovery by us or other intelligent life
at some point in the future will continue out into our galaxy and
although they will be long dead they could quite reasonably be expected to
outlive the human race and even the earth itself not bad for a piece of late
20th century space hardware. So what do you think of the old spacecraft still
floating around out there somewhere let me know in the comments, don't forget to
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