The Conversation
After travelling for nearly 10 years, NASA’s New Horizons spacecraft is finally set to fly past Pluto in humankind’s first close encounter with the dwarf planet.
But the spacecraft is at least a decade old (arguably more like two decades, as spacecraft need to use tried-and-tested components). If it had been built with today’s technology, New Horizons could have been able to send back a lot more data a lot faster. So how do space scientists cope with using old technology to make new discoveries and how will it affect the science they can do?
The search for Pluto began in 1906 when started a project to find a ninth planet. Unfortunately, he died just ten years later, but the search was eventually continued by who found the of the planet on 18 February 1930, when he noticed a that year.
New Horizons is actually carrying aboard, on his request.
Some 60 years after this discovery, a started to work getting a spacecraft to Pluto and its moon Charon. This was being done at a time when we didn’t know about its four additional companions, the moons (discovered in 2005), and Kerberos and Styx (). We also didn’t know that .
were developed, from Pluto 350, which was a small spacecraft with only four instruments, to a large and highly capable spacecraft similar to , which is exploring Saturn and its surroundings. Ultimately these ideas didn’t get beyond the design phase.
But the race was on. By the late 1990s and believed it would freeze onto the surface before 2020 as Pluto moved away from the Sun. So in order to be able to study Pluto’s atmosphere it was important to get something launched quickly. led to the selection of the New Horizons project in November 2001, which launched in January 2006.
Obviously we can continually improve the part on the ground as technology advances. to support and the to the giant planets. But we obviously can’t go and change anything on a spacecraft to Pluto which .
Spacecraft communicate with Earth by transmitting to radio telescopes on Earth. The speed that we can receive images and other data gets slower the further away a spacecraft gets, just like being far from the telephone exchange can mean you get slower broadband at home. If a spacecraft took two minutes to transmit an image from Mars to Earth then it would take more than 10 minutes at Jupiter, 20 minutes at Saturn, and an hour at Pluto! This was a difficult problem that the designers of New Horizons had to overcome.
Generally speaking, higher-frequency microwaves allow us to reduce those times. If you want to map the entire surface of Pluto this is very important. At the birth of the space age, missions such as which flew past Mars in 1964 used “, which is a frequency between 2 and 4 GHz (FM radio is about 100 MHz).
More than a decade later Voyager used the higher frequency “”, between 8 and 12 GHz, allowing to return much more data than Mariner. Most spacecraft still use X-band (including New Horizons) but there is a move to use higher frequencies and NASA launched its first mission using “”, 27-40 GHz, in 2009, just two years after New Horizons was launched.
If New Horizons had been able to use Ka-band it would have potentially been able to return much more data (by a factor of ), or return a similar amount of data more quickly than the year it will take to send back all the measurements made at Pluto (to around three to four months). But this might not have led to such large improvements. The design of spacecraft is not straightforward. One small change in a particular area can affect the entire spacecraft design and mission plan.
As for the actual instruments it is harder to know how things could have been different. The Cassini spacecraft carries a camera known as the which used a telescope that was built as a spare part for Voyager. This is a camera designed in the early 1970s, put on a spacecraft designed in the 1990s, and is still returning amazing scientific images 40 years later that continue to enable us to understand Saturn’s secrets.
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