ISEE-3 space craft (mission was to investigate comet) returns to earth

[luc]

I found this to be an interesting story: (_http://www.planetary.org/blogs/emily-lakdawalla/2014/02070836-isee-3.html)

I've periodically reported on the status of the International Sun-Earth Explorer (ISEE-3), a spacecraft that was launched in 1978 to study Earth's magnetosphere and repurposed in 1983 to study two comets. Renamed the International Cometary Explorer (ICE), it has been in a heliocentric orbit since then, traveling just slightly faster than Earth. It's finally catching up to us from behind, and will return to Earth in August. It's still functioning, broadcasting a carrier signal that the Deep Space Network successfully detected in 2008. Twelve of its 13 instruments were working when we last checked on its condition, sometime prior to 1999.

[...]
It's with great sadness that I report today that the Goddard Space Flight Center team has determined that we cannot, in fact, communicate with this spacecraft.

From the official NASA explanation:

The transmitters of the Deep Space Network, the hardware to send signals out to the fleet of NASA spacecraft in deep space, no longer includes the equipment needed to talk to ISEE-3. These old-fashioned transmitters were removed in 1999. Could new transmitters be built? Yes, but it would be at a price no one is willing to spend. And we need to use the DSN because no other network of antennas in the US has the sensitivity to detect and transmit signals to the spacecraft at such a distance.

Further, the article's author states:

I followed up with Leonard Garcia, who has been one of the leaders of the attempt to regain control of ISEE-3, to ask what, in fact, the cost was. He told me that when the Deep Space Network realized what was going to be involved in regaining this capability, they did not even proceed as far as developing a cost estimate; "they decided this wasn't going to be possible."

Now I'm not an expert, but NASA's refusal to communicate with that space craft seems suspicious to me. I mean, it's just radio signals, they sure can receive and transmit these? And whatever protocol is used by the craft, I think it would be relatively easy for an expert to write some software to decode it, especially in today's world of software defined radio and computer technology. Even if I'm wrong and to decode/encode the signals would cost a lot of money - wouldn't it be worth it? Where is the curiosity? This all really doesn't make sense to me.


From Wikipedia about the ISEE-3/ICE:

Second mission: International Cometary Explorer

ICE mission

On June 10, 1982, after completing its original mission, ISEE-3 was repurposed. It was renamed the International Cometary Explorer (ICE). The primary scientific objective of ICE was to study the interaction between the solar wind and a cometary atmosphere. After a successful thruster burn to knock it loose from its halo orbit on September 1 of that year, it used the instability of the Earth/Moon and Earth/Sun Lagrange points, making a series of lunar orbits over the next 15 months. Its last and closest pass over the Moon, on December 22, 1983, was a mere 119.4 km above the moon's surface. By the beginning of 1984, ICE was in heliocentric orbit.

Giacobini-Zinner encounter

After ejection out of the Earth-Moon system, ICE entered a heliocentric orbit ahead of the Earth on a trajectory intercepting that of Comet Giacobini-Zinner. On 11 September 1985, the craft passed through the plasma tail of Comet Giacobini-Zinner. Due to the nature of its original mission, ICE carried no cameras. It instead carried instruments for measurements of energetic particles, waves, plasmas, and fields.

Halley encounter

ICE transited between the Sun and Comet Halley in late March 1986, when other spacecraft (Giotto, Vega 1 and 2, Suisei and Sakigake) were in the vicinity of Comet Halley on their early March comet rendezvous missions (see Halley Armada). ICE flew through the tail and its minimum distance to the comet nucleus was 28 million km[2] (for comparison the Earth's minimum distance to Comet Halley in 1910 was 20.8 million km[3]).
Heliospheric mission

An update to the ICE mission was approved by NASA in 1991. It defines a Heliospheric mission for ICE consisting of investigations of coronal mass ejections in coordination with ground-based observations, continued cosmic ray studies, and the Ulysses probe. By May 1995 ICE was being operated with only a low duty cycle, with some support being provided by the Ulysses project for data analysis.

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On May 5, 1997, NASA ended the ICE mission, and ordered the probe shut down, with only a carrier signal left operating.

_http://en.wikipedia.org/wiki/International_Cometary_Explorer

From the article again:

How could this happen? Well, the fact that ISEE-3 is still broadcasting a carrier signal was actually an error; it should have been shut down. If they had planned for it to still be functioning at this point, they would have maintained the capability to communicate with it. I don't comprehend the intricacies of deep-space communications well enough to understand the obstacles here, and I don't question their conclusion, but that doesn't make me any less sad.